INVESTIGATION OF TRIBOLOGICAL, AGING AND CORROSION CHARACTERISTIC OF PARTICULATE FILLED HYBRID
A thesis submitted in partial fulfillment of the requirements for the degree of
Master of Technology
VIVEK KUMAR BAJPAI
ROLL NO. 1542240517
Department of Mechanical Engineering Bansal Institute of Engineering & Technology
A. K. T. U Luck now, Uttar Pradesh, India
INVESTIGATION OF TRIBOLOGICAL, AGING AND CORROSION CHARACTERISTIC OF PARTICULATE FILLED HYBRID
A thesis submitted in partial fulfillment of the requirements for the degree of
Master of Technology
VIVEK KUMAR BAJPAI
ROLL NO. 1542240517
Department of Mechanical Engineering Bansal Institute of Engineering & Technology
A. K. T. U Lucknow, Uttar Pradesh, India
This is to certify that the thesis entitled “Investigation of Tribological, aging and corrosion Characteristic of particulate filled Hybrid Composite” Submitted by VIVEK KUMAR BAJPAI (ROLL NO.1542240517) in fulfillment of the requirements for the award of Master of Technology Degree in Mechanical Engineering at the Bansal Institute of Technology, Lucknow is an authentic work carried out by him under my supervision and guidance. To the best of my knowledge, the matter embodied in this report has not been submitted to any other University/ Institute.
Mr. Abdul zabbar
Mechanical Engineering Department
Bansal Institute of Technology, Lucknow
I avail this opportunity to extend my hearty indebtedness to my guide Mr. Adul Zabbar, Dept. of Mechanical Engineering, Bansal Institiute Of Technology, Lucknow for his invaluable guidance, motivation, untiring efforts and meticulous attention at all stages during my course of work.
I express my sincere thanks to Prof. Sudarshan, Head of the Department of Mechanical Engineering, Bansal Institiute of Technology, Luck now for providing me the necessary facilities in the department. I am also grateful to Dr. Ashiwani Kumar & Mr. Hari Kant for his constant concern and encouragement for execution of this work.
I am also thankful to Mr. Ranjan Kumar Behera, Metallurgical & Materials Engineering, for his co-operation in experimental work. I am greatly thankful to all the staff members of the department and all our well-wishers, classmates and friends for their inspiration and help.
Vivek Kumar Bajpai
List of figures 7
Chapter-1. Introduction 10
1.1 Background and Motivation 11
1.2 Objective 13
Chapter-2. Literature Review 14
2.1 Aluminum alloys 15
2.2 Aluminum-Magnesium alloys 15
2.3 Aluminum Metal Matrix Composite (AMC) 16
2.4 Tribology 17
2.5 Wear 18
2.6 Strengthening mechanisms in PRMMCs 21
2.7 Corrosion of Aluminum Alloys 23
2.8 Uses of Aluminum and their alloys 26
Chapter-3. Materials& Methods 27
3.1 Introduction 28
3.2 Fabrication of sample 28
3.3 Wear Test 29
3.4 Stereo Microscope 30
3.5 Profilometer 31
3.6 Aging Test 32
3.7 Corrosion Test 33
Chapter- 4. Results and Discussion 34
4.1 Introduction 35
4.2 Wear Experiment 36
4.3 Microstructure Of Worn Surface 43
4.4 Analysis Of Aging Surface 44
4.4.1 SEM(Scanning Electron Microscopy)analysis 45
4.4.2 XRD(X-Ray Diffraction ) analysis 47
4.5 Corrosion characteristic 50
4.5.2 Analysis of EDX 51
4.5.3 SEM (Scanning Electron Microscopy) Analysis 52
Chapter- 5. Conclusions 55
5.1. Conclusions Summary Of Results 56
5.2.Scope Of Future Work 57
LIST OF FIGURES
Fig. 2.1Mechanism of pitting corrosion of hybrid composite
Fig. 3.1Pin On Disc Tribo-Meter
Fig. 3.2Stereo Microscope Machine
Fig. 3.3Stylus ProfilometerVeeco Dektat, Experiment Set Up
Fig. 3.4(Scanning Electron Microscopy)Machine
Fig. 4.1XRD Pattern of the Al-5% Mg-12%Sic
Fig. 4.2Optical Microscope Structure (Al-5% Mg-12%Sic)
Fig. 4.3Correlation between weight loss and Sliding time of various normal
load rate as 50 N, 60 N,70 N,80 N
Fig. 4.4Correlation between weight loss and normal load conduct in
Fig. 4.5Plot between weight loss and Sliding time of various normal load rate as
50 N,60 N,70 N,80 N
Fig. 4.6Plot between cumulative weight loss and sliding time at various RPM like as 100,200,400, 500 and 600rpm)
Fig. 4.7Graph between cumulative weight loss and sliding speed
Fig. 4.8Graph between surface roughness of the worn sample and applied load
Fig. 4.9Plot between co-efficient of friction and sliding time at different applied
load like as (a) 50N (b) 70N (c) 80N
Fig. 4.10worn surface of the Coupon
Fig. 4.11Optical Image of the worn surface at different applied loads like 50N, 60N,
Fig. 4.12Phase Diagram Of Al-Mg Structure
Fig. 4.13SEM (Scanning Electron Microscopy) image of The composite
specimen at room temperature
Fig. 4.14SEM(Scanning Electron Microscopy) Image of the Al-5% Mg-12%Sic composite specimen solution treated at260 C for 1hr. and aged at four different temperatures showing Micro-vicker’s Hardness (a) 1300C (b) 1600C
Fig. 4.15SEM (Scanning Electron Microscopy) Image of the Al-5% Mg-12%Sic composite specimen solution treated at260 C for 1hr. and aged at four different temperatures showing Micro-vicker’s Hardness (c) 1900C (d) 2400C
Fig. 4.16XRD (X-Ray Diffraction ) analysis of the composite solution treated at 2600C for 1hr. and aged at 1300C
Fig. 4.17XRD (X-Ray Diffraction) analysis of the composite solution treated at 2600C
for 1hr. and aged at 1600C
Fig. 4.18XRD (X-Ray Diffraction ) analysis of the composite solution treated at 2600C
for 1hr. and aged at 1900C
Fig. 4.19XRD (X-Ray Diffraction ) analysis of the composite solution treated at 2600C
for 1hr. and aged at 2400C
Fig. 4.20Plot between Wt. of the corroding specimen and no. of days exposed to sea
Fig. 4.21Analysis of EDX of normal composite sample
Fig. 4.22Analysis of EDX of the corroded sample
Fig. 4.23SEM (Scanning Electron Microscopy) micrograph of normal composite sample
before exposure to sea water
Fig. 4.24 SEM (Scanning Electron Microscopy) micrograph of the composite sample after 1 week exposure to sea water
Fig. 4.25 SEM (Scanning Electron Microscopy) micrograph of the composite sample after 3 weeks exposure to sea water
Fig. 4.26 SEM (Scanning Electron Microscopy) image of the sample kept in sea water after 6 weeks showing pitting corrosion
Fig. 4.27The view of Plot Showing Pitting Corrosion
In the recent Years, the global need for less cost, high performance and excellent quality manufactures has due to a move in research from Monolithic to composite material. In case of MMCs aluminum metal matrix composite due to high strength to weight ratio, low cost and good wear resistance are widely fabricated and used in auto mobile and marine application. In the current research work, the Alumunium – magnesium – silicon carbide composite (Al 5% Mg 12% Sic) were fabricated by using a stir casting techniques and studied for tribological, Aging and corrosion properties. The wear behavior of composite is examined at room condition at four various loads, 50 to 80 N and with varying sliding speed i.e 100, 200, 300, 400, 500, 600, 700 rpm conducting on the pen on disk tribo-meter equipment then the fabricated component was solution treated at a temperature of 250? C for 1 hour and then aged at various temperatures such as 130? C, 160?C, 190?C and to 240?C to study the aging characteristic of the component. The fabricated composite is kept in sea water for 40 days and weight loss was computed in every 8 days to investigate the corrosion characteristic. The steady state test performed on the pin on disk tribometer micro structural characteristic of surface, micro hardness and surface roughness examined as worn surface are also prepared. The aging and corrosion mechanism as of establish with add of XRD analysis and SEM analysis it is investigated that, the addition of silicon carbide to the Al-Mg matrix composite chance the wear resistance and hardness. The dominant corrosion mechanism is investigated to by pitting corrosion phenomenon
Key words: Aging, pitting corrosion, Steady state test.
1.1 Background and Motivation:
The headway of composite materials has transform into a vital turning point in the recorded setting of science and development as it permits the synergizing of clear properties of its fixings, in particular the support stage and the mass matrix stage and stifles the insufficiencies of each of them 1. The composite materials in light of metals and their compounds which are named as metal matrix composites (MMCs) have adjusted wide research wherever all through the world in the midst of the past 20 years as they are found to be appropriate contender materials for fundamental and mechanical applications in aviation segment, marine segment, protection area and general building applications. The amazing limit of MMCs to unite the support (for the most part ceramic material) properties (high caliber and adaptable modulus) with that of the metallic stage (high adaptability and sturdiness) influences them to fit for bearing higher weight and shear loadings besides sustainability at raised temperatures 2,3. The utilization of aluminum based MMCs (AMCs) is extending in an assortment of businesses of business esteems as they give phenomenal purposes of enthusiasm over customary strong materials with respect to more firmness and particular quality, improved high temperature wear protection limits, adjustable coefficient of warm augmentation (CTE) and protection from warm weariness. The applications of AMCs incorporates outfits and braking system in automobiles, fuel get to entryway covers and ventral blades in automobiles, golf club shafts, bike outlines, track shoes in military tanks, flywheels, ice hockey sticks, Cryostats, rocket turbine lodging, rocket nose tips, and so forth 4-6. AMCs with fortification as particles are getting importance as a result of their isotropic properties when contrasted and fiber and stubble fortifications which show anisotropic mechanical properties. These particulates fortified metal matrix composites (PRMMCs) indicate high quality, hardness, and wear and erosion protection 4, 7. They have transcendent plastic confining potential than fiber and stubble strengthened composites which along these lines diminishes their as SEM (Scanning Electron Microscopy) billing cost. The properties of PRMMCs depend on the size and properties of the fortifying particles, inter-particle dispersing, and particle-matrix interface condition and shape and volume division of the particle 1.PRMMCs can be created through an assortment of as SEM (Scanning Electron Microscopy) bling courses, for example, powder metallurgy, dispersion holding (strong state preparing), mix throwing, soften infiltration, spray testimony (fluid state handling) and in-situ handling procedures 8. The powder metallurgy course is the most supported course of creation for PRMMCs since it holds the upside of limiting harmful response between the metal and the ceramic fortification stage amid preparing. Furthermore, the impact of segregation and the propensity to arrangement of inter-metallic stages is decreased in powder metallurgy handling when appeared differently in relation to getting ready in fluid state 1, 9.
The mechanical and physical properties of aluminum-magnesium based metal matrix composites (MMCs) have made themselves engaging for auto, space, marine and aviation applications. Diverse exploratory techniques are used to create such MMCS, which consolidate distinctive schedules to make profitable outlining shapes, for instance, super-plastic transformations, and these might be used to convey crucial Metal Matrix Composite ace alloys, for instance, powder preparing alloys or liquefy infiltration. In light of the many-sided quality of a portion of alternate procedures, the last two techniques are the most comprehensively used, and the necessity for new as SEM (Scanning Electron Microscopy) bling offices in some unique cases. A modest test strategy in light of the blending procedure has been proposed, that can convey composites by traditional aluminum throwing and foundry rehearses 10. Regardless, the nonattendance of wettability between most ceramic particles and the fluid aluminum and most ceramic particles is the prime inconvenience of the blending methodology, which makes only composites with a low wt. % up to 5% ceramic particles. The increments of SiC particles to Al_4% Cu refines its smaller scale structure and enhances the versatile modulus and yield strength, while the malleability and extreme tensile strength are diminished. Diminishing the wetting edge between SiC particles and fluid Al has handled this issue by an uncommon treatment. Al_4% Cu strengthened with unmistakable weight percents of SiC particles, running from 0 to 30 wt. %, have been attempted and made 11.
The Tribological or wear properties of the Al– Mg– Cu mixes were on a very basic level upgraded by the expansion of SiC particles; nevertheless, wear and abrasion protection of the composites was significantly higher than that of the unreinforced aluminum and Al-Mg alloys. The connected load was for the most part conveyed by SiC hastens which oppose abrasion impacts. The expansion of SiC particles made a huge difference in wear and corrosion protection of Al– 4wt%Mg– Cu mixes. The region of SiC in Tribo- film between two surfaces in contact realizes three-body abrasion and wears system which expanded the coefficient of friction 10.
Objectives of the present work:
To examine the wear conduct of the Al-5% Mg-12%Sic composite specimen fluctuating different parameters like:(a) Time (b) Applied load (c) Sliding speed (d) Sliding distance (e) Surface roughness
To examine the states of different parameters that can diminish co-proficient of friction and wear and enhance the mechanical procedures of the composite.
To enhance the hardness of the composite and decrease wear by the age solidifying instrument by finding a legitimate maturing temperature.
To ponder the corrosion characteristic and to discover the corrosion instrument in charge of the corrosion happening when the composite is presented to ocean water.
To explore the new development over previous research can be obtained by provide back ground information of different issues obtained/occur in particular topic. These gaps between the researches emphasize to focus on the particular points which are considered as base of present research work. This chapter summarizes various issues encountered on material for over a period of decade on wear phenomena aging and corrosion characterization of hybrid composites. The literature briefly outlined all the relevant topics; to enhance above mentioned properties; there is a need of stringent research for engineering applications. Following section deals with literature review on:
The aluminum alloys are depicted in following point as:
Aluminum (Al) is the second most ample component on earth.
Studies demonstrate that 10% weight lessening rises to 5.5% development in efficiency.
The developing interest to decrease vitality utilization, asset exhaustion, air contamination and race to monetary development has prompted the exploitation of Aluminum and its alloys.
Properties of Aluminum alloys 12:
The properties of aluminum alloy are listed in below:
Aluminum alloys display high strength to weight proportions.
Al-alloys cover an extensive variety of estimations of strength, going from 10 Nmm-2 for versatile breaking point of unadulterated Al to 500 N mm-2 for 7000 arrangement alloys
Aluminum alloys are adequately malleable to be utilized as a part of auxiliary applications.
These alloys don’t lose strength at low temperatures; in reality Al-Mg alloys demonstrate increment in their strength at low temperatures.
They are corrosion-safe and have great weld ability.
They display high tensile strength.
Numerous Al alloys created give strength, wear protection and hardness at hoisted temperatures.
Aluminum hasseveralseries in its terminology based on components, it alloys with. For example, 3XXX for alloying with manganese, 5XXX for alloying with magnesium and 6XXX for alloying with magnesium and silicon.
Advantages of magnesium additions to Aluminum:
Magnesium has 66% the heaviness of Aluminum, in this way expansion of Magnesium to Aluminum prompts diminish in the thickness of the compound.
Magnesium has higher particular strength than Aluminum. Along these lines the expansion of Magnesium brings about expanded strength of combination when contrasted with Aluminum.
Magnesium expansion prompts an expansion in the strength to weight proportion. Subsequently the alloys are more reasonable for vehicle and air ship parts as it expands the fuel productivity.
Addition of magnesium to aluminum brings about precipitation and age solidifying of combination. Along these lines the strength is altogether expanded.
The most critical preferred standpoint of Magnesium expansion is that it enhances the wetta-bility of strong ceramic support in Aluminum metal matrix composites.
Better wett-ability would bring about more homogeneous appropriation of support particles in the matrix.
Magnesium additionally enhances the formability and cast-ability of aluminum.
2.3 Aluminum Metal Matrix Composite (AMC):
Aluminum based Metal matrix composites (AMCs) suggest the class of predominant lightweight aluminum driven material systems. The support particles in AMCs could be as bristle or particulates, persistent or irregular fibers, in volume and weight fractions going from a couple of percent to 60%. Properties of AMCs can be uniquely crafted to the solicitations of particular current applications by reasonable blends of support, matrix and processing course 15.
Advantages of AMC:
More prominent strength
Diminished density (weight)
Controlled thermal extension coefficient
Enhanced high temperature properties
Improved and customized electrical execution
Enhanced damping abilities.
Enhanced abrasion and wear protection
Control of mass (particularly in responding applications)
Advantages of SiC addition:
SiC is extraordinary compared to other generally utilized ceramic fortifications in Aluminum metal matrix composites
SiC have high corrosion protection, high thermal conductivity, low thermal extension coefficient, high hardness and great obstinate properties.
The expansion of SiC to aluminum enhances its strength and other thermal and mechanical properties.
SiC enhances strength of the composite and the raised temperature hardness.
Tribology classification is gotten from a Greek word “tribos” implies rubbing. Tribology or wear is the science and innovation of interfacing or contact surfaces in relative movement and the practices related thereto; their outline, friction, grease and wear 16.
The economic aspect of Tribology:
It has been evaluated that 30% of the vitality created in the mechanical parts of the world is expended at last in friction forms.
In profoundly industrialized nations like England, Japan or the republic of Germany, some $2,000 million for each annum are lost because of wear forms.
Regardless of the possibility that these figures are taken as unpleasant assessments, they unmistakably demonstrate the significance of tTribology for protection of vitality and materials 17.
Importance of Tribological studies:
Tribological portrayal is, in like manner, basic for expanding material life and execution. Particularly in the fields of aviation, car and tooling, where disappointments from contact and wear can be catastrophic.
Tribology is fundamental in cutting edge equipment in which sliding and moving between surfaces happen.
In automobiles, brakes, bolts, nuts, clutches, tires and so on. Friction is utilized as a profitable friction. Useless wear and friction happens in profitable vehicle parts like motors, cams, gears, direction and so forth.
Friction and wear cost a lot of cash as vitality misfortune and material misfortune. It prompts lessen in national proficiency. Decreasing in wear and friction can incite individual fulfillment. Accordingly, Tribology data is basic and gigantic for capital sparing.
Thus this particular composite has been inspected for Tribological properties 17.
Wear is the mischief caused by a material surface due to the relative development with other achieving surfaces which generally brings about pointless material mishaps. Wear can realize expulsion of material from either or both the achieving surfaces. Wear is described as “the harm to a solid surface, for the most part including the dynamic loss of material, due to relative development between two moving surfaces 18. Be that as it may, for engineering perspectives, wear can be described in the going with ways:
Wear is damage to the material surface which realizes “loss of material” from the surfaces. Beside material misfortunes, Wear has alternate points of view to it.
As wear suggests the mischief to the achieving surfaces, wear can be insinuated “the development of material” at first look, paying little respect to the way that it does exclude material misfortune from the surface.
A third piece of wear which consolidates the damage to the surface, yet not material misfortune or dimensional changes. A sign of this strategy for wear might be by the advancement of different systems of breaks at first look. This mode gets the chance to be vital with optically straightforward materials. Thusly wear is the mischief to the material surface which negatively impacts the life and execution of the part.
2.5.1 Types of Wear
Wear can be grouped into various sorts in the event that it happens in dry or greased up conditions or sorts of wearing contacts. Dry friction, which is the essential worry without greases or dry condition, is characterized as the friction under not deliberately greased up conditions. In any case, it is outstanding that it is friction under oil by barometrical gasses, particularly by oxygen 19.
On the premise of kind of wearing contacts, wear is either:
Single-stage wears where one strong causes material expulsion from the sliding surface against which it is in relative movement.
Multi-stage wear, where wear, from a strong, gas or fluid goes about as a transporter for an auxiliary stage that truly creates the wear.
A principal technique for ordering wear was first sketched out by Burwell and Strang 20. Later Burwell 21 altered the arrangement to incorporate five unmistakable sorts of wear, namely (a) Abrasive (b) Erosive (c) Adhesive (d) Corrosive (e) Surface fatigue
18.104.22.168 ABRASIVE WEAR:
Most machine parts and sliding surfaces all around encounter grinding wear. Grating wear happens when a hard surface slides or rubs against a milder surface. As showed by ASTM, unpleasant wear happens as a result of the hard particles or projections that are constrained to move along the milder surface. Hard particles or severities on the harder surface cut or wrinkle the gentler surface realizing rough wear. The hard particles can be accessible on one of the sliding surfaces, or may have begun from them two. In sliding wear, the cranky attitudes on the harder surface make the wear. Occasionally wear pieces torn from the surfaces get again and again plastically twisted and work hardened and even oxidized and get the chance to be harder than both of the achieving surfaces, as needs be realizing rough wear of both the surfaces. The dissolved particles may similarly be exhibited from outside like soil from outside the system. There are assorted instruments of wear which work in the midst of the harsh wear, achieving clearing of material. These systems are: (a) Fatigue (b) fracture and (c) melting. The methodology of abrasion is mind boggling and in like manner is a blend of the impressive number of systems working in the meantime. The abrasion procedure incorporates furrowing, cutting, wedge development, miniaturized scale weariness and smaller scale breaking.
22.214.171.124 ADHESIVE WEAR:
Adhesive wear happens when two surfaces are in close contact with each other. In Adhesive wear, a limited holding occurs between the solid surfaces in contact, which achieves the trading of material beginning with one surface then onto the following or loss of material from both the surfaces. At any rate, this wear obliges an adjacent contact between the conveying solid surfaces. Adhesive wear achieves game plan of seizures, repulsive and torn surfaces.
126.96.36.199 SURFACE FATIGUE WEAR:
Fatigue is the disappointment caused by dynamic loading. Rehashed loading can achieve wear also. Along these lines the surface wear which is a direct result of break rising up out of material exhaustion is portrayed as surface shortcoming wear. A system of micro cracks is framed underneath the material surface because of the dynamic loading. Exactly when these parts are subjected to cycles of rehashed loading and unloading, they spread. In the wake of achieving the basic size, these subsurface micro cracks develop quickly and rise at the surface, in this manner bringing about evacuation of level sheets of disengaged particles. The nearness of the very much utilized out surface joins sharp and precise edges around the pits surrounded.
188.8.131.52 COROSSIVE WEAR:
Corrosion is the debent SEM (Scanning Electron Microscopy) of a material as a result of some physiochemical reactions with the incorporating condition. Destructive wear might be portrayed as the dynamic debilitating of an unprotected metal surface on account of correspondences with the incorporating media, like salts, acids and gasses. Thin movies are framed on the material surface in light of particular tribo-chemical reactions. Metals generally react with oxygen to shape oxides. These oxides shape a layer over the metal and may realize the improvement of layers of scales at first look, as the interfacial bond in low with the fundamental metal or composite. The surface includes offensive pits, torments, and openings. Destructive wear is risky as it might realize finish breaking down of the metal.
184.108.40.206 EROSION WEAR:
Erosive wear can be portrayed as metal expulsion in light of impingement of solid particles on the material surface. The strong particles which affect the surface are at some speed and along these lines have momentum and kinetic energy. On striking the surface the particles disinate SEM (Scanning Electron Microscopy) their momentum and energy to the material surface realizing the evacuation of material and arrangement of notches. Disintegration might be achieved by solid particles or even by a gas or a liquid, which could pass on solid particles, impinging on a surface. The impact of the erodent makes the wear happen. Disintegration wear achieves basic damage to assistant materials if there ought to be an event of sand blasting or in pipelines conveying slurry and in this manner ought to be dealt with.
2.6 Strengthening mechanisms in PRMMCs:
Indeed, even with utilizing particles which have unrivaled properties, it isn’t conceivable to viably exchange the heap from the matrix to it through the interface. Along these lines, for clarifying the strengthening of MMCs because of particle incorporation, a basic idea in view of stress exchange systems can’t be exclusively utilized.
1. Strain hardening
The sensational increment in the quantity of dislocation-dislocation communications encourages strain solidifying which decreases dislocation mobility. Thus, bigger anxieties are required for facilitate twisting to occur. In this manner, it expands the strength and hardness of the composites. The variety of strength of metal gems as a component of dislocation density is appeared in the figure beneath.
2. Grain boundary strengthening
This strengthening happens when the grain boundary works as a hindrance to the movement of float dislocations. In PRMMCs, the particles hinder the grain development of the matrix by binding of dislocations at the grain limits. So grain refinement happens which improves both the strength and sturdiness of the composite.
3. Solid solution strengthening
The limitation of dislocation development because of the nearness of solute particles constitutes strong arrangement strengthening which for the most part happens in matrix alloys. Connection happens between the strain fields of the solute particles and the dislocations show in the lattice.
4. Precipitation hardening
Encourages nucleate in the matrix combination when the solute fixation surpasses as far as possible, these accelerates block the dislocation movement and hence strengthen the composite. The nucleation and development of these encourages rely upon the solutionizing temperature, cooling rate and the maturing kinetics.
5. Dispersion strengthening
The particles go about as a boundary to the dislocation movement and encourage circling of the dislocation around them. This is known as orowan bowing mechanism. Once a dislocation goes through the particles, remaining loops of dislocations are conformed to every particle.
Orowan strengthening is given by Gb/l, where G is the modulus of inflexibility of the matrix; b is the Burgers vector, and l the particle dispersing.
Age hardening or maturing process, is a warmth treatment process used to expand the high temperature strength or yield strength of pliable or pliable materials, including most auxiliary and crucial alloys of aluminum, magnesium, titanium, nickel and numerous stainless steels. The vital necessities of age hardening are second stage particles. These particles annoy or disavow the development of dislocations all through the whole lattice. You can make sense of if second stage particles will accelerate into arrangement or not from the solidus line on the stage chart for the optional particles. Physically, such strengthening mechanism can be attributed both to modulus and size effects, and to surface or interfacial energy. The region of hard second stage particles frequently causes lattice bends. These lattice mutilations give result when the hasten particles differentiate from the host atoms in size and crystallographic structure. Greater encourage particles prompts a compressive uneasiness while littler accelerate in a host lattice that prompts a tensile anxiety. Dislocation abandons introduce similarly influence a worry to field. Over the dislocation there is a high compressive anxiety show and underneath there is a high tensile anxiety.
Different Aging Techniques:
Maturing of a material, in which room temperature is taken as maturing temperature, is alluded as characteristic maturing.
Simulated maturing of a metal matrix composite (MMC) is the warmth treatment at raised temperatures in order to get the adjustments in the concoction and mechanical properties of a compound because of the moving, producing and casting process. For the most part, the physical and substance properties of recently rolled, forged and cast metals falsely change and settle gradually at room temperature. Fake maturing will quicken such changes all the more quickly at raised temperatures. This procedure confirms exactness and quality in close resistance particulars. It additionally helps organizations and makers influence the machine-to prepared parts accessible all the more rapidly to mechanical engineers and merchants.
2.7 Corrosion of Aluminum Alloys:
Various boat superstructures and liquid load holders are made of aluminum as a result of its low weight and commendable quality. The most understood aluminum alloys for use in destructive circumstances, for instance, seawater are the 5xxx and 6xxx game plan composites, which demonstrate adequate quality and astonishing corrosion protection. This game plan is extremely appropriate in various marine structures, apparatus and port structures. Combination 6063 is a warmth treatable aluminum-magnesium-silicon composite. It gives awesome mix of extrude ability and mechanical properties. It furthermore responds well to tidying substance illuminating, anodizing and shading 22. Ship payload compartments are displayed to sea condition. Not only the outside of the heap compartments are exhibited to destructive condition, the internal compartments are in like manner displayed to destructive liquid media. Marine corrosion is an enduring issue to move vessel and in addition ports and anything kept in the sea or displayed to the sea condition for a period of time.
Corrosion is a basic procedure which accepts a fundamental part in monetary issues and security. The term ‘aqueous corrosion’ portrays the greater part of the most troublesome issues experienced when metal material is in contact with sea water. Diverse strategies have been used to diminish corrosion. A couple of strategies and systems have been delivered to battle corrosion productivity are reliably being searched for after, as an outcome of outrageous sum spent on corrosion consistently. The usage of inhibitor for the control of corrosion of shore and toward the ocean metal and mixes which are in contact with the mighty marine condition is a recognized practice 23.
Benzoate blends offer intriguing possible results for corrosion limitation and are particularly vital because of their secured usage and high dissolvability in water. Corrosion inhibitors give off an impression of being engaging in perspective of their negligible exertion and basic dealing with appeared differently in relation to other preventive methodologies. Customarily inhibitors are generally chemicals that collaborate with a metallic surface, or the condition this surface is revealed, giving the surface a specific level of protection. Inhibitors consistently work by adsorbing themselves on the metal surface by surrounding a film and diminishing corrosion. Obviously, corrosion can’t be avoided; however its reality can be diminished to a lower significance. Aluminum and its compounds are separated into two wide classes, castings and formed or mechanically worked things. The current is subdivided into warm treatable and non-warm treatable blends, and into various structures conveyed by mechanical working. The corrosion protection of metal aluminum is subordinate upon a guarded oxide film. This film is steady in liquid media when the pH is between around 4.0 and 8.5. The oxide film is typically self-reviving and accidental scratched spot or other mechanical damage of the surface film is immediately repaired.
Different change coatings have been made with their essential reason not simply being the protection of aluminum from utilization also the difference in paint hold. A standout among the most comprehensively used pretreatments in the aerodynamic exchange is the chromium (VI) based Alodine1300S offered by Henkel. It gives a twofold limit of going about as an against damaging layer and improving the hold of paints and bonds. Grilli et al. 6 have reported that the failure of a lap shear joint gathered from an Alodine secured substrate of 6xxx composite and an epoxy stick is essentially official in the concrete stage. Additionally, Alodine1300S is steady more than a broad assortment of pH, and gives the substrate a low surface electrical protection, this being an indispensable segment for flight applications 24.
2.7.1 Pitting corrosion:
There are a lot of various sorts of corrosion; however the most standard sort in the aluminum-water system, at room temperature, is the setting corrosion. The procedure can be partitioned into the two stages, viz., start organize and the spread stage. In the underlying stage the setting is started by anions, similar to chloride that enters into the oxide layer. The pits are limited in neighborhood contortions and cracks of the latent film or where the aloof film is debilitated because of imperfections or heterogeneous particulates, for example, Al3 Fe inter-metallic.
742952155161In the proliferation arrange (Fig. 2.1) aluminum oxidizes into aluminum particles at the base of the pit. A diminishment of either hydrogen or water occurs in contact with the construct metal in light of a position outside of the pit. With the lessening response the pH on the outlet of the pit will gradually increment to give an antacid pH. The aluminum particle will outline a film of aluminum chloride or aluminum oxy-chloride in the pit and settle it. Before long the aluminum chloride will hydrolyze into Aluminum hydroxide. This prompts a decreasing in the pH worth to a more acidic condition, which fabricates the corrosion rate within the pit. Aluminum hydroxide quickens at the edge of the pit and spreads the opening, which consistently impedes trade of particles and back off the corrosion procedure.
FIG. 2.1 Mechanism of pitting corrosion of hybrid composite
2.8 Uses of Aluminum and their alloys:
Aluminum is a perfect metal to supplant heavier metals in autos inferable from its trademark properties like great formability, corrosion protection, high strength, high stiffness to weight ratio, and reusing properties.
It is utilized as a part of energy prepare, frame body structure and aerating and cooling. Created aluminum is picking up its motivation in warm shields, bumper fortifications, air-sack lodgings, pneumatic systems and seat outlines.
The high strength to weight ratio is the prime purpose behind its utilization in the car area as it prompts less fuel utilization.
Aluminum-Magnesium alloys are utilized as a part of plate brakes, forged wheels which encounter outrageous loading conditions 13.
2.8.2 Aircraft Industry:
Aluminum, alloys with various component and discovers its application in high working temperature and additionally in the low temperature district of profoundly stacked parts with high resistance to corrosion under anxiety.
2.8.3 Space equipment:
High estimations of particular strength and its high inflexibility gives high longitudinal stability, which empowers it to be utilized as a part of tanks, inward tank and packaging of the rocket.
Light weight and corrosion resistance settles on it a perfect decision for its utilization in auxiliary applications.
The expulsion creation process causes it conceivable to expand the geometrical property of the whole cross-area by outlining a shape that at the same time gives the least weight and the most basic proficiency.
It is anything but difficult to get hardened shapes without utilizing developed areas, in this way abstaining from welding or shooting.
Daintiness encourages it simple to have less difficult erection, transport of completely created parts and decrease of the heap transmitted to establishments.
Al-Mg alloys are utilized as a part of electrical contact resistors 14.
Aluminum additionally is utilized for bundling, in holders (refreshment jars).
Aluminum is additionally utilized as a part of cryogen conditions in contact with fluid H2O, H2 and He.
MATERIALS AND METHOD
This section manages the points of interest of the trial methods followed in this investigation.
An Aluminum-3%Magnesium-10% silicon carbide composite square of dimension 100mm x 100mm x 30mm is set up by blend casting course in an enlistment warming heater. Three round and hollow examples of diameter 10mm and a stature of 30 mm were cut from the square utilizing a very aligned machine for the Wear Experiment. Wear conduct of these examples was contemplated by directing a few Wear Experiments on mechanized Ducom friction and wear screen stick on-plate Wear Experiment machine. The micro structures of the harmed/worn specimens and the break morphology of the surfaces were seen under Stereoscope. Profilometric examines were done to consider the surface unpleasantness. At that point five examples were cut from the primary specimen for the maturing treatment. The composite was arrangement treated at a temperature of260 C for 1hr and then matured at four unique temperatures viz. 130 C, 160 C, 190 C, and 240 C to examine the maturing conduct of the composite. The micro hardness was measured with the Microvicker’s hardness testing machine. At that point SEM(Scanning Electron Microscopy) and XRD(X-RAY DEFFRACTION PATTERN ANALYSIS investigation is done to get the subtle elements of the stages exhibit. A cut of the composite specimen is kept in ocean water for a month and a half (42 days) and the weight loss was measured with the assistance of an electronic measuring machine in each 7 days to examine the corrosion conduct. At that point the SEM (Scanning Electron Microscopy) examination is done to get the corrosion mechanism. The accompanying gives a nitty gritty outline of the means taken for various tests.
3.2 Sample Preparation:
The Al-3Mg-10SiC composite has been manufactured by utilizing blend casting method. An altered blend casting system for preparation of the Al-Mg composite is outlined utilizing minimal effort scrap Mg, utilizing a plunger for making the amalgam expansion. A gentle steel cylinder holder is covered with aluminum and used to hold the aluminum liquefies. An empty shaft which has its stirrer sharp edges joined to engine and V-belt course of action for better mixing. The plunger bar is appended to punctured case which holds the magnesium. Aluminum pieces are softened in the pot at temperature of 800oC and blended at 500 rpm. Magnesium turnings are included in a steady progression through the empty axle. The magnesium is discharged after the aluminum thwart covering liquefies and the Mg breaks up in 15 seconds. At that point the fortification SiC particles are included the comparable way. The liquefy is filled shape and cooled. At that point tests of the required dimensions are cut for the wear and different tests.
3.3 Wear Experiment:
A pin on disk Wear Experiment machine with a Computerized Ducom friction and wear screen (Model: DUCOM Wear and Friction co-productive Monitor, TR-20-M100, Bangalore, India) is utilized the for the Wear Experimenting.
Fig. 3.1 Pin On Disc Tribology Equipment
The test is finished by turning a counter-confront test disk against a stationary test example pin.
The disk, which turns is made of high carbon, extinguished and tempered steel of diameter 130 mm and hardness of 70 HRC.
The Al-5% Mg-12%Sic examples were held stationary in the specimen holder and the typical load is connected through a lever mechanism.
An electronic measuring balance having a precision level of 0.1 mg is utilized to quantify the weight loss of the example.
No grease is utilized as test is done in dry conditions.
The examples were weighed at customary interims to quantify weight loss.
It was under cautious examination that the examples wearing in the test are routinely cleaned with woolen material in order to evade the trapping of wear flotsam and jetsam and to accomplish consistency in experiential methodology.
The tests were finished by differing one among the beneath said parameters and keeping alternate parameters constants:
time (b) applied load (c) sliding speed (d) sliding distance
Stereo microscope was used to analyze the crack morphology of the worn surfaces of sample.
3.4 Stereo Microscope:
The stereo microscope is a kind of optical microscope and does not utilizes transmitted light rather utilizes light reflected from the surface of a protest. The instrument utilizes two distinctive optical ways with various target and eyepieces to give diverse points to one side and left eyes. This course of action gives a 3-D perception of the example being tried. The contrast between the light microscope and stereo microscope is that stereo microscope utilizes reflected light though light microscope utilizes transmitted. The thought about light permits experimentation examples that would some way or another be excessively murky or too thick for microscopy.
Fig. 3.2 Stereo Microscope Machine
At that point the Profilometer was utilized to break down the harshness of the ragged surfaces of the specimen.
Profilometer is utilized to think about surface harshness of the well used examples. An enhanced plot of the surface profile was created with some normal parameters, for example, Ra.
Fig. 3.3 Stylus Profilometer Veeco Dektat, Electrometallugy
Stylus Profilometer is fundamentally utilized as a part of ventures and research work to gauge surface wrap up. The Profilometer have been being used in research and ventures for quite a while. Initially an opened up plot of the surface profile was created with some normal parameters, for example, Ra. These parameters were acquired by methods for a reasonable meter and a basic electronic circuit. Before the finish of 1970 computerized PCs were included, and the information acquisition system altered. Huge assortments of information were acquired upon digitization.
A standout amongst the most fundamental part in stylus Profilo-meter is the stylus, a tip which really touches the surface and goes about as a sensor. It acts in the same as skin, eyes, and so on as an interface between the external condition and the mind. Stylus tip material, shape, size and power are the important parameters for this situation.
The interface between the stylus and the inward electronics is known as gage in specialized terms. Gage contains some vital electronics that control the following power and sends a criticism because of any adjustments in unpleasantness that encourages the stylus tip to move over the surface without harming itself. The gage gives a yield that opens up and demodulates the electronic signals. It at that point changes over the computerized flag to client understandable dialect and stores the outcome for investigation.
3.6 Aging Test:
The composite specimens were cleaned and arrangement treated at a temperature of260ºC for a hour in the Pit Furnace (fig. 3.4) . They were then water extinguished at room temperature. This was trailed by maturing the extinguished composites at 130ºC, 160ºC, 190ºC and 240ºC for a hour. The maturing conduct of the composite was examined utilizing SEM (Scanning Electron Microscopy) pictures and Microvicker’s micro-hardness estimation. Every hardness value was the normal of no less than three estimations. The stages framed were additionally investigated utilizing XRD (X-RAY DEFFRACTION PATTERN ANALYSIS examination.
Fig. 3.4 Pit Furnace machine in Metallurgical and Materials Engineering Department
3.7 Corrosion Test:
The composite example is kept in ocean water for a month and a half (42 days) and the weight loss was measured with the assistance of an electronic measuring machine in each 7 days to contemplate the corrosion conduct. The corrosion mechanism was examined in various time interims utilizing a Scanning Electron Microscope (SEM(Scanning Electron Microscopy)) machine (fig. 3.5).
Fig. 3.5 Scanning Electron Microscope SEM (Scanning Electron Microscopy)) machine
RESULTS AND DISCUSSION
First the XRD (X-RAY DEFFRACTION PATTERN ANALYSIS) of the sample is done to identify the phases present in the Al-5% Mg-12%Sic composite sample at room temperature.
Fig. 4.1 XRD Pattern of TheAl-5% Mg-12%Sic
Fig. 4.2 Optical Microscope Structure (Al-5% Mg-12%Sic) at magnification of 10X
Then the sample is polished and the microstructure is observed in an optical microscope and SEM (Scanning Electron Microscopy) to identify the phases.
4.2 Wear Experiment:
4.2.1 Correlation between weight loss and sliding time of various normal loads
The Figure 4.3 shows the correlation between sliding time and cumulative weight loss at various loads such as 50N, 60N, 70N and 80N and with different sliding speeds such as 100,200, 300, 400, 500,600 and 700 rpms, conducting on a pin on disk Tribo-meter machine. The mass loss was computed using weighing equipment. The track diameter was fixed at 90mm. The wear loss increases with increase in sliding speed .it is observed that the minimum loss at minimum sliding time and higher loss at higher sliding time. It is mainly attributed that the higher loss due to the coefficient friction is increased at higher sliding time. It is another region that the interaction between filler and matrix is very poor, so that the it is found that maximum weight loss. The Figure shows the variation in wear with sliding time at four different applied loads.
Fig. 4.3 Correlation between weight loss and Sliding time of various normal load rate as (50 N,60 N,70 N,80 N)
4.2.2 Correlation between weight loss and normal load conduct in Tribological Test Experiment
The Figure 4.4 and 4.5 depicts the correlation between the weight loss and normal load at various loads such like 50N, 60N, 70N. 80N as usually the sliding time increases wt. of the sample decreases constantly which increases the cumulative wt. loss. But decreases higher sliding time wear rate. At first the surface shows as rough, so the sliding movement occurs in a small areas at the peaks and time to time the peaks break and the contact area is enhanced. So the flattening of the surface observes which effect is the co-efficient of friction decreases and wear is also decreases at the higher sliding time. Thus sliding over a longer duration of time leads to metal loss and decease in wear. As increases of load, because of increased pressure and temperature, deeper grooves are created. So, weight loss is higher leading to higher wear at higher loads.
Fig.4.4 Correlation between weight loss and normal load conduct in Tribological Test Experiment
But as the normal load enhance the rate of wt. loss decreases, leading to lower wear rate. The grooves become smooth and in dry condition, because at higher loads which can be observed from the Optical Image of the worn surface. So the co-efficient of friction is directly Proportion to wear rate. When co-efficient of friction decreases then wear rate also decreases.
4.2.3 Relation between cumulative weight loss and sliding distance at various applied loads
The Figure. 4.6 and 4.7 show the plot between cumulative weight loss and sliding distance at various applied loads such 50N, 60N, 70N. 80N as the sliding speed and sliding distance increases, so the value of wear increases, but the decreases wear rate at higher sliding Speed and sliding distance. The hardening occurs of the surface layer composition of the waste debris Because of sliding over longer distances and at higher sliding speeds and it reduces the wear rate also.
Fig. 4.5 Plot between cumulative weight loss and sliding distance at various applied loads such 50N, 60N, 70N. 80N
Fig. 4.6 Plot between cumulative weight loss and sliding time at different rpms like 100,
200, 300, 400,500, 600, 70
Sliding Speed are inversely proportional to surface roughness so Higher sliding speed leads to decrease in surface roughness, the co-efficient of friction decreases by a small quantity of wear debris and Decrement of surface roughness. So the wear rate decreases at higher sliding speeds.
Fig. 4.7 Graph between cumulative weight loss and sliding speed
Fig. 4.8 Graph between surface roughness of the worn sample and applied load
4.2.4 Correlation between surface roughness of the worn sample and applied load
The Figure 4.8 shows the correlation between surface roughness of the worn sample and applied load. It is observed that Profilo-meteris a device using as surface roughness measurement and the Plot draw between Ra value and varying applied load. The increase in load spark the higher surface temperature it cause the gradual flattening of the protrusions, resulting higher slide speed in steady state at high temperature, which decrease the surface roughness ,decreases the co-efficient of friction, as well as the shear force.
4.3.1 Co-efficient of friction vs wear
The Figure 4.9 shows the correlation between coefficient of friction and sliding time at various load such as 50-80N. In starting, the surface is rough, so the sliding movement takes place in small areas at the top point and time to time the top points break and the enlargement contact area. So the flattening of the surface ensure, which take place to decrease in the co-efficient of friction.
Fig. 4.9 Plot between co-efficient of friction and sliding time at different normal loads like (a) 50N (b) 70N (c) 80N
4.3 Microstructure of Worn Surface:
The Figure shows the micro-structure of worn surface. The surface of the worn sample is observed by using the optical microscope machine.The sliding direction shown by arrow.
Fig. 4.10 worn surface of the specimen
The wear surface shows, crack propagation, damaged regions, and groove formation, along the transverse and longitudinal directions. As increasing the load, depth grooves are created because of enhanced wear temperature and pressure. The grooves are smooth and in dry condition at higher loads; so rate of wearing reduces as frictional force also reduces.
Fig. 4.11 Optical Image of the worn surface at different applied loads like 50N, 60N, 70N, 80N at 10X magnification.
4.4 Analysis of Aging Surface:
The composite specimen were brighten and solution operated for 60 minutes at a temperature of 260ºC .Then after water quenching process done at room temperature. This complete process followed by aging the quenched composites at 130ºC, 160ºC, 190ºC and 240ºC for 60 minutes. The aging action of the composite was analyzing using, Micro-vicker’s micro-hardness measurement, SEM (Scanning Electron Microscopy) images and XRD (X-RAY Diffraction Pattern) analysis. Each hardness value was the average of noticeably three measurements. The temperature for solution treatment was taken to be 2600C from Al-Mg Structure Phase Diagram.
Fig. 4.12 Phase Diagram of Al-Mg Structure
From Al-Mg Structure Phase Diagram it is shows that at 5% Mg we founded a homogeneous state of Al at a temperature more than approximately 2300C.So2600C is taken as the solution treatment temperature. Then an increment in hardness, this specimen was aged at different temperatures to get by precipitation hardening process due to the generation of SiC precipitates at the molecule boundaries.
4.4.1 SEM (Scanning Electron Microscopy) Analysis:
Fig. 4.13 SEM (Scanning Electron Microscopy) image of the composite specimen at room temperature
Aging temp=130 C Aging temp=160 C
Fig. 4.14 SEM(Scanning Electron Microscopy) Image of the Al-5% Mg-12%Sic composite sample solution treated at260 C for 1hr. and aged at four different temperatures showing Micro-Vicker’s Hardness (a) 1300C (b) 1600C
Aging temp=190 C Aging temp=240 C
Fig. 4.15 SEM (Scanning Electron Microscopy) image of the Al-5% Mg-12%Sic composite sample solution treated at260 C for 1hr. and aged at four different temperatures showing Micro-vicker’s Hardness (c) 1900C (d) 2400C
The Micro-vicker’s hardness of the composite sample is 67.4HV at room temperature. So at 1300C which is an aging temperature, there is an increment in micro hardness amount of the composite due to the generation of more no. of SiC precipitates as compare than unaged sample. The top hardness value is visualized at160 0C which is an aging temperature. The reason is show from the SEM (Scanning Electron Microscopy) images. The SEM (Scanning Electron Microscopy) image of 1600C aging temperature shows the generation of larger amount of minute Sic precipitates. Due to precipitation hardening, so the hardness is largest. At the aging temperature of 190 0C there is a exact vision of molecule increment of SiC particles which is the prime reason of a sharp reduction in hardness amount at 190 0C.At the aging temperature of 245deg 0C the SiC molecules start deliquesce. So there is a reduction in the no. of SiC precipitates, which take over to a reduction in the hardness value.
4.4.2 XRD (X-RAY Diffraction Pattern Analysis):
Fig. 4.16 XRD (X-RAY Diffraction Pattern Analysis) analysis of the composite solution treated at260ºC for 1hr. and aged at 130ºC
Fig. 4.17 XRD (X-Ray Diffraction) analysis of the composite solution treated at260 ºC for 1hr. and aged at 160 ºC
The XRD (X-RAY DEFFRACTION PATTERN) analysis of the composite solution treated at2600C for 1hr. and aged at 130 0C and 1600C shows the generation of complex state such as Al0.95Mg0.05, which may be the cause for the higher hardness value of the aged samples than the unaged ones. Also Al0.95Mg0.05 may help in the generation of larger no. of SiC precipitates at the grain boundaries.
Fig. 4.18 XRD (X-RAY Diffraction Pattern) analysis of the composite solution treated at 260ºC for 1hr. and aged at 190ºC
The XRD (X-Ray Diffraction) analysis of the composite solution dealing at260ºC for 1hr. and aged at 190ºC does not show any generation of complex state like Al0.95Mg0.05, which may be the cause for lower hardness value. The XRD (X-Ray diffraction ) analysis of the composite solution dealing at 260ºC for 1hr. an aged at 240ºC shows large intensity Al top. So the precipitates are deliquescing in the large Al matrix, this cause of lower hardness value.
4.5 Corrosion characteristic:
The composite sample is kept for 6 weeks (42 days)in sea water and with the help of an electronic weighing machine the weight loss was measured in every 7 days to analyzing the corrosion characteristic SEM (Scanning Electron Microscopy) images of the corroded sample are taken after 1st, 3rd and 6th week and Plotted the graph between no of days and the wt of the sample visible to sea water.
7.44 gms 7.42 7.4 in sample 7.38 7.36 of the 7.34 7.32 Wt. 7.3 7.28 0 5 10 15 20 25 30 35 40 45 No of days exposed to sea water
Fig. 4.20 Plot between Wt. of the corroding specimen and no. of days exposed to sea water
In the plot view an increment in wt. of the composite sample in the 1st week of the experiment. Due to corrosion phenomena, continuously reduction in wt. of the sample. The cause is show from the SEM (Scanning Electron Microscopy) and EDX analysis.
4.5.1 Analysis of EDX:
Element Weight% Atomic%
O K 17.65 26.59
Mg K 1.85 1.84
Al K 71.03 63.45
Si K 9.47 8.13
Fig. 4.21 Analysis of EDX of normal composite
Element Weight% Atomic%
O K 49.23 62.56
-404495-337185Na K 0.01 0.01
Mg K 10.38 8.68
Al K 30.13 22.70
Si K 4.97 3.60
S K 1.45 0.92
Cl K 0.61 0.35
Fe K 3.23 1.17
Totals 100.00 Fig. 4.22 Analysis of EDX of the corroded sample
The Study of the normal composite of EDX only reflect the presence compounds of containing Al, Mg, Si, whereas the EDX of the corroding sample conforms the generation of compounds containing, Sulfur, Sodium, Chlorine Iron along with Al, Mg & Si on the composite sample surface which is absorbed from the sea water. This is cause of the increment of the wt. of the composite after 1st week of the exposure to sea water.
The SEM (Scanning Electron Microscopy) image of the corroding surface also conforms the generation of a large amount of compounds on the composite surface.
10185402000254.5.2 SEM (Scanning Electron Microscopy) Analysis:
Fig. 4.23 SEM (Scanning Electron Microscopy) micrograph of normal composite sample before exposure to sea water
After 1 week exposure The SEM(Scanning Electron Microscopy) image of the composite sample, sea water shows the generation of a high amount of compounds on the composite surface by the reaction of Al, Mg, and SiC with the compounds present in the sea water. Sea water contains O2, H2, Cl, Na, Mg, S, Ca, K, Br, C, etc., which are very reactive to Al and Mg.
19824702447925The wt. of the corroding sample decreases continuously after 1st week till 6th week. The SEM (Scanning Electron Microscopy) micrograph of the composite sample after 3 weeks exposure to sea water shows that the compounds formed due to the corrosive attack on the sample surface are removed continuously causing wt. loss of the sample. Then fresh surface is exposed to the sea water for fresh attack. The SEM (Scanning Electron Microscopy) image shows large corroded portions which are again exposed to fresh corrosive attack
Fig. 4.24 The View of plot showing pitting corrosion
The corroded portions initiate pits for the starting of pitting corrosion. Then the corrosive elements present in the sea water like Na, Cl, S etc. attack around the pit boundary to form bigger pits and more wt. loss.
This chapter is provided as
Thus, Sic particles in the matrix act as pinning dots to keep the wear debreus particles on the wear surface and due to this some of the debrus get accumulet arround there this particles, It is found that the less wear of fabricate composite is compared to unfilled alloy.
The steady state test to measure the weight loss for varying the sliding time and sliding distance for Al-Mg – Sic composite molecules. The weight loss increase with increase in sliding time and distance.
The debars and wear rate decreases due to the long time sliding and long distance sliding.
At the normal load increases, deep grooves are generated because of enhanced pressure and temperature. So weight loss is much leading to maximum wear at maximum load but as the applied load enhanced rate of weight loss decreases leading to minimum wear rate. Because at maximum load the grooves become soft and in dry situation.
The wear resistance and hardness at alive of fabricated composite is higher than the unfilled alloy during sliding. Enhanced wear and abrasion resistance of composite can be conducted to the pressure of Sic particles when decreased the capacity for material flow at material flow.
The wear rate decreased with increased in sliding time, sliding speed and sliding distance of the Al-Mg-Sic carbide composite thus the coefficient of friction decreases with increases in sliding speed and normal load of fabricated composite.
Improved maximum temperature, strength, resistance due to plastic flow of matrix as worn surface and fabricated composite demonstrates higher load pressure compared to the unfilled alloy.
Age hardening method; enhance the hardness of fabricated composite majorly by the formation of maximum number of Sic particles.
Peek hardness was examined at the aging temperature of 160? C because of the formation of higher number of Sic precipitates as the fabricated composite.
At the temperature 190?C and more the specimen was examined to be over aged leading to grain growth of the Sic precipitates and these exhibited minimum hardness value.
The fabricated composite was investigated high pressure to pitting corrosion when it was exposed to sea water containing O2,H2, Cl, Na, Mg, S, Ca, K, Br, C etc.
2. SCOPE FOR FUTURE WORK
It is investigated the erosion wear behavior of the Al – 5% Mg 12% Sic metal matrix composite sample.
Influence of various corrosive mechanisms the corrosion characteristic of the fabricated composite sample.
Influence of temperature on the wear and corrosion characteristic of the fabricated composite sample.
The hardness and strength of alloy improves due to higher temperature of Sic.
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