单晶锗纳米尺度二次划痕特性

现有的单一划痕法磨削机理研究不能反映多个磨粒随机分布所引起的多次划痕之间的相互作用,为了阐明单晶锗磨削过程中多次划痕相互作用对材料去除机理的影响,采用Cube压头对单晶锗进行了不同刻划力的多次刻痕实验。结合Cube压头的几何形状与刻划表面的弹性回复,建立了划痕硬度模型,并对二次刻划中的划痕深度、应力场、弹性回复率、划痕硬度和摩擦特性进行分析,研究第一次刻划时载荷变化对于后续刻划的影响。结果表明:随着第一次刻划载荷的增大,二次刻划时单晶锗的脆塑转变的临界载荷、临界深度、弹性回复率和划痕硬度均在减少,幂函数对于切向力、法向力与刻划深度的拟合准确度降低;最大主应力增加,导致裂纹不断扩展,最终造成材料发生脆性断裂。

Experimental study of nanoscale secondary scratch characterization of single-crystal germanium

Existing studies on the grinding mechanism of single-scratch method cannot reflect the interaction between multiple scratches induced by the random distribution of multiple abrasive grains. In order to elucidate the effect of the interaction of multiple scratches on the material removal mechanism during the grinding process of single-crystal germanium, multiple-scratch experiments were carried out on single-crystal germanium with different scratching forces using a Cube indenter. Combining the geometry of the Cube indenter and the elastic recovery of the scribed surface, a scratch hardness model was established, and the scratch depth, stress field, elastic recovery, scratch hardness, and friction characteristics in the second scratching were analyzed to investigate the effect of the load change during the first scratching on the subsequent scratching. The results show that: the critical load, critical depth, elastic recovery rate and scratch hardness of the brittle-plastic transition of single-crystal germanium in the second scratching decrease with the increase of the first scratching load; the accuracy of the power function fit to the tangential and normal forces and the depth of scratching decreases; and the maximum principal stress increases, which results in the continuous expansion of cracks and ultimately causes brittle fracture of the material. These findings provide important insights into the mechanics of grinding hard and brittle materials.