陶瓷基复合材料伪半固态触变成形

半固态材料具有触变性和优良的组织结构,即成形零件质量好,力学性能与锻件的力学性能相近,成形零件的尺寸和精度能达到净近成形或净终成形,而传统陶瓷的制备主要根据粉末冶金方法通过成型和烧结工序完成.综合半固态金属加工技术、粉末冶金以及21世纪陶瓷成形发展的方向,提出了一种新型成形方法-伪半固态触变成形,从而为陶瓷复合材料以及高熔点材料在更多领域的应用起到了推进作用.     

粉末注射成形铜的烧结工艺研究

采用粉末注射成形技术制备铜制件,研究粉末注射成形中烧结工艺参数对烧结效果的影响,以获得理想的注射成形工艺及烧结工艺参数.通过采用真空烧结和氢气气氛烧结、改变烧结升温速率和烧结温度,对比了烧结件的烧结质量和烧结收缩等情况.结果表明,铜粉末注射成形坯的烧结必须在氢气气氛保护下进行;烧结升温速率不宜过快或过慢,本研究采用5℃/min的升温速率效果较好;烧结温度低于且接近铜的熔点温度,烧结温度高,烧结件收缩率大但致密度也大.     

阻尼孔活塞粉末冶金产品开发与模具设计

通过对产品使用性能的合理分析,运用粉末冶金成形原理,在压制毛坯时一次性将阻尼孔压制成形,对烧结后的毛坯采用精整工艺,控制零件关键尺寸精度与形位公差,辅以适当的机械加工工序,在自动模上成功地开发了细孔类粉末冶金结构件,与其他工艺相比,零件尺寸稳定,提高了生产率,降低了生产成本,取得了良好的经济效益。     

铜粉粒径对3D打印成形和烧结成形性能的影响

研究了不同粒径Cu粉末对打印成形和烧结成形性能的影响,从浆料稳定性、烧结效果和成形质量3个方面对不同粒径的效果进行评测。利用能谱仪、扫描电子显微镜对烧结后的样品进行微观组织及元素含量进行对比分析,采用热重分析仪分析样品烧结中的变化过程。结果表明,20μm铜粉受内在范德华力的影响更容易发生团聚,导致浆料堆积从而影响打印成形;1μm粉末在烧结后最为致密、整体收缩率最低,成形效果较好。     

成形压力对Fe16Al2Cr多孔材料性能的影响

以Fe16Al2Cr预合金粉末为原料,采用模压成形、真空烧结的方法制备了Fe16Al2Cr多孔材料,研究了粉末成形压力与Fe16Al2Cr多孔材料性能的关系。结果表明：小于31 μm的Fe16Al2Cr粉末的压制成形性能较差,压坯强度低;烧结过程中,厚度收缩远大于径向收缩,并随着成形压力的增大而减小;在较高的烧结温度下,成形压力和烧结时间对径向收缩几乎没有影响;而孔隙度、最大孔径和透气度随着成形压力的增大而降低,并随烧结时间延长而增大;增大成形压力,延长烧结时间,有利于提高Fe16Al2Cr多孔材料的剪切强度。     

成形压力对Fe16A12Cr多孔材料性能的影响

以Fe16A12Cr预合金粉末为原料,采用模压成形、真空烧结的方法制备了Fe16A12Cr多孔材料,研究了粉末成形压力与Fe16A12Cr多孔材料性能的关系.结果表明:小于31μm的Fe16A12Cr粉末的压制成形性能较差,压坯强度低;烧结过程中,厚度收缩远大于径向收缩,并随着成形压力的增大而减小;在较高的烧结温度下,成形压力和烧结时间对径向收缩几乎没有影响;而孔隙度、最大孔径和透气度随着成形压力的增大而降低,并随烧结时间延长而增大;增大成形压力,延长烧结时间,有利于提高Fe16A12Cr多孔材料的剪切强度.     

激光微区烧结微成形技术研究

目前微小零部件的制造方法很多,激光微成形即为其中一种。介绍了在激光选区烧结技术的基础上,结合微成形特点开发的激光微区烧结成形技术。该技术可对金属粉末进行直接微区烧结成形,所成形的金属微型零件强度高,不需后续处理,大大节省了从原材料到最终实体的时间,并具有环境污染小、材料利用率高、成形速度快和效率高的特点。     

定向切削铜纤维烧结成形（英文）

分析定向切削铜纤维烧结载体的成形机理,研究烧结温度、烧结氛围和烧结时间对烧结成形的影响,并且分析不同烧结条件下烧结纤维的拉伸力学性能。结果表明,烧结温度和烧结氛围对烧结成形具有重要影响,而烧结时间的影响不是特别显著。在低温还原氛围和800°C下烧结60 min,可以形成烧结颈使得纤维之间紧紧连结在一起,并且在纤维表面形成粗糙的微结构,同时可以获得最佳的拉伸力学性能。     

纳米材料激光选择性烧结成形的研究

纳米材料由于颗粒尺寸微小，致使其产生一些特异的性能，在应用过程中，把纳米粉末材料成形为大体积的材料及成形纳米零件产生了巨大的困难，激光选择性地成形纳米材料是利用激光烧结能量信号，能迅速加热，剧冷的特性，最大限度地控制纳米材料在烧结过程中颗粒生长的纳米材料成形的方法。本研究中，在激光选择性烧结成形纳米材料Al2O3的基础上，对纳米材料烧结成形过程中产生的问题进行了分析与探讨。     

多工序冲压成形的过程控制研究

基于多工序冲压成形过程的设计与开发,构建了面向过程的多工序冲压成形控制系统模型,对影响多工序冲压成形过程质量的主要过程变量进行了识别与分析,并介绍了SPC与EPC的整合在冲压成形过程控制中的应用思路,提出以最终冲压件(包括工序件)的技术特性指标和质量要求为目标,通过多工序冲压成形过程的设计与开发,采用合适的过程控制技术,实时调整、改进冲压生产过程,控制最终冲压件的质量。     

钛及钛合金粉末的注射成形

介绍了钛及钛合金粉末注射成形技术的发展、应用现状及制备工艺。指出了钛及钛合金粉末注射成形技术研究方向和扩大应用的途径是：①使用价格低廉的氢化脱氢粉和气体雾化粉混合得到的钛及钛合金粉作为注射成形的原料粉末；②开发新型高效的钛及钛合金粉末注射成形用的粘结剂体系；③优化混炼工艺；④优化注射条件参数以消除注射缺陷；⑤开发先进的脱脂工艺，使脱脂时间进一步缩短并减少脱脂缺陷，以降低成本；⑥研究钛及钛合金烧结工艺以及超小型零件的注射成形工艺，控制产品尺寸精度，提高产品性能。扩大产品的尺寸。     

活检钳零件金属粉末注射工艺与模具

以医疗器械部件为例,介绍了金属粉末注射成型工艺、成型缺陷控制、收缩率控制、烧结技术;还介绍了金属粉末注射成型的模具结构、模具材料,模具寿命达100万次以上。金属注射成型作为一种制造高质量精密零件的近净成型技术,将成为零部件加工新工艺手段。     

MIM工艺对W—Ni—Fe高密度合金力学性能的影响

研究了粉末装载量和烧结温度对ＭＩＭ钨基高密度合金力学性能的影响,并将ＭＩＭ工艺与传统压制／烧结工艺进行了比较,实验结果表明,采用装载量为４７％（体积分数）的喂料,在１５３０℃烧结２ｈ得到的９７Ｗ－２Ｎｉ－１Ｆｅ高密度合金具有优良的力学性能的达到的性能为σｂ＝９３６ＭＰａ,σ０．２＝６４９ＭＰａ,δ＝１１．４％,ＨＲＣ＝３１,优于传统压制／烧结工艺制得的合金。     

新型钨铜复合材料的制备和性能研究的新进展

针对如何改善粉末冶金钨铜系高比重合金的烧结性能，提高其致密度，获得特殊结构的微观组织等问题。就近年来钨铜复合材料研究的几个主要热点：纳米结构材料、梯度结构功能材料、金属注射成形等进行了综述。     

注射成形制备多孔钛及其性能

以氯化钠作为造孔剂,利用金属注射成形(MIM)工艺制备多孔钛。研究烧结温度、造孔剂粒度和含量对多孔钛孔隙度、微观形貌和力学性能的影响。结果表明,随着烧结温度的升高,多孔钛的孔隙度逐渐下降而抗压强度和弹性模量逐渐升高;随着造孔剂粒度的减小,多孔钛的孔径也随之减小;随着造孔剂含量的增多,多孔钛的孔隙度逐渐增大;MIM多孔钛植入体的最佳烧结温度为1100～1200℃,NaCl的最优粒度为150～250μm。     

Fabrication of bronze components by metal injection moulding using powders with different particle characteristics

The aim of this work is to fabricate bronze components by metal injection moulding (MIM) studying the possibility of changing partially or totally the gas atomised powder by water atomised ones that are cheaper than the former. In order to carry out this study, a bronze 90/10 gas atomised spherical powder (usual MIM powder <22 μm) and two water atomised irregular powders (particle size <35 μm and <140 μm) were mixed in different proportions. As received powders and their mixtures were used to fabricate feedstocks and processed by MIM to evaluate the influence of powder particle size and morphology on debinding and sintering stages. Finally, both mechanical properties hardness and maximum flexural stress were determined to characterize the sintered materials. The addition of irregular fine and coarse powders was found to affect the moulding process, although densities and mechanical properties close to values of gas atomised one were obtained after sintering. Therefore, the use of water atomised bronze powders could be a promising way to diminish production costs in this technology.     

Study of metal injection molding of highly porous titanium by physical modeling and direct experiments

The prospects of metal injection molding (MIM) technique for manufacturing of highly porous titanium parts was studied by physical modeling, based on feedstock warm compaction experiments. The space holder method and typical MIM binder were used in all cases of the study. The influence of the starting powder (dehydrided and atomized) in feedstock on resulting properties of porous titanium was investigated. The size of space holder particles and space holder amount were adjusted to obtain porosity and pore size desired for medical implants application. NaCl and KCl were studied and compared as prospective space holder materials. The porous samples were characterized regarding their microstructure, uptake of interstitial contents and mechanical properties. For comparison, same investigations have been conducted on samples, which were prepared by established space holder technology based on cold isostatic pressing (CIP) and sintering. Finally, first direct MIM experiments and attempts of feedstock optimization were carried out. The peculiarities and problems of metal injection molding of highly porous titanium have been discussed.     

Fabrication and properties of extrusion-based 3D-printed hardmetal and cermet components

Hardmetal and cermet bodies were printed by fused-filament fabrication (FFF) and composite-extrusion modelling (CEM) in an SDS (shaping – debinding – sintering) process. For FFF the filaments were prepared from hardmetal (WC-10Co) and cermet powder (Ti(C,N)-Co/Ni-based) and organic binder. The CEM feedstock consisted of WC-Co MIM powder. A 3D filament printer as well as a 3D printer working with a MIM granulate were employed to fabricate printed bodies by FFF and CEM, respectively. The solvent debinding process was performed in cyclohexane (FFF-printed bodies) or water (CEM-printed bodies). Thermal debinding of all parts was performed in a tube furnace up to a temperature of 800 °C. The pre-sintered parts were then subjected to vacuum sintering by application of conventional vacuum sintering profiles up to 1430 °C for hardmetals and up to 1480 °C for cermets. Dimensional and mass changes upon the various preparation steps as well as microstructure and porosity of the sintered bodies were investigated. While the microstructure is practically identical to that of conventionally prepared materials, some cavities were present from the printing process because of yet non-optimised printing strategy. By change of printing strategy the cavities could be minimised or even avoided. The study shows that with the applied 3D extrusion-printing techniques, hardmetal and cermet components with innovative geometries are accessible.     

Sintering study of injection molded W-8%Ni-2%Cu compacts from mixed powders by thermoanalytical techniques

Heavy alloy parts from W-8%Ni-2%Cu powder mix were fabricated by MIM using a feedstock with 50 vol.% binder. The binder was removed by solvent de-binding followed by thermal de-binding. Sintering of the heavy alloy brown parts was investigated by employing various thermoanalytical techniques such as DIL, TGA and DTA up to 1460 °C. During sintering, the evolved gases were analyzed in a mass spectrometer which was coupled to the dilatometer. Thermal analysis helps to understand the sintering process regarding phase transformation, melting of alloy matrix and chemical reactions. From these thermoanalytical measurements, a kinetic analysis was made. High sintered density (> 99%) and fine-grained homogeneous microstructures were achieved by rate controlled sintering as confirmed by metallographic analysis.     

Net-Shape Forming and Mechanical Properties of MIM418 Turbine Wheel

Near-net shape forming of the turbine wheel with a hollow internal structure was realized by adopting the die with side core-pulling mechanism. MIM418 turbine wheel with relative density above 99.5% is obtained by the combination of vacuum sintering and hot isostatic pressing. A high volume fraction (57%) of near cuboidal γ′ phase with average particle size of 0.52 μm is formed in γ matrix. Small amount of discrete carbides with size of 0.2-0.4 μm is distributed uniformly on grain boundaries and within grains. The tensile strength, yield strength, and ductility of MIM418 superalloy reach 1425 MPa, 1004 MPa, and 19.4%, respectively, which are much higher than that of the cast K418 superalloy.