【作者】 翟亮；

【导师】 彭德林；

【作者基本信息】 哈尔滨工业大学 ， 材料加工工程， 2007， 硕士

【摘要】 随着能源问题和环境问题的日益突出,为了寻找传统能源的替代产品,人们在热电材料方面做了不少有益的探索,热电材料的研制也成为了研究的热点。本文采用电弧炉真空氩气保护下熔炼与铸造的方法,制备了TiNiSn材料。重点对TiNiSn热电材料腐蚀性能、组织形貌及热电性能和热膨胀等性能进行了研究。对铸态下获得的TiNiSn材料所做的相鉴别分析表明,在铸态TiNiSn材料中存在着TiNiSn、TiNi2Sn、Ni3Sn2、TiNi、Ti3Ni4、Ti6Sn5,同时材料中存在Sn相;能谱分析表明铸态TiNiSn材料中存在着Ti6Sn5、TiNi2Sn相,同时材料中存在微裂纹;利用透射电镜观察分析铸态TiNiSn材料中存在Ti6Sn5和Ti3Ni4相。用3wt.% NaCl水溶液进行的浸泡腐蚀实验的结果表明,经过热处理后材料的耐蚀性有了明显的提高。铸态试样的点蚀和应力腐蚀同时进行,在浸泡进行到25天的时候试样表面已完全腐蚀;热处理96小时的试样表面没有发生明显的点蚀,腐蚀进行到55天时表面还没有达到完全的腐蚀。铸态和热处理态的试样中都存在铸造和加工缺陷,腐蚀总是首先从这些地方开始的,850℃下热处理96小时的试样的点缺陷基本消除,但应力缺陷的仍然存在于材料中,因此在腐蚀的过程中,还是出现了自试样的边缘部位开始的应力腐蚀。XPS结果表明,浸泡试样的表面反应产物是Sn的氧化物,Ti和Ni在浸泡的过程中脱离了试样表面。电化学实验表明,热处理48小时和热处理96小时的试样都出现了明显的钝化区,热处理96小时试样的维钝电流密度低于热处理48小时试样的维钝电流密度,显示了TiNiSn材料随着热处理时间的增加,耐腐蚀性能不断提高的特性。物理性能测试结果表明,随着测试温度的升高,铸态TiNiSn材料的电阻率下降,Seebeck系数、热导率和优值系数都升高。材料的抗压和硬度试验表明,该材料属脆性材料,热处理的进行能提高材料的硬度。更多还原

【Abstract】 Thermoelectric materials are currently being investigated for their potential against the problems of energy and environment. They can be served as a substitution of traditional energy. TiNiSn materials were prepared in arc furnace under Ar atmosphere. Corrosion properties, morphology, physical properties, and some mechanical properties of TiNiSn material were investigated.XRD analysis of as-cast TiNiSn material showed that it was difficult to get single-phase TiNiSn. TiNi2Sn, Ni3Sn2, TiNi, Ti3Ni4, Ti6Sn5, and Sn were tested in the sample. Results of energy spectrum analysis of the as-cast sample showed that there were Ti6Sn5 and TiNi2Sn phases, and also there were some micro-cracks in the material. TEM image of as-cast TiNiSn material and diffraction pattern on appointed site showed that there were Ti6Sn5 and Ti3Ni4 in the as-cast TiNiSn material.Results showed that resistance ability of corrosion in 3wt.% NaCl solution can be improved by heat treatment. The as-cast sample corroded fast, there are pitting corrosion and surface tension corrosion. It was corroded thoroughly after 25 days. There are not pitting corrosion on the sample treated for 96 hour, and this sample was not corroded thoroughly until the 55th days. There were many casting flaws and processing stresses in the as-cast and heat treatment samples. And the corrosion started from those areas. Pitting flaws in the sample of 96 hours heat treatment in vacuum furnace were basically eliminated, but the processing stresses still existed. Corrosion of this sample was mainly surface tension corrosion. Results of XPS showed that Sn was oxidized on surface of the sample. Ti and Ni were corroded off the surface of the sample.There are significant passivation areas in samples treated for 48h and 96h, current density of sample treated for 96h is higher than sample treated for 48h. With increase of heat treatment time, corrosion resistance increases.Results of the physical property showed that with the increase of the temperature, electrical resisitivity of the as-cast TiNiSn material decreased. Seebeck coefficient, heat conductivity, and ZT value increased. The mechanical experiment indicated that TiNiSn material was brittle material. Heat treatment could improve hardness of the material.更多还原