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纳米Fe-Cu粉末的制备及其对铁基压坯烧结行为的影响 总被引:2,自引:0,他引:2
以化学共沉淀法制备出纳米Fe-Cu复合粉末并对其性能进行了表征,分别以此纳米Fe-Cu粉末和电解Cu粉与铁粉进行混合获得铁基粉末混合料,成形压坯在H2气氛中不同温度下进行烧结,测定基加入不同形态Cu(合金)粉末铁基烧结坯的烧结性能,结果表明,在相同的Cu添加量及烧结条件下,添加纳米Fe-Cu粉末较加入电解Cu粉于铁基压坯中可以明显地提高压坯烧结后的密度,硬度及强度等性能,而添加纳米Fe-Cu粉末压坯在较低温度下烧结可达到添加电解Cu粉压坯在较高温度下烧结后的性能水平,说明采用纳米Fe-Cu粉末形式向铁基压坯中引入Cu有利于制备高密度,高性能的铁基烧结材料。 相似文献
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超细碳化钨-钴硬质合金的原子力显微镜研究 总被引:1,自引:0,他引:1
以液相复合-连续还原碳化方法制备的纳米碳化钨-钴复合粉末为原料,采用低压烧结制备了性能优良的超细碳化钨-钴硬质合金.运用原子力显微镜(AFM)对超细碳化钨-钴硬质合金的表面形貌进行了观察、缺陷和粒度分析,同时对合金的力学性能进行了测试.结果表明,采用低压烧结获得的烧结试样的洛氏硬度HRA≥93.5,抗弯强度TRS≥3300MPa,平均晶粒度<220nm.制备了具有高强度、高硬度的超细碳化钨-钴硬质合金.纳米碳化钨-钴复合粉末制备的超细硬质合金组织结构均匀,但局部仍然存在着组织缺陷,分析了产生缺陷的机理. 相似文献
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纳米WC硬质合金制备新工艺 总被引:16,自引:0,他引:16
文章综述了制备纳米WC、WC Co粉体的几种方法。着重阐述了纳米WC Co硬质合金的烧结新工艺 :微波烧结、二阶段烧结、快速热等静压烧结和等离子体活化烧结等。与传统烧结方法相比 ,使用这些烧结新工艺制备的产品性能更优异 ,有很大的发展前景。 相似文献
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利用高能球磨、真空烧结工艺制备了纳米YG8-RE硬质合金。考察了球磨时间对粒度及烧结试样性能的影响,并研究了稀土加入量及烧结温度的影响。通过密度、硬度、金相组织、扫描电镜观测等检测手段对以上各个因素进行优化,从而制得了性能较好的纳米YG8-RE硬质合金。 相似文献
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研究了在放电等离子烧结(SPS)条件下,纳米碳化钒(V8C7)对超细WC基硬质合金的相组成、微观组织及性能的影响。结果表明:超细WC基硬质合金主要由WC和Co3C两相组成,相对于未烧结的硬质合金材料,WC的衍射峰向小角度方向偏移;纳米碳化钒可以有效抑制超细WC基硬质合金中WC晶粒的长大,并且随着纳米碳化钒比表面积的增大而增强,添加比表面积为63.36m2/g的纳米V8C7后,硬质合金中大部分WC的晶粒尺寸0.5μm;纳米碳化钒对超细WC基硬质合金的性能具有重要影响,并且随着纳米碳化钒比表面积的增大而增加,添加比表面积为63.36m2/g的纳米V8C7后,超细WC基硬质合金具有较高的性能(相对密度99.7%,洛氏硬度93.4,断裂韧性12.7MPa.m1/2)。 相似文献
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采用真空烧结法制备了板状WC晶粒WC-(Co-Ni)硬质合金,通过XRD、SEM、EDS等手段研究了Ni/(Ni+Co)比对硬质合金组织和性能的影响规律。结果表明:随着Ni/(Ni+Co)比的增大,硬质合金显微组织中板状WC晶粒的比例逐渐减少,硬质相颗粒的尺寸逐渐增大且平均长厚比逐渐减小。当Ni/(Ni+Co)比过大时,硬质合金中硬质相颗粒出现了团聚现象,使其力学性能显著降低。当Ni/(Ni+Co)比为0.3和0.5时,WC-(Co-Ni)硬质合金的综合力学性能较高,这与其硬质相颗粒较细和平均长厚比较大有关。当Ni/(Ni+Co)比为0.5时,WC-(5Co+5Ni)硬质合金具有较优的综合力学性能,其抗弯强度、硬度和断裂韧性分别为2 448 MPa、90.0HRA、21.2 MPa·m~(1/2)。 相似文献
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In the present investigation the microstructure and mechanical properties of WC-10Co, WC-8.3Ti(C,N)-12Co, WC-8.3Ti(C,N)-6Co-6Ni and WC-7Ti(C,N)-2Mo2C-6Co-6Ni cemented carbides were studied. Introduction of Ti(C,N) in WC-10Co cemented carbide imposed sintering difficulties and hot isostatic pressing was required to obtain fully dense material. The modification of the binder cobalt with nickel and molybdenum did not noticeably affect the sintered microstructure. In general the mechanical properties of Ti(C,N)-containing cemented carbides were inferior to those of WC-10Co cemented carbide. 相似文献
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Xiangzhao Zhang Guiwu Liu Junnan Tao Yajie Guo Jingjing Wang Guanjun Qiao 《材料科学技术学报》2018,34(7):1180-1188
Three novel Cu–Ni–Al brazing filler alloys with Cu/Ni weight ratio of 4:1 and 2.5–10 wt% Al were developed and characterized, and the wetting of three Cu–Ni–Al alloys on WC–8 Co cemented carbide were investigated at 1190–1210?C by the sessile drop technique. Vacuum brazing of the WC–8 Co cemented carbide to SAE1045 steel using the three Cu–Ni–Al alloys as filler metal was further carried out based on the wetting test results. The interfacial interactions and joint mechanical behaviors involving microhardness, shear strength and fracture were analyzed and discussed. The experimental results show that all the three wetting systems present excellent wettability with final contact angles of less than 5?and fast spreading. An obvious degeneration layer with continuous thin strip forms in the cemented carbide adjacent to the Cu–Ni–Al/WC–8 Co interface. The variation of microhardness in the joint cross-section is closely related to the interactions(such as diffusion and solid solution) of WC–8 Co/Cu–Ni–Al/steel system. Compared with the other two brazed joints, the WC–8 Co/Cu–19 Ni–5 Al/steel brazed joint presents more reliable interlayer microstructure and mechanical property while brazing at the corresponding wetting temperatures for 5 min, and its average shear strength is over 200 MPa after further optimizing the brazing temperature and holding time. The joint shear fracture path passes along the degeneration layer, Cu–Ni–Al/WC–8 Co interface and brazing interlayer, showing a mixed ductile-brittle fracture. 相似文献
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Effects of Cu on Microstructures,Mechanical, and Magnetic Properties of Fe–Ni–P Alloys Fabricated by Liquid Phase Sintering 下载免费PDF全文
The Fe–Ni–P–Cu alloys with different copper content (0, 0.5, 1, and 2 wt%) are fabricated by liquid phase sintering (LPS) at 950 °C. The nano‐Cu powder is mechanically mixed for 90 min with Fe–Ni–P composite powder using the ethanol as the medium. The microstructure, microhardness and compressive properties of Fe–Ni–P–Cu alloys are investigated. The results indicate that the copper is beneficial to improve the mechanical properties of sintered specimens. The sample contains a small amount of γ‐(Fe, Ni) phase when the copper content is 1 wt%, which results in its the highest compressive yield strength (948.1 MPa). The highest microhardness of 371 HV is accessible in Fe–Ni–P–Cu alloy with 2 wt% Cu. The fracture surface analysis indicates that sintered specimens with Cu addition exhibit a typical intergranular mode. 相似文献
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X. Zhao F. Neves J. B. Correia K. Liu F. M. Braz Fernades V. Koledov S. von Gratowski S. Xu J. Huang 《Journal of Materials Science》2018,53(19):13432-13441
This work reports on an efficient powder metallurgy method for the synthesis of NiTi alloys, involving mechanical activation of pre-alloyed NiTi2 and elemental Ni powders (NiTi2–Ni) followed by a press-and-sinter step. The idea is to take advantage of the brittle nature of NiTi2 to promote a better efficiency of the mechanical activation process. The conventional mechanical activation route using elemental Ti and Ni powders (Ti–Ni) was also used for comparative purposes. Starting with (NiTi2–Ni) powder mixtures resulted in the formation of a predominant amorphous structure after mechanical activation at 300 rpm for 2 h. A sintered specimen consisting mainly of NiTi phase was obtained after vacuum sintering at 1050 °C for 0.5 h. The produced NiTi phase exhibited the martensitic transformation behavior. Using elemental Ti powders instead of pre-alloyed NiTi2 powders, the structural homogenization of the synthesized NiTi alloys was delayed. Performing the mechanical activation at 300 rpm for the (Ti–Ni) powder mixtures gave rise to the formation of composite particles consisting in dense areas of alternate fine layers of Ni and Ti. However, no significant structural modification was observed even after 16 h of mechanical activation. Only after vacuum sintering at 1050 °C for 6 h, the NiTi phase was observed to be the predominant phase. The higher reactivity of the mechanically activated (NiTi2–Ni) powder particles can explain the different sintering behavior of those powders compared with the mechanically activated (Ti–Ni) powders. It is demonstrated that this innovative approach allows an effective time reduction in the mechanical activation and of the vacuum sintering step. 相似文献
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采用球磨对SiC粉体颗粒进行整形,并借助反应烧结制备SiC陶瓷密封材料,考察了颗粒整形对反应烧结SiC陶瓷成型、烧结性能、显微结构和力学性能的影响规律。结果表明,整形后的SiC颗粒的球形度高,粒径分布更为均匀;整形SiC粉体的振实密度和素坯密度明显提高,烧结体的显微结构更加均匀,主晶相为6H-SiC和Si,分布均匀,残炭很少;颗粒整形明显改善SiC陶瓷的成型性能及力学性能,当压力为15MPa时,整形后的SiC素坯密度为2.08g/cm~3,烧结体密度为3.06g/cm~3,抗弯强度和断裂韧性分别达到456MPa和3.87MPa·m1/2。 相似文献
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Xiangkui Zhou Kai Wang Zhifeng Xu Qiang Wang Guojian Li Jicheng He 《计算机、材料和连续体(英文)》2014,41(2):153-162
At present, the functionally gradient cemented carbide (FGCC) substrate with enrich cobalt on surface is mainly formed from medium grained WC grains. In order to further improve the properties of gradient cemented carbides, the ultrafine powder was chosen in this study and the functionally gradient cemented carbide with ultrafine grains was prepared by a two-step process, where the cemented carbide is first lower pressure pre-sintered and then subjected to a gradient sintering. The results show that it is possible to form gradient layer with enriched cobalt on surface by this method and also the grain growth can be inhibited by low pressure pre-sintering. Ultrafine grain gradient cemented carbide was fabricated after the gradient sintering, the thickness of gradient layer was about 43μm and the average grain size of WC is about 0.42μm. The formational mechanism of the functionally gradient cemented carbide with ultrafine grains are discussed through analyzing the influence of ultrafine microstructure, which was obtain by lower pressure pre-sintering, on atomic diffusion and grain growth during gradient sintering process. 相似文献
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《Materials Letters》2005,59(19-20):2566-2569
Nanometer scale WC–11Co powder was sintered by spark plasma sintering (SPS) process in order to improve the properties of the cemented carbides. Properties such as density and hardness were measured. The microstructures of sintered WC–11Co cemented carbides were observed. The grain size of WC in alloys was also obtained. The results showed that spark plasma sintering could lower the sintering temperature, increased the density and circumscribed the growth of grain size of WC. Besides, the hardness of the sintered cemented alloys that was dependent on the grain size and densification could also be improved by SPS. SPS was an effective method to get WC–11Co cemented carbides with fine grain size and good properties. 相似文献
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H. Hamatani Y. Ichiyama J. Kobayashi 《Science and Technology of Advanced Materials》2013,14(4):319-326
The objective of the present study is to develop multi-functioned coating to the components, which are made of copper with electroplated Ni and are widely used for steel making industry. In this paper, we report the mechanical and thermal properties of Ni based superalloys with carbide sprayed by high velocity oxygen fuel (HVOF), and the detailed effects of sprayed material, spraying conditions, and initial powder structure on these properties. It was found that, among commercial Ni self-fluxing alloys (without fusing treatment), coating with a carbon content of 0.58 mass% had the most preferable properties, with a good balance of the hardness, strength, and thermal shock resistance. The thermal shock resistance depended not only on the strength of the coating but also on the volume contraction when tested at high temperatures. For the several developed Ni based superalloys with carbide, Ni20Cr8Mo5Fe–WC and Ni16Cr15Mo3–WC demonstrated the prominent adhesion strength and thermal shock resistance with high Galvanic corrosion resistance through optimized spraying condition. Also, 20 mass% NiCr–Cr3C2 coating sprayed by using employed relatively small primary particle succeeded in achieving the multi-superior properties; high adhesion strength, high corrosion resistance and thermal shock resistance. 相似文献