可加工陶瓷的弱界面结构特征及其研究进展

评述了具有弱界面结构的可加工陶瓷的研究进展.弱界面通过层状结构相或两相间的弱结合引入材料中,在材料加工过程赋予材料一定的“塑性”,或使裂纹产生偏转、分支和桥联,改变陶瓷的断裂行为和加工去除形式.分析了陶瓷可加工性与弱界面结构设计的关系,指出了显微结构优化设计与制备高性能可加工陶瓷的途径.     

一种新型可加工陶瓷材料: CeZrO2/CePO4

对可加工Ce-ZrO2／CePO4陶瓷材料的设计制备和性能进行了研究。结果表明：在载荷作用下弱界面处易形成微裂纹，并发生裂纹联接，使材料在加工过程中以晶粒去除形式为主，实现了该材料的金属刀具加工，且加工损伤变小。弱界面处微裂纹的形成、偏转和桥联等形式，耗散了主裂纹扩展的能量，增加了材料的断裂功，可在一定程度上改善材料的强度等力学性能。随着CePO4加入量的增加，弱界面增多，Ce-ZrO2／CePO4陶瓷材料的可加工性变好但力学性能却变差。烧成温度等工艺因素对Ce-ZrO2／25％CePO4(质量分数)陶瓷的强度等力学性能影响较大，在1550℃下加热2h，颗粒尺寸与发生裂纹桥联等形式相适应，可充分发挥弱界面的作用。     

可加工陶瓷材料的机械加工技术

介绍云母玻璃陶瓷、氧化物陶瓷和非氧化物陶瓷3类可加工陶瓷材料的显微结构特性与材料可加工性的关系，层片状结构与弱界面使陶瓷材料具备可加工性。分析了可加工陶瓷材料机械加工过程中的特性；适宜的加工工艺参数、低加工损伤及材料的沿晶界断裂模式。结合金属材料的可加工性研究，讨论了适于陶瓷材料可加工性评价的研究方法。     

可加工陶瓷结构设计及研究进展

从微观结构设计出发,进行可加工陶瓷制备与性能的研究已成为陶瓷材料研究领域的热点之一。本文对各类可加工陶瓷的结构设计及其研究进展作一综合评述,并对结构陶瓷可加工性与材料结构设计的关系以及陶瓷材料可加工性的评估及表征进行了简要介绍。     

可加工陶瓷研究进展

介绍了国内外可加工玻璃陶瓷、石墨系复相陶瓷、h-BN系纳米复相陶瓷、可加工层状复相陶瓷、可加工多孔陶瓷、稀土磷酸盐系复相陶瓷和Mn＋1AX。化合物等7种可加工陶瓷的制备机理的研究现状,并对该领域今后的发展方向进行了进一步探讨。     

CePO4/Ce-ZrO2可加工陶瓷加工机理的研究

以CePO4／Ce-ZrO2为基体，通过复合不同加入量的第二相CePO4颗粒，并借助扫描电子显微镜对材料压痕、磨削及切削表面进行分析，研究了CePO4／Ce-ZrO2陶瓷材料的可加工机理。单相CePO4材料的弯曲断口显示出层片状断裂机制；而复相CePO4／Ce-ZrO2陶瓷由于两相之间弱结合界面的存在，压痕裂纹扩展形式发生明显变化，由连续扩展机制过渡为不连续扩展。基于上述两种重要机制形成的大量微裂纹是赋予材料可加工性的主要原因，材料加工去除是以微裂纹的连接来实现的。同时，大量微裂纹起到耗散主裂纹扩展能量的作用，有效阻止了较大裂纹的形成，使材料加工损伤大大降低。最后，给出了CePO4／Ce-ZrO2陶瓷加工机理的简单模型。     

可切削陶瓷的研究进展

综述了可加工玻璃陶瓷、可加工复相陶瓷和可加工Ti3SiC2陶瓷的结构、性能．介绍了近年国内外在这方面的最新研究动态及进展，并展望了今后的研究重点。     

可加工陶瓷材料的研究进展

工程陶瓷以其优异的性能得到了广泛的应用，但由于其固有的脆硬性，使其难以加工，阻碍了其应用范围的扩大，通过陶瓷自身显微结构设计来增加陶瓷材料的可加工性是解决陶瓷难加工问题的关键。本文简要介绍了陶瓷可加工性与弱界面设计的关系和可加工陶瓷的研究进展。     

可加工陶瓷及工程陶瓷加工技术现状及发展

陶瓷材料具有轻质、高强、超硬、耐高温、耐磨、耐腐蚀、化学稳定性好等优良特性。但陶瓷烧结体难以机加工,同时加工成本高、精度低限制了其在工程领域的广泛应用。本文综述了可加工陶瓷的分类、加工技术、陶瓷材料加工性能的表征,以及影响陶瓷材料可加工性能的因素等。     

SiC/SiC复合材料抗氧化界面相的研究现状及展望

SiC/SiC复合材料具有耐高温、抗氧化、耐烧蚀、抗热震等优异性能,是航空航天领域理想的高温结构材料。界面相是影响SiC/SiC复合材料性能的关键因素之一。依据陶瓷基复合材料界面相设计理念的不同,本工作将SiC/SiC复合材料界面相分为层状结构、难熔氧化物、稀有金属盐、多元陶瓷4大类,综述了各类界面相的材料种类与形式、力学及抗氧化性能改性效果、性能影响因素及作用机理、存在的问题,并对未来发展趋势进行了展望。     

A comprehensive review of electric discharge machining of advanced ceramics

Advanced ceramics are widely used in high temperature and wear related situations due to their unique physical and chemical characteristics. With the increasing demand for ceramics, the machining techniques of ceramics become a hot and tough issue because ceramics are extremely fragile and difficult to process. Traditional mechanical machining techniques like milling, turning, and drilling are subjected to large cutting forces and heat leading to extensive tool wear and poor machining performance. Electric discharge machining (EDM) has an outstanding ability of no-contact machining brittle and hardness materials with complex shapes via generating extreme high-temperature plasma channel to melt and vaporize materials. Therefore, in this paper, the research trends of latest EDM technologies for advanced ceramic materials were comprehensively reviewed. Firstly, according to the electrical conductivity of advanced ceramics, different EDM processes were introduced in details. Secondly, the existing physical models and material removal mechanisms of EDM process of ceramics were compared and analyzed. Then the machining performance indicators, such as MRR, Ra, TWR, surface topography, and micro-structures, were respectively investigated. Additionally, the new hybrid machining techniques of EDM were presented to provide some potential for efficiently machining advanced ceramics. Eventually, this paper also discussed the challenges associated with electrical discharge machining of advanced ceramic materials, and suggested some related research areas which possibly attract significant research attentions in the future.     

可加工陶瓷材料机械加工技术的研究进展

随着可加工陶瓷材料的研发与应用,可加工陶瓷材料的机械加工技术逐渐成为当今的研究热点之一.本文综述了可加工陶瓷在机械加工过程中的材料去除特性、刀具磨损、加工工艺及可加工性评价,内容涉及加工表面质量、去除机理、加工损伤、材料去除率、刀具参数、切削参数、表面粗糙度、冷却和可加工性综合评价,并提出了今后的研究发展方向和趋势.     

Analysis of CNC machining technology in production of plaster moulds

Abstract

The present paper continues the further application of machining techniques in the ceramics industry with the aim of optimising company resources in new competitive markets. The work is focused on plaster model and mould generation by computer based geometric design, machine tool path creation, and subsequent production through CNC machining using a robotic machining centre. Many constraints were identified related specifically to the machining of plaster used in the manufacture of ceramic ware. Because of the limited information, since most machining investigations have only considered metal machining or fired ceramics, a large number of machining experiments were conducted. It is concluded that substantial advantages are gained through the use of this new approach for ceramic production processes, and the subjects for follow on research are defined.     

Laser drilling of structural ceramics—A review

Structural ceramics are becoming widely popular in numerous fields because of high mechanical and physical properties. It is of great difficulty for conventional techniques to machine brittle and hard materials. As one of nontraditional machining methods, laser beam machining has emerged as an effective technique for drilling of ceramics. This paper reviews the research work on laser drilling of structural ceramics from its different pulse width. Lasers have been discussed to understand effects of critical experimental parameters on the quality characteristics and physical mechanisms involved in drilling ceramics. In addition, it is held that heat and liquid-assisted laser processing serves as a useful method to improve processing quality. Computational approaches of ANSYS and COMSOL are used to predict laser input parameters’ effects on quality of hole and describe the physical phenomena during processing. Comments on laser drilling of ceramics developments and future directions are provided at the end.     

Multiscale toughening of ZrB2-SiC-Graphene@ZrB2-SiC dual composite ceramics

The design of bioinspired architectures is effective for increasing the toughness of ceramic materials. Particularly, a dual composite equiaxial architecture is ideal for fabricating weak interface-toughened ZrB₂-SiC ceramics with isotropic performance. In this paper, ZrB₂-SiC-Graphene@ZrB₂-SiC dual composite ceramics were synthesized via an innovative processing technique of granulating-coating method. ZrB₂-20 vol.% SiC containing 30 vol.% Graphene was selected as weak interface to realize multiscale toughening and improve the thermal shock resistance of ZrB₂-SiC ceramic materials. The incorporation of ZrB₂-SiC-Graphene weak interface into the ZrB₂-SiC matrix improved the damage tolerance and critical thermal shock temperature difference. The design of equiaxial structures moderated the anisotropy of performance in different planes. The graphene sheets incorporated in the ZrB₂-SiC-Graphene interface phase played a key role in multiscale toughening, including macroscopic toughening of crack deflection and microcracks, and microscopic toughening of graphene bridging and pull-out.     

工程陶瓷材料磨削加工技术研究

工程陶瓷材料具有优良的物理、化学、力学性能,在许多领域得到广泛的应用。目前,使用金刚石工具(主要是砂轮)的磨削加工是工程陶瓷去除加工的基本途径。本文概述了陶瓷材料磨削加工技术的进展,并对磨削后的陶瓷工件表面损伤进行了分析。     

New observations on wear characteristics of solid Al2O3/Si3N4 ceramic tool in high speed milling of additive manufactured Ti6Al4V

Additive Manufacturing (AM) technologies applied to the titanium alloys have attracted attention from industries in recent years. Despite one of the main goals of AM is the reduction of manufacturing steps, semi-finish/finish machining operations are still required so as to obtain the desired geometrical tolerance and surface features. In this study, the solid end mill was manufactured by Al₂O₃/Si₃N₄ (Sialon) ceramic materials and employed in high-speed slot milling of Ti6Al4V alloy fabricated by the Direct Metal Laser Sintering (DMLS) AM technology to study the tool wear characteristics during processing. The Raman spectroscopic method was employed to characterize the molecular structures of Sialon ceramics for the manufacturing of the cutting tool. The morphologies and elemental maps of wear region of the ceramic tool were examined by scanning electron microscope and energy dispersive spectroscopy techniques. The results show that the adhesion wear and diffusion wear are the dominant wear mechanisms, and the chemical stability of Al₂O₃/Si₃N₄ (Sialon) ceramics fabricated as the solid ceramic tool to the attack of the atoms from additive manufactured Ti6Al4V is relatively weak under the atmosphere. The difference of thermal expansion coefficients of diffusion layer and tool substrate accelerates the initiation and propagation of thermal cracks formed on the diffusion interface. Moreover, fracturing and crater-like groves near the tool edge were finally formed due to the removal of adhered workpiece material.     

Y_2O_3透明陶瓷的研究进展

Y2O3透明陶瓷具有优异的光学和热学性能,是一种有较高应用价值的功能材料,现已成为单晶的可替代材料。介绍了Y2O3透明陶瓷的研究进展,阐述了Y2O3透明陶瓷的粉体合成、坯体成型、高温烧结和机械加工的制备工艺,并分析了成型时坯体开裂的原因。