陶瓷注射成型混料工艺及坯体产生缺陷研究

采用保形性较好的聚苯乙烯粘结剂体系和ZrO2-3%Y2O3(摩尔分数)粉末混合制备喂料。研究了加料顺序对喂料性能的影响,通过研究混料时间对喂料均匀性的影响确定合适的混料时间,分析了注射成型和脱脂过程产生缺陷的成因。结果表明,当先混合ZrO2粉末、聚苯乙烯(PS)与油,再加入硬脂酸(SA)和邻苯二甲酸二丁酯(DBP)时,所制备的喂料更均匀、性能更好;混料时间为63min时,喂料均匀。     

陶瓷注射成型的关键技术及其研究现状

陶瓷注射成型是一种近净尺寸陶瓷可塑成型方法,是当今国际上发展最快、应用最广的陶瓷零部件精密制造技术.详细阐述了陶瓷注射成型技术的关键因素,重点介绍了粘结剂、注射成型及脱脂等关键工艺及其研究现状,并在此基础上评价和展望了该技术的发展前景.     

精细陶瓷成型工艺现状及趋势

由于陶瓷的传统成型技术已经不能满足现代各工业领域的要求，新的成型工艺不断涌现。综述了国内外近十年来研究比较活跃的、适于成型复杂形状的注射成型及各种湿法成型技术，并且讨论了今后精细陶瓷成型工艺的发展趋势。     

Al2O3陶瓷注射成型热塑性粘结剂及脱脂工艺研究

重点研究了氧化铝陶瓷注射成型中热塑性粘结剂的选取和对应的热脱脂工艺。结果表明，当Al2O3粉料质量百分含量为70％、选用石蜡／聚丙烯／硬脂酸（mpw：mpp：mSA=79：20：1）热塑性粘结剂时，采用适当的热脱脂工艺，可获得结构缺陷少、性能较高的Al2O3陶瓷材料。     

陶瓷胶态注射成型新工艺

清华大学在863计划的支持下,在80年代末开展的注射成型及压滤成型工艺研究和90年代进行的凝胶注模成型和直接凝固注模成型工艺研究的基础上,发展了一种全新的胶态注射原位快速凝固成型新工艺。该工艺是一种高性能陶瓷复杂形状零部件的低成本制备技术,是一种近净尺寸的先进制备工艺。与现有的陶瓷注射成型和胶态成型工艺相比较具有明显的先进性、创新性。首先与通常的陶瓷注射成型工艺相比较,避免了使用大量高分子粘结剂所造成的排胶困难,它只需要使用少量的有机     

CIM中最新脱脂工艺的进展

陶瓷注射成型是一种近净尺寸可塑成型方法，可高效率成型形状复杂的陶瓷部件。脱脂是陶瓷注射成型中最复杂、最重要的环节，本文介绍了陶瓷注射成型最新脱脂工艺进展，详细介绍了催化脱脂和水基萃取脱脂的脱脂原理，并对各种脱脂工艺的优缺点进行了比较。     

陶瓷与金属粉末注射成型烧结制品的研究

用粉末注射成型的方法制备了不同成分配比的ＺｒＯ２陶瓷粉末与不锈钢粉末注射成型制品、对这种金属陶瓷材料进行了成分分析,残余应力分析及断口分析,同时进行了ＴＥＭ分析。     

陶瓷注射成型制备技术的研究与进展

陶瓷注射成型(CIM)是将聚合物注射成型方法与陶瓷制备工艺相结合而发展起来的一种制备陶瓷零部件的新工艺.目前,陶瓷注射成型己广泛用于各种陶瓷粉料和各种工程陶瓷制品的成型.用该工艺制备的各种精密陶瓷零部件,已用于航空、汽车、机械、能源、光通讯、生命医学等领域.主要从陶瓷注射成型过程、粉体表面改性、脱脂新工艺、微注射成型、国内外研究和应用等方面就陶瓷注射成型的发展过程作了系统的阐述.最后对陶瓷注射成型技术进行了展望.     

CIM中最新脱脂工艺的进展

陶瓷注射成型是一种近净尺寸可塑成型方法 ,可高效率成型形状复杂的陶瓷部件。脱脂是陶瓷注射成型中最复杂、最重要的环节 ,本文介绍了陶瓷注射成型最新脱脂工艺进展 ,详细介绍了催化脱脂和水基萃取脱脂的脱脂原理 ,并对各种脱脂工艺的优缺点进行了比较。     

陶瓷注射成形中脱脂工艺及其新进展

陶瓷注射成形是先进的陶瓷近净成形技术,可高效成形形状复杂的陶瓷部件.而脱脂是陶瓷注射成形中最复杂和重要的环节.详细介绍了陶瓷注射成形各种脱脂工艺的脱脂原理,并对各种脱脂工艺的优缺点进行了比较.     

Influence of the Compacts Homogeneity on the Incidence of Cracks during Thermal Debinding in Ceramic Injection Molding

During thermal debinding in ceramic injection molding, the inhomogeneity of green body is a key origin of cracks. In this study, the impact of low molecular weight binders on the homogeneity of the green body was investigated. Incidence of cracks during thermal debinding indicated that the volume ratio of wax to stearic acid should be out of high viscosity and incompletely wetting region. In these two formulation regions,typical inhomogeneous microstructures were observed. By mercury intrusion method, it was shown that pore size distribution of the debinded compacts was determined by thermal degradation of low molecular weight binders. A particle-rich region model was established to predict the nucleation of cracks caused by solid loading fluctuation. The criterion of cracks nucleation was that local capillary force from solid loading fluctuation was larger than the suction force from the surroundings.     

Effects of Injection Molding Parameters on the Production of Microstructures by Micropowder Injection Molding

Micropowder injection molding (μPIM) is a potential low-cost process for the mass production of metal or ceramic microstructures. In order to obtain good molded microstructures and to avoid molding defects, it is important to select suitable injection molding parameters. In this paper, the selection of injection molding conditions for the production of 316L stainless steel microstructures by μPIM is presented. Silicon mold inserts with 24 × 24 microcavities were injection molded on a conventional injection molding machine. The dimensions of each microcavity were Φ 100 μ m × depth 200 μm, giving an aspect ratio of 2. The distance between each microcavity was 200 μm. Five sets of experiments were conducted by varying one injection molding parameter at a time. The parameters included injection pressure, holding pressure, holding time, mold temperature, and melt temperature. Higher injection pressure and holding pressure were required during the injection molding process due to the small dimensions of the microcavities and the large number of microcavities (576 microcavities). High mold temperature was required for complete filling of the microcavities. Molded microstructures without visual defects were obtained using appropriate injection molding parameters. Catalytic debinding and sintering of the 316L stainless steel microstructures were successfully conducted.     

Processing of Ceramic Rifled Gun Barrel

Ceramic gun barrels have the potential to provide a significant increase in barrel life as well as reduction in weight for small caliber systems. The potential use of ceramic tubes as gun barrels may be severely limited due to the difficulty in introducing the rifling on the inner diameter. The processing of ceramic gun barrels with internal rifling pattern poses a tremendous processing challenge to the materials community. The rifling lands and grooves and desired twist rate, coupled with the difficulty of machining ceramics, makes the economic manufacturing of such gun barrels extremely difficult. The current paper describes the preliminary efforts of fabricating an alumina gun barrel tube that was around 100-mm long with a 25-mm inner diameter (ID), a 33-mm outer diameter, and eight lands and eight grooves. Over and above the lands and grooves in the ID, the barrel had to have a 10:1 twist (one complete twist in 250-mm) incorporated into it. The paper will describes our preliminary attempts at processing such a rifled gun barrel tube made of alumina.     

陶瓷微结构件的注射成形工艺及其微观组织

采用粉末微注射成形技术制作了ZrO2陶瓷微结构件,分析了其注射成形工艺,包括喂料配制、注射工艺及烧结工艺对微观组织的影响.实验结果表明,粉末体积分数为55%的生坯注射成形后在1 500℃下烧结2 h,采用排水法测得其微结构相对密度高达98.5%,采用纳米硬度分析法得到其微结构的显微硬度值为13.75 GPa.扫描电子显微镜(SEM)结果表明,提高模具温度和注射压力,有利于微结构的填充,进而改善微结构件的微观组织;高的烧结温度可以增加零件的致密度,但容易导致晶粒的过度长大和尺寸不均匀.激光共聚焦光学显微镜观察结果表明,使用亚微米级陶瓷超细粉得到的微结构具有良好的表面质量,其烧结前、后的表面粗糙度值分别为0.33μm和0.28μm.此外,提高粉末含量可以减小零件收缩率,从而有利于微结构的尺寸精度控制.     

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.     

粉末微注射成型的研究进展

粉末微注射成型由于其市场前景广阔而迅速成为当今的研究热点,但由于其流动机理尚不明朗导致产品质量不稳定.介绍了当前研究粉末微注射成型的流动模型,以及在粉末材料、粘结剂与脱脂、注射机与模具、烧结及尺寸控制方面的研究进展.指出研究的关键在于从两相流模型和颗粒模型在微尺寸型腔的流动机理入手,提高微型零件尺寸精度、力学性能及改善微观组织结构.     

大尺寸ZrO2注射成型坯体热脱脂缺陷成因探究

采用蜡基ZrO2粉末喂料注射成型获得大尺寸ZrO2陶瓷粉末注射产品（坯体）,并根据喂料热分析曲线的变化特点,系统研究了大尺寸ZrO2坯体的热脱脂过程及规律。通过对热脱脂前后坯体的重量损失、尺寸收缩、外观缺陷和微观组织形貌的分析评估,着重探讨了大尺寸ZrO2坯体热脱脂过程中存在的主要缺陷和成因。研究表明,流蜡、鼓泡和开裂等热脱脂缺陷主要发生在低温脱脂阶段,其主要原因是液态石蜡扩散及分解过程的失衡。为此,结合“失重率控制”的思路和喂料的热失重规律,对热脱脂工艺进行了优化,在不延长总脱脂时间的前提下,显著提高了大尺寸ZrO2坯体的脱脂合格率。     

新型陶瓷注射成形喂料催化脱脂过程的研究

陶瓷注射成形是一种受到日益广泛关注的技术 ,但其中脱脂一步传统采用的热脱脂技术脱脂速度慢 ,效率较低。本研究采用以聚甲醛为主要粘结剂制备了可快速脱脂的新型陶瓷注射成形喂料体系 ,并进行催化脱脂工艺的研究 ,记录了该过程中样品失重的情况 ,分析了脱脂阶段不同特征及其原因 ,指出催化脱脂过程速度的控制因素是气态催化剂和气体产物扩散过程。通过脱脂前后样品表面及截断面的扫描电镜分析 ,直观反映了脱脂前后样品微观形貌上的差异及特点。观察了脱脂过程不同时刻样品外围与中心区域的微观形貌 ,证明了脱脂过程是由外围逐渐向内部扩散的 ;记录了经注射成形的试样烧结前后的密度变化