SiC单晶刻划过程的脆塑性转变特征研究

Research on Transition Characters of Plastic and Brittle for Scribing SiC Single Crystal

SiC单晶化学性能稳定、导热系数高、热膨胀系数小、耐磨性能好,广泛用于大功率器件产业。但由于其材料的硬度很大,加工非常困难。脆性材料塑性域加工为提高该类材料的表面质量,降低加工时间和成本提供了有效的途径。本文采用不同刀具角度和刀尖圆弧半径的单点金刚石刀具对4H-SiC单晶进行刻划实验,利用声发射、摩擦力传感器来监测刻划过程中声发射信号强度以及摩擦力的变化,并通过LeicaDCM3D以及SEM观察划痕沟槽表面形貌、切屑状态,综合分析以获得4H-SiC单晶在不同角度、刀尖圆弧半径下塑脆转变的临界切削深度。结果表明,增大刀具角度有利于塑性域加工;在相同条件下,刀尖圆弧半径越大,临界切削深度越大。

Silicon carbide single crystal is widely used in high-power devices industry due to its chemical inertness, high thermal conductivity, small thermal expansion coefficient, good wear resistance.However,it is difficult to process because of its high hardness.In recent years,ductile regime machining of brittle materials has made significant progress,proved which is an efficient method to machine brittle materials.In this paper,six single point diamond tools with different included angle and radius are used to make scratching experiments on SiC single crystal wafers.Acoustic emission and friction sensor are used to monitor the intensity of acoustic emission and the change in friction during the experiments.In order to study the critical depth of cut in different included angles and radiuses,comprehensively using Leica DCM3 D and SEM to observe surface morphology and chip state.The results show that larger included angle is good to ductile regime machining,and the critical depth of cut is higher for a larger tool nose radius.