Study On Lapping Mechanisms Of Silicon Carbide Ceramic Balls

Silicon carbide is a kind of ceramics with optimum combination of properties, such as low density, low coefficient of thermal expansion, high hardness, high elastic modulus, resistance to high temperature, and resistance to corrosion, etc. and extensively applied in ceramic ball bearings, ball plug, gyro and measuring devices etc. Silicon carbide balls have irreplaceable application in some fields. However, because of its inherent brittleness, machining silicon carbide is quite difficult and the manufacturing cost is very high, that limits it application in varies fields. It can be known that above 90% removals is happen in lapping process, which is a key process of machining. The improving of final roundness and surface quality are much relative to this process. So this study is focused on lapping process to explore the removal mechanisms.A serial of tests were conducted on silicon carbide (SiC), silicon nitride (Si₃N₄), zirconium oxide (ZrO₂) and aluminum oxide (Al₂O₃) ceramic balls to explore the effects of mechanical properties and microstructures on the ceramic ball lapping. The results are as follows: Hardness and fracture toughness have influences on material wear, but can't control wear, which is also effected by the material microstructure. Under the same lapping conditions, the material removal rate of silicon carbide ball is the highest, and the roundness and the surface quality are most difficultly controlled.The lapping tests of silicon carbide balls were carried out to systematically analyze the influences of lapping speed, load, fluids, and abrasive on lapping process. The reasonable lapping process and parameters can be fixed as follows: (1) The lapping fluid can be chosen as water-based fluid; (2) The lapping loads in the primary lapping and the fine lapping can be controlled as 12N/ball and 9N/ball respectively; (3) The rotational speeds in the primary lapping and the fine lapping are chosen as 32r/min and 20r/min respectively; (4) the abrasives in the primary lapping and the fine lapping...