【作者】 崇学文；

【导师】 黄传真；

【作者基本信息】 山东大学 ， 机械制造及其自动化， 2011， 博士

【摘要】 本文采用碳热还原合成晶须增韧陶瓷刀具材料的方法,研制成功了Ti(CxN1-x)系晶须和LTW系列新型陶瓷刀具。提出了碳热还原合成晶须增韧陶瓷刀具材料的设计思路,对碳热还原合成晶须、晶须生长机理、材料力学性能、微观组织、增韧补强机理、切削性能等进行了系统研究。为Ti(CxN1-x)系晶须和LTW系列新型陶瓷刀具的进一步应用奠定了基础。研究了碳热还原合成晶须增韧陶瓷刀具材料的设计方案。从碳热还原合成碳氮化钛系晶须、陶瓷刀具材料体系、刀具材料粉末制备、刀具材料制备、切削性能等方面,提出了碳热还原合成晶须增韧陶瓷刀具材料的设计方案。提出了碳热还原合成碳氮化钛系晶须的设计方案,根据Ti(C,N)连续固溶体的特性,改变晶须原料配比的C/Ti比值,可制备出x取值不同的Ti(CxN1-x)系晶须。研究了碳热还原合成晶须增韧陶瓷刀具材料粉末的制备。重点研究了碳热还原合成晶须工艺参数、晶须生长助溶剂和催化剂等,研制成功了三种碳热还原合成晶须,即TiCo.3No.7、TiCo.5No.5和TiCo.7No.3,为碳氮化钛系晶须增韧陶瓷刀具材料粉末的制备奠定基础。研究了碳热还原合成碳氮化钛系晶须的生长机理。从晶须生长的基本过程、热力学原理、动力学原理、生长机理以及影响晶须生长品质的因素等方面,建立和完善了碳热还原合成晶须的理论。提出了碳氮化钛晶须的气-固(VS)生长机理,建立了碳氮化钛晶须的气-液-固与气-固微观生长机理模型。研究了碳热还原合成晶须增韧陶瓷刀具的制备工艺及力学性能。研制成功了LTW310(Al2O3/Ti(C0.5N0.5)p/Ti(C0.3N0.7)w),LTW510(Al2O3/Ti(C0.5N0.5)p/Ti(C0.5N0.5)w)和LTW710(Al2O3/Ti(C0.5N0.5)p/Ti(C0.7N0.3)w)三种新型刀具材料。LTW310的力学性能为抗弯强度752.5MPa,断裂韧度8.83MPa·m1/2,硬度21.9GPa。LTW510的力学性能为抗弯强度812.9MPa,断裂韧度7.64MPa·m1/2,硬度20.0GPa。LTW710的力学性能为抗弯强度753.8MPa,断裂韧度8.12MPa·m1/2,硬度20.2GPa。并研究了LTW系列新型陶瓷刀具的力学性能与微观组织之间关系。研究了碳热还原合成晶须增韧陶瓷刀具材料的增韧补强机理,建立了Ti(C,N)p和Ti(C,N)w协同增韧模型。研究表明,Ti(C,N)w与Ti(C,N)p协同增韧补强为主要增韧机制,纳米颗粒增韧补强为辅助增韧机制。研究了碳热还原合成晶须增韧陶瓷刀具的切削性能。连续切削淬硬40Cr合金钢的切削速度达到600m/min,断续切削淬硬45#钢的切削速度达到300m/min。LTW系列刀具与LT55刀具的抗磨损和抗破损性能良好且相当。刀具磨损以前刀面月牙洼磨损和后刀面犁沟状磨损为主,破损以前刀面贝壳状剥落和刀刃碎断为主要失效形式。更多还原

【Abstract】 Ti(CxN1-x) whiskers and the novel kinds of LTW series ceramic cutting tools were fabricated successfully by means of carbothermal synthesizing technology. The new design thought for carbothermal synthesized whisker toughening ceramic cutting tools was proposed. The carbothermal reduction process, whisker growth mechanism, mechanical properties, microstructure, toughening and strengthening mechanism, cutting performance were studied systematically. The design scheme for the synthesis of Ti(CxN1-x) whiskers by carbothermal reduction process was also proposed. According to the characteristics of the Ti(CxN1-x) continuous solid solution, Ti(CxN1-x) series whiskers where x value is various were successfully fabricated by controlling the molar ratio of C and Ti. This research laid the foundation of the further application of Ti(CxN1-x) whiskers and the LTW series ceramic cutting tools.The process for fabricating carbothermal synthesized whisker toughening ceramic cutting tool preforming powders was investigated. The study focused on the process parameters of carbothermal process parameters, and the optimization and selection of flux and catalyst. The novel whiskers such as TiC0.3N0.7, TiC0.5N0.5 and TiC0.7N0.3 were prepared successfully, which laid a foundation for developing Ti(CxN1-x) whisker toughening ceramic cutting tools.The growth mechanism of Ti(CxN1-x) series whiskers used in the ceramic tools was investigated. The theory of Ti(CxN1-x) whisker growth was analyzed and improved from the aspects of the basic process of whisker growth, thermodynamic principle, kinetics principle, whisker growth mechanism and the factors influencing the quality of whiskers. The V-S (Vapor-Solid) growth mechanism of Ti(CxN1-x) whisker was proposed and analyzed. The micro-growth mechanism model of V-S and V-L-S (Vapor-Liquid-Solid) growth mechanism of Ti(CxN1-x) whisker was established. The fabrication process and the mechanical properties of Ti(CxN1-x) whisker toughening ceramic cutting tools were studied. The novel kinds of whisker-toughening ceramic cutting tools such as LTW310 (Al2O3/Ti(C0.5N0.5)p/Ti(C0.3N0.7)w), LTW510 (Al2O3/Ti(C0.5N0.5)p/Ti(C0.5N0.5)w) and LTW710 (Al2O3/Ti(C0.5N0.5)p/Ti(C0.7N0.3)w were developed successfully. The flexural strength, fracture toughness and Vickers hardness of LTW310 are 752.5MPa,8.83MPa·m1/2 and 21.9GPa respectively. The flexural strength, fracture toughness and Vickers hardness of LTW510 are 812.9MPa, 7.64MPa·m1/2 and 20.0GPa respectively. The flexural strength, fracture toughness and Vickers hardness of LTW710 are 753.8MPa,8.12MPa·m1/2 and 20.2GPa respectively. The relationship between the microstructure and the mechanical properties was also investigated.The toughening and strengthening mechanism of the whisker toughening ceramic cutting tools was studied. The synergistic toughening mechanism model of Ti(C,N)w and Ti(C,N)p was established. The research results showed that the main toughening mechanism was the synergistic toughening and strengthening mechanism of Ti(C,N)w and Ti(C,N)p, whereas the assistant toughening mechanism was the toughening and strengthening mechanism by nano particle.The cutting performance of the carbothermal synthesized whisker toughening ceramic cutting tools was studied. The cutting speed for continuously turning the quenched alloy steel 40Cr was 600m/min, and the cutting speed for intermittent turning the quenched carbon steel 45# was 300m/min. The wear resistance and the fracture resistance of novel series tools LTW was good and similar to the compared commercial ceramic cutting tool LT55. The wear mechanisms were mainly controlled by crater wear on rake face and furrow wear on flank face, and the fracture mechanisms were mainly controlled by the conchoidal flaking-off on flank face and the breakage on the main cutting edge.更多还原