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Functionally graded LM25/15 wt.% Tungsten carbide composite of dimension Øout 150 mm x Øin 110 mm x 100 mm and thickness 20 mm was studied to understand the influence of process parameters (applied load, sliding velocity, sliding distance) on the dry sliding wear rate and co-efficient of friction. A 5-level 3 parameter central composite design was developed using response surface methodology considering applied load (10-50N), sliding velocity (1-3 m/s) and sliding distance (500-2500 m) as input parameters. Dry sliding experiments were performed on pin-on-disk tribometer at ambient conditions. Significance tests, Analysis of Variance and confirmation experiments were done to check the accuracy of generated regression model. Generated surface plots revealed wear rate to be increasing as applied load and sliding distance increases and decrease as sliding velocity increases. Worn surface analysis performed revealed formation of deep grooves at high load, MML formation at high velocities and heavy delamination and particle pull-out at high sliding distances.

Present paper discusses the influence of T6 heat-treatment on mechanical and reciprocating wear properties of centrifugally cast functionally graded (FG) aluminium A356 (Al-7.5Si-0.3Mg) alloy. Microstructural studies confirmed varying grain structure from outer to inner layer, with outer layer having the best grain refined structure in as-cast (AC) condition. High concentration of spheroidised eutectic silicon particles was observed in outer layers of heat-treated (HT) alloy. Enhanced hardness (14.16%) and tensile strength (49.25%) was observed for outer layer of HT FG alloy, when compared to AC alloy. Fracture analysis confirmed a mixed mode of failure for HT FG alloy. Taguchi's Design of Experiments was used to study the reciprocating wear and frictional characteristics of outer layers of AC and HT alloy by varying applied load, sliding distance and frequency. Analysis of Variance and Signal-to-Noise ratio results of AC and HT alloy confirmed applied load and frequency to be the influencing parameter for wear rate and co-efficient of friction respectively. Worn surface analysis revealed a transition in wear mechanism for applied load, whereas extreme delamination wear and wear debris formation was observed at high sliding distances. As the HT alloy has very good age-hardening properties, they can be employed for automotive applications to meet the specific requirements.

Chopped carbon and basalt fibers were incorporated in an epoxy resin matrix by hand layup method. Three composites were fabricated with a fixed carbon fiber (CF) content (20%) and varying basalt fiber (BF) content (10%, 15%, 20%) along with a pure epoxy composite. Field emission scanning electron microscopy (FE-SEM) images ensured uniform distribution of fibers in the matrix. The mechanical properties of the composites were studied and it was seen that the properties increases with increase in fiber content. Composite with 40% fiber content exhibited better hardness, tensile strength and impact strength among other composites. The dry sliding wear behaviour of the composite with better mechanical properties was chosen and wear behaviour was analysed using pin on disc wear tester varying process parameters such as load (15 N, 20 N, 25 N), velocity (0.75 m s−1,1 m s−1,1.25 m s−1) and distance (500 m, 1000 m, 1500 m). Taguchi's technique was used for performing wear analysis and the optimum parameters for achieving maximum wear resistance was found to be at 15 N, 500 m and 1 m s−1. Analysis of Variance was used to find the effect of parameters on wear rate and it was observed that distance had higher influence on wear rate followed by load and velocity. A regression equation was also developed and confirmation test verified that error percentage in predicting wear rate was less than 6%. FE-SEM images of worn samples were taken and it was understood that breakage and displacement of fibers was the main factor causing wear. The composite exhibited good wear properties making it applicable for low-wear applications.