The Development And Performance Of Chemical-Mechanical Grinding Tools For Al₂O₃ Ceramics

Al2O3 ceramics with high hardness (The Mohs hardness is 9), high temperature resistance, corrosion resistance, wear resistance, have gained more and more applications in high-tech field such as energy sources and space technology, etc. The ceramics parts which were used as nuclear main pump seal rings, spacecraft nozzles, combustor liners, jet engine blades and so on, working in harsh environments with high temperatures, high pressure and corrosion. The harsh conditions demand the parts must have high machining accuracy, low surface roughness and no surface/subsurface damage. However, Al2O3 ceramics is a typical hard and brittle material that is difficult to process. Serious surface and sub-surface damages are raised when machined with traditional diamond grinding wheel. And if the chemical mechanical polishing is applied to remove the damages, it may raise many problems like low processing efficiency, high processing costs, alkaline or acidic slurry.In this paper a new method named Al2O3 ceramic chemical-mechanical grinding processing was proposed to solve these problems. By this method, Al2O3 ceramic could gain better precision and high processing efficiency. The main content and conclusion are shown as follows:(1) Based on the new method of chemical-mechanical grinding processing, the chemical composition of the grinding tools was selected and optimized combined with considering the physicochemical characteristics of Al2O3 ceramics. The mold of the chemical-mechanical grinding tools was developed and the constant loading grinding equipment was established on the CJK6145 lathe. The dressing method and the preparation of the chemical-mechanical grinding tool were developed.(2) The grinding performances of the three chemical-mechanical grinding tools (SiO2, MgO, Fe2O3) were studied, including surface roughness and the material remove rate. And the 3D Optical Profiler,3D Topography Instrument and Optical microscope were applied to detect surface topography, surface damage. The results showed that the SiO2 grinding tools had the best effect, and with which the surface roughness Ra of Al2O3 ceramics was reduced from 1063nm to 28nm. The next was the MgO grinding tools. It achieved a roughness of Ra 54nm. The worst was the Fe2O3 grinding tools with the roughness Ra 200nm. (3) The chemical compostition on the grinded surface were analyzed by EPMA. The material removal mechanism could be explained as chemical and mechanical coupling action. The formulation of chemical-mechanical grinding tools was advanded basded on the material removal mechanism. It achieved higher removal rate.