High productive machining of C/SiC preceramics

Abstract High productive machining of C/SiC preceramics is investigated in relation to the fabrication of complex‐shaped reaction‐bonded silicon carbide ceramics. Machinability is analyzed at different manufacturing steps of ceramics preparation. Machining after the carbonization step is shown to be the most efficient. Great value of material removal rate of 360 mm ³ /s is achieved by high productive CNC‐milling of carbonized preceramics at a feed rate of 50 mm/s without any defects upon the processed surfaces, edges, and corners. Diamond tool wears approximately .01% (weight loss per mass of material removed) in the process of green CNC‐milling is two orders lower compared with the milling of sintered ceramics (2.8%). Specifics of surface processing are investigated depending on carbon content in preceramics. The increase of bonding carbon from 8 to 16 vol.% decelerates loose abrasive grinding three times, improves the accuracy of surface leveling, and leads to a change of fracture mechanism. The obtained results can be helpful for the advantageous manufacture of complex‐shaped silicon carbide ceramics.