Research On Precision Grinding Subsurface Damage And Prediction Of Silicon Carbide Ceramic

With the development of space optical technology, the material of largediameter aspheric space optical mirror are made for more stringent requirements.Silicon carbide ceramic with its excellent mechanical properties becomes thepreferred material for space mirrors. Diamond wheel grinding is the main way ofcurrent forming processing of SiC. Subsurface cracks of grinding are generateddue to high hardness and brittleness of the material. In order to eliminate theinfluence of cracks on the workpiece, the inefficient polishing process is used,which makes the processing cycle become longer. Therefore in the process ofgrinding research and control the depth of silicon carbide ceramic subsurfacecracks and shorten the processing cycle are very meaningful.In this paper, diamond Vickers indenter is used to indentation and scratch testto simulate wheel single grain grinding process. Vickers hardness and fracturetoughness of silicon carbide ceramic material are obtained. Analyze the way ofmaterial removal in the grinding process. The ion beam cross-section polishingtechnique is used to observe the characterization of indentation and scratchsubsurface cracks. Analyze the influence of subsurface indentation load forindentation crack depth and the influence of the scratch depth for sub surfacecracks depth.Though ion beam cross-section polishing the silicon carbide ceramic grindingsubsurface cracks information are observed. Propose broken surface layer depth,the maximum depth of subsurface cracks, cracks distribution in the depth directionand the crack density comprehensive evaluation method of grinding subsurfacecracks. Conduct a silicon carbide ceramic grinding experiment. Analyze theinfluence of the spindle speed, feed rate and depth of grinding for the grindingsurface broken layer depth, the maximum depth and subsurface cracks and cracksdensity of the silicon carbide ceramic, and the influence of grinding parametersfor the subsurface cracks on the depth distribution. Optimize the grindingparameters to get the best grinding subsurface quality.Fixed a scale model of the subsurface cracks grinding depth and surfaceroughness from the study of single grain grinding subsurface crack sizecalculation model. On the basis of above, a prediction model of silicon carbideceramic grinding subsurface crack depth is established. Though measuring thesurface roughness and the grinding parameters to predict the subsurface crackdepth. Conduct the silicon carbide ceramic grinding experiment. Verify thecorrectness of the prediction model by contrast subsurface crack depth predicted and experimental values.