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基于多道次局部小变形累积整体成形的思路,采用新型的楔形压制对大尺寸多孔性喷射沉积SiC颗粒增强Al-8.5Fe-1.3V-1.7Si复合材料板坯进行有效致密,对楔形压制致密后的板坯进行多道次轧制制得复合材料板材,对比研究了传统的挤压致密后轧制的工艺。结果表明,楔形压制能产生有效的静水压力,使板坯中的孔洞有效弥合、沉积坯中的弱界面和层状组织得到有效改善,从而使其成形性能得到提高。与传统的挤压后轧制工艺相比,通过楔形压制后轧制,工艺更为简单可行,SiC颗粒分布更均匀,其力学性能也更好。板材室温下的抗拉强度达520MPa,屈服强度为450MPa,伸长率为6.5%。 相似文献
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1 问题的提出在粉末冶金工艺过程中,成形是一道重要工序,钢模压制是最常见的成形方法。粉末采用模压方式成形时,由于粉末颗粒之间粉末与模冲、模壁之间存在摩擦,使压制过程中力的传递和分布发生改变,由于压制力分布不均匀,造成压坯各个部分密度和强度的不均匀分 相似文献
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根据粉末压制特点及粉末冶金工艺,将氧化铁粉末压制成形,研究压制压力等参数对氧化铁粉末压坯密度的影响.找出不同颗粒大小、不同压制压力下、不同比例添加剂、不同种类添加剂的氧化铁粉末对压坯密度的影响规律,为顺利地成形高密度的粉末冶金制品,提供工艺上的参考依据. 相似文献
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基于离散单元法的粉末高速压制流动过程模拟 总被引:2,自引:0,他引:2
将离散单元法应用于粉末高速压制流动过程研究,以模拟粉体流动的非连续特性。将粉末视为粘弹性的离散颗粒,推导了力与位移表达的粉末高速压制粘弹性本构关系,建立了粉末高速压制成形颗粒流动的离散单元法控制方程;并给出了该模型的动态松弛法求解过程。基于离散单元法求解器PFC软件,对粉末高速压制成形过程颗粒流动情况及密度分布进行了模拟,模拟结果与实验结果较吻合。分析了阻尼系数变化对求解过程的敛散性和压坯密度分布的影响 相似文献
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粉末高速压制成形(HVC)技术在2001年由瑞典H6ganasAB公司提出,并在瑞典Hydropulsor公司生产的HVC设备上实现了速度≤10m·s^-1的压制成形。高速压制成形原理是通过应力波在粉体中的传播使粉末致密,该技术具有压制生坯密度高、密度分布均匀、产品综合性能优异的特点,可以通过连续多次压制实现小设备压制大零件等,所以备受青睐。多个国家的研究者开展了相应的研究工作,材料涉及铁、铜、钛及其合金、磁性材料、陶瓷材料等。高速压制的粉末致密化机理不同于传统压制,今后还有待进一步深入开展研究。 相似文献
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以WC-Ni-Cr_3C_2-P系合金粉末为研究对象,通过密度测试、SEM断口形貌分析等手段研究了粉末粒度配比、预热处理、压制能量、高径比、质量能量密度等工艺参数对生坯密度、烧结密度、弹性后效、烧结径向收缩率等成形性能指标的影响规律。研究结果表明:粗WC颗粒(2μm)与细WC颗粒(0.4μm)相互搭配的WC-Ni-Cr_3C_2-P系合金粉末具有更好的成形性能;预热处理不能改善该系合金粉末的成形性能;未添加石蜡作为有机成形剂会出现生坯开裂的情况,能保证成形的压制能量范围较窄,但在生坯密度和烧结密度两方面均比添加有机成形剂时更高,实测压制能量为1425 J时,未添加有机成形剂的生坯密度和烧结密度分别达到10.67和13.48 g·cm~(-3),而添加有机成形剂的生坯密度和烧结密度分别只达到9.99和13.39 g·cm~(-3);生坯密度随质量能量密度的提高而提高,添加和未添加有机成形剂粉末的质量能量密度的临界点分别为101.79和118.75 J·g~(-1),质量能量密度超过临界点,并不能进一步提高生坯密度。 相似文献
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The stainless steelmaking dust pellets were reduced in isothermal temperature condition simulating the direct recycling practice in the stainless steel production and the kinetics of the reduction process was investigated.The pellets were formed after mixing the dust with carbon as the reducing agent and dolomite as the binder and smelting flux. An electric furnace was used to heat the pellets and an electrical microbalance was used to check the mass of the pellets in the reduction process. The reduction rate was calculated according to the data of pellet mass change in consideration of the evaporation of moisture, zinc and lead at high temperature. The results of the experi-ments show that the reduction process is in two consecutive stages. The reduction kinetic models were set up for each stage and the kinetic parameters such as activation energy and frequency factor were determined. The apparent activation energy of the first stage is 21.69 kJ/mol, and this stage is controlled by chemical reaction. The apparentactivation energy of the second stage is 17.35 kJ/mol, and this stage is controlled by the diffusion of carbon monox-ide through the resultants of reaction. 相似文献
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介绍了热水器外壳顶盖类薄壁筒体件垂直成形修边模及其工作过程 ,模具调试时出现的问题及解决方案。改善了产品质量 ,提高了劳动生产率 相似文献
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结合铸件质量要求,基于铸造数值模拟技术,分析了低压铸造的充型凝固过程,预测了铸件中的缺陷分布;最终通过试制,确保了压气室低压铸件质量,为该件的顺利生产奠定了基础. 相似文献
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Study on interfacial heat transfer coefficient at metal/die interface during high pressure die casting process of AZ91D alloy 总被引:1,自引:0,他引:1
The high pressure die casting (HPDC) process is one of the fastest growing and most efficient methods for the production of complex shape castings of magnesium and aluminum alloys in today's manufacturing industry. In this study, a high pressure die casting experiment using AZ91D magnesium alloy was conducted, and the temperature profiles inside the die were measured. By using a computer program based on solving the inverse heat problem, the metal/die interfacial heat transfer coefficient (IHTC) was calculated and studied. The results show that the IHTC between the metal and die increases right after the liquid metal is brought into the cavity by the plunger, and decreases as the solidification process of the liquid metal proceeds until the liquid metal is completely solidified, when the IHTC tends to be stable. The interfacial heat transfer coefficient shows different characteristics under different casting wall thicknesses and varies with the change of solidification behavior. 相似文献
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P.G. Behere 《NDT & E International》1993,26(2)
Use of an infrared technique for identifying the dished/flat ends of nuclear fuel pellets for PHWR is suggested. The studies show that this method can be used for on-line checking of the orientation of the pellets. 相似文献