特种陶瓷成型方法

成型技术是制备陶瓷材料的一个重要环节.特种陶瓷成型方法总的来说可分为干法成型和湿法成型两大类,干法成型包括钢模压制成型、等静压成型、超高压成型、粉末电磁成型等;湿法成型大致可分为塑性成型和胶态浇注成型两大类;近些年来固体无模成型技术在特种陶瓷的成型研究中也取得了较为快速的发展.对特种陶瓷的这些成型方法进行了简要介绍,指出了各种成型方法的优缺点,并展望了特种陶瓷成型方法的发展趋势.     

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.     

陶瓷成型技术及应用

由于对陶瓷材料的性能要求的提高,传统的成型方法制备的陶瓷已经不能完全满足现代工业的需求,随着学科间交流的广泛,各种新的陶瓷成型工艺不断涌现。本文以制品形状为分类标准,综述了国内外目前研究活跃的多种干法成型、湿法成型方法,并讨论了今后陶瓷成型工艺的发展趋势。     

超高分子量聚乙烯加工研究进展

本文详细介绍了超高分子量聚乙烯(UHMWPE)的模压成型、挤出成型、注塑成型、凝胶纺丝等加工方法,并指出了各种方法的优缺点。     

用凝胶注模成型制备压电陶瓷体及其电学性能研究

对PZT陶瓷浆料胶体化学特性进行了研究,成功制备了高固相含量低粘度的PZT陶瓷浆料.对含不同分散剂凝胶注模成型PZT样品电学性能的研究及其与普通干压法制备样品的比较表明,成型过程中的各种有机添加剂如单体和交联剂等不会对PZT的性能造成影响,而某些无机成份如选择不当的分散剂,则会起到一种掺杂剂的作用,从而影响成型后样品的各种电学性能.本文结果说明,对于电子陶瓷材料,在应用凝胶注模这种成型方法时,必须考虑各种添加剂可能对样品性能造成的影响     

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。     

汽车B柱Rollforming成型仿真的有限元建模

利用MSC．Marc软件研究了汽车B柱变截面辊弯成型仿真的建模方法，主要包括板料模型和成型辊模型的建立，各种参数的设置，及成型辊的速度加载等，并通过仿真模拟及仿真结果分析，验证了模型的正确性。     

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。     

微孔发泡材料成型装置及其可视化研究进展

微孔发泡材料成型装置对微孔发泡材料的制备及基础研究至关重要。微孔发泡材料成型装置的设计与创新直接关系到发泡制品质量的改善、生产效率的提高以及微孔发泡相关基础研究。根据成型方式的不同,微孔发泡材料成型装置主要分为四类,即间歇发泡成型、连续挤出发泡成型、注塑发泡成型、模压发泡成型装置,分别阐述了各类装置设计原理和结构特点,并总结了几种发泡装置的优点和不足;同时总结了各种可视化装置设计方案,与挤出、注塑发泡成型方式下的可视化装置相比,自由发泡可视化装置结构较简单、成本较低廉、操作较简便,目前研究和应用居多;但是,存在与发泡环境相差很大的问题,很难用于实际生产。最后展望了当前微孔发泡材料成型装置设计中亟需解决的问题,并提出了今后微孔发泡材料成型装置的设计思路及研究前景。     

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。     

An intelligent hybrid system for initial process parameter setting of injection moulding

Currently, determination of the initial process parameter settings for injection moulding is mainly performed by moulding personnel, and the effectiveness of the parameter setting is largely dependent on the experience of these personnel. In this paper, an intelligent hybrid system, called HSIM, is described, which is used to determine a set of initial process parameters for injection moulding based on the artificial intelligence (AI) techniques, case-based reasoning (CBR), and hybrid neural network (NN) and genetic algorithm (GA). HSIM can determine a set of initial process parameters for injection moulding quickly, without relying on expert moulding personnel, from which moulded parts free from major moulding defects can be produced.     

Compaction and in plane permeability characteristics of quasi unidirectional and continuous random reinforcements

Compaction and permeability behaviour are important influences on the processing of composites for a range of manufacturing techniques including liquid composite moulding (LCM) and compression moulding. This paper describes an experimental study of the factors influencing these characteristics for two glass fibre reinforcement media used in LCM: continuous strand mat and an aligned fabric produced using warp knitting technology. The compaction relationships for the materials are presented as functions of process variables such as pressure, temperature, and forming rate. In plane permeability relationships measured using rectilinear and radial flow tests are presented for different fibre orientations and packing fractions. The results are discussed with reference to processing by resin transfer and structural reaction injection moulding.

MST/3248     

Performance of sub-micron diamond films coated on mould inserts for plastic injection moulding

In this article, results obtained from an investigation focusing on the application of diamond coatings on inserts for thermoplastic injection moulding applications are reported. The injection moulding industry can potentially benefit significantly from the use of diamond coatings on moulds typically employed in the injection moulding systems. Diamond films were coated on steel and onto silicon inserts and subsequently tested in real operating conditions. The moulded objects were analysed and the results were compared between bare steel and silicon inserts. The as-grown diamond coatings were characterised prior to and post the routine injection cycles using a number of techniques, such as Raman spectroscopy and SEM. Furthermore, the polymer finishing quality was assessed by optical microscopy for each material and coating used, and the results are presented and discussed in this article.     

浸塑成型中冷却时间的优化

采用数学建模的方法对浸塑成型中制件的冷却过程进行了模拟。通过对浸塑件冷却过程中的传热作合理简化,建立传热过程的扩散方程,并由边界条件的齐次化等数学方法,推导出确定浸塑件冷却时间的计算方程。将方程应用于聚氯乙烯(PVC)浸塑件冷却时间的计算与确定,并对比经验公式做了讨论与分析。结果表明,通过公式计算确定的冷却时间可以减少生产中脱模困难的问题,降低制件的后收缩率,达到优化浸塑工艺和改善制件性能的目的。     

高聚物基骨替代材料复合技术的研究进展

概述了高聚物基骨替代材料复合技术的研究现状，着重介绍了高聚物基体和增强材料的选择要求，注射模塑成型、仿生沉积、原位复合等复合技术，并评价了不同基体材料的生物学性能。     

Structure and anisotropy of stiffness in glass fibre-reinforced thermoplastics

Techniques which are readily available, and which may be considered suitable for the qualitative or quantitative assessment of fibre orientation distribution in short glass fibre-reinforced thermoplastics are reviewed. The results of using several of these techniques in structural studies on injection mouldings of glass fibre-reinforced grades of polypropylene and polyamide 66 are presented. Uniaxial tensile creep tests were carried out on specimens cut from the mouldings and the anisotropy of stiffness of each moulding is compared with that predicted from the structural studies. Certain of the structural techniques are considered to be unreliable or of restricted applicability and it is concluded that the technique of contact micro-radiography is the most versatile; being capable of yielding reliable qualitative or quantitative information on fibre orientation distribution. Detailed structural studies on edge-gated injection moulded discs, using the technique of contact micro-radiography, show that the fibre orientation distribution varies dramatically through the thickness of the mouldings, even in cases where uniaxial tensile creep tests suggest isotropy of stiffness in the plane of the moulding. Care must therefore be taken when seeking to relate flexural data to tensile data and strength data to stiffness data.     

Rheological characterisation of discrete long glass fibre (LGF) reinforced thermoplastics

Three experimental techniques have been employed to assess the rheological behaviour of discrete long glass fibre reinforced polypropylene and propylene/ethylene copolymers. A Carri Med cone and plate rheogoniometer has been used to determine shear viscosity as a function of strain rate and time at temperatures relevant to the extrusion and injection moulding processes. A bubble inflation test (BIT) has been designed and used to characterise the behaviour of these composites under the extensional flow fields typical of blow moulding and thermoforming. Finally a squeeze load test (SLT), similar to those developed for sheet moulding compounds (SMC) and glass mat thermoplastics (GMT), has been used to explore the rheological behaviour of the long glass fibre (LGF) materials under compression moulding conditions, in particular to assess the relative importance of shear and extensional flow.     

Structural composites for multifunctional applications: Current challenges and future trends

This review paper summarizes the current state-of-art and challenges for the future developments of fiber-reinforced composites for structural applications with multifunctional capabilities. After a brief analysis of the reasons of the successful incorporation of fiber-reinforced composites in many different industrial sectors, the review analyzes three critical factors that will define the future of composites. The first one is the application of novel fiber-deposition and preforming techniques together with innovative liquid moulding strategies. The second is the combination of these techniques by optimization tools based on novel multiscale modeling approaches, so fiber-reinforced composites with optimized properties can be designed and manufactured for each application. In addition, the third is the enhancement of composite applications by the incorporation of multifunctional capabilities. Among them, electrical conductivity, energy storage (structural supercapacitors and batteries) and energy harvesting (piezoelectric and solar energy) seem to be the most promising ones.     

Surface roughness and impact strength of injection-moulded polystyrene

The formation of regular surface waves in injection moulded polystyrene was investigated as a function of the moulding conditions and the molecular weight distribution of the polymer. The injection velocity and the position of measurement relative to the gate of the mould have the greatest effect on the average roughness measured with a Talysurf machine. The packing pressure has only a minor effect in reducing the roughness. It is proposed that the waves occur if there is time for surface buckling in the fountain flow at the melt front. The waves are shown to have negligible effect on the unnotched impact strength, which is dominated by molecular orientation, so the waves merely detract from the surface appearance of the moulding.     

A comparative study on mechanical properties of sisal-leaf fibre-reinforced polyester composites prepared by resin transfer and compression moulding techniques

Resin transfer moulding (RTM) is a novel technology, which bridges the gap between labour intensive hand lay-up process and capital-intensive compression moulding. The present study investigates the tensile and flexural behaviour of sisal fibre reinforced polyester composites as a function of fibre length and fibre content. The composites were prepared by RTM and compression moulding techniques. The properties obtained for composites fabricated by both RTM and compression moulding were compared. From the studies it was found that mechanical properties increase with increase in fibre loading in both cases. The void content and water absorption properties at varying fibre loading were evaluated and found maximum for the compression moulded composites. To analyse the fracture surface morphology of the composites scanning electron microscopy was also performed. A good correlation between morphological and mechanical properties has been observed. Finally, the Young’s modulus and water absorption properties of the composites fabricated by RTM were compared with theoretical predictions.