共查询到18条相似文献,搜索用时 186 毫秒
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以镍粉和钛粉为原料,采用自蔓延燃烧合成技术制备了多孔NiTi形状记忆合金,研究了压坯压力、镍含量、钛粉粒径等参数对合金孔隙尺寸、孔隙均匀性和显微组织的影响。结果表明:自蔓延燃烧合成的NiTi合金为螺旋分层结构;压坯压力在100~200 MPa范围内再经自蔓延燃烧合成的NiTi合金的孔隙均匀,且为三维连通结构,比较理想;镍质量分数为40%左右时,孔隙的分布和三维贯通性均较理想;当钛粉粒径较大时,出现了大量的液相和NiTi2、Ni3Ti等杂质相,反应很不充分,钛粉粒径在50~100μm之间为好。 相似文献
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选区激光熔化成型具有外界温度感知能力的NiTi形状记忆合金是4D打印金属材料技术的基础研究,根据选区激光熔化技术对粉末性能的要求,研究NiTi形状记忆合金不同气雾化制粉工艺对选区激光熔化成型性及制件超弹性的影响规律具有重要意义。通过对比分析真空惰性气体雾化(VIGA)、电极感应熔炼气雾化(EIGA)制粉工艺对NiTi合金粉末杂质含量、流动性、球形度等性能的影响,发现VIGA制粉工艺由于采用坩埚熔炼,导致合金杂质元素增加、粉体性能恶化,粉末粒度分布偏向细粉侧,极易形成卫星粉,导致粉末流动性差,在打印过程中铺粉困难而难以成型,并且氧含量的增加导致打印过程中易发生球化、开裂等现象,使得VIGA工艺制备的NiTi合金粉末SLM成型性较差。而采用EIGA工艺制备的粉末粒度分布均匀、流动性好、氧含量低,满足选区激光熔化技术对NiTi合金粉末的特性要求。并对比分析两种工艺制备的粉末打印样品的表面形貌,成型了具有完全回复性能的超弹NiTi形状记忆合金样件。 相似文献
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研究了一种以镍钛(NiTi)形状记忆合金带材为基本驱动材料的平面涡卷式扭转驱动器。该驱动器利用NiTi合金的单程形状记忆效应与回复弹簧的相互作用,实现驱动器在高低温状态下正反两向的扭矩输出。分析了驱动器的基本结构形式和驱动原理,探讨了NiTi合金驱动部件的设计方法和基本制备工艺。设计制作了驱动器原理样机,并测试了驱动器的输入输出特性。测试结果表明,该驱动器在给定的高低温环境(10~60℃)下能够在正反两个方向连续稳定地输出扭矩,最大行程范围为0~175°,最大输出扭矩达到0.33N·m。实测结果证明了驱动器设计方案与制备工艺的可行性。 相似文献
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利用粉末冶金法制备了不锈钢多孔材料,研究了造孔剂含量对其孔隙率和抗压强度的影响。结果表明:随着造孔剂含量的增加,不锈钢多孔材料的平均孔隙率增大、抗压强度下降;造孔剂的质量分数控制在40%~50%之间时,可在保证强度的前提下使不锈钢多孔材料具有较高的孔隙率。 相似文献
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The combined corrosion–wear of powder metallurgy duplex stainless steels obtained by the mixing of ferritic and austenitic powders in several proportions was studied. All the materials were sintered in a nitrogen atmosphere. Tribological and tribocorrosion behaviour was analyzed using a pin-on-disc. Electrochemical techniques: open circuit potential measurements, potentiodynamic polarization measurements and potentiostatic measurements at passive potential under sliding conditions were used. The obtained results were interpreted and related to microstructural features. The tribocorrion behaviour for powder metallurgy duplex stainless steels was a function of the applied electrochemical potential. 相似文献
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Raymond H. Baskey 《摩擦学汇刊》2013,56(1):116-123
Novel rotating seal materials were developed by powder metallurgy techniques for potential aircraft applications at high speeds and high temperatures. A systematic wear study without lubrication included several commercially available materials and the following types of experimental materials: (a) pure refractory hard metals, (b) binary alloys of refractory hard metals bonded with nickel and, (c) ternary alloys of refractory hard metals bonded with nickel and infiltrated with silver. Two ternary alloys, containing nickel bonded WB or CrN and infiltrated with silver, showed superior wear qualities against either tool steel or a nickel—chromium—iron alloy at a sliding speed of 29,000 ft/min under a 14 lb/in2 load and at ambient temperatures as high as 1300 F. A commercial titanium carbide composition showed excellent wear characteristics in contact with an identical composition at a sliding speed of 14,000 ft/min under a 16 lb/in2 load and at an ambient temperature of 1050 F. 相似文献
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通过以钛金属粉末冶金技术制备的多孔过滤钛材料为基体,以涂敷 Sn,Sb 氧化物为中间层,再涂敷 Mn(NO3)2溶液,然后进行热分解的方法制备贱金属多孔钛阳极。为了研究多孔钛基贱金属阳极在析氧领域的应用,在1 mol/L 的 H 2 SO4溶液中做强化寿命测试,电流密度为20000 A/m2。由试验结果可知,随着基体多孔钛的厚度的增加,在不改变涂层成分的条件下,多孔钛基贱金属阳极的强化寿命呈线性增加,当到达一定厚度之后,强化寿命为一定值,不再随着基材厚度的增加而增加。通过研究多孔钛基贱金属阳极失效前后的表面形貌,从表观上分析了多孔钛基贱金属阳极的失效机理。 相似文献
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Ibrahim Mahmoud 《Wear》1982,79(2):271-273
Conventional high speed steel (HSS) tools and HSS tools manufactured by powder metallurgy were used to mill mild steel workpieces. Response surface methodology was used to investigate the effect of speed and feed of cut on tool life.Tool life can be increased by using powder metallurgy methods of manufacture for practical values of the cutting speed. 相似文献