This paper is aimed at addressing the difficulty in machining ceramic matrix composites(CMCs).The study is performed by conducting a continuous surface grinding tests on different lengths by 300 mm and 500 mm to analyze the typical damage characteristics;comprehensively evaluating the machined surface morphology by using 3D surface roughness parameters:Sa,Sz,Ssk,Sku,Sdr,and Sbi;and systematicly studying the quality stability of the continuous surfaces with different machined lengths.The results show that the effective length after grinding exceeds 70%,yet peeling and overcut damages occur randomly.Peeling damage is due to the low bond strength at the coating-composite interface,while overcut damage is caused by minor angular errors between the ideal machined surface and the fiber braid layers.Both peeling and overcut damages can lead to the exposure of porosity in the CMC layers,the damage to surface integrity and the effect on surface gas tightness;however,there's no pore defect expan-sion due to machining.Excluding the aforementioned damaged areas,the machined surface is smooth and flat,presenting a mirror-like state that can offer better load-bearing capacity and lower fluid obstruction.There is no significant difference in surface quality stability between 300 and 500 mm machining lengths,but the surface roughness values Sa and Sz of the machining length by 500 mm due to the different tool wear are higher than that of machining length of 300 mm.
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