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排序方式: 共有167条查询结果,搜索用时 15 毫秒
41.
为了解决传统烧结方法制备W-Cu合金存在的烧结温度高、烧结时间长、晶粒长大严重等缺点,利用电场对材料烧结的促进作用,本文采用放电等离子烧结(SPS)和大电流电阻烧结两种电场快速烧结方法制备W-Cu合金。借助阿基米德排水法测量密度和金相显微镜、扫描电镜等分析测试方法,对两种电场快速烧结方法在不同烧结温度条件下(800℃、900℃、1000℃)制备的W-20wt%Cu合金的致密化程度及显微组织结构进行了对比研究。通过对两种烧结方法中电场密度的计算和烧结体显微组织结构中铜池的出现,结果表明:在本实验条件下,相比放电等离子烧结法,采用大电流电阻烧结法在加热过程中更容易产生场致发射效应,这有利于W-Cu合金组织的均匀分布,促进烧结致密化。大电流电阻烧结体的相对密度和显微组织结构均优于放电等离子烧结体;采用放电等离子烧结,烧结温度从800℃提高到900℃时,烧结体的相对密度增大,合金内部孔洞和晶粒的大小、分布更加均匀,但当烧结温度达到1000℃时,烧结体的相对密度增幅不大,烧结体孔洞集中,且晶粒团聚;而在大电流电阻烧结时,随着烧结温度升高,烧结体的相对密度增大,显微组织结构的均匀性也得到提高。 相似文献
42.
Jinglian Fan Tao LiuSong Zhu Yong Han 《International Journal of Refractory Metals and Hard Materials》2012,30(1):33-37
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. 相似文献
43.
H. Abbaszadeh A. MasoudiH. Safabinesh M. Takestani 《International Journal of Refractory Metals and Hard Materials》2012,30(1):145-151
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. 相似文献
44.
钨铜复合材料具有高导电导热性能、低膨胀系数、良好的高温强度和抗电弧烧蚀性能,在电气工程、机械加工及电子信息等领域获得了广泛应用。介绍了钨铜复合材料的传统工艺及制备新技术,综述了其在电器开关、电极、微电子及军工等领域的应用,并对其制备技术和应用开发进行了展望。 相似文献
45.
《Advanced Powder Technology》2020,31(8):3657-3666
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. 相似文献
46.
热压烧结法制备钨铜复合材料的工艺研究 总被引:1,自引:1,他引:1
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. 相似文献
47.
WANG Junbo CHEN Wen'ge DING Bingjun 《武汉理工大学学报(材料科学英文版)》2006,21(4):32-35
Nanostructured ( NS )W-Cu composite powder was prepared by mechanical alloying ( MA ), and nanostructared bulk of W-Cu contact material was fabricated by hot press sintering in an electrical vacuum furnace. The rnicrostructure, electric conductivity, hardness and break down voltage of NS W- Cu alloys were measured and compared to those of conventional W-Cu alloys prepared by powder metallurg'y. The experimental results show that microstructural refinement and uniformity can improve the breakdown behavior and the electric arc stability of nanostructared W- Cu contacts materials. Also, the wanostructured W- Cu contact material shows the characteristic of spreading electric arcs, which is of benefit to electric arc erosion. 相似文献
48.
49.
纳米晶W-Cu复合粉末烧结行为 总被引:5,自引:1,他引:5
研究了机械合金化制备的纳米晶W-xCu(x=15,20,25)复合粉末的烧结行为.结果表明,纳米晶W-Cu复合粉末烧结致密化强烈地依赖于烧结温度与烧结时间.当烧结温度从1 150℃提高到1 200℃时,烧结30min后的烧结体相对密度由91%~94%增加到97%~98%;当烧结温度超过1 300℃时,烧结体发生快速致密化,5 min内相对密度即可达到98%左右.研究还发现,W-Cu合金中W晶粒尺寸也强烈地依赖于烧结温度,即烧结温度愈高,W晶粒长大愈显著.当压坯在1 200~1 250℃烧结30 min后,所得到的晶粒度约为300~500 nm,其中经1 200℃烧结时的晶粒尺寸约为300~350 nm.另外,Cu含量增加有利于烧结致密化,并降低W晶粒长大的趋势. 相似文献
50.