【作者】 程晓亮；

【导师】 王扬； 杨立军；

【作者基本信息】 哈尔滨工业大学 ， 航空宇航制造工程， 2020， 博士

【摘要】 陶瓷材料优良的力学、热学、电学、光学等性能,使其在高新技术行业和先进制造领域占据着不可替代的作用。然而,陶瓷材料的硬度高、熔点高及脆性大等固有特点,又使其在切割加工过程中易出现表层和亚表层损伤及切缝处的热损伤等缺陷问题。热裂法切割以其无材料去除、断面质量好、损伤小等加工特点,逐渐被应用于切割玻璃、陶瓷等硬脆性材料。然而,目前国内外学者在采用面热源进行陶瓷材料的热裂法切割时,尚存在裂纹扩展机制不明晰、缺乏轨迹控制研究和加工能力不足等问题。因此,本文采用微波面热源热裂切割微波低吸收率陶瓷材料及利用激光面热源热裂切割硅晶圆材料,开展面热源热裂法切割陶瓷材料的裂纹扩展机制、裂纹轨迹修正与控制、面热源加工能力和断面质量等理论及试验研究。本文以硅晶圆和微波低吸收率陶瓷材料为主要研究对象,分别建立了适用于热裂法切割这两种材料的面热源模型。建立了面热源加热陶瓷材料的有限元模型,通过面热源加热陶瓷材料测温试验验证了有限元模型的准确性。仿真分析了面热源作用下两种材料的温度场和应力场的分布特征。基于面热源作用下温度场仿真及其分布特征的分析,发现最高温度区域深度对材料表面和深度方向的温度梯度有重要影响。基于面热源作用下应力场仿真及其分布特征的分析,发现面热源作用下的最大压应力区深度对其前后方的拉应力区梯度和深度有重要影响。在面热源加热陶瓷材料有限元模型的基础上,建立了单面热源热裂切割陶瓷材料有限元模型。进行了微波单面热源热裂切割微波低吸收率陶瓷裂纹扩展的仿真和试验,结果表明微波单面热源作用下工件上下表面裂纹扩展轨迹不一致。结合断裂力学理论,分析了单面热源作用下的裂纹轨迹偏移机制;提出了微波限定性吸收方法修正裂纹轨迹偏移;通过仿真和试验研究验证了该方法的有效性,并揭示了微波限定性吸收方法修正裂纹轨迹偏移和裂纹扩展机制。探讨了微波限定性吸收方法对断面质量影响规律。研究表明,单面热源热裂切割陶瓷材料,容易出现不稳定的裂纹扩展模式。针对单面热源作用下的裂纹扩展问题,提出了微波双面热源热裂切割陶瓷材料方法。进行了双面热源加热陶瓷材料温度场仿真,结果表明双面热源作用下90%以上的扫描段形成了类似于体热源的加热形式。然后,进行了微波双面热源作用下陶瓷材料应力场和裂纹扩展仿真。基于此,探究了双面热源作用下的裂纹起裂机理和扩展模式。分析了裂纹前缘应力分布特征,揭示了双面热源作用下可获取高裂纹扩展质量的原因。通过双面热源切割陶瓷试验,对比分析了双面热源热裂相对于单面热源热裂切割的优势,并研究了微波功率和切割速度对双面热源作用下裂纹偏移扩展、断面质量的影响。研究表明,微波双面热源加热方式可实现8 mm厚度氧化铝陶瓷高质量的切割。相对于单面热源,大大提高了面热源的加工能力。针对激光面热源切割硅晶圆,开展了热裂法切割硅晶圆轨迹控制和断面质量优化的研究。进行了端部预制裂纹的切割试验研究,发现非对称切割条件下存在裂纹偏移扩展的问题。基于热裂切割仿真,揭示了非对称切割条件下的裂纹偏移机制。针对端部预制裂纹方法中出现的轨迹偏移问题,进行了表面预制裂纹热裂切割试验和仿真研究。提出了表面预制裂纹与面热源反向的加热方法,发现该方法可改变常规方法下的裂纹扩展模式并获得轨迹无偏移效果,揭示了该方法产生裂纹无偏移扩展的机制。开展了反向加热方法下的非对称切割硅晶圆的工艺试验,探究了激光功率、预制裂纹槽深和槽宽、激光扫描速度对切缝质量的影响,并提出了获得较高切缝质量的工艺策略。更多还原

【Abstract】 For its excellent mechanical,thermal,electrical and optical properties,ceramics play an irreplaceable role in high-tech industry and advanced manufacturing field.However,due to the material property of high hardness,high melting point and brittleness,it tends to result in the mechanical damage in surface and sub-surface of the workpiece material or the thermal damage in the cutting kerf.With the characteristics of no material removal,good section quality and small damage,thermal-cracking cutting method is gradually applied to cutting hard and brittle materials such as glass and ceramics.However,there are still some problems such as insufficient processing capacity,indeterminacy of crack propagation mechanism and lack research of trajectory control when using surface heat source to cut ceramic materials.Therefore,in this paper,we use microwave surface heat source to cut ceramic materials with low absorptivity for microwave and laser surface heat source to cut silicon wafer materials to do some theoretical and experimental research on crack propagation mechanism,crack trajectory revising and controlling,processing capacity and section quality in surface heat source cutting ceramic materials.In this paper,the surface heat source models for cutting silicon wafers and ceramics with low absorption for microwave were established respectively.The finite element models of surface heat source heating ceramic materials were established,and the accuracy of the finite element models were verified by heating ceramics experiments.The distribution characteristics of temperature field and stress field of the two materials under the action of surface heat source were simulated and analyzed.Based on the simulation results of temperature field and the analysis of its distribution characteristics,it is found that the depth of the highest temperature region has an important influence on the temperature gradient along the surface and the depth direction of material.Based on the simulation results of the stress field and the analysis of its distribution characteristics,it is found that the depth of the maximum compressive stress zone has an important influence on the gradient and depth of the tensile stress zone before and after the surface heat source.A thermal-cracking model of cutting ceramics was established based on the finite element model of heating ceramic material with single surface heat source.The simulation and experimental research on the thermal-cracking of ceramics with low absorption for microwave by using microwave surface heat source were carried out.It is found that the crack-propagation paths on the upper and lower surfaces of the workpiece is inconsistent under the action of single surface heat source.Combined with fracture mechanics theory,the deviation mechanism of crack propagation under single surface heat source was analyzed,and a microwave limited absorption method was proposed to revise the offset of crack-propagation path.The effectiveness of this method was verified by simulation and experimental research.The mechanism of microwave limited absorption method revising the offset of crack-propagation path is revealed.The influence of microwave limited absorption method on section quality was discussed.This research showed that the unstable propagation mode tends to appear in thermal-cracking of ceramics with single surface heat source.In order to solve the problems on crack propagation in single surface heat source cutting method,thermal-cracking method with dual surface heat source in microwave cutting ceramic material was proposed.Through the simulation of the temperature field of heating the ceramics by dual surface heat source,it is found that more than 90% of the scanning section forms a heating type similar to the volume heat source.Then,based on the stress field and crack propagation simulation,the crack initiation mechanism and propagation mode were explored.The stress distribution characteristics of crack front edge were analyzed,and the reason for high crack-propagation quality under the dual surface heat source was revealed.Through the cutting experiment,the advantages of dual surface heat source over single surface heat source were analyzed,and the influence of microwave power and cutting speed on the deviation propagation of cracks and the crosssection quality under the action of dual surface heat source were studied.The experimental results showed that microwave cutting of 8 mm thick alumina ceramics with high-quality can be achieved by dual surface heat source.The processing capacity of the surface heat source is greatly improved by using dual surface heat source.The research on controlling the crack-propagation path and the optimization for the quality of cross section in cutting silicon wafer with laser surface heat source are carried out.It is found that the crack-propagation tends to deviate from the ideal path in asymmetric cutting mode when the pre-crack is on the end of workpiece.Based on the cutting simulation,the deviation mechanism for crack-propagation under the condition of asymmetric cutting was revealed.The simulation and experimental research on thermalcracking method with pre-crack on the surface of workpiece were carried out to solve the problem of trajectory deviation in the method of pre-crack on the end of workpiece.The method of surface heat source is on the reverse side of surface pre-crack was proposed.It is found that the method can change the crack propagation mode under the conventional method and obtain the effect of non-offset propagation.The mechanism of non-offset crack propagation was revealed.The experiment research on asymmetric cutting silicon wafer based on the method of heating the reverse side of surface pre-crack were carried out.The effect of laser power,depth and width of the pre-crack groove,and laser scanning speed on the kerf quality of silicon wafer were studied.The technological strategy to obtain high quality of cutting kerf was put forward.更多还原