In this research work, development of a multi-response optimization technique was performed, using Genetic Algorithm (GA) optimization technique in wire electrical discharge machining (WEDM) keeping in mind about the priorities of multiple users. Boron carbide has been selected as work piece for experiment. The effect of five process parameters such as pulse on time (Ton), pulse off time (Toff), peak current (IP), water pressure (WP), servo feed (SF), were investigated on the responses such as machining speed and surface roughness (Ra) in WEDM operation. Further, two responses were modeled empirically through regression analysis. The developed models can be used by the machinists to predict the machining as well as the surface characteristics over a wide range of machining input parameters. The analysis of variance (ANOVA) is also applied to investigate the effect of influential input parameters. Finally, the confirmation experiments were conducted with optimal set of machining parameters and minor deviations have been found.

Magnesia doped multiwalled carbon nanotube (CNT)/alpha-alumina nanocomposites have been fabricated by spark plasma sintering at 1500 degrees C under 50 MPa in argon. Owing to combined grain refining effect of nanotube and magnesia, nanocomposites possessed smaller matrix grains and extensively lower matrix crystallites than pure alumina. Thermal expansion mismatch between matrix and filler rendered up to four times higher compressive lattice microstrain to the nanocomposites over pure alumina. Despite very low CNT loading (e.g. 0.13 wt-%), nanocomposites offered considerably higher hardness (as high as 24.42 GPa), negligible indentation size effect (Meyer exponent = 1.906-1.941) and enhanced elastic response over pure alumina. Up to 0.27 wt-% nanotube loading, much higher wear resistance was observed for the nanocomposites over pure alumina. The presence of uniformly dispersed and structurally intact nanotubes coupled with lower matrix grains and crystallites having compressive lattice strain were the key factors behind achieving such improved mechanical properties of the present nanocomposites.