陶瓷生坯边位压裂纹的产生与扩展规律

Crack Formation and Propagation of Green Ceramics by Edge-indentation

为揭示陶瓷生坯切削加工过程中的材料去除机理及其裂纹扩展特性,利用冷等静压成型技术制备出氧化铝陶瓷生坯,通过边缘位压试验研究切屑成型、裂纹产生和扩展规律。结果表明:在较小位压宽度时,切屑形成主要为压碎方式,载荷波动相对较小;在较大位压宽度时,主要是由裂纹扩展而形成的大块切屑为主,载荷存在规律性波动。裂纹扩展路径受刀具楔角和印压厚度的影响,在较小刀具楔角时(≤35°),裂纹主要沿着圆弧扩展,当刀具楔角增大时(≥45°),裂纹扩展路径先沿直线扩展后沿圆弧扩展到表面;切屑长度随着印压宽度的增大逐渐增大,但印压宽度≥1.5mm时,切屑长度与印压宽度的比例关系基本维持在1.6左右。

To reveal the material removal mechanism and crack propagation during the cutting process of green ceramics.The alumina green ceramics are prepared by cold isostatic pressing technology,and chip forming,crack generation and propagation are studied by edge-indentation tests.The results show that when the width of edge-indentation is small,the formation of chips is crushing mode,and the load fluctuation is relatively small.When the width of edge-indentation is larger,the chips are mainly formed by crack propagation,and the load fluctuation is larger.The crack propagation is affected by tool wedge angle and width of edge-indentation.The crack propagates mainly along the arc at smaller tool wedge angle(≤35°),and with the increase of tool wedge angle(≥45°),the crack propagation path extends first along a straight line and then along an arc to the surface.The chip length increases with the increase of the width of edge-indentation.But,when the width is≥1.5 mm,the ratio of chip length with width of edge-indentation basically maintains at about 1.6.