粉末冶金温压技术概述

本文概述了粉末冶金温压成形技术的基本原理和基本工艺过程,将温压成形零件的一些性能做了简述和对比,列举了几个采用温压成形技术的实例。     

粉末冶金流动温压成形技术

本文主要介绍了金属粉末流动温压成形技术的发展、特点及关键问题分析。流动温压成形技术作为一种崭新的粉末冶金零部件近终形成形技术，结合了常规温压技术和金属注射成形技术的优点，可直接成形零件的复杂几何形状如侧凹、螺纹孔等而不需要其后的二次机加工，既克服了传统粉末冶金技术在成形方面的不足，又避免了注射成形技术的高成本，具有十分广阔的应用潜力。     

温压技术的应用、发展及其在我国的工业化前景

根据国内外粉末冶金零件市场的走势，论证了温压技术在我国工业化的重要性。综述并讨论了温压技术的应用及发展趋势。介绍了作者们开发的温压专用粉末加热装置和温压成形粉末冶金材料的性能，其成果为温压原材料及设备的国产化打下了基础。     

流动温压成形“十”字形零件及其烧结工艺的研究

传统的粉末冶金方法难以制备复杂零件,最近发展起来的流动温压技术通过增加混合粉末的流动性克服了这一难题。本研究采用常用的水雾化铁基粉末,通过加入适量的粘结剂,利用流动温压技术在约160℃的温度下压制出"十"字形零件,然后分别在1120℃和1300℃进行烧结,并研究了其流动温压成形特性、微观结构及烧结性能。结果表明,利用流动温压技术制备出的"十"字形零件表面光滑且没有明显的收缩或者膨胀现象。本文揭示了流动温压技术在制备复杂粉末冶金零件方面的应用。     

提高粉末冶金制品压坯密度的新技术

粉末冶金是一项以较低的成本制造高性能铁基粉末冶金零件的生产技术。然而 ,其制备的粉末压坯密度通常较低 ,因而影响了零件的性能。在此介绍了几种提高粉末冶金零件压坯密度的新技术 ,如温压、流动温压、高压温压以及高速压制等 ,并指出了粉末冶金技术的发展方向     

高密度铁基粉末冶金零件制备技术

介绍了东睦新材料集团股份有限公司已经使用的高密度铁基粉末冶金产品制造技术,包括温压成形、温模压制、复压复烧等,并讨论了这些技术的优缺点。所述高密度铁基粉末冶金零件制备技术虽可以提升粉末冶金零件的密度,强度也达到较高的水平,但是零件的精度及粗糙度等尚不能满足高端应用的要求,仍需进一步机加工。未来仍需提升粉末冶金模具的制造精度、粉末特性和工艺稳定性,开发低成本、高精度、高强度的烧结铁基零件制备技术。     

粉末冶金温压工艺的研究进展及展望

温压是一项以较低的成本制造高性能粉末冶金零件的新型成形技术，本文综述并讨论了温压工艺的粉末原料、聚合物、温度、压力、烧结环节及致密化机理。在此基础上，介绍了温压工艺的新发展——流动温压、高压温压等，并对其应用前景进行了展望。     

高密度粉末冶金零件制备技术现状

近年来,随着零件成形技术的不断改进,粉末冶金工业得到了快速发展。本文主要介绍了温压技术、动力磁性压制技术、爆炸压制技术、粉末锻造技术、快速全向压制技术、轧制成形和高速压制技术的基本原理、特点和应用情况,指出高速压制技术是粉末冶金工业寻求低成本高密度材料加工技术的又一次新突破,具有广阔的应用前景。     

温压工艺最新进展--流动温压技术

流动温压技术兼有温压技术和金属注射成形技术的优点,既克服了传统粉末冶金技术在成形方面的不足,又避免了注射成形技术的高成本.由于微细粉末的加入和较多的润滑剂含量而使混合粉末在温压时转变成一种具有良好流动性和充填能力的黏流体,从而可以直接成形零件的复杂几何形状如侧凹、螺纹孔等而不需要其后的二次机加工,具有很大的应用潜力.     

W-34Ni-5Fe合金的流动温压成形

流动温压工艺是一项以短流程低成本制造复杂几何形状零件的粉末冶金新工艺.该文作者自行设计并制造了一套流动温压成形横向流动能力及横向压力测量装置,用于研究流动温压专用混合粉末的制备,考察压制速度、温度及轴向压力对W-34Ni-5Fe混合粉末横向成形能力的影响.结果表明,该混合粉末在一定的温度下具有横向流动的能力,横向压力随压制速度和轴向压力增大而增大;横向距离愈长,横向压力愈小,将混合粉末加热到粘结剂的熔点温度96℃时横向压力最大.实验初步证明了流动温压成形十字形粉末冶金零件的可行性.     

Effect of Intermediate Annealing Temperature on Response of Repressing to Densification of Pre-Alloyed Cr-Mo Steel

 Increasing density is one of the important factors for producing high quality powder metallurgy (PM) parts, which has beneficial effect on mechanical properties. One of the common techniques for achieving this goal is double compacting, which seems to be a potentially attractive method in PM route, also for Cr-Mo alloyed-steels. The objective of this research was to investigate the effect of first compacting pressure and intermediate annealing temperature on attaining higher densities and minimum interconnected porosity for Cr-Mo pre-alloyed steel. The effect of mentioned parameters was studied by measuring density, transverse rupture strength and macrohardness of repressed samples. The results show that for each first compacting pressure, the density range of repressed samples increases with the increasing annealing temperature up to a certain limit, due to C dissolution which causes free porosity and further densification. Annealing temperatures higher than optimum one should be avoided, since too much carbon dissolution results in harder and less deformable compacts. On the other hand, with regard to repressed density and other resulted properties, the amount of first compacting pressure offers considerable advantage in obtaining higher level of density and consequently improved mechanical properties.     

粉末净成形压制工艺优化及三维复杂零件结构设计的数值模拟

基于粉末连续体,运用MSC.Marc有限元软件对粉末净成形压制工艺进行优化,并对减重齿轮的结构设计进行数值模拟。通过与实验数据对比分析,验证了材料模型及仿真模拟的可靠性,在此基础上利用有限元软件研究分析压制方式、压制速度、摩擦系数、压制温度、保压时间等五组因素对压坯密度分布的影响。结果表明,压制方式是最显著的影响因子,采用双向压制、温压成形、低压制速度、小摩擦系数及保压方式的组合压制工艺能有效地改善粉体的密度分布。利用有限元软件对减重齿轮的结构进行优化设计,研究圆环高径比与压坯相对密度的关系,并确定减重孔最佳尺寸。结果表明,采用强制摩擦压制方式代替浮动压制方式,可有效改善孔洞薄壁处密度。此外,结合Workbench有限元软件对减重齿轮进行结构力学模拟仿真,分析薄壁处的受力情况,以满足对齿轮强度的要求。     

粉末冶金结构零件的材料与质量

论述了:(1)影响粉末冶金结构零件质量的两大因素:原材料和成形工序;(2)发展粉末冶金结构零件需要纠正的几种错误认识;(3)粉末冶金材料的特点。     

打捆压实液压系统故障原因分析与改进

针对高速线材自动打捆压实液压系统故障,分析了其产生原因,通过改进过滤系统、加强系统维护、加强油品污染监控和现场监控等措施,有效地降低了备件费用消耗,提高了设备完好率,为高线的高产和稳产提供了设备保障。     

Investigation into the influence of pushing-out regulation during the formation of powders on the quality of uranium dioxide wares

The results of pilot and analytical researches of the stress condition diagram near the pellet ends upon its pushing out from the mold after compaction to reveal the causes of crack formation are presented. It is shown that free surfaces can appear on the green pellet end from the lower punch, due to which a dangerous boundary between the loaded and unloaded parts of a green pellet can be formed which can lead to cracking at certain compacting procedures. The numerical investigations for establishing the maximal shear stresses in a green pellet upon pushing out according to standard regulations and with counterpressure are performed. A technical proposal on the expediency of using the counterpressure upon pushing out after compacting the pellets from uranium dioxide powders is substantiated. It is established that the application of counterpressure excludes the formation of end cracks in green pellets in a wide range of compaction pressures and with the use of various binders and opens up prospects for compacting powders without binders and green pellets without chamfers.     

多层粉末冶金复合制品成形方法介绍

本文介绍了单轴向压制多层粉末冶金复合制品的成形方法。这些方法,适用于制造双层粉末冶金含油轴承及各种不同材质的中、高强度多层复合烧结机械零件,是80年代发展的新技术。     

Effect of particle dispersion on the densification of parts from columbium carbide powder at different sintering temperatures

Summary Attainment of relative densities of up to 97% in parts from columbium carbide powder is only feasible when fine comminution of the powder, cold compacting, and sintering at temperatures not exceeding 0.6 T_melt. are employed.It is possible to calculate, within the limits needed from the practical point of view, the sintering temperature and powder dispersion necessary for the production of parts from columbium carbide powder, having the required volume density.In the production of low-porosity columbium carbide parts, sintering temperature may be substantially lowered if the dispersion of the powder to be sintered is increased, thereby significantly simplifying production technology.The densification process of columbium carbide is analyzed from the point of view of the theory of viscous flow during sintering. On this basis, the feasibility of quantitative evaluation of the minimum degree of powder dispersion necessary for securing intensive sintering of the material at a given temperature is demonstrated. The lattice destruction energy of columbium carbide, calculated from experimental data, is about 410 kJ/mole.     

阴模、芯棒和压模套均可浮动的拉下式压模设计实例

本文介绍了设计125t粉末冶金专用液压机多台阶粉末冶金零件成形模架、模具的方法。并简述了利用机械定位形式解决压坯密度和轴向高度难以控制的问题。