| Hot machining has been applied to the turning of extremely hard metals. Ceramics materials have been traditionally formed to near net shape and fired. If finer tolerances are required, then the fired part is ground. The cost of the grinding operation is expensive, up to 90% of a parts total costs are grinding costs. Previous attempts to use lasers for hot machining of ceramics by carbon dioxide lasers have resulted in severe degradation of material properties. Carbon dioxide and Nd:YAG laser assisted machining of ceramics were evaluated based on the physics, materials, and mechanics of the process to determine the feasibility of the process. These factors were also evaluated to determine the limitations of carbon dioxide and Nd:YAG laser assisted machining and candidate materials. Nd:YAG laser assisted machining of silicon nitride experimentally produces a surface finish of 0.3 micrometers. The structure of hot isostatic pressed silicon nitride is grains of beta silicon nitride separated by intergranular silica SiO... |
