Al2O3基陶瓷材料增韧的研究进展

Al_2O_3基陶瓷材料具有高的化学稳定性,有较好的应用前景,但其脆性限制了它的推广应用,对氧化铝陶瓷进行增韧是解决其脆性问题的一条重要途径。简要介绍了目前氧化铝陶瓷的增韧方法和增韧机理,综述了氧化铝陶瓷增韧的研究现状,分析了氧化铝陶瓷增韧研究中存在的主要问题,展望了氧化铝陶瓷增韧的发展方向,提出了原位生长及复合增韧是高性能Al_2O_3基陶瓷材料的研究重点。     

透明氧化铝陶瓷的研究新进展

氧化铝陶瓷是第一个实现透明化的先进陶瓷材料,拓展了先进陶瓷材料的研究和应用领域;并作为高强度气体放电灯的关键部件——电弧管而获得实际应用.近半个世纪以来,人们在提高透过率的理论研究和优化制备工艺方面取得了众多成果.本文对影响氧化铝透过率的本征因素进行分析,综述了近年来透明氧化铝陶瓷发展的最新研究进展,主要包括亚微米晶透明氧化铝、晶粒定向透明氧化铝以及固态晶体生长法获得氧化铝单晶三个方面,最后展望了透明氧化铝陶瓷的发展趋势.     

单晶与多晶氧化铝陶瓷材料断裂性能与陶瓷基复合材料

有关多结晶氧化铝陶瓷的断裂力学性能,在国内外已有较深入的研究,但是关于单结晶透明氧化铝陶瓷的断裂力学研究目前尚未见有任何报导、对其断裂机理也尚在探讨。本课题为了开发单晶氧化铝陶瓷作为人工心脏瓣膜的生物医学工程研究,首先测定了两批共10件氧化铝单晶陶瓷材料的断裂韧性值,提出单晶陶瓷三维微裂纹扩展模式,在观察大量电子显微镜图片的基础上阐明陶瓷材料的微观断裂机理,进而提出增加陶瓷韧性之复合材料途径。     

长柱状晶高韧性氧化铝陶瓷的制备与性能研究

针对一般氧化铝陶瓷材料断裂韧性差的缺点 ,通过球磨的方法向初始原料氢氧化铝中添加晶种 ,并采用热压烧结方式 ,使氧化铝生长成长柱状晶粒结构 ,产生了明显的增韧效果 ,使这种氧化铝瓷体的断裂韧性比一般氧化铝陶瓷材料提高一倍以上 ,可达到 6 .70 MPa· m1 /2。对几种不同烧结温度下烧结的瓷体进行了显微结构分析和力学性能测试 ,研究了长柱状氧化铝晶粒的生长过程及力学性能变化特点     

几种生物陶瓷材料的裂纹扩展特性

采用破坏力学中的双扭矩实验法，研究了玻璃陶瓷、云母陶瓷、氧化铝陶瓷、氧化锆陶瓷材料分别在大气、水环境中的静负荷和循环负荷下的裂纹扩展特征，阐明了水环境和循环负荷对材料裂纹扩展特性（KI－V特征）的影响。所研究的材料在水环境下的裂纹扩展速度均加快，但玻璃陶瓷和氧化锆陶瓷材料更为明显。在静负荷下这几种材料的裂纹扩展阻力由小到大的次序为：玻璃陶瓷（N－0），玻璃陶瓷（N－11），云母陶瓷，氧化锆陶瓷和氧化铝陶瓷，对于氧化铝和氧化锆陶瓷材料在循环负荷下的裂纹扩展速度均明显加快。     

生物陶瓷材料的疲劳寿命预测

采用断裂力学中的四点弯曲试验法,研究并预测了氧化铝和氧化锆陶瓷材料在大气和水环境中的循环疲劳破坏特性.结果表明,在相同的应力条件下,氧化铝和氧化锆陶瓷材料,尤其是氧化锆陶瓷,在水环境中的疲劳寿命比大气中的低.通过将预测结果与实验结果比较和对人造股关节的应用,验证了这种疲劳寿命预测方法的有效性和适用性.     

用天然硅铝矿物制备氧化铝碳化硅复相陶瓷的研究

本文采用天然硅铝矿物原位制备氧化铝碳化硅复相陶瓷，并通过ＸＲＤ及热力学计算验证了反应过程，研究了材料显微结构及对力学性能的影响，从而制备出氧化铝碳化硅复相陶瓷材料开辟一种新途径。     

氧化铝陶瓷制备技术研究

概述了氧化铝陶瓷材料制备技术现状及其所存在的不足,首次提出了等离子束熔融法制备氧化铝陶瓷的新工艺,介绍了等离子束熔融法制备氧化铝陶瓷技术特点,同时展望了该技术的发展趋势.     

氧化铝陶瓷的制备与应用

氧化铝陶瓷是一种以氧化铝(Al_2O_3)为主体的陶瓷材料,用于厚膜集成电路。氧化铝陶瓷有较好的传导性、机械强度和耐高温性。需要注意的是需用超声波进行洗涤。     

陶瓷的定义及分类

正什么是陶瓷?陶瓷是陶器和瓷器的总称。人类早在约公元前8000年前的新石器时代就发明了陶器。陶瓷行业市场调查分析报告显示,陶瓷材料大多是氧化物、氮化物、硼化物和碳化物等。常见的陶瓷材料有粘土、氧化铝、高岭土等。     

Nonsingular toughening and R-curve behavior in nominally pure alumina

Moire interferometry is employed to study toughening in medium to large grain size nominally pure alumina. The fracture scale length, which is characterized by the grain size of the alumina, is systematically varied from 35 to 102 m. R curves are derived from bulk mode I compliance calculations for the differing grain sizes and from the near tip moire fringes. The level of material toughening that arises from the nonsingular processes of crack bridging and grain boundary friction are found by comparing the bulk and near tip moire R curves.     

氧化铝基陶瓷复合材料的微观结构与增韧机理

应用相交增韧、相变－晶须复合及相变－颗粒复合等方式对氧化铝陶瓷进行增韧．遇过各材料强韧性的测试、微观结构的分析以及断口形貌的对比,研究了各材料的断裂特点及不同增韧方式的增韧机理与效果,得出材料的强韧性与其断口形貌密切相关;双重增韧材料中,两种增韧方式不是简单的叠加,而是存在相互作用;同时在性能试验后的材料基体内观察到位借的存在．     

基于扩展有限元的陶瓷复合材料多重增韧机制

为了提高陶瓷材料的断裂韧性和可靠度,改善材料抵御破坏的能力,将优化的多重增韧机制应用到氧化铝基陶瓷材料的开发中。相变增韧机制可以耗散部分能量,降低裂纹尖端处的应力集中程度,阻止或延缓裂纹扩展速率。当增强相分布较为合理、材料的致密度较高时,裂纹偏转与桥接增韧机制可以有效地削弱裂纹扩展动力,提高材料的断裂韧性。利用扩展有限元（X-FEM）手段讨论了裂纹扩展问题,为分析陶瓷复合材料的多重增韧机制提供了新思路。     

Toughening characterization in alumina platelet–hydroxyapatite matrix composites

Fracture toughness of Al₂O₃ platelet-reinforced hydroxyapatite (HAP) ceramics was investigated using the Vickers' indentation technique. The geometrical anisotropy of alumina platelets induces an anisotropic toughening. The efficiency of reinforcing mechanisms remains maximum for a crack propagating with an angular deviation inferior to 30° around the direction perpendicular to alumina disc faces. This is assumed to result from a crack deflection mechanism which induces a favorable contribution of mode II failure. A small effect of hydroxyapatite grain size becomes noticeable in the direction parallel to alumina disc faces. The toughening depends on the size and volume content of alumina platelets. Large size platelets provoke a spontaneous microcracking of the HAP matrix which is detrimental to the mechanical reliability, whereas small platelets lead to a strong toughening. The results relate to the intensity of thermoelastic residual stresses within the matrix around alumina inclusions. © 1999 Kluwer Academic Publishers     

Alumina-mullite-zirconia composites obtained by reaction sintering: Part I. Microstructure and mechanical behaviour

Zirconia particles can be added to the matrix to overcome the brittleness inherent in ceramic materials, thereby strengthening the material through tetragonal-monoclinic phase transformation of the zirconia. This work focuses on the effect of the percentage of zirconia and mullite in the mechanical and thermomechanical properties of alumina-mullite-zirconia composites that were obtained by reaction sintering of alumina and zircon. Different samples were processed, resulting in composites with an alumina matrix, which was always volumetrically predominant. A percentage of alumina and mullite with maximized mechanical and thermomechanical properties was observed. This maximization is discussed in terms of the microstructure obtained for the composites mentioned above. The toughening mechanisms provided by zirconia and mullite inclusions, based not only on the R-curve behaviour but also on the analysis of the fracture surface, are also discussed in this report. An additional paper will be forthcoming, containing detailed discussions concerning the R-curve behaviour of the same composites.     

人工关节材料的研究进展

高可靠性、耐磨人工关节材料的研究开发对人工关节的临床应用极为重要.简述了人工关节的分类,对Al2O3与ZrO2人工关节的研究现状、可靠性和耐磨机制进行了综述,对ZrO2的增韧机理和稳定剂CeO2进行了讨论,最后对Ce-TZP/Al2O3作为一种新的人工关节材料在临床上的应用进行了展望.     

Science of zirconia-related engineering ceramics

In this paper, we comprehensively review the physical principles behind the improvement of mechanical properties of zirconia (ZrO₂) related ceramics. First, the transformation behaviour of different phases in zirconia is discussed. We next present an overview of two zirconia-related commercially important systems e.g. ZrO₂-MgO and ZrO₂-Y₂O₃. The commercial engineering ceramic materials, generated from these systems, are known as partially stabilized zirconia and tetragonal zirconia polycrystal respectively. The third important material is called zirconia toughened alumina. The evolution, characterization and importance of the microstructure in relation to the basic systems are also presented. Attention is then focussed on to three toughening mechanisms e.g. phase transformation toughening, microcrack toughening and crack deflection toughening. We carefully assess the roles they play in improving toughness. We discussR-curve behaviour arising out of these toughening mechanisms and the implications ofR-curve behaviour in engineering applications. Finally, the subcritical crack growth and tribological behaviour of these materials are discussed.     

仿生设计的Al2O3／纤维增强树脂层状复合材料

把贝壳珍珠层的韧化机制和结构机理应用于陶瓷基复合材料的仿生设计中，制备出Ａｌ２Ｏ３／环氧树脂及Ａｌ２Ｏ３／芳纶纤维增强环氧树脂叠层仿珍珠层复合材料。三点弯曲试验表明，与单相Ａｌ２Ｏ３相比，Ａｌ２Ｏ３／环氧树复合材料的断裂功提高２５％，而Ａｌ２Ｏ３／芳纶纤维增强环氧树脂的断裂功提高８０倍Ａｌ２Ｏ３／环氧树脂复合材料的断裂形貌与珍珠层相似，裂缝曲折扩展；而Ａｌ２Ｏ３／芳纶纤维增强环氧树脂复合材料除具有     

燃烧反应超快升温热压制备碳纳米管/氧化铝复合材料

报道一种制备碳纳米管增强氧化铝基复合材料的新方法,用燃烧反应所产生的热量为热源代替传统烧结炉,在燃烧反应完成的同时施加机械压力来实现快速烧结,当碳纳米管掺量为1%(质量分数)时复合材料的断裂韧性同比提高了50%,该方法有利于避免碳纳米管的高温破坏,复合材料的增韧作用主要来自于碳纳米管的拔出效应和桥联机制.