Experimental Study On Grinding Of SiC_f/SiC Ceramic Matrix Composites

SiC_f/SiC is a composite material formed by adding braided SiC fibers inside SiC ceramics.Compared with traditional SiC ceramics,in addition to maintaining high temperature stability and wear resistance of SiC,SiCf/SiC also has higher impact toughness,flexural strength and oxidation resistance,and is widely used in aero-engines,nuclear reactors and other cutting-edge Equipped with high temperature components.The high hardness and toughness of SiC_f/SiC also make the manufacturing process difficult and the processing cost is high.It requires a diamond grinding wheel with higher hardness to process it.Grinding is currently the main method for processing SiCf/SiC composites,but due to the anisotropy of SiCf/SiC composites,it is further difficult to process with high efficiency and low damage.In this paper,aiming at the high-efficiency grinding process of SiC_f/SiC ceramic matrix composites and reducing the surface damage,the formability manufacturing process of the interaction of factors such as grinding wheel structure,abrasive wear,grinding process and stress-strain field is integrated.The grinding mechanism and damage mechanism of SiC_f/SiC are studied through experiments.The main contents are as follows:(1)Using the existing horizontal precision air-floating grinder,according to the needs of2.5DSiCf/SiC grinding experiments,design appropriate fixtures and process them,build a SiC_f/SiC rotary grinding experimental platform,and realize real-time grinding force.Measurement and multi-fiber orientation processing of SiC_f/SiC.(2)SiC_f/SiC has the same high-speed toughening effect as SiC ceramics.In this paper,the single factor test method is used to carry out the SiCf/SiC grinding test to study the influence of grinding parameters on the grinding force.Less affected;(3)Experiments were carried out to study the influence of grinding wheel speed,feed speed and grinding depth on the surface roughness.It was also found that the surface roughness increased with the increase of grinding depth and feed speed.(4)The surface after grinding was observed,and the differences in the removal mechanism of fibers in the transverse,longitudinal and normal directions were discussed,and the surface damage mechanism and material removal mechanism of SiC_f/SiC were revealed.It can be seen from the observation of the micro-morphology of the material that under the larger feed rate and grinding depth,the fibers and matrix debris are more,and the fiber surface adheres to the matrix more,and the surface quality is poor.Under the feed speed and grinding depth,the fiber and matrix debris are smaller,the fiber surface is relatively smooth,and the surface quality is better.(5)In this paper,resin-bonded diamond grinding wheel was used to grind SiC_f/SiC ceramic matrix composites,and the change of abrasive grain morphology on the surface of grinding wheel was observed by confocal microscope before and after the test.It was observed that after the grinding test,the tip of the abrasive grains showed signs of being smoothed,and some abrasive grains had peeling marks on the surface.After abrasive wear,the height is reduced by about 10%,but it does not affect the use of the grinding wheel and the effect of machining the workpiece.In this paper,the grinding mechanism of SiC_f/SiC ceramic matrix composites is revealed,and the grinding removal mechanism of SiCf/SiC is clarified,which has a certain effect and value on the optimization of grinding process parameters.It is of great significance and value to strengthen the application of SiC_f/SiC ceramic matrix composites and improve national defense capabilities.