Processing Damage on the Surface of Engineering Ceramics

Due to the combined effect of thermal stress and machining stress in grinding engineering ceramics, the ceramic surface/sub surface processing damage will be caused, and the surface performance, Fracture toughness and Flexural strength will be reduced, which will affect the reliability of parts.

Classification of Surface Damage in Engineering Ceramic Processing

According to the shape characteristics of surface damage defects in engineering ceramics after grinding, these defect features can be divided into four categories: cracks, fragmentation, pores, and scratches.

(1) Surface crushing defects. There are many reasons for the broken surface defects of ceramic materials, which can be roughly divided into the factors introduced in the processing process, such as the generation of amorphous layer, stress, Thermal shock, etc; In addition, the damage introduced during the material preparation process, including inherent defects such as pores, inclusions, and delamination, further expands and forms the fracture surface during the processing due to various reasons.

(2) Surface crack defects. For grinding cracks, the surface formation process can be seen according to the grinding mechanism of engineering ceramics and the experimental research results. The material removal methods can be divided into brittle fracture removal, powder removal and plastic removal. Due to different material characteristics and processing conditions, such as strength, hardness, Fracture toughness, and abrasive cutting depth, machining crack defects will be more or less left on the ceramic machining surface.

(3) Surface porosity defects. Pore defects are defects formed in ceramic materials during the embryo production process due to the influence of bubbles, impurities, and other factors. When observed under a microscope, the outline of the broken defect is similar, but the color is darker than that of the broken defect. This is because the interior of the pores is generally relatively deep, making it difficult to reflect light.

(4) Surface scratch defects. The surface of the grinding wheel is not smooth. The surface shape of the specimen is very obvious, and these concave areas leave scratches on the surface of the specimen due to insufficient material removal during the grinding process.

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