A factorial design approach technique was adopted to understand the high stress abrasive behaviour of a diamond reinforced composite coating for various compositions at different loads and abrasive sizes. A linear regression equation was developed and used for understanding the influence of the diamond concentration, applied load, and abrasive sizes on the wear response. A negative value of the coefficient associated with diamond concentration, together with its interactions with the applied load; suggest that the wear rate decreases with increasing diamond concentration. By contrast, a positive coefficient suggests an increase in wear rate due to an increase in related factors such as the applied load and abrasive size. The coefficients associated with the interactions of the parameters are insignificant by comparison with the individual parameters, thereby demonstrating that the interaction effect of these parameters towards the wear rate is insignificant. The wear rate may be extracted in terms of the diamond concentration, the applied load and the abrasive grit size using the above linear regression equation.

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High-velocity oxy-fuel (HVOF) spray ceramic oxide coatings have immense potential in industrial applications. However, they are not widely used yet due to the lack of an adequate scientific database created after testing these coatings for specific industrial applications. Two such ceramic coating powders, Al 2 O 3 + (40%)TiO 2 and Cr 2 O 3 , were deposited on AISI 309 SS stainless steel by the HVOF spray technique, in order to enhance its wear resistance. This stainless steel is used in many components of thermal power plants in India, where it suffers one or more types of wear. The as-sprayed coatings were characterized by XRD and SEM analyses. Subsequently, the sliding wear behaviours of the uncoated, HVOF spray Al 2 O 3 + (40%)TiO 2 and Cr 2 O 3 coated AISI 309 SS were investigated according to ASTM standard G99-03 on a pin-ondisc wear test rig. Cumulative wear rate and coefficient of friction (μ) were calculated for the coated as well as the uncoated specimens for 30, 50, and 70 N normal loads at a constant sliding velocity of 1 m/s. Some of the worn-out surfaces were characterized by SEM analysis. Both the as-sprayed coatings exhibited typical splat morphology of a thermal spray process. The XRD analysis indicated the formation of Al 2 O 3 and TiO 2 phases for the Al 2 O 3 + (40%)TiO 2 coating, and Cr 2 O 3 phase for the Cr 2 O 3 coating. It has been concluded that HVOF spray Al 2 O 3 + (40%)TiO 2 and Cr 2 O 3 coatings can be useful in minimizing the wear problem of AISI 309 SS. These coatings were found to be successful in retaining their surface contact with the substrate after the wear tests. The HVOF spray Cr 2 O 3 coating can be recommended as a slightly better choice to reduce the wear of AISI 309 SS in comparison with the Al 2 O 3 + (40%)TiO 2 coating.

In the present work, the artificial aging kinetics of SiCp particles reinforced AA7075-SiCp composite fabricated by stir casting method was investigated. The aging behavior of AA7075-SiCp composite was investigated by Rockwell hardness tests and differential scanning calorimetry (DSC). Results show there are no changes in the sequences of formation and dissolution of precipitate. Reinforced particles are uniformly distributed throughout the matrix. The hardness profile shows increase in hardness with the comparison of AA7075 base alloy. In addition to SiCp in the matrix, precipitation kinetics has changed compared with base alloy since higher dislocations present in composite, hence requires lower activation energy to form ή precipitate and takes less time to reach the maximum hardness. In contrast, the addition of SiCp at low volume percent also showing accelerated aging phenomena in the composite during the aging process. High-resolution transmission electron microscope (HRTEM) micrograph of peak age (T6) condition divulges that enormous fine and plate-like ή (MgZn2) precipitates are uniformly distributed in the composite.

In the present work, the artificial aging kinetics of SiCp particles reinforced AA7075-SiCp composite fabricated by stir casting method was investigated. The aging behavior of AA7075-SiCp composite was investigated by Rockwell hardness tests and differential scanning calorimetry (DSC). Results show there are no changes in the sequences of formation and dissolution of precipitate. Reinforced particles are uniformly distributed throughout the matrix. The hardness profile shows increase in hardness with the comparison of AA7075 base alloy. In addition to SiCp in the matrix, precipitation kinetics has changed compared with base alloy since higher dislocations present in composite, hence requires lower activation energy to form ή precipitate and takes less time to reach the maximum hardness. In contrast, the addition of SiCp at low volume percent also showing accelerated aging phenomena in the composite during the aging process. High-resolution transmission electron microscope (HRTEM) micrograph of peak age (T6) condition divulges that enormous fine and plate-like ή (MgZn2) precipitates are uniformly distributed in the composite.