不同圆角半径金刚石划擦单晶SiC过程中的材料去除机理研究

The Material Removal Mechanism of Monocrystal Si C Scratching by Single Diamond Grit with Different Tip Radius

以单晶碳化硅(Si C)作为加工对象,通过不同尖端圆角半径的圆锥型金刚石磨粒划擦试验观察了单晶Si C的去除过程,并采用FEM与SPH耦合算法模拟仿真了三种不同尖端圆角半径的单颗磨粒划擦Si C过程中的材料去除过程,试验结果与模拟结果基本一致。在此基础上,采用仿真手段从最大等效应力和接触力的角度分析了三种不同尖端圆角半径对单晶碳化硅材料脆塑转变过程材料去除机理的影响。仿真结果表明:随着尖端圆角半径的增加,弹塑性变形-塑脆临界的转变点趋近于0.14μm,而且纯粹的塑性变形模式逐渐消失;脆塑临界去除模式所占的区域逐渐变长,由脆塑临界-脆性去除的转变点的深度也在不断变深;脆塑转变过程中的微裂纹的长度及粗细程度逐渐增加,材料破坏的形式也逐渐升级。

To achieve the ductile processing of monocrystalline carbide, the scratching experiments for monocrystalline silicon are carried out with diamond grits in different tip radius. Based on the experiment results, the brittle-ductile transition of single monocrystalline silicon carbide on scratching with a cone-shaped diamond grain in different tip radius is simulated by the method of coupling FEM and SPH. The simulation results are found to be basically in conformance with the results of the experiment. The influence of brittle-ductile transition on three different tip radius are discussed. The results show that the grinding process of monocrystalline silicon carbide can be divided into three stages-flexible and plastic processing, brittle-ductile transition processing, brittle processing. With the increase of tip radius, the critical depth from elastic-plastic deformation to ductile-brittle transition tends to be 0.14 microns, and pure plastic deformation mode gradually disappears. The region of ductile-brittle transition become longer, and the critical depth of ductile-brittle transition to brittleness removal mode are deeper. The length and thickness of micro crack in ductile-brittle transition increase gradually, and the form of material damage also gradually upgrade.