稀土和稀土氧化物对钨铜电触头材料性能影响的对比分析

利用粉末冶金技术制备出添加不同含量稀土和稀土氧化物的W-Cu电触头材料,比较稀土和稀土氧化物对W-Cu合金物理性能、力学性能的影响,同时利用金相显微镜观察组织形貌。结果表明,添加稀土单质较添加稀土氧化物更能提高W-Cu材料的相对密度、硬度及导电性能;而且W-Cu合金中最适宜的稀土添加量(质量分数)为3%。     

钨铜合金表面粗糙度对抗电弧烧蚀性能的影响

将纯W、纯Cu和W70Cu30合金分别进行机械磨光、电解抛光和机械抛光后获得3种不同的表面状态,在专有设备上模拟电触头材料的电弧烧蚀过程,通过扫描电子显微镜观察首击穿烧蚀形貌。结果表明:通过机械抛光获得的表面粗糙度最小,对于W70Cu30合金可达到0.044μm,电解抛光次之,机械磨光最大;随表面粗糙度降低,W70Cu30合金的击穿场强逐渐增大,烧蚀区域趋于规整化,烧蚀产物增加,烧蚀坑的分布更加集中,纯W、纯Cu也表现出相同的现象;在本实验条件下材料表面粗糙度在0.2~0.3μm时,其抗电弧烧蚀性能最好。     

W-Cu合金物理性能模型及理论值计算

本文对不同成分(10 wt.%～50 wt.%Cu)钨铜合金现有的组织结构模型和理论物理性能参数计算模型进行了归纳总结,在此基础上推导了不同模型下的主要物理性能参数的理论值(包括密度,热容,热导率,电导率,热膨胀系数等)。根据不同模型(体积混合物模型,German互联结构模型,Gasik微观力学模型)的特点进行了分析和比较,讨论了不同模型的适用范围,选取得到了不同成分钨铜合金的物理性能参数理论值,并与实验结果进行了比较,为钨铜合金的成分和性能设计与控制提供了初步的理论依据。     

Synthesis of ultrafine/nanocrystalline W-(30-50)Cu composite powders and microstructure characteristics of the sintered alloys

Ultrafine/Nanocrystalline W-Cu composite powders with various copper contents (30, 40 and 50 wt.%) have been synthesized by sol-spray drying and a subsequent hydrogen reduction process. The powders were consolidated by direct sintering at temperatures between 1150 and 1260 °C for 90 min. The powder characteristics and sintering behavior, as well as thermal conductivity of the sintered alloys were investigated. The results show that the synthesized powders exist in ultrafine composite particles containing numerous nanosized particles, and the composition distributed very homogeneously. As the copper contents increase, the grain size of the powders decreases. The subsequent sintered parts show nearly full density with the relative density more than 99% at the temperature of 1250 °C. The sintered parts have very fine tungsten grains embedded in a bulk matrix. With increased copper contents, the tungsten grain size decreases and the microstructural homogeneity of the sintered alloys improves further. The thermal conductivity properties, while a little lower than that of the theoretical value, depend on the copper contents.     

Investigation on the characteristics of micro- and nano-structured W-15 wt.%Cu composites prepared by powder metallurgy route

The properties of W-15 wt.%Cu composites were investigated by preparing two distinct composites of micrometer and nanoscale structures. Micrometer composite was produced by mixing elemental W and Cu powders and nanometer one was synthesized through a mechanochemical reaction between WO₃ and CuO powders. Subsequent compaction and sintering process was performed to ensure maximum possible densification at 1000-1200 °C temperatures. Finally, the behavior of produced samples including relative density, hardness, compressive strength, electrical conductivity, coefficient of thermal expansion (CTE) and room temperature corrosion resistance were examined. Among the composites, nano-structured sample sintered at 1200 °C exhibited better homogeneity, the highest relative density (94%) and mechanical properties. Furthermore, this composite showed superior electrical conductivity (31.58 IACS) and CTE (9.95384 × 10^- 6) in comparison with micrometer type. This appropriate properties may be mainly attributed to liquid phase sintering with particle rearrangement which induced by higher capillary forces of finer structures.     

活化烧结制备W-Cu复合材料及其性能

研究添加元素Ni对W-Cu复合材料组织和性能的影响.利用预混粉、机械球磨和活化液相烧结法制备不同Ni含量W-Cu复合材料,采用电子扫描显微镜、X射线衍射仪、激光导热仪等对复合材料的显微组织、物相、热导率、热膨胀系数和硬度进行检测与分析.结果表明:当W-Cu复合材料中不添加Ni元素时,W颗粒团聚形成闭合孔隙,液相Cu无法...     

纳米晶钨铜合金表面上不寻常的电弧分布及电击穿机理

在真空电炉中利用机械合金化和热压烧结法制备出纳米晶块体钨铜合金。在进行电击穿实验时，电弧在其表面出现了分散现象，明显不同于相应传统材料电弧集中在局部的现象。这是由于纳米材料在电击穿时由于较低的逸出功、大量晶界的存在和纳米尺度的粒子能窄化钨铜界面的势垒而诱发大量电子发射所致。     

钨铜射流成形的细观数值模拟分析

为研究钨铜复合材料聚能射流成形的细观机理及材料细观结构对射流成形的影响,基于随机投放原理编制了钨铜复合材料细观离散化模型生成程序,建立了不同两相配比及钨颗粒尺寸的钨铜药型罩细观离散化模型。应用动力学仿真AUTODYN-2D软件中的欧拉算法,对钨铜细观模型及其等效均质药型罩开展了聚能射流成形的细观尺度有限元数值模拟分析。研究结果表明,钨铜材料在爆炸载荷驱动下铜相与钨相速度有显著差异,钨颗粒含量沿射流尾部至头部分布不均匀,呈现依次递减的趋势。在一定钨颗粒尺寸下,射流中钨含量相对变化量随着原始药型罩中钨含量降低而增大,钨体积含量30%的钨铜材料形成射流中平均钨含量降低65%,其中头部钨含量下降达90%;在给定罩材两相配比时,射流中钨含量随着钨颗粒尺寸的增大而降低,高钨含量的钨铜射流成分分布不均匀性对颗粒尺寸的变化更加敏感。     

Fabrication of W-Cu functionally graded composites using high energy ball milling and spark plasma sintering for plasma facing components

W-Cu functionally graded composites (FGCs) up to six layers have been developed using high energy ball milling and spark plasma sintering (SPS) at a lower temperature of 900 °C. The relative density of W-Cu composites increased from 85.4% (W₈₀Cu₂₀ layer) to 95.7% (W₂₀Cu₈₀ layer) with increasing Cu content. All the W-Cu FGCs exhibited a graded structure even after SPS and showed a gradual change in hardness, Young’s modulus, and coefficient of thermal expansion (CTE). Furthermore, W-Cu composites showed a CTE and modulus between those of W and Cu and could be used as an intermediate layer between W and Cu in plasma facing components. The thermal cycle testing at 800 °C has confirmed that the W-Cu FGCs developed in this study can withstand thermal shock and showed a superior performance over directly bonded W-Cu sample. The W-Cu FGCs developed in the present study are not only suitable for plasma facing components but can also be used where the thermal stresses are introduced due to the large mismatch in CTE or elastic modulus.     

热压烧结法制备钨铜复合材料的工艺研究

铜钨复合材料是以铜、钨元素为主的一种两相结构假合金,广泛应用于电接触材料,电子封装和热沉材料.作者研究了采用轴向热压烧结来制备纳米W-15%Cu复合材料的方法,分析了工艺参数对该复合材料性能的影响及其影响机理.实验为获得超细晶粒显微组织和优异均匀性纳米W-15%Cu复合材料提供了重要的实验基础和依据.