【作者】 哈岸晖；

【导师】 杨贤金；

【作者基本信息】 天津大学 ， 材料学， 2007， 硕士

【摘要】 本文研究了NH4HCO3对多孔TiNi合金孔隙性能和机械性能的影响,根据实验结论制备了梯度多孔TiNi合金,并对其进行了性能测试。实验表明,在相同的烧结工艺下,随着NH4HCO3添加量的增多,材料孔隙率、开孔率升高,孔隙连通性增强,孔隙圆度略有降低。添加质量比为35:100的NH4HCO3的TiNi粉末烧结后可制得孔隙率达到60%的多孔TiNi合金。体现出NH4HCO3的优异造孔性能。同时,研究结果显示多孔TiNi合金的抗弯强度、弹性模量、抗压强度等机械性能随着NH4HCO3的添加量的增加(等同于孔隙率的提高)而降低。此外,在研究过程中发现三层结构的梯度多孔TiNi合金的三点弯曲测试曲线存在“伪屈服”现象。这是由于试样心、表孔隙结构差异明显造成的特殊现象。在研究中还注意到梯度多孔TiNi合金的抗弯强度受结构影响较大。随着心部低孔隙率层所占体积比例增加,抗弯强度增加。抗弯强度的实际值比理论值高,表现出优异的复合性能。在以上研究的基础上,本课题利用元素粉末冶金法选用国产Ti粉和Ni粉成功制备出具有三维连通网状开孔结构的梯度多孔TiNi合金。合金表层孔隙率为60%,大孔孔径尺寸为100~200μm;心部孔隙率为30%,孔径尺寸为10~60μm,双层梯度结构结合紧密,结合强度为48MPa。更多还原

【Abstract】 In this paper, the influence of NH4HCO3 on the pore characteristics and mechanical properties of porous TiNi alloy were studied. The gradient porous TiNi alloy was prepared according to the results, and then, the alloy’s properties were tested.The results indicated that the connection of the pores, the porosity and open-porosity increased with the increasing of NH4HCO3, but the roundness of the pores decreased slightly at same time. The samples with a porosity of 60% were fabricated by adding NH4HCO3 about 35g in 100g mixed powder which proved NH4HCO3 is good in forming pores. In terms of the mechanical properties, the bending, Young’s modulus, compressive strength and hardness were tested. The results indicated that these mechanical properties decreased with increasing NH4HCO3 content (which is equal to the increase of the porosity).Moreover, there was pseudo yield phenomenon according to the test curve of three points bending of the gradient porous TiNi alloy with three layers structure. The reason of this phenomenon was the obvious structure difference between the surface and interior layer.The bending strength of the gradient porous TiNi alloy was influenced by its structure. The strength improved greatly with the increasing of the interior layer proportion. Furthermore, the real strength was higher than the theoretical strength which proved the good compound effect of this gradient structure.Basing on the above experiments, the gradient porous TiNi alloy with pore characteristics of interconnected three-dimensionally meshy open structure have been fabricated by using domestic Ti and Ni powder through element powder metallurgy. The porosity range and mean big pore size range of the surface layer were 60% and 100-200μm. The porosity range and mean big pore size range of the interior layer were 30% and 10-60μm.The adhesion of the double gradient structure is firm, and its the adhesive strength is about 48MPa.更多还原