结构陶瓷材料显微结构对摩擦磨损特性影响的研究

结构陶瓷具有高强度、耐高温和耐磨蚀等优点,作为摩擦学部件已得到广泛的应用。从陶瓷材料的显微结构讨论了陶瓷材料的摩擦磨损行为及机制,以促进正确设计和使用陶瓷材料作为摩擦学部件。     

工程陶瓷在水压元件中的应用与研究

在归纳了水压元件对材料的特殊要求的基础上，比较分析了工程塑料和工程陶瓷应用于水压元件时的优缺点，综合讨论了工程陶瓷在水环境中的摩擦学特性及其在水压元件中的工程应用实例。重点研究了整体工程陶瓷使用中存在的问题和解决措施，陶瓷涂层技术在水压元件中应用的可行性及关键技术。指出在整体工程陶瓷元件应用于水压传动尚不成熟的情况下，使用陶瓷涂层技术是经济可行的。     

陶瓷光固化技术及其应用

陶瓷材料因具有高硬度、高强度、耐高温、抗腐蚀等优异性能,被广泛应用于航空航天、生物医疗等领域,但是应用于上述领域的复杂结构陶瓷的制造仍然是一个重要的挑战。增材制造技术通过逐层堆积材料的方式来获得实体,在制造复杂结构陶瓷方面具有传统成形方式所无法比拟的优势。在众多陶瓷增材制造技术中,陶瓷光固化技术因其理想的成形质量而受到广泛关注和重视。在介绍立体光固化、数字光处理这两种主流陶瓷光固化技术的原理和特点的基础上,系统地介绍和分析了立体光固化技术和数字光处理技术的研究现状、应用以及存在的问题。最后,对陶瓷光固化技术及其应用进行了总结和展望。     

显微结构对Y-TZP/Al2O3复合陶瓷磨料磨损性能的影响

以不同Y2O3加入方式(如化学共沉淀和机械混合)制备的Al2O3增强Y-TZP陶瓷(AZD)为研究对象，研究了显微结构对陶瓷耐磨性的影响。结果表明：化学共沉淀法制备的CYADZ与机械混合的MYADZ的硬度和断裂韧性值相近：CYADZ结构均匀、品粒细小，而由于Y2O3的不均分布，MYADZ结构不均、晶粒相差较大。球磨磨料磨损后，CYADZ复合陶瓷较MYADZ复合陶瓷耐磨性好，宏观力学性能如硬度和断裂韧性对陶瓷材料耐磨性的影响应以显微结构为先决条件。     

热等静压氮化硅HIP-Si3N4试件断裂韧性测试方法

热等静压氮化硅(Hot Isostatic Pressured silicon nitided ceramics)，一种新型工程陶瓷，作为耐高温、抗腐蚀复合材料，这里简述了陶瓷材料的断裂理论及韧性测试的意义。介绍了直接压痕法、弯曲压痕强度法等几种韧性测试方法。     

莫来石基陶瓷材料耐磨性能的研究

研究了莫来石基陶瓷的化学组成、显微结构和烧结温度等对其耐磨性能的影响规律。结果表明：ＺｒＯ２引入莫来石中可显著提高陶瓷的耐磨性能。摩擦过程中,ｔ－ＺｒＯ２会发生应力诱导相变,消耗裂纹成核和扩展的能量,并可使陶瓷的组织结构致密、晶粒间强度提高,降低沿晶断裂现象,氧化锆和氧化铝协同增韧莫业石陶瓷具有更好的耐磨性能,Ａｌ２Ｏ３颗粒的引入增加了陶瓷的硬质相,并提高了陶瓷的力学性能,Ａｌ２Ｏ３颗粒的体积含量     

Si3N4陶瓷高效有机磨削液界面化学反应机理的研究进展

磨削加工是S i3N4陶瓷最主要的加工方法。利用磨削液界面化学反应膜降低摩擦系数同时软化表面层,提高磨削效率是一个全新的研究方向。本文基于用半塑性去除的方式高效磨削S i3N4陶瓷,系统综述了在使用以醇类磨削液为代表的各种有机磨削液时,界面化学反应对提高S i3N4陶瓷材料去除率的辅助作用。文中以研究作用机理为目的,运用分类、比较和归纳的方法,结合使用先进的测试设备,分析了醇类磨削液配方中长、短碳链醇及其水溶液作磨削液的作用效果。此外,还从不同的角度探讨了全卤代烃、阳离子表面活性剂和四乙氧基硅烷等3类有机物作为磨削液成分的有效作用,并揭示了作用机理,从而为研制高效率、低成本加工陶瓷材料的磨削液提供了理论基础。     

Tribological properties and processing challenges of bulk structural ceramic nanomaterials

Abstract

With the recognition that bulk nanostructured ceramics, defined by the grain size of at least one of the constituent microstructural phases being smaller than 100 nm, possess some appealing physical, mechanical and tribological properties, they have been the subject of considerable research activities in recent years. Among the various properties of structural ceramics, the most remarkable and reproducible improvement produced by the refinement of the grain size to nanoscale levels or through reinforcement of the matrix by nanosized particles, has been in the tribological properties. This review critically analyses the effects of microstructural refinement to nanoscale levels on the wear resistance of structural ceramics and ceramic composites. This is followed by an overview of the tribological behaviour of different ceramic nanomaterials. It must be noted that although nanostructured ceramics possess superior properties with respect to their conventional counterparts, the challenges involved in the successful processing of such materials have hindered their penetration of the commercial market to any notable degree. In light of this, the review outlines the challenges involved and the techniques developed for the successful processing of bulk nanocrystalline ceramics. Finally, the review concludes with critical comments on some of the unresolved issues related to bulk nanostructured ceramics, along with a brief mention of the scope for future research.     

Thermal contact conductance of coated surfaces

The thermal contact resistance phenomena are increasingly important as the size of mechanical and electronic components decrease. Applying a coating material with high thermal conductivity is an effective way to enhance the thermal contact conductance. This work conducted an experimental and theoretical study to investigate the effects of diamond film coatings on the thermal contact conductance. A model based on statistical elastoplastic surface contact mechanics was developed to study the thermal contact conductance of coating material. Diamond films were sputtered on the substrate of ceramics by microwave plasma chemical vapor deposition. Test samples have different surface roughnesses, deposition times and deposition qualities. A range of test conditions was conducted to evaluate the thermal contact conductance of coated films and for comparisons with the theoretical model.     

A study of mirror-like grinding of fine ceramics with in-process electrolytic dressing

Fine ceramics have the properties of high hardness, chemical inertness, high thermal resistance and low electrical conductivity, but, because of high hardness and brittleness, they are very difficult to machine. Therefore, a superabrasive diamond wheel is used for mirror-like grinding of this material. In this study, an in-process electrolytic dressing system for carrying out mirror-like surface grinding was constructed. Using this system the grinding force for fine ceramics was reduced. This work shows that the application of electrolytic dressing is beneficial in obtaining a mirror-like surface when grinding fine ceramics.     

Tribological properties of high-melting oxides and nonmetallic compounds at elevated temperatures. Part 1: Oxides

Information on the tribological properties of high-melting oxides and nonmetallic oxygen-free compounds at elevated temperatures in vacuum and in air is reviewed. This information will allow the identification of promising wear-resistant materials for use in high-temperature friction units; such materials could include ceramics based on high-melting oxides (aluminium, zirconium, chromium); ceramics based on nonmetallic high-melting compounds (silicon carbide and nitride and, to a lesser extent, boron carbide and cubic nitride); and composite materials based on oxides and nonmetallic compounds, including those containing high-melting metal-like compounds. To reduce the contact friction of these materials between themselves and with other materials, solid lubricating substances are necessary as components of composite materials or their coatings. It is advisable to use ceramic materials, applied using modern techniques, as coatings on friction units.     

Physical properties and cutting performance of silicon nitride ceramic

Silicon nitride, a nitrogen compound of highly covalent bond character, has low density, high hardness, low thermal expansion and high thermal conductivity and excellent oxidation and corrosion resistance. Therefore it is considered to be a promising material for high temperature engineering components.However, it has very poor sinterability compared with the conventional oxide ceramics owing to its low self-diffusivity. By investigating starting materials, sintering additives and processing, a hot-pressed silicon nitride ceramic having grains enveloped by crystalline boundary phases can be produced.The silicon-nitride-based ceramic has high strength, high Weibull modulus, fracture toughness and thermal conductivity, and low thermal expansion compared with existing cutting tool ceramics such as Al₂O₃ + TiC, and it is expected to have superior thermal shock resistance.This new ceramic cutting tool shows superior performance in cutting cast irons at high speeds (10–16.75 m s^?1 (600–1000 m min^?1)) and rates (about 1.0 mm rev^?1), where conventional tools cannot be used.     

Cross-flow ceramic structures produced by plastic processing

This paper reports part of an attempt to harness the scope and versatility of polymer manufacturing operations and use them in ceramics processing. It describes the preparation of extruded zirconia ridged plates, the film-blowing of zirconia and the solvent welding of stacks of these components to produce cross-flow structures. Assemblies of this type, prepared from a single ceramic, find application in heat exchangers. Assemblies of composite ceramics, when the problems of cofiring of different powders are overcome, provide solid oxide fuel cell structures. The organic vehicle used for these processes was based on polystyrene. The structures were sintered and then examined for the defects which are characteristic of these plastic-forming operations when applied to ceramics.     

热等静压氮化硅 (HIP- Si3N4)试件制备及性能测试

热等静压氮化硅(Hot Isostatic Pressure），一种新型工程陶瓷，作为耐高温、抗腐蚀复合材料摩擦副的一方，这里从配料、湿磨与湿筛、干馏与粒化、成型与脱脂、氮化、热静等压烧结等工序介绍了它的制备，并用BET，XPS方法对产品的物化及机械性能进行试验分析。     

基于纳米操作机的多晶ZnO晶界电学特性研究

文中基于安装在扫描电子显微镜（Scanning Electron Microscopy, SEM）中的纳米操作机,对具有微米级细晶粒的氧化锌（ZnO）压电陶瓷进行了单晶粒边界的直接电学测量。由纳米操作机操纵的双探针作为微电极夹在机械手上,测量了ZnO压电陶瓷晶界的伏安特性曲线、非线性系数以及20个晶粒的平均尺寸。在20 Hz~1 MHz的频率范围内,通过等效电路拟合,以阻抗复平面表示实验数据。实验表明低频直流高阻阻抗的本质可归因于晶界,同时20 Hz下的电阻分布可用于预测ZnO压电陶瓷在某些较低频率下的阻抗特性。     

Summarized characteristics for determination of the service life by the wear of industrial ceramicss

The calculation dependence developed based on the theoretical methods and experimental results includes the summarized characteristics to determine the wear rate of industrial ceramics. It takes into account the ceramics’ mechanical and thermophysical properties, the resistance to cracking, the stress-strain state, the thermal condition of the rubbing bodies, and the effect of the environment. The proposed dependence is compared with the available semiempirical dependencies of the ceramics’ wear rate.     

An experimental study on machining techniques of cutting composite armors

The machining of laminated composite components or armors consisting of engineering ceramics, fiber-reinforced plastic, and even aluminum or titanium alloy is a great challenge to manufacturing engineers. So far, quite limited literatures can be found concerning the machining of laminated composite components, and the quite limited studies are mainly focused on the stacks consisting of metal plates and composite materials. Also, there is hardly any report concerning the cutting techniques of laminated composite components or armors. In this work, the cutting techniques of three types of composite armors such as the Kevlar fiber-reinforced plastic (KFRP) protection inner lineplate, the ceramic composite armor (ceramics/glass fiber-reinforced plastics/aluminum alloy laminate), and the double-plate composite armor (ceramics/KFRP laminate) were studied experimentally on a desktop cutting machine, using a sintering diamond saw. Two types of machining processes such as cocurrent cutting and reverse cutting were discussed, and finally, reverse cutting is recommended for better cutting quality. Cutting tests indicated that under proper processing conditions, high-quality cutting of composite armors can be carried out by using a sintering diamond saw.     

Advances in tribology: the materials point of view

The application of advanced materials in various areas of contemporary technology can lead to improvements in the function, quality and performance of engineering components and systems. In this paper, an overview of the developments in high performance materials, both organic and inorganic based, is given. This includes thin hard coatings because of their increasing importance in tribological improvements. For these types of materials the requirements for tribo-engineering applications are analysed. Research results from BAM concerning ceramics and ceramic composites, polymers and polymer composites as well as hard coatings illustrate the friction and wear behaviour of these materials and their potential for tribo-engineering applications.     

气孔对氧化锆基陶瓷材料摩擦磨损性能的影响

用环-块摩擦磨损试验机在室温下研究了不同气孔率的氧化铝增强氧化锆陶瓷(ADZ)与高铬铸铁(HCCI)摩擦副的摩擦磨损性能。结果表明:在润滑介质为5%NaOH溶液和含质量分数2%SiO2颗粒的5%NaOH溶液条件下,陶瓷的摩擦因数不受气孔率的影响,陶瓷的磨损率随气孔率的增大而增加。小于临界孔径的微孔几乎不影响陶瓷的磨损,开、闭气孔的存在都对陶瓷的耐磨性有负面影响。