Machining of TiB<sub>2</sub>- SiC Ceramic Composites through WEDM Process

Abstract

In the present study Spark Plasma Sintering (SPS) technique is used to synthesis of particulate Ceramic Matrix Composites (CMCs). SPS is a type of hot pressing method and in this method, the rate of heating is from 100C to 1000C per minute with high densification. TiB2 (average size of 14 μm) particles were chosen as matrix and SiC (average size of 1 μm) particles were used as reinforcement. In the first stage of the study, synthesis of CMCs with TiB2 matrix and SiC reinforcement with varying volume% (0, 5, 10 and 15 vol.%) was carried out using Spark Plasma Sintering furnace available at IIT Madras in 1100°C, 40MPa and 10 min hold of time. But machining of CMCs from conventional machining processes is difficult especially to make complex and precise parts from CMCs. Hence, in the second stage of the work, Wire Electric Discharge Machining (WEDM) studies were carried out on the processed four composites by varying current (2, 3 and 4 A), Pulse on (Ton-30, 60 and 90 μs) and Pulse off time (Toff-5, 10 and 15 μs) as per Taguchi L9 orthogonal array. WEDM studies revealed that at 4A current, 60μs Ton and 5μs Toff gave maximum material removal rate (MRR) of 2.93 mm3/s, 2.27 mm3/s, 2.71 mm3/s and 0.62 mm3/s for CMC with 0% SiC, 5% SiC, 10% SiC, 15% SiC vol.% reinforcement respectively. To reduce material wastage during machining, kerf width is considered and in which 3A current, 90μs Ton and 5μs Toff gave the least kerf of 0.35 mm, 0.32 mm, 0.33 mm and 0.28 mm for 0% SiC, 5% SiC, 10% SiC, 15% SiC vol.% reinforcement respectively.