粉末注射成形的成形原理与发展趋势

粉末注射成形技术是一种高效的近净成形技术,适用于生产小型的、具有复杂形状的零部件。本文综述了粉末注射成形技术的发展历程;概述了粉末注射成形原理,包括粉末和粘结剂的选择、混炼,注射成形及后续的脱脂、烧结;并介绍了粉末微注射成形技术的技术特点、注射工艺和微注射成形的应用;分析了粉末注射成形技术的局限性;展望了粉末注射成形技术的发展趋势,认为其材料体系将朝多方向发展,且应开发新的粘结剂和新的脱脂工艺以减少脱脂后在材料中的残留,开发少粘结剂、无粘结剂注射成形工艺;微粉末注射成形将朝成形数微米甚至纳米级的零部件的方向发展,防止粉末的氧化和保形是关键。     

金属粉末注射成形的原理与发展趋势

金属粉末注射成形技术是一种高效的近净成形技术,适用于生产小型的、具有复杂形状的零部件。本文综述了金属粉末注射成形技术的发展历程;概述了金属粉末注射成形原理,包括粉末和粘结剂的选择、混炼,注射成形及后续的脱脂、烧结;并介绍了金属粉末微注射成形技术的技术特点、注射工艺和微注射成形的应用;分析了金属粉末注射成形技术的局限性;展望了金属粉末注射成形技术的发展趋势,认为预制复合粉末有助于解决混炼和注射造成的成分不均匀,减小烧结过程由于收缩不均匀导致的制件变形,且应开发新的粘结剂和脱脂工艺以减少脱脂后其在材料中的残留和碳化,开发少粘结剂注射成形工艺。     

当代金属注射成形技术

一、前言 金属注射成形(Metal Injection Molding,简称MIM)是一种从塑料注射成形行业中引伸出来的新型粉末冶金近净成形技术,其基本工艺过程为:首先是选择符合MIM要求的金属粉末和粘结剂,然后在一定温度下采用适当的方法将粉末和粘结剂混合成均匀的注射成形喂料,经制粒后在注射成形机上注射成形,获得的成形坯经过脱脂处理后烧结致密化成为最终成品。 金属注射成形技术在制备具有复杂几何形     

金属注射成形技术的研究

金属注射成形技术是近年来发展最为迅速的粉末冶金近净成形枝术.从粘结剂、脱脂、烧结、精度及成分控制和计算机模拟等方面阐述了金属注射成形技术(MIM)的研究现状,指出MIM技术的应用领域和材料体系向多方面拓展、粘结剂体系的多样化与脱脂方法的多样化和计算机技术的应用将使MIM技术更加完善.     

超细WC-Co硬质合金注射成形的研究进展

总结了近年来超细WC-Co硬质合金注射成形在原料粉末、粘结剂体系、混炼、注射成形、粘结剂脱除和烧结等方面的研究现状.讨论了不同脱脂方式的发展及其对碳含量的影响,重点阐述了控制晶粒长大、尺寸精度等关键技术存在的困难及解决途径.展望了超细WC-Co硬质合金注射成形技术的发展前景.     

粉末注射成形粘结剂及脱脂技术研究进展

综述了粉末注射成形中粘结剂配方及其脱脂技术研究进展,并比较了现行工业上常用的三大脱脂方法,讨论了粉末注射成形脱脂工艺的发展趋势。     

粉末注射成形技术

1 项目简介 粉末注射成形是传统粉末冶金与现代塑料注射成形工艺相结合而形成的一门零部件新型成形技术,其基本工艺过程是:首先将固体粉末与有机粘结剂均匀混合,经制粒后在加热状态下用注射成形机将粒状料注入模腔内冷凝成形,然后用化学或热分解的方法将成形坯中的粘结剂脱除,最后经烧结致密化得到最终产品。该技术的最大特点是可以直接制造出具有最终形状的零部件,最大限度地减少机加工量和节省原材料,而且材料适应性广,凡是可以制成粉末的金属、合金、陶瓷等均可用此技术直接     

陶瓷注射成型用PVB树脂基粘结剂研究

本文研究了应用于陶瓷注射成形技术的聚乙烯醇缩丁醛(PVB)基粘结剂体系,它主要包括PVB、邻苯二甲酸二辛酯(DOP)、润滑剂和偶联剂.该粘结剂体系与Al2O3粉末有较强的相互作用,可以制备混炼均匀和高固含量的Al2O3陶瓷注射料,并且注射料具有高的生坯强度和良好的注射成形性.根据该粘结剂体系的TGA曲线,可以选择合适的热脱脂程序,经热脱脂和烧结得到结构致密的陶瓷制件.     

粉末注射成形技术在烧结NdFeB永磁体制备中的应用

全面介绍了采用注射成形技术制备烧结NdFeB永磁体的工艺过程；总结了粘结剂、磁场取向及成形、脱脂和烧结工艺对最终产品的影响；比较了注射成形和传统粉末冶金压制成形制备的NdFeB磁体的性能；在分析现状的基础上，指出了现阶段存在的问题。     

金属粉末注射成形粘结剂选择的基础

分析了金属粉末注射成形粘结剂组分间热力学相容性和粘结剂流变性的影响因素,并结合实验验证,综述ＭＩＭ粘结剂选择的方法。     

金属注射成形技术的研究现状

金属注射成形 (MIM)已成为国际粉末冶金领域发展迅速 ,最有前途的一种新型近净成形技术。本文综述了MIM技术的研究现状 ,指出了MIM的发展趋势     

金属注射成形蜡基粘结剂的研究

本文研究了综合蜡基和油基粘结剂优点的改进型蜡基粘结剂体系 ,其组成为PP PW 植物油 SA 改性剂。改进型蜡基粘结剂分阶段热解 ,各组元间有较强的相互作用 ,相容性较好。该粘结剂和金属粉末具有较好的混合均匀性 ,改性剂的加入提高了粉末装载量。喂料是一种假塑性流体 ,非牛顿指数n较大 ,粘流活化能ΔEη 较低 ,具有良好的注射填充性。改进型蜡基粘结剂既可热脱脂 ,又可溶剂脱脂 ,溶剂脱脂速度快、维形能力好。     

金属注射成形喂料的流变学性能评价

从理论上对金属注射成形喂料的流变学性能进行分析发现,评价ＭＩＭ喂流变不遥主要指标是喂料的粘度及粘度对应变和温度的敏感性,这些指标可统一用ＭＭ喂料综合流学因子进行评价,运用该评价因子研究几种不同粘结剂组成的Ｆｅ－Ｎｉ及Ｗ－Ｎｉ－Ｆｅ合金喂料的流变学性能。     

MIM粘结剂中聚合物性质的估算

介绍了金属注射成形中一些聚合物性质的估算方法，并探讨了一些粘结剂的表面性能。     

新型金属注射成形催化脱脂型粘结剂的催化快速分解研究

催化脱脂是目前MIM技术领域新的发展方向,研究了新型金属注射成型催化脱脂型粘结剂的催化快速分解,研究结果表明,该催化脱脂型粘结剂在以HNO3为催化剂进行催化脱脂时,注射成形坯经3－4h催化脱脂后,脱脂坯内部已形成大量的连通孔道,脱脂时间,脱脂温度以及 不同粘结剂组成影响催化脱脂效果。     

溶剂脱脂型MIM粘结剂的研究

对溶剂脱脂的原理及其影响因素进行了阐述，介绍了溶剂脱脂型粘结剂的研究发展情况。认为水溶性粘结剂是一类环境友好的粘结剂，具有良好的应用前景，从分子量和溶度参数两个影响因素出发，简述了溶剂脱脂型粘结剂的设计方法。     

A Low-Binder-Content Ink System for 3D Printing High-Density and Small Feature Size 316L Stainless Steel Parts

Binder ink system is the backbone of binder jet 3D printing (BJ-3DP) technology. Compared with metal injection molding (MIM), BJ-3DP needs much less amount of binder, which means less exhaust gas generation during the debinding process and more environmental friendliness. More than that, low content of binder is also supposed to benefit the structure properties of the printed metal parts. Herein, an ultralow-binder-content ethanol–water–PVP ink system is demonstrated for the BJ-3DP 316 L stainless steel parts by applying thermal bubble inkjet technology. The PVP binder concentration is as low as 80 mg mL⁻¹, which can achieve an ultralow solid content of 0.2 wt% in the printed green part. The two-component solution with water and ethanol provides not only the rheology property adjustment freedom for the ink jetting and infiltration in the metal powders, but also the two boiling points for the step-by-step capillary bridge formation process. By applying the low-binder-content ink, the fully densified 316 L stainless steel parts after sintering can obtain the relative density up to 99.4%, Vickers hardness up to 185 HV, tensile strength up to 542 MPa, 25% elongation at break, and feature size as small as 200 μm.     

Investigations on Metal Injection Molding of 316L Stainless Steel

Metal Injection Molding (MIM) was performed with water atomized and gas atomized 316L stainless steel powders and powder blends thereof. Feedstocks were prepared using a thermoplastic binder system and subsequently molded into tensile test specimens. Different debinding procedures and sintering treatments were applied and their influence on carbon content in the product was compared. Chemical decomposition processes of the binder and the influence of powder morphology on debinding and sintering behaviour are discussed. Shrinkage of the MIM-fabricated parts was examined and correlated to the powder characteristics. As a result a procedure is suggested to achieve mechanical properties expected for 316L stainless steel.     

Isotropic forming of porous structures via metal injection molding

Metal injection molding (MIM) is a near net-shape process that offers the unique ability to manufacture porous components with homogeneous porosity, pore structure and permeability. MIM is a process that can significantly reduce production cost when large quantities of components with complex shape need to be delivered. In this study, MIM is used to produce porous 316L stainless steel structure from both water and gas atomized powders. The porous components made by MIM were characterized to evaluate their suitability for small pore structure applications. The porous structures were analyzed for porosity, pore size, permeability, and thermal conductivity as a function of powder type and processing conditions. A typical MIM powder (<20 μm) processed at 50 vol% loading in a binder system produced a uniform pore structure with a permeability of less than 1⋅10^{− 13} m² and a maximum pore radius of less than 5 μm. Water-atomized powder proved to be better suited for low-solids-loading metal injection molding (<50 vol% loading) since its irregular shape provided greater strength and fewer defects during the molding and debinding process steps. Measurements of thermal conductivity show that the water-atomized powder had less thermal conductivity (∼2 W/m-K) than the gas-atomized powder (∼3 W/m-K). This study shows that MIM is a suitable process that can be used to manufacture functional porous structures that require isotropic pore size and complex shape.