【作者】 丁代存；

【导师】 赵军；

【作者基本信息】 山东大学 ， 机械制造及其自动化， 2005， 硕士

【摘要】 本文以Si₃N₄为基体,以纳米TiC为增韧补强相,以材料的力学性能为优化目标,研制成功了一种纳米复合陶瓷刀具材料Si₃N₄/TiC_（nano）（以ST表示）。并对其烧结性能,力学性能,摩擦磨损性能以及刀具的切削性能进行了研究。ST陶瓷刀具的力学性能参数为:抗弯强度为920MPa,断裂韧性为7.2MPa·m^1/2,维氏硬度为16.8GPa。本文还以Si₃N₄/TiC_（nano）纳米复合陶瓷材料为例,研究了纳米复合陶瓷材料的增韧机理。 研究了ST系列纳米复合陶瓷刀具材料的制备工艺,纳米TiC的含量对陶瓷刀具材料的微观结构和力学性能的影响,研究了烧结助剂含量对材料的烧结性能、力学性能和微观结构的影响规律;对烧结温度、烧结时间等工艺参数对材料力学性能、微观结构和致密度的影响进行了分析。 从Si₃N₄/TiC_（nano）纳米复合陶瓷刀具材料的断裂行为和残余应力两方面对纳米复合陶瓷材料的强韧化机理进行了分析。断裂行为研究表明:裂纹扩展过程中遇到纳米TiC颗粒时,裂纹将发生偏转、扭曲、分叉、终止。由于残余应力的存在,材料在发生断裂时,裂纹倾向于在颗粒处钉扎或穿过晶粒,裂纹的偏转、钉扎和断裂模式的改变都可使材料的韧性得以提高。 对Si₃N₄/TiC体积比分别为82/10、72/20、62/30的三种材料抗磨损对比试验,结果表明体积配比为62/30的材料耐磨性最好,几种材料的磨损机理基本相同,主要是塑性变形、粘着磨损和分层剥落。 通过对淬火45#钢、灰铸铁进行连续切削试验和断续切削试验,研究了Si₃N₄/TiC纳米复合陶瓷刀具材料的切削性能,并分别与SG-4、LT55、SNM88陶瓷刀具进行了对比,结果表明所开发的陶瓷刀具具有较好的抗磨损、抗破损性能。更多还原

【Abstract】 Aiming at the optimal mechanical properties ,a kind of Si3N4-based nano-composite ceramic tool materials, Si3N4/TiC (denoted as ST) reinforced by nano-TiC were developed successfully. Their sintering behaviors .mechanical properties, friction-wear behaviors as well as cutting performance were studied. The flexural strength of ST ceramic tool material is 920MPa, fracture toughness 7.4MPa-m1/2, and Vicker’s hardness 14.75GPa. Research was also carried out on toughening mechanism of nano-composite ceramic material.Fabrication process as well as the effects of the volume fraction of nano-TiC in ST on the mico-structrues and mechanical properties of ceramic tool materials were studied. The principles for the selection of sintering additives in the development of Si3N4-based ceramic tool materials are determined, and the influence of the volume fraction on the sintering behaviors, mico-structure and mechanical properties of Si3N4-based ceramic tool materials are analyzed. The influence of sintering temperature and holding time on the density, micro-structure and mechanical properties of the ceramic tool materials are studied.The toughening mechanisms of nano-composite ceramic material are studied in terms of fracture behavior and residual thermal stresses. The fracture behavior is characterized by crack deflection, twisting, divarication, and stopping or pinning as well as transgranular fracture during the crack propagating as a result of the reinforcment of TiC nano particles. All these fracture patterns contribute to the increase in fracture toughness of the materials.The wear resistance was investigated for three materials with different volume ratio of Si3N4/TiC(82/10 72/20 62/30). It was proved from the wear experiment results that the wear performance of Si3N4/TiC(62/30) is better than those of other two kinds of materials. The wear mechanism are plastic deformation, adhesive wear and spalling.The cutting performance of the Si3N/TiC nano-composites ceramic tools are investigate by means of continuous and intermittent turning of cast iron and hardenedsteel, with parallel experiments conducted using ceramic tools SG-4, LT55 and SNM88. The results manifest that the newly developed ceramic tools are possessed of higher wear and fracture resistance.更多还原