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Aluminium hybrid functionally graded metal matrix composites (FGMMCs), meet growing demands for supreme tribo-mechanical performance in automotive and aviation industry. This research experimentally compares the influence of carbide ceramics (B4C, SiC, TiC) as reinforcements, in improving reciprocating tribology performance and mechanical strength of A333 hybrid composites against alloy. Hollow cylindrical samples of A333/6 wt%B4C/4 wt%TiC and A333/6 wt%B4C/4 wt%SiC hybrid FGMMCs were developed using horizontal centrifugal casting. Metallography analysis on both composites revealed increasing ceramic gradient distribution towards outer composite wall. Particle rich zone of A333/B4C/SiC hybrid FGMMC showed maximum micro-hardness (198.9 HV) and tensile strength (267.9 MPa). Elemental mapping confirmed effective distribution of ceramics and detected elemental composition of both composites. Particle rich layer of A333/B4C/SiC hybrid FGMMC exhibited improved wear resistance in comparison with all three layers of A333/B4C/TiC hybrid FGMMC and alloy. Third-body abrasion and tribo-chemical wear were the predominant mechanisms revealed for both composites during worn surface analysis.

The present work discusses an attempt to enhance the mechanical and reciprocal wear response of Al–7Si-0.3 Mg alloy through the addition of 10 wt% SiC as reinforcement and subsequent T6 treatment. Friction and reciprocating wear behavior of both untreated and heat treated functionally graded composites were studied under unlubricated sliding conditions, employing a linear reciprocating pin-on-plate system over a range of applied load (10–50 N) and sliding distance (500–2500 m). Microstructural studies revealed reinforcement particle gradation across the cast thickness for untreated composite with minimal particle clusters whereas, heat treated composite showed the presence of fine α-spheroidised eutectic silicon. The outer layer of heat-treated composite when compared to outer layer of as-cast composite, revealed an 18 % increase in hardness, 70 % increase in tensile strength and 8 % decrease in wear rate. Wear studies confirmed a linear dependency between wear rate and applied load whereas, coefficient of friction displayed fluctuating trends. Wear mechanisms were identified, with worn morphology and EDS analyses in agreement with the results obtained and was correlated with the observed metallurgy and mechanical properties. These composites were identified as potential candidates for applications such as brake drums/rotors, cylinder liners, cylinder blocks and pistons.

Dry sliding performance of Cu-11Ni-4Si/10wt.%Al2O3 graded composite was investigated statistically and experimentally using pin-on-disc wear tester. Microstructural analysis revealed maximum gradient concentration of ceramics towards the inner radial wall of developed composite. The wear analysis was based on Taguchi’s L27 orthogonal array and Regression models, at tribo-parameters (load-15, 25, 35 N, slide velocity-1.5, 2.5, 3.5 m/s and slide distance-750, 1500, 1250 m). Wear raised with proportional rise in load and distance. Trend analysis of influential factors against wear response was studied using Analysis of Variance. The influence of process conditions and their interactions on the wear are also detailed. Worn surface analysis identified the formation of Mechanically Mixed Layers at intermediate velocity. This had a major influence over the improvement of wear resistance. This developed composite is suggestable for diverse automobile components of various tribology applications.

Functionally graded (FG) Al8Si3Cu alloy and 8 wt% titanium carbide (TiC) reinforced composite (∅out100 × ∅56in × 100 mm) was fabricated through horizontal centrifugal casting, followed by T6 heat treatment. Metallographic analysis confirmed fine grain structure at FG alloy outer layers, whereas heat-treated alloy displayed spheroidised eutectic silicon. Gradient microstructure was observed for FG composite. Enhanced hardness for outer layer (10.31%) and tensile strength for outer zone (58.71%) were observed for heat-treated Al8Si3Cu/TiC composite owing to the high concentration of spheroidised eutectic Si and TiC particles, compared to as-cast composite. Linear reciprocating wear analysis performed on as-cast, heat-treated alloy and composite, respectively, at varying load (10–40 N) and sliding distance (500–2000 m) confirmed increasing wear rate, with heat-treated composite having superior wear resistance. Delamination wear was the predominant wear mechanism influencing wear behaviour of heat-treated composite. The alloy and composite were characterized using X-ray diffraction (XRD), energy dispersive spectrometry (EDS), optical microscopy (OM) and scanning electron microscopy (SEM).

Performance characteristics of SS410 stainless steel during the drilling process while conducting experimental studies is discussed in this paper. The material was blocked up from the ingot form and has the following dimensions of 100x75x15 mm. Drilling experiments were carried out on BMV 35 T12 Gaurav BFW CNC machine using HSS drill bit. Process parameters such as Speed (S) (30, 40, 50, 60 m/min), Feed (F) (0.05, 0.075, 0.1, 0.125 mm/rev) and Point angle (P) (100, 110, 120, 130 degree) were varied for about four levels, to determine the test cases with the help of Taguchi’s Orthogonal Array. The methods used for analysing the results were; response table, Signal to Noise ratio and Analysis of Variance. It was concluded that better surface finish was obtained at high spindle speed, low feed, and high point angle, better material removal rate was obtained at high spindle speed, high feed, and low point angle and better dimensional accuracy (ovality) was obtained at low speed, low feed, and low point angle. Analysis of Variance (ANOVA) results revealed feed as the most significant parameter that influenced the surface roughness (Ra) of SS410 material, followed by speed and point angle. Similarly, for material removal rate (MRR) and ovality (O), speed was the most influencing parameter followed by feed and point angle. To predict the Ra, MRR and O, regression analysis was also performed and was validated through confirmation test.

This research compares the reciprocating tribo-mechanical behaviour of functionally graded A333 (Al-9Si-3Cu) alloy, Al-9Si-3Cu/6wt%B4C mono-composite and Al-9Si-3Cu/6wt%B4C/4wt%TiB2 hybrid-composite. Cylindrical test samples of both alloy and composites were horizontal centrifuge cast. Metallography of alloy revealed grain refinement and throughout presence of B4C particles along the cross-section of both functionally graded composites. Whereas, a rising gradient of TiB2 particles were observed towards the outer zone of hybrid composite. Comparative analysis on micro-hardness and tensile strength, revealed an improvement of 37.4% and 17.6% respectively for outer hybrid-composite; 22.6%, and 12.2% respectively for outer mono-composite with respect to alloy. Reciprocating wear analysis confirmed superior anti-wearing at outer hybrid-composite. Worn morphological analysis confirmed predominant delamination wear mechanism for outer zones of alloy, mono and hybrid composites. Abrasive, adhesive and delamination wear in combination, led to oxide layer formation at intermediate sliding distances. Hybrid composite is functionally graded and developed for automotive engine component applications.

Recently, cylinder liners of automotive and aircraft engines are encountered severe wear due to piston slap occurred by the repeated sliding stroke of piston. This research focuses on providing an alternative material for cylinder liners, which can be obtained through friction stir processing on AA7075 with different weight ratios of reinforcements like Al2O3 and SiC. Friction stir processing is executed with a tool rotational speed of 1000 r/min and traveling speed of 56 mm/min at 2° tool tilt angle. The images of optical microscopy reveal the fine-grains with a homogeneous distribution of secondary phase particles and also offer decrement in particle clustering except at some localized regions. It is identified that addition of 3.7 wt.% Al2O3 + 3.0 wt.% SiC in AA7075 enhanced the microhardness about 33.96% higher than base matrix. Hence, wear resistance of the specimen is improved. Dry sliding wear behavior of specimens is analyzed using pin on disc at 20, 40, and 60 N load conditions to create the actual sliding behavior of piston on cylinder wall. Increasing the wt.% of Al2O3 particles enhanced the wear resistance of AA7075 surface hybrid composites at 20 N load due to the formation of protective tribofilm. Specimen with 3.7% Al2O3 + 3.0% SiC has better lubrication and load-bearing capacity that exhibits superior tribological behavior at 40 and 60 N. Higher Fe content of 5.44 wt.% has been obtained through spectroscopy analysis in S5, which is 8% and 6% higher than S3 (7.5% of Al2O3) and S7 (6% of SiC), respectively. The scratching action of this hard specimen on the counterpart brings more Fe content. Increase of Al2O3 particles paved the way for tribofilm formation and identified through scanning electron microscopy micrographs. The observation from worn specimens shows that finer wear debris had increased by adding more quantity of SiC particles due to abrasive wear mechanism.

The present study focused on strontium (Sr)-induced A383 alloy and composite reinforced with 6 wt% boron carbide (B4C) particles processed by stir casting technique. From metallographic analysis, it was confirmed that Sr addition modified needle structures of α-Si to fine α-Si. This grain refinement enhanced the hardness of A383-Sr alloy by 52.72% and A383-Sr/B4C by 73.6%, and tensile strength of A383-Sr by 69.93% and A383-Sr/B4C by 81% when compared to A383 unmodified alloy. Fractography analysis proved that both Sr-induced alloy and composite had brittle failure with clear formation of flakes and cleavages. Reciprocating wear test was conducted at various loads (15 N, 25 N, 35 N) and at sliding distances (500 m, 1000 m, 1500 m). It was observed that wear rate was proportional to the applied load. Wear rate increased with increase in sliding distance, but after 1000 m, there was decline in wear rate. Worn surface analysis revealed the presence of oxide layer after 1000 m which enhanced wear resistance. A383-Sr/B4C composite possessed superior wear resistance compared to other.

The functional grade composite Cu-11Ni-4Si/10wt.%TiC along with Cu-11Ni-4Si alloy was stir cast, followed by horizontal-centrifuge cast technique. Cast sample was prepared at a dimension Fout100 x Fin85 x 100 mm. A comparative analysis for non-lubricated slide tribology at inner wall zone (1-5 mm), middle wall zone (5-10 mm) and outer wall zone (10-14 mm) of composites and alloy, was performed utilizing pin-on-disc tribometer. Observed a proportional raise in wear and friction with rise in applied loads and slid distances. For alloy and composite, a slight decline in wear was seen at medium velocity; showing a gradual deduction in friction with rise in slid velocity, while alloy wear showed a linear growth. Rate of increase in wear response with respect to change in distance was less prominent, compared to its response with load. Worn surfaces analysis of composite using Scanning Electron Microscope showed the presence of Mechanically Mixed Layers, which reduced friction at higher slid velocities resulting in lower wear. The phase formations and presence of oxides were confirmed by X-ray diffraction (XRD) and Energy dispersive spectrometers (EDS) results respectively.

This study investigates the effect of Strontium (Sr) grain modifier addition on Al-9Si alloy and B4C reinforced composite fabricated by two step gravity casting technique. The optimum level of Sr was identified as 0.08 wt.% for complete modification. The modified cast components were thermally treated by T6 temper to enhance the tribo-mechanical properties. Metallographic observation revealed the transformation of acicular Si grains to fine fibrous in as-cast condition, which later transformed to spheroidised eutectic Si after heat treatment. The combined effect of grain modification by Sr and the influence of spheroidised eutectic Si enhanced the mechanical properties. Heat treated modified composite exhibited superior tribological properties when compared to other components under varying applied normal loads and sliding distances. Worn mechanism of heat treated modified composite was observed to be minor delamination wear regime at high load (55 N) and sliding distance (1500 m).

Functionally graded Cu-10Sn-5Ni/10B4C composite was fabricated using horizontal centrifugal casting. Microstructural and mechanical properties were superior at reinforcement-rich inner zone where w...

LM25 aluminum alloy reinforced with 10 wt% of TiB2, WC, and ZrO2 were squeeze cast to investigate the effect of T6 heat treatment on tribo-mechanical properties. Among all, WC-reinforced composite achieved superior mechanical properties at the aging time of 8 h. Microstructural examination performed on all composites and alloy concluded that the presence of WC in T6 LM25 caused reduction of α-Al dendrite size, exhibiting superior properties for this composite. X-ray diffraction analysis conducted on alloy and WC-reinforced superior composite revealed formations of phases, which improved their mechanical properties. Energy-dispersive X-ray spectroscopy analysis quantified the actual intensity of WC presence in the superior composite along with its other constituents. Response surface methodology model developed for wear test of the superior composite involves parametric range like applied load (10–50 N), sliding velocity (1–4 m/s), and sliding distance (500–2500 m). Analysis of variance along with regression analysis proved that, statistical analytical model developed good relationship between the actual wear rate and process parameters. Response surface plots represented the linearly increasing wear trend with respect to load and sliding distance. Wear rate dropped initially and raised later on along with velocity. Scanning electron microscopy exhibited the surface deformation prevailing on the composite surface at high load.

A comparative study was drawn for evaluating mechanical and tribological properties between as-cast, heat treated (HT) Functionally Graded (FG) A359/10 wt% B4C and homogenous A359/6 wt% B4C composites (wt% equivalent to FGM outer zone, determined by chemical dissolution method) processed through horizontal centrifugal and gravity casting techniques respectively. Metallographic analysis confirmed decreasing gradation of reinforcement particles from outer to inner layers for as-cast FG composite, whereas even distribution of reinforcement was observed throughout for homogenous composite. Formation of fine alpha-spheroidized eutectic silicon was observed in HT composite. Comparative analysis carried out for mechanical properties of as-cast to HT composite confirmed an improvement of 37.9 % for outer layer of FG composite and 32.6 % for homogeneous composite in micro-hardness, while an improvement of 24.1 % for outer layer FG composite and 5.6 % for homogeneous composite was observed for tensile strength. Reciprocating wear analysis confirmed superior resistance to wear for outer zone of HT FG composite, with an increasing trend for wear rate and friction co-efficient under the effect of load and sliding distance. A decreasing trend was observed for wear rate and friction co-efficient as weight percentage of reinforcement increased. Worn morphological analysis confirmed predominant delamination wear mechanism for homogenous composites, whereas a combination of abrasive, adhesive and delamination wear was observed for FG composite. Keywords: Functionally graded composite, Homogeneous composite, Heat treatment, Reciprocating wear.

This study investigates the tribo-mechanical behaviour of as-cast and heat treated A359/ 6 wt.% Ti-based particulate reinforced homogeneous composites (TiB2, TiO2, and TiC) processed through modified stir casting technique. Metallographical observation on as-cast homogeneous composites revealed a uniform distribution of reinforcements throughout the cross-section. In heat treated composites, the tribo-mechanical properties were enhanced by the formation of spheroidized alpha eutectic Si. TiB2 and TiO2 exhibited superior interfacial bonding with Al-matrix, whereas TiC showed marginal wetting. Linear reciprocating wear experiments were performed on all as-cast and heat treated components by varying loads (15–55 N) and sliding distances (500–2500 m). Results revealed superior hardness (182.5 HV), tensile strength (271.6 MPa) and wear resistance for heat treated A359/TiB2 composite than TiO2 and TiC reinforced composites. The wear rate and coefficient of friction was observed to be dependent on the applied load and type of reinforcement particle in the composites. Worn surfaces of composites exhibited severe delamination wear mechanism.

Cu-10Sn-4Si reinforced with 10 wt. % SiC was synthesized using stir casting technique and cylindrical specimens of diameter 20 mm and length 150 mm were obtained.Dry sliding wear behavior of copper composite was analyzed by performing experiments using pin-on-disc tribometer. Taguchi’s method was utilized for designing the number of experiments using L16orthogonal arrayfor investigating the wear behavior. Three factors and four level design was selected namely Load (15N,25N,35N,45N), Velocity (1.5m/s,2.5m/s,3.5m/s,4.5m/s) and Distance (500m,1000m,1500m,2000m).Optimization of parameters was done using the Signal-to-Noise ratio. Analysis of Variance results revealed that load had the most impact on wear rate followed by sliding velocity and distance. The regression equation was developed and validated with confirmation experiment. X-ray diffraction analysis was conducted on the worn specimen to find out phase formations. Scanning Electron Microscopy analysis were performed on the surface of worn specimens and found that more delamination occurred at a load of 45 N

CuNiSi/Si3N4 is fabricated by using the stir casting method. Metal matrix composite developed is tested to study the adhesive wear behaviour on wear and friction apparatus under dry sliding state using Taguchi’s L27 orthogonal array. The process parameters were load (15,25,35N), sliding velocity (1,2,3m/s) and sliding distance (750,1250,1750m). In light of the outcomes, load applied is the most influencing variable on the wear loss abided by sliding distance and velocity. Scanning electron microscope analysis exposed serious delamination of specimen under high load and sliding distance. The developed copper composite can replace aluminium bearings, cylinder liners, radiators, connecters.

Fabrication of Aluminum LM13/MoS2/TiO2 hybrid metal matrix composite via stir casting technique was carried out to analyze the wear characteristics at an elevated temperature of 150° C using pin on disc tribometer. The parameters namely load, sliding velocity and sliding distance were varied for five levels as per the run order generated from Response Surface Methodology. From experiments, it was observed that the wear rate decreased with reduced sliding velocity initially due to mechanically mixed layer formation and then increasess. Also the results showed a reduction in wear rate with low loading and sliding distance conditions. Minimum wear rate was observed at a load of (11N), sliding velocity (1m/s) and sliding distance (848m) which was the ideal condition. Results concluded that the load applied was the significant factor over rate of wear leading to the occurrence of deep grooves along with delamination at higher loads. At minimal loads, appearance of shallow grooves in the sliding direction was observed.Major Applications of AMMC include the manufacturing of piston liners in automobiles and bearings, gears for aircraft engines which are often subjected to high friction and temperatures.

The current study focuses on improving the mechanical and reciprocating wear characteristics of centrifugally cast functionally graded A356(Al-7Si-0.3 Mg)/10 wt.% B4C composite through T6 heat-treatment. Comparative analysis was performed between as-cast and heat-treated composite. Metallographic analysis confirmed the presence of reinforcement particles alongside grain boundaries and spheroidised eutectic silicon particles in heat-treated composite. Outer layer of heat-treated composite displayed superior hardness (24.09%), ultimate tensile strength (44.8%) and tribological properties when compared to outer layer of as-cast composite. With increasing applied load (15, 25, 35 N), wear rate and co-efficient of friction increased whereas wear rate and co-efficient of friction decreased as sliding distance (500, 1000, 1500 m) increased. Worn morphologies confirmed extreme delamination wear and particle pull-out at high applied loads whereas traces of oxide formations were observed at high sliding distance. Heat-treated composites have superior characteristics due to the presence of spheroidised eutectic silicon particles and precipitate formation, which makes it an alternative material for reciprocating applications in aerospace and automotive industry.

This research aims to fabricate Cu-10Sn-5Ni /10wt%TiC functionally graded composite (Øout100 X Øin70 X 100 mm) through horizontal centrifuge cast technique and to study its tribo-mechanical characteristics. Microstructural observation revealed higher percentile of reinforcement particles at inner wall zone compared to middle and outer zones. Vicker’s micro hardness tests revealed proportional increase of hardness along the radial wall towards inner periphery. Inner (7-15 mm) zone had higher tensile strength (291 MPa) compared to outer (1-7 mm) zone (236 MPa). Non-lubricated tribology experiments were performed at inner, middle and outer region of composite using pin-on-disc tribometer under a wide range of loads, sliding distances and sliding velocities. From the wear experiment results, it was observed that inner region had minimal wear due to rich particle presence. Scanning Electron Microscopy on worn specimen at low and high wear parametric conditions exhibited features like delamination, ploughing, micro cutting, particle pull-out, plastic deformation with flaky wear debris and thin film formation.

Non lubricated slide performance of functional grade copper matrix composite, fabricated using horizontal centrifuge cast technique was investigated using pin-on-disc tribo-tester. Rate of wear and friction coefficient of the inner wall thickness of hollow cylindrical cast specimen was analyzed using Taguchi based L27 orthogonal array, where the percentage of graphite particles were observed higher. Variable process parameters those influenced the rate of wear directly or indirectly were: applied load (15, 25 and 35 N), slide velocity (1.5, 2.5 and 3.5 m/s) and slide distance (750, 1500 and 2250 m). Rate of wear and friction coefficient showed a proportional dependency with applied load and slide distance, whereas showing a decline during intermediate slide velocity. Signal-to-Noise ratio predicted the minimal tribo-condition, on ‘smaller-the-better’ basis. Analysis of Variance technique quantified the influence of affecting parameters, along with their interactions. Regression analysis was utilized for the validation of the experimental data. Micrographs and scanning electron microscopy exhibited the wear mechanisms and mechanically mixed layer formation during worn surfaces analysis.

This research investigates the effect of heat treatment on mechanical and tribological properties of Cu–11Ni–4Si—10 wt% B4C functionally gradient composite, which is fabricated by the centrifugal casting method. The cast specimens are solutionized at 700 °C for 90 min, followed by air quenching/water quenching. The specimens are artificially aged at different temperatures (500 °C, 550 °C, and 600 °C) and time (1 h, 2 h, and 3 h). The optimum heat treatment condition is established based on the microstructure, microhardness, and tensile strength. The specimens that are heat-treated at optimum condition are subjected to tribological tests by varying the load between 15.8 and 44.44 N and sliding velocity between 0.8 to 2.2 m/s for a sliding distance of 1000 m and 1500 m. The surface morphology and topography of the worn surface are analyzed using FESEM and AFM, respectively. The influence of load and sliding velocity on the wear rate of the specimens is explored using the mathematical models, which are developed using a hybrid polynomial–radial basis function. The results indicate that the load has a direct influence on the wear rate, while the wear rate follows crest parabolic pattern with an increase in the sliding velocity.

Functional grade composites Cu–10Sn–5Ni reinforced with 10 wt%SiC and 10 wt%Al2O3, respectively, and their alloy was developed through horizontal centrifuge cast technique. Sample composites and alloy were cast at cylindrical dimensions of Φout100 × Φin70 × 100 mm. They were later subjected to tribology analysis during non-lubricated sliding. Anti-wear performance variations at inner (0–8 mm) and outer (8–15 mm) wall thicknesses of both composites and alloy were experimented using pin-on-disc tribo-tester. Experimentation with increasingly varied parameters like load and slid distance showed a rising trend of wear and friction. This was observed while comparing between the least (10 N, 500 m) and highest (60 N, 3000 m) varied parameter; for both alloy and composites. Also, a proportional decline in coefficient of friction with increase in slid velocity was exhibited for both composites; whereas alloy showed a linear rise. Worn specimen analysis using scanning electron microscopy on both composites revealed Mechanically Mixed Layer formation at both zones. This caused reduction in friction coefficient at high velocity (6 m/s). Keywords: Centrifuge casting, Functional graded materials, Adhesive wear, Scanning electron microscopy

The research aims to fabricate LM25 alloy and composites reinforced with 15 wt% TiB2, 15 wt% ZrO2 and 15 wt% WC using squeeze casting technique. The fabricated cylindrical castings were of dimensions 50 mm diameter and 150 mm length. Microstructural analysis revealed better distribution of reinforcement particles for each composite, which provided better hardness and tensile properties. Physical and wear properties were studied comparatively to understand the influence of reinforcements, and tungsten carbide (WC)-reinforced composites showed better performance. Fractographic analysis revealed ductile mode of failure for LM25 and a combination of ductile and brittle mode for its composites. Dry sliding performance of both alloy and composites was analysed under different sliding conditions of applied load (10–50 N), slide distance (500–2500 m) and slide velocity (1–5 m/s) using pin-on-disc tribometer. WC-reinforced composite improved resistance to wear by 70% compared to alloy. Wear analysis of composite using scanning electron microscope showed change in wear features from mild to severe at high loads. The developed LM25/WC composite was found to be most suitable for non-lubricated slide applications.

Aluminum/titanium diboride (TiB2) in-situ metal matrix composite was produced by reaction between aluminum alloy and potassium hexafluoro titanate (K2TiF6) and potassium tetrafluoro borate ...

Functionally graded material containing LM13 aluminium alloy as matrix and alumina as reinforcement (10 wt. %) was fabricated (Φout150 × Φin90 × 100 mm) by centrifugal casting. Samples were machined from the cylindrical cast along its longitudinal axis. Variation in hardness along the radial cross-sectional wall revealed 33.7% improvement at the outer periphery due to higher presence of alumina. This zone was preferred for dry sliding wear experiments, designed based on Taguchi L27 orthogonal array by varying the process parameters like sliding velocity, sliding distance and load using pin-on-disc tribometer. Analysis of variance revealed velocity as most influential wear factor, next to load. An optimal condition to minimise adhesive wear was determined at a load of 15 N, sliding velocity of 3.5 m/s and sliding distance of 1250 m. Scanning electron microscope analysis on abraded surfaces showed formation of tribolayer at high velocities and delamination at high loads.

The current study aims to synthesize copper alloy and functionally graded Cu-10Sn-5Ni/10Si3N4 composite using horizontal centrifugal casting method and compare their mechanical and adhesive wear characteristics. The fabricated castings have dimensions of Oout100 x Oin70 × 100 mm. Microstructural analysis revealed that inner region of composite possesses higher concentration of reinforcement particles, resulting in better hardness and tensile properties at this region compared to outer regions of both unreinforced alloy and composite. Analysis of dry sliding wear performance and frictional coefficient was performed at inner region of the composite under different sliding conditions using Taguchi’s method on pin-on-disc tribometer. Signal-to-Noise ratio and Analysis of Variance results concluded that applied load had the most influence on wear rate and coefficient of friction followed by sliding distance and sliding velocity. Worn surface morphologies of composite specimens revealed a transition from mild to severe wear at high loads. The fabricated composites are well suitable for sliding tribological applications.

Centrifugally cast functionally graded Cu–11Ni–4Si/10 wt% TiC composite of dimension Oout100 × Oin70 × 100 mm was heat treated to enhance the mechanical and tribological characteristics. Samples from inner zone (9–15 mm) were initially solution treated (850 °C/1 h), water quenched, and aged at varying temperatures (450, 500, and 550 °C) and ageing time (4, 6 and 8 h). The highest hardness (192 HV) displayed by the specimen aged at 550 °C/6 h was chosen for dry sliding tribological studies performed at varying applied loads (10–30 N), sliding velocities (1–3 m/s) and sliding distances (500–1500 m). An improvement of 65% was observed on comparing the micro-hardness values of heat-treated and non-heat-treated composites, while a decrease of 54.8% was observed on comparing the wear rate of heat-treated alloy and composite at optimum parameters. The wear rate increased with applied load, decreased initially and then increased with sliding distance and sliding velocity. Analysis of variance predicted applied load as the major influential parameter, followed by sliding distance and sliding velocity. Worn surface analysis revealed increase in delamination along with mild to severe wear transition with increase in applied load, and the formation of a mechanically mixed layer with increase in sliding velocity. This composite having high wear rate and hardness could be utilized for automotive load bearings, cylinder liners and brake drum applications.

The key objective of the paper is to investigate the mechanical and wear Properties of functionally graded copper composite (Cu–11Ni–4Si) reinforced with 10 wt% graphite synthesised using stir casting followed by horizontal centrifugal casting technique. Microstructural analysis conducted radially from outer surface exhibited an increasing gradient of particle distribution and maximum hardness of 195 HV was observed at inner surface. Tensile strength of outer and (1–8 mm) and inner zone (9–15 mm) was determined and failure mechanism was analysed. Mechanical tests revealed better properties at inner surface and wear resistance of this layer was analysed using pin-on-disc tribometer based on Taguchi’s L27 orthogonal array with three process parameters, applied loads (10, 20 and 30 N), sliding velocities (1, 2 and 3 m s−1) and sliding distances (500, 1000 and 1500 m). Optimum parameters were identified and confirmation of experiments was carried out. Worn surface was analysed using Scanning Electron Micrograph and oxide layer formation was noticed at increased velocities which enhanced wear resistance.

The functionally graded Cu-11Ni-4Si/10wt%WC composite and its alloy have been synthesized using horizontal centrifugal casting technique to compare the mechanical and tribological improvement and its utility for bearings and bushes. Microstructure analysis and mechanical tests showed 43% improvement in hardness and 160% improvement in tensile strength at inner radial distances compared to the outer composite periphery. Fractural analysis showed ductility for alloy, whereas for composites, brittleness at outer and a combination of both ductility and brittleness were observed at inner. Proportional rise in the wear rate and coefficient of friction was observed with increasing load and sliding distances for both composite and alloy. Composite showed a slight decline in the wear rate and coefficient of friction with an increase in the sliding velocity, while alloy showed a linear rise. Worn surfaces analysis of composite showed the formation of oxide layers, which reduced the coefficient of friction at higher sliding velocity, resulting in lower wear rate.

Cu-11Ni-4Si/10wt.% Si3N4 functionally graded composite of dimension Oout 100 mm × Oin 70 mm × 100 mm was fabricated via centrifugal casting and the mechanical and three body abrasive wear behavior were studied. Microstructural analysis along the radial direction revealed high concentration of Si3N4 particles at the inner periphery of the composite, and XRD analysis confirmed the presence of introduced reinforcement. Highest micro-hardness (207 HV) was observed at the inner periphery of composite having highest concentration (53 vol.%) of reinforcement particles and the inner zone displayed higher tensile strength (425.58 MPa). Abrasive wear test based on L27 orthogonal array, was performed only at inner periphery based on the mechanical behavior. Signal-to-Noise ratio and Analysis of Variance were performed to analyze the influence of parameters such as load, speed and time on wear rate. Results showed that applied load had the highest influence (60.45%) on wear rate followed by speed and time. Scanning electron microscopy analysis was carried out on worn samples and was observed that wear changed from mild to severe as parameters were increased. This composite is suited for automotive applications where the improved abrasive wear characteristics can be utilized to a greater effect.

Aluminium 6063 alloy as substrate was coated with WC-12% Co using the detonation spray gun technique. The coated specimen showed 5.6x increase in hardness over the uncoated substrate. Wear analysis...

LM13/12wt.%Si3N43wt.%Gr hybrid composite was fabricated by liquid metallurgy route and its tribological characteristics were tested using pin-on-disc tribometer. The experiments were conducted as per L27 orthogonal array to study the influence of process parameter at normal and elevated temperature (150 °C) by varying process parameters such as load (10, 20, 30 N), sliding velocity (1, 2, 3 m/s) and sliding distance (750, 1250, 1750 m). The results revealed that the wear rate at both temperatures was proportional to load due to the stress induced which fractures Si3N4 particles and stripes aluminium matrix. As the sliding velocity increases, wear rate showed an increasing trend due to three body abrasion from eroded Si3N4 grits. The wear rate was inversely proportional to sliding distance, because of MML (Mechanically mixed layer) formed from chemical reactions between tribo-layers. When load increases COF (Coefficient of friction) decreases then increases due to lubricating and tillage effect. As velocity and distance increases, COF decreases due to thermal softening, hardening of layer and also the lubrication effect produced by chemical reactions. Analysis of variance (ANOVA) and S/N ratio at room temperature and elevated temperature for both Wear rate and COF were developed to study the most significant parameters on corresponding responses. Confirmation experiments were conducted to validate multi-linear regression model. Worn surfaces were examined using scanning electron microscope (SEM) to investigate wear characteristics. Energy dispersive X-ray spectroscopy (EDAX) and X-ray diffraction (XRD) results confirmed the formation of MML and different phases formed during wear mechanism. The developed material can be used to fabricate cylinder liners, cylinder blocks and brake rotors.

Al 6060 alloy was coated with TiO2 by spray pyrolysis technique at 400 °C using Titanium isopropoxide as precursor. The adhesion of the coating with the alloy was enhanced by annealing at 450 °C for 1 h which increased the hardness by 50%. Dry sliding wear resistance was experimented based on Taguchi’s L27 array using pin-on-disc tribometer by varying parameters such as applied load (15, 25 and 35 N), sliding distance (500, 1000 and 1500 m) and sliding velocity (1.5, 2.5 and 3.5 m/s). Analysis of Variance predicted the major influence by load, followed by velocity and distance. Trend depicted an increase in wear rate with load and distance, whereas with velocity it decreased initially and then increased. Optimum condition for maximum wear resistance was determined from the Signal-to-Noise ratio. Experimental results were validated using regression equation with an error less than 3%. Scanning Electron Microscope analysis of the worn surfaces had revealed more defoilage and lay-off as the applied load was increased.

The objective is to fabricate Cu-10Sn alloy and its composites reinforced with varying wt% of SiC (5, 10 and 15) to investigate its dry sliding wear behaviour. Microstructural analysis for composites revealed well dispersed SiC particles within matrix except for 15 wt% SiC composite, where agglomeration took place. Amongst all composites and alloy, 10 wt% of SiC composite had better hardness (144 HV). The tribological analysis using Pin-on-Disc tribometer for all alloy and composites revealed increase in wear rate with increase in load and distance for all combinations of parameters (load, sliding distance, and sliding velocity). Worn surface analysis concluded that the wear rate decreased with increase in velocity for both 5 and 10 wt% SiC composite due to formation of Mechanically Mixed Layer. The composite with 10 wt% SiC showed enhanced wear resistance and hence can be used for tribological applications like bearings and bushes.

This paper aims to study the dry sliding wear characteristics of LM13 aluminum alloy matrix containing titanium disulfide (TiS2) as the reinforcement (10 wt%, average size 37 µm) fabricated...

This paper involves the fabrication of LM13/TiO2 (12 wt%)/MoS2 (3 wt%) hybrid metal matrix composite and unreinforced alloy using liquid metallurgy route and evaluation of mechanical properties and...

The tribological performance of functionally graded composites (FGCs) under abrasive and reciprocating test conditions are reviewed, from the numerous studies performed over the last three decades. FGCs produced differing wear analysis trends under varying process conditions and parameters. A general framework identifying the process parameters as well as assessing the wear performance through wear modes and mechanisms is presented. The tribo-system material loss is reduced by optimizing the process parameters independently, for specific engineering applications depending on the industrial demands. Moreover, the different challenges faced during wear analysis were discussed and their prospects in various scientific and technological fields are addressed.

Surface coating on metal substrates has remained a difficult challenge for researchers due to the conflicting requirements for different properties. In recent years, due to their mechanical, thermal, electrical, and tribological properties in many advanced engineering applications, functionally graded coatings (FGCs) have become fascinating materials for researchers worldwide to obtain coatings with specific requirements. FGCs are a novel type of traditional composites in which phases are not equally distributed to form a smooth gradient structure; thus, gradient coatings have shown a new research path. Therefore, this paper critically reviews the different FGC processing techniques by describing the fundamental problems and potential of these processes based on existing literature. Additionally, this research presents the most important potential applications and future challenges for gradient coatings. Consequently, the results expected from the paper are considered a guideline that enables the interested in this field to make informed decisions.

The objective of this research is to fabricate a functionally graded Cu/SiC composite (Oout100 × Oin85 × 100 mm) using a horizontal centrifugal casting technique and to examine its mechanical and dry sliding wear characteristics. Microstructure of the composite was observed at outer (1 mm), middle (8 mm) and inner (14 mm) regions using a metallurgical microscope and results showed that the inner region had a high concentration (35%) of reinforcement particles compared to the other two regions. Mechanical properties were tested along the radial direction of the composite and results showed that maximum tensile strength and hardness were found to be 341 MPa and 280 HV respectively, at the inner region of the composite. Fractograpy examination revealed that the outer and inner regions were fractured by ductile and brittle modes of failures, respectively. The dry sliding wear tests were performed only at the inner region of the composite with selected parameters of load (10–30 N), sliding distance (500–1500 m) and sliding velocity (1–3 m/s) using a pin-on-disc tribometer. Analysis of variance and signal-to-noise ratio were used to study the effects of parameters on the wear rate of the composite and it was found that the load (54%) had highest influence followed by sliding distance (18.2%) and sliding velocity (3.7%). Worn surfaces were observed by a scanning electron microscope and it was confirmed that mild wear, severe plastic deformation, ploughing, delamination and wear debris were important wear mechanisms at different sliding conditions. Hence, this composite is suggested for use in bearings and bushes application, where the wear resistance is a primary consideration.

This study investigates the mechanical and tribological properties of a functionally graded Cu–Sn–Ni/Al2O3 metal matrix composite, synthesized using horizontal centrifugal casting technique...

Functionally graded metal matrix composite (Cu-10Sn/10 wt% SiC) was successfully fabricated by horizontal centrifugal casting method. The cast specimen of O100 x 100 x 20 mm was obtained. The centrifugal die rotates at 900 rpm and particle rich zone is obtained at inner periphery of cast sample due to the density difference between matrix and reinforcement. The specimen of dimension 75 x 25 x 12.5 mm was cut from the cast and abrasive wear test was carried out only at inner surface as per Taguchi’s Design of Experiment technique. L16 Orthogonal array was selected and experiments were carried out using three body dry abrasion tester by varying the process parameters such as load (25, 45, 64,89N), time (3, 5, 7, 9 mins) and speed (50,100,150,200 rpm) for four levels. Silica sand AFS 50/70 was used as an abrasive medium. The influence of these wear process parameters was analysed using Minitab software. Taguchi design provides analysis of experiments using Signal-to-Noise ratio and Analysis of Variance to find out the optimum level of parameters as well as its influence of each parameter on the response. The results revealed that, wear rate increases with increase in applied load and decreases and then increases as speed and time increases. Time was observed to be the most dominating factor (38.1%) followed by load (27.6%) and speed (22.8%). The worn surfaces were analyzed at varying parametric condition using Scanning Electron Microscope and found severe delamination with plouging as the major mechanism at high load condition.

Requisite for advanced materials with high hardness, high tensile strength and improved wear properties has been drastically increased in recent times. The main objective of this paper is to fabricate unreinforced copper alloy and Cu-Sn/SiC composite with varying wt% of SiC (5, 10, and 15) by liquid metallurgy route and to investigate its microstructure, mechanical properties and dry sliding wear behavior. The hardness and tensile strength of alloy and composites are measured on Vickers micro hardness tester and Universal Testing Machine respectively. Tensile test specimens are further subjected to fractography analysis and the results shows ductile mode of failure for alloy and mixed ductile and brittle mode failure for composites. Based on the test results, it is observed that Cu-Sn/10 wt% of SiC have uniform distribution of particles with optimum mechanical properties. Hence only these 10 wt% SiC composite is considered for dry sliding wear analysis and experiments are conducted using Pin-on-disc tribometer. Analysis of process parameters in three levels such as applied load (15,25,35 N), sliding distance (750,1250,1750 m) and sliding velocity (1,2 and 3 m/s) is done by Taguchi’s Design of Experiments technique based on L₂₇ orthogonal array. From Signal-to-Noise ratio and Analysis of Variance approach, the rank of process parameters as well as its influence on the response is found. The results reveal that the wear rate increases as applied load and sliding distance increases and the wear rate decreases as sliding velocity increases. The load is found to have the highest influence on wear rate (38.5%) followed by sliding distance (7%) and sliding velocity (7%). Interaction between the process parameters also contributed towards wear rate. The worn surfaces were examined using Scanning Electron Microscopy and observed the formation of mechanically mixed layer at high velocity condition. Thus, the fabricated composites can be used in applications like bearings and bushes to improve the wear resistance.

The objective of this work is to fabricate functionally graded unreinforced copper alloy (Cu–10Sn) and a Cu–10Sn/SiC composite (Oout100 × Oin70 × 100 mm) by horizontal centrifugal casting process and to investigate its mechanical and tribological properties. The microstructure and hardness was analysed along the radial direction of the castings; tensile test was conducted at both inner and outer zones. Microstructural evaluation of composite indicated that the reinforcement particles formed a gradient structure across the radial direction and maximum reinforcement concentration was found at the inner periphery. Hence maximum hardness (205 HV) was observed at this surface. Tensile test results showed that, the tensile strength at inner zone of composite was observed to be higher (248 MPa) compared to that of the outer zone and unreinforced alloy. As mechanical properties showed better results at inner periphery, dry sliding wear experiments were carried out on the inner periphery of composite using pin-on-disc tribometer. Process parameters such as load (10–30 N), sliding distance (500–1500 m) and sliding velocity (1–3 m/s) were analyzed by Taguchi L27 orthogonal array. The influence of parameters on wear rate was analyzed by signal-to-noise ratio and analysis of variance. Analysis results revealed that load (54%) had the highest effect on wear rate followed by sliding distance (18.2%) and sliding velocity (3.7%). The wear rate of composite increased with load and sliding distance, but decreased with sliding velocity. Regression equation was developed and was validated by confirmatory experiment. Worn surface of composite was observed using scanning electron microscopy and transition of wear was observed at all extreme conditions.

This paper studies the dry sliding wear behavior of Al–Si6Cu/Ni coated SiC metal matrix composite fabricated using stir casting technique. The SiC reinforcement particles coated with Ni by electroless coating were incorporated at 10-wt% into the metal matrix. The wear behavior was studied on unlubricated pin-on-disc tribometer based on design of experiments modelled using Response Surface Methodology for various sliding parameters such as applied load, sliding velocity and sliding distance. The minimum wear rate condition and optimum condition of the parameters were detected from the developed model. The analysis of variance showed the influence of each parameter on wear rate. The confirmation experiments were done to ensure the validity of the developed regression model. The worn-out surface morphologies of the metal composite were studied using scanning electron microscope analysis. From the experimental results it was found that the parameter which influenced the wear behavior was applied load followed by sliding velocity and distance. The confirmatory experiments confirmed the RSM’s design as precise statistical model in developing regression results with less error. The surface plot of wear characteristics showed that irrespective of the conditions of sliding velocity and distance the wear rate increased on increasing the load. The wear rate exhibited a non linear relationship with sliding velocity and distance. The scanning electron microscopy revealed that higher material deformation was observed at higher load resulting in severe wear of the composite material.

Centrifugal casting was adopted for fabricating AlSi5Cu3/10 wt% SiC functionally graded metal matrix composite under three different centrifugal speeds of 800, 1000 and 1200 rpm, and hollow cylindrical components (φout 150 × φin 132 × 150 mm) were obtained. Microstructures of outer and inner periphery of all composites were observed through optical microscope and micro hardness of outer, intermediate and inner region of composite was tested using Vicker’s hardness tester. Results revealed that outer region of the composites centrifuged at all speeds have particle rich region with higher hardness. Abrasive wear experiments were conducted only on surface of particle rich region based on Taguchi’s technique by varying parameters such as centrifugal speed of casting process, rotating speed and applied load of abrasive wear tester. Analysis of variance results revealed that, centrifugal speed had highest significance on wear rate. Abraded surfaces were examined using scanning electron microscope and the maximum wear resistance was observed on particle rich zone of composite centrifuged at 1200 rpm.

Several engineering components require location specific performance under operating conditions. A compositional/microstructural gradient can provide the performance required at specific locations and these materials were named as functionally graded materials. Functionally graded aluminiu...

The aim of the work is to fabricate functionally graded aluminium (Al-Si6Cu)/ nickel coated SiC metal matrix composite using centrifugal casting route. SiC particles (53-80 µm) were coated with nickel using electroless coating technique to enhance the wettability with aluminium matrix. Several attempts were made to coat nickel on SiC by varying the process temperature (65 °C, 75 °C, and 85 °C) to obtain a uniform coating. Silicon particles coated with nickel were characterised using EDS enabled Field Emission Scanning Electron Microscope and it was found that the maximum nickel coating on SiC occurred at a process temperature of 75°C. This nickel coated SiC particles were used as the reinforcement for the manufacture of functionally graded metal matrix composite and a cast specimen of dimensions 150×90×15 mm was obtained. To ensure the graded properties in the fabricated composites, microstructure (at a distance of 1, 7 and 14 mm) and hardness (at a distance of 1, 3, 7, 10 and 14 mm) from outer periphery taken in the radial direction was analysed using Zeiss Axiovert metallurgical microscope and Vickers micro hardness tester respectively. The microstructure reveals presence of more SiC particles at the outer periphery compared to inner periphery and the hardness test shows that the hardness also decreased from outer periphery (90 HV) to inner periphery (78 HV).Tensile strength of specimen from outer zone (1-7mm) and inner zone (8-14 mm) of casting was also tested and found out a value of 153.3 Mpa and 123.3 Mpa for the outer zone and inner zone respectively. An important observation made was that the outer periphery of casting was particle rich and the inner periphery was particle deficient because of centrifugal force and variation in density between aluminium matrix and reinforcement. Functionally graded Al/SiC metal matrix composite could be extensively used in automotive industry especially in the manufacture of liners and brake drums.

This paper deals with the study of dry sliding wear of LM25/silicon dioxide (10 wt.%) functionally graded composite. The composite was fabricated using stir casting technique and the melt was poured into a horizontal centrifugal die rotating at 1200 min−1. After casting, the specimen (length 150 mm, external diameter 150 mm and internal diameter 130 mm) was subjected to microstructure and hardness tests at three different depths from the outer periphery (1 mm, 8 mm and 13 mm). The results of the respective tests revealed that the outer periphery of the specimen had higher particle concentration and hardness. Then, wear test was done on a pin-on-disc tribometer at room temperature with the experiments designed using response surface methodology and by taking specimens of size 8 x 8 x 15 mm such that the surface undergoing wear was at 1 mm from the outer periphery of the cast. The process variables of load (10 - 40 N), velocity (1 - 4 m/s) and sliding distance (400 - 1200 m) were varied using a level 5 design and experiments were carried on for 20 different optimal combinations. From the regression equation generated for the wear response, it was found that load had maximum effect on the wear rate. The confirmation experiments proved that the regression model could serve well in predicting the wear rate for the given ranges of the continuous factors, for the given composite. Surface plots showed that the wear rate had an increasing trend with respect to load, which was the dominating continuous factor. Though the wear rate increased, severe delamination of the functionally graded composite was delayed. The optimum levels of the continuous factors to minimize the wear rate were found using response optimisation and found to be 10 N, 1.7576 m/s and 2000 m respectively. Scanning electron microscopy analysis of the worn surface of the specimens connected to the obtained trends and thus further validated the model developed. Thus, a functionally graded LM13 composite with silicon dioxid reinforcements is developed and a wear model to predict its wear rate under different process parameters is proposed with predictions of optimal performance conditions. This composite can increase life of components of wear applications in aerospace and automobile industry.

Functionally graded LM13 Al/10 wt% TiB2 metal matrix composite has successfully produced under centrifugal casting. Hollow cylindrical composite with dimensions 150 × 150 × 15 mm was produced under rotating centrifugal speed of 1100 rpm. Microstructural characteristics were studied on the composite surfaces at distance of 1, 5.5, and 10 mm from outer periphery of the casting, and the results revealed that surface at distance of 1 mm has presence of more reinforcement particles. An objective of this study was to characterize abrasion wear behavior at the composite surfaces using dry abrasion tester. Mathematical models were developed using response surface methodology to study the relationship of parameters such as load, speed, and distance from outer periphery with abrasion wear rate. Face centered Central Composite Design with 20 experiments was preferred for dry abrasion test. Adequacy of model was predicted through analysis of variance, and the significance test result shows that load has major...

In this paper, the abrasive wear behavior of Al LM 25/10 wt% TiC metal matrix composite has been studied experimentally. The composite specimens were fabricated using stir casting technique. Microstructural evaluation revealed uniform distribution of reinforcement particles throughout the matrix. Abrasive wear experiments were designed for different values of load, speed and time through response surface methodology and were performed using three body abrasion tester. Surface plots for wear rate against all combinations of parameters revealed that wear rate increased with increasing load and time, but decreased with increasing speed. The generated regression equation established proper relation between parameters and wear rate, confirming the accuracy of the developed model. The results of optimization of process parameters revealed that a minimum wear rate of 0.00104 mm3/Nm was obtained at 27 N, 139 rpm and 3 min. Scanning electron microscope analysis results substantiated that wear rate was comparatively more at higher loads.