Study On SiC Scratching With Single Diamond Grain

Silicon carbide, include SiC ceramics and single crystal SiC, has increasinglywide applications in many fields due to its excellent properties. Both SiC ceramicsand single crystal SiC are required with high quality machined surface in their actualtechnical application. However, the high hardness and high brittleness of SiC is theone of the main obstacles for its wide application. Processing with diamond tools hasbecome the main way to machine the SiC.In this paper, theoretical analysis and experimental research about SiC ceramicsand single crystal SiC has been scratch with the different taper single diamond. Thescratch length and scratch volume had been theoretical calculated throng thekinematic analysis. Scratch force and acoustic emission (AE) signals were measuredunder various machining conditions. The actual scratch length and scratch volumewith different conditions were obtained with3D-video system. The influence ofmachining parameters on the actual scratch length and scratch volume are analyzed.Contrast the scratch forces, AE information and scratches for two different siliconcarbides, the mechanism of brittle removal process was investigated.The main findings are summarized as follows:(1) The scratch force signal curves are not symmetric distribution with thescratching profile. There are obvious oscillations on the curves of normal forcesignals. The scratch forces increase with the scratch depth, but decrease with thescratching velocity. However, the table speed has little influence on the scratch forces.The scratch forces are also increase with the diamond grain taper.The scratch forceshave relation with the theoretical plowed surface area.The scratch forces for thesingle crystal SiC are greater than those of the SiC ceramic.(2) For the two SiC materials, the AE signals such as the ring counter, the energy,the duration time, and signal strength increase with the scratch depth. It is difficult tofound the obviously relationship between the machining parameters with the AEsignals, although there are greater volatility of the AE signals. (3) Scratch depth is the key factor to impact on scratch length, which the othermachining parameters have little influence. Scratch volume will vary with thediamond taper angle and the workpiece material with the similar scratch length. Thescratch volume of single crystal SiC is significantly larger than that of SiC ceramics.(4) The grain boundaries in the SiC ceramic could weak the brittle crackextension in the scratch process.The results of this paper would provide a further understanding of the removalmechanism of silicon carbide.