【作者】 李翀；

【导师】 李庆芬；

【作者基本信息】 哈尔滨工程大学 ， 材料学， 2008， 博士

【摘要】 Ti₃AlC₂是一种新型的结构与功能一体化材料,兼有金属与陶瓷的双重特性,具有广阔的应用前景。但是用不同制备方法与合成工艺获得的Ti₃AlC₂块体材料在尺寸和性能上均有一定差异。本文在系统实验的基础上首次用自蔓延准热等静压（SHS/PHIP）法制备出了φ150mm的Ti₃AlC₂陶瓷块体材料,并且对该材料的相关性能与应用进行了深入研究。SHS/PHIP法具有节能、环保、低成本、高效率、合成与致密化能够一步完成和产物尺寸大等优点。本文通过具体实验确定了用SHS/PHIP法制备φ150mm的Ti₃AlC₂陶瓷块体材料的最佳工艺参数（成分配比为3Ti-1.5Al-1.8C、最佳预制坯相对密度为52%左右、压坯轴向压力为16.5MPa、预压力为1.5MPa、延迟时间为9s、高压压力为70MPa、高温保压时间为32s）,并且分析了工艺参数对SHS/PHIP法制备Ti₃AlC₂陶瓷块体材料的影响。本文采用多种实验方法和分析测试手段,从实验和理论两方面具体地研究了用SHS/PHIP法制备出的大尺寸Ti₃AlC₂陶瓷块体材料的微观组织结构、力学性能、抗热震性能、机械加工性能、电性能、热性能、抗氧化性能。研究结果表明:用SHS/PHIP法制备出的大尺寸Ti₃AlC₂陶瓷的微观组织结构具有三元层状可加工碳化物的典型特征。它不但具有非常好的机械加工性能、高导电性和低热膨胀系数,还具有优异的力学性能、抗氧化性能和抗热震性。论文提出了用SHS/PHIP法制备出的Ti₃AlC₂陶瓷块体材料作为某设备用电刷材料的设想,以解决某设备在工作中存在电信号采集可靠性差、噪音大、存在“自燃”现象等问题。在自主搭建的模拟某设备工作的测试平台上,对Ti₃AlC₂陶瓷电刷应用的可行性进行了验证与分析。实验结果表明,Ti₃AlC₂陶瓷电刷具有较低的载流摩擦系数（小于0.1）、较小的载流磨损量（约为0.005mm³/h）和稳定的滑动接触电压降。因此,从生产制造成本、可加工性、导电性、载流摩擦特性的角度考虑,用SHS/PHIP法制备出的Ti₃AlC₂陶瓷块体材料完全有可能成为某设备用电刷的候选材料。论文还提出了用SHS/PHIP法制备出的Ti₃AlC₂陶瓷块体材料作为电解Al隋性阳极材料的设想,以解决Al电解碳阳极在电解过程中温室气体排放量大、能耗大等环境问题。在自主搭建的小型电解槽内对Ti₃AlC₂惰性阳极的应用进行了可行性验证与分析。实验结果表明,Ti₃AlC₂惰性阳极在电解过程中具有较低和较为稳定的槽电压,并且可电解出金属Al。因此,从生产批量、材料尺寸、导电率、可加工性、槽电压的稳定性的角度考虑,用SHS/PHIP法制备出的Ti₃AlC₂陶瓷块体材料可以初步作为Al电解惰性阳极用候选材料。但从电解产品Al的纯度以及惰性阳极的耐蚀性的角度考虑,用Ti3AlC₂陶瓷块体材料作为Al电解惰性阳极的应用还需要进行深入的研究,特别是电解工艺参数的优化与电解腐蚀机理的问题。更多还原

【Abstract】 Ti₃AlC₂ is a novel structural and functional material which combines the merits of both metals and ceramics.The unique combination of these properties makes Ti₃AlC₂ a candidate material in many diverse applications.However, Ti₃AlC₂ block material prepared by means of different preparation methods or synthesis processes possesses different size and shows different properties.In the paper,based on the systemic experiments,SHS/PHIP（Self-propagating High-temperature Synthesis/ Pseudo Hot Isostatic Pressing） was developed to prepareφ150mm Ti₃AlC₂ ceramics block material for the first time.SHS/PHIP has many advantages,such as environmental protection,energy conservation,low cost,high efficiency,simultaneous synthesis and densification. The optimal process parameters of Ti₃AlC₂ ceramics prepared by SHS/PHIP were determined as follows:the best component（3Ti-1.5Al-1.8C）,the best relative density of perform（52%）,the axial pressure（16.5MPa）,the pre-load（1.5MPa）, the time delay（9s）,the high pressure（70MPa） and the pressure time（32s）. Furthermore,the reasons why the process parameters have an effect on densification behaviors were analyzed on the basis of the experiments.The experimental and theoretical methods are applied to studying microstructure,mechanical properties,thermal schock resistance,machining property,electrical conductivity,hot property,and oxidation resistance.Research results show that microstructure of large size Ti₃AlC₂ ceramics prepared by SHS/PHIP has typical layered feature of ternary carbide compound.In addition to good workability,high conductivity and low thermal expansion coefficient,it has excellent mechanical properties,excellent oxidation resistance and excellent thermal shock resistance.Ti₃AlC₂ ceramics block material is proposed as a candidate to the electrical brush material of a model equipment in order to solve problems of unreliable electrical signal collection,working noise and self-combustion.Feasibility test with respect.to operation of Ti₃AlC₂ ceramic electrical brush was carded out at the self-designed testing equipment which simulated work condition.The experimental results show that Ti₃AlC₂ ceramic electrical brush has low current friction coefficient less than 0.1,low current wear capacity which is 0.005mm³/h and stable contact drop.Allowing for such factors as production cost, machinability,electrical conductivity and current friction properties,Ti₃AlC₂ ceramics block material prepared by means of SHS/PHIP is capable of being a candidate to the electrical brush material of a model equipment.Ti₃AlC₂ ceramics block material by SHS/PHIP is proposed as a candidate to inert anode instead of carbon anode of Al electrolysis in order to reduce a lot of greenhouse gases discharge and energy consumption.Feasibility test with respect to application of Ti₃AlC₂ inert anode was performed in the self-designed electrolyzing cell.The experimental results show that Ti₃AlC₂ inert anode has low and stable cell voltage,and is able to electrolyze metal Al.Allowing for such factors as production cost,blank size,electrical conductivity,machinability and stability of cell voltage,Ti₃AlC₂ ceramics block material prepared by SHS/PHIP can be used as inert anode material of Al electrolysis.However,because of purity of product Al and erosion resistance of inert anode,the application of Ti₃AlC₂ inert anode should be studied further,especially mechanism of electrolytic erosion and the optimization of process parameter.更多还原