共查询到17条相似文献,搜索用时 156 毫秒
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采用溶剂脱脂和热脱脂相结合的方法,研究了超细316L不锈钢粉末注射成形坯的脱脂工艺。注重考察了升温速度和保温时间对不锈钢注射坯的热脱脂工艺的影响。研究表明注射成形坯经正己烷溶剂脱脂后,石蜡组元全部被脱除。其它组元在后续的热脱脂中被去除,确定了优化的升温速度和保温时间,试样没有出现缺陷,并缩短了脱脂周期,该周期大约为10小时。 相似文献
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Ti-Mo吸气材料注射成形脱脂工艺的研究 总被引:1,自引:0,他引:1
采用粉末注射成形技术制备Ti-Mo合金吸气材料。研究了脱脂工艺对坯体质量、微观结构及其元件性能的影响。讨论了化学脱脂中的溶剂、温度、时间对坯体脱脂率的影响,较优的脱脂溶剂为三氯乙烯,在脱脂温度为50℃、脱脂时间为6h条件下,脱脂率达71.55%;通过DTA/TG曲线对热脱脂工艺进行了优化,确定了热脱脂工艺参数为室温-120℃,升温速率10℃/min;120~230℃,升温速率5℃/min;230~500℃,升温速率2℃/min,保温60 min;再经过800℃烧结工艺,制备出性能优异的Ti-Mo吸气剂元件,吸气性能特征为S10=738.5 mL/s,Q120=995.6Pa·mL。 相似文献
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以羰基Fe,Ni粉为原料,蜡基聚合物为粘结剂,采用粉末注射成形技术制备了4J42 Invar合金零件.研究了粉末注射成形Invar合金的脱脂及烧结工艺.结果显示:"溶剂脱脂 热脱脂"工艺能有效快速地实现粘结剂的完全脱除;经1350℃氢气烧结,可以获得致密度98.5%,30~300 ℃内平均热膨胀系数为4.5×10-6 K-1、漏气率<1.4×10-9 Pa·m3·s-1的PIM 4J42 Invar合金.金相显微组织及XRD分析表明合金为单一稳定的奥氏体(γ相)组织. 相似文献
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使用传统蜡基粘结剂和改进型蜡基粘结剂分别研究了Ti(C,N)基金属陶瓷粉末注射成形,热脱脂和溶剂脱脂 热脱脂工艺过程,其中包括根据粘结剂TGA制定并优化热脱脂的工艺曲线、不同的溶剂和温度对溶剂脱脂的影响、后续热脱脂工艺路线的确定.结果表明:使用改进型蜡基粘结剂的2#试样热脱脂工艺简单、周期短并易于控制;2#溶剂脱脂率明显高于使用传统蜡基粘结剂的1#试样;经过溶剂脱脂 热脱脂,1#试样脱脂率达到93%,2#试样脱脂率达到96%以上;1#烧结试样的抗弯强度为700 MPa左右,2#则达到1300 MPa,从烧结样品抗弯断口和显微组织的SEM图片得到了验证.Ti(C,N)基金属陶瓷注射成形采用改进型蜡基粘结剂比传统蜡基粘结剂脱脂效果好、力学性能高,改进型蜡基粘结剂更适合Ti(C,N)基金属陶瓷注射成形. 相似文献
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为了提高发热元件的使用寿命,消除二硅化钼棒材中的内部缺陷,对大尺寸棒材的连续挤出成型技术进行了研究,分析了粘接剂种类、添加量及加水量对泥料特性和坯体干燥特性的影响,并研究了粘接剂种类和脱脂条件等对二硅化钼棒材组织结构和力学性能的影响.实验结果表明,高粘度的粘接剂会导致高的内部缺陷和表面缺陷发生率,仅通过工艺条件的改变不能从根本上解决这一问题.而低粘度粘接剂虽然有利于消除内部缺陷,但棒材表面缺陷的发生率却与脱脂工艺密切相关.因此,只有粘度适中的粘接剂与适宜的脱脂工艺相配合,才能有效地抑制棒材内部缺陷和表面缺陷的发生.在本实验中,以B2的粘接剂与脱脂条件3相配合,可以制得高密度无缺陷的大尺寸二硅化钼棒材,将产品的成品率从原来的80%提高到了96%. 相似文献
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Rajesh V. Shende Daniel S. Krueger Stephen J. Lombardo 《Journal of Materials Science: Materials in Electronics》2001,12(11):637-643
Supercritical extraction using carbon dioxide was examined for the removal of binder from multilayer ceramic capacitors. The binder contained poly(vinyl butyral) (PVB) and dioctyl phthalate (DOP), and the dielectric and metal electrode materials were barium titanate and platinum, respectively. At 40 MPa of carbon dioxide at 95 °C, approximately 55 wt % of the binder could be removed, and this was mainly the dioctyl phthalate component. The use of entrainers such as 2-propanol, methyl isobutyl ketone, and n-hexane was seen to have negligible effect on the degree of binder removal. The dielectric constant, loss tangent, and breakdown voltage of devices processed by supercritical extraction were similar as compared to devices processed by thermal oxidation alone. Although it was not possible to extract all of the binder with supercritical carbon dioxide, removal of the DOP fraction increases the pore space in the body by a factor of two. Transport model calculations indicate this partial removal of binder mitigates the buildup of pressure in the subsequent thermal processing step and can reduce the processing time for thermal removal of the remaining binder by a factor of 25. 相似文献
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《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1987,257(1):35-39
The fabrication and quality control of Ni-3 wt.% U (93% 235U) alloy rods (diameter: 8 mm, total length: 8 m) used as a reference fission product source (RFPS) are described. This RFPs is needed for the calibration of the fuel element rupture detector which is used for the continuous monitoring of the delayed neutron activity in the primary sodium of the Super Phenix fast neutron reactor. Special care was taken to obtain a sufficient alloy purity, a bright surface finish and a homogeneous 235U content on the surface of the rods. Finally the usefulness of the RFPS in Super Phenix has been demonstrated. 相似文献
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Fu Penghuai Peng Liming Jiang Haiyan Zhang Zhenyan Zhai Chunquan 《Materials Science and Engineering: A》2008,486(1-2):572-579
The microstructure, mechanical properties and fracture behavior of gravity die cast Mg–4Y–2Nd–1Gd–0.4Zr (wt.%) (WNG421) alloy are studied at room temperature in different thermal conditions, including as-cast, solution-treated and different aging-treated (both isothermal and two-step aging) conditions. The results indicate that WNG421 alloy shows different behaviors of crack initiation and propagation in different thermal conditions during tensile test at room temperature. After pre-aged at 200 °C for 5 h, the hardness of WNG421 alloy first reduces and then increases when secondary aged at 250 °C (two-step aging). The peak hardness and corresponding tensile strength of the two-step aged alloy both increases compared with those in 250 °C isothermal peak-aged condition. Tensile strength of WNG421 alloy at room temperature in low temperature (200 °C) isothermal peak-aged condition is much higher than that in high temperature (250 °C) isothermal peak-aged condition. 相似文献
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Lin Luo Rui Tian Xueshan Xiao Institute of Materials Shanghai University Shanghai China 《材料科学技术学报》2009,25(5)
A series of Dy(Gd)-based bulk amorphous alloy rods were prepared by water-cooled copper mold method. Thermal stability and structure of Dy-Gd-Co-Al alloys were investigated by differential scanning calorimetry and X-ray di-raction,respectively.The results show that the Dy-Gd-Co-Al alloys have good glass-formation ability,and the Dy31Gd25Co20Al24 alloy can be readily cast into full glassy rods up to 5 mm in diameter.The glass-forming ability of multicomponent alloys was greatly dependent on their chemical in... 相似文献
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M. N. Rahaman R. E. Dutton S. L. Semiatin 《Materials Science and Engineering: A》2003,360(1-2):169-175
A method is described for the fabrication of dense thin sheets of γ titanium aluminide (γ-TiAl) by a powder metallurgy route involving hot isostatic pressing (HIP) of tape-cast monotapes. Gamma-TiAl powder (particle size <90 μm) was incorporated into a concentrated slurry by mixing with an organic binder in a solvent and the system was tape-cast to form sheets with a thickness of 400–600 μm. After insertion of the tape-cast sheet into a HIP can and binder removal in situ by thermal decomposition, HIP at 1100 °C under a pressure of 130 MPa produced dense sheets with a thickness of 250–400 μm. The free, dense sheets with a fine-grain microstructure were obtained by dissolution and oxidation of the HIP can. The carbon content of the fabricated sheets was 0.035 wt.%. Facile adaptation of the process to the production of γ-TiAl thin sheets with complex shapes is expected. 相似文献
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An alloying element of 0–1.5 wt.% Si was added to an Fe–42%Ni system, and alloy strips were fabricated using a melt drag casting
process. The effects of the Si and annealing treatments on the thermal expansion properties of Fe–42Ni alloy were investigated.
The addition of Si enlarged the coexisting temperature region of the solid–liquid phase and reduced the melting point, which
improved the formability of the alloy strip. An alloy containing 0.6 wt.% Si had a lower thermal expansion coefficient than
any other alloy in the temperature range from 20 to 350 °C. The grain size increased with the rolling reduction ratio and
annealing temperature, which caused an increase in magnetostriction and consequently a decrease in the thermal expansion coefficient
of the strip. The alloy strip containing 1.5 wt.% Si had a higher thermal expansion coefficient than the alloy containing
0.6 wt.% Si because of grain refining caused by the precipitation of Ni3Fe. 相似文献
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Xueli Du Mingli Qin Yue Sun Zhihao Yuan Baohe Yang Xuanhui Qu 《Advanced Powder Technology》2010,21(4):431-434
AlN powders doped with Y2O3 (5 wt.%) were compacted by employing powder injection molding (PIM) technique. The binder consisted of paraffin wax (PW, 60 wt.%), polypropylene (PP, 35 wt.%) and stearic acid (SA, 5 wt.%). The feedstock was prepared with a solid loading of 62 vol.%. The binder was removed through debinding process in two steps, solvent debinding followed by thermal debinding. At last, the debound samples were sintered in flowing nitrogen gas at atmospheric pressure. The result reveals that thermal debinding atmosphere has significant effect on the thermal conductivity and structure of AlN ceramics. The thermal conductivity of injection molded AlN ceramics thermal debound in flowing nitrogen gas is 231 W m?1 K?1. 相似文献