牙科陶瓷材料与修复体制作研究的新进展

在牙科材料学的发展和研究中，具有与自然材料相近的高稳定性、高耐用性和美学特性的陶瓷材料受到了人们的欢迎。然而，复合材料本身具有的脆性使其极易作为修复材料，在承受较大的咬合压力时很容易发生断裂或损坏。而近几年，随着人们对牙齿的美学和修复材料的生物安全性要求不断提高，对新型牙科复合陶瓷的开发和新的工艺技术进行了深入的探讨。     

牙科修复中陶瓷的应用

陶瓷是最常采用的制作牙齿的材料，发展迅速。瓷修复体质地致密、耐磨，表面光洁，菌斑不易附着，有良好的生物相容性，使用安全，应用广泛。本文从材料学角度介绍了不同类型的陶瓷在牙科修复中的应用以及提高陶瓷材料强度的方法，提高牙科修复体的质量，促进全瓷修复体的运用与普及。     

氮化硅陶瓷在四大领域的研究及应用进展

氮化硅陶瓷不仅具有较高的力学性能还具有良好的透波性能、导热性能以及生物相容性能,是公认的综合性能最优的陶瓷材料。作为轴承球的致密氮化硅陶瓷广泛应用在机械领域;作为透波材料的多孔氮化硅陶瓷广泛应用在航空航天领域;随着对氮化硅陶瓷材料的深入研究,其在导热性和生物相容性方面的优异特性逐渐被科研工作者认识并得到开发和应用。本文详细阐述了氮化硅粉体的制备方法,并综述了氮化硅陶瓷作为结构陶瓷在机械领域和航空航天领域的研究进展,此外还介绍了其作为功能陶瓷在半导体领域、生物制药领域的研究和应用现状,最后对其未来发展进行了展望。     

玻璃陶瓷牙科材料研制中若干重要问题的探讨

锂硅酸盐玻璃陶瓷牙科材料包括用于CAD/CAM加工的主晶相为偏硅酸锂以及热压铸造的主晶相为二硅酸锂的材料,具有高强度、优异的生物相容性、良好的透光性和美学性能以及独特的修复通用性。通过分析国内外文献和专利上报导的锂硅酸盐玻璃陶瓷牙科材料采用的玻璃成分、晶化温度制度以及析出的主晶相,讨论如何根据牙科材料性能要求来确定玻璃陶瓷的主晶相,并以此来选择玻璃成分和相应的结晶温度制度。此外还指出了锂硅酸盐玻璃陶瓷牙科材料今后研制的发展方向。     

陶瓷材料计算机配色方法的探讨与实践

以牙科陶瓷为例探讨了陶瓷材料计算机配色的方法和机理,建立了牙科陶瓷计算机配色数据库,通过实验对数据库进行了修正,分析了配色不准的原因并提出了解决办法.     

牙科陶瓷配色方法和应用的初步研究

探讨牙科陶瓷配色的方法和机理，通过将钒锆黄、锆镨黄、锆铁红、铬铝锌红对牙科陶瓷进行配色。采用分光光度计测量了样品的L＊、a＊、b＊值和色差，并与VitaA2和ceramcoA2瓷粉对比，研究了样品色差与配方之间的关系。     

氮化硅基多孔陶瓷的制备技术、孔隙结构及其相关性能

氮化硅多孔陶瓷是近年来得到广泛关注的一类新型的结构?功能一体化陶瓷材料,在航空航天、机械、化工、海洋工程等重要领域有着广阔的应用前景。本文介绍了氮化硅基多孔陶瓷的主要制备技术,回顾了氮化硅基多孔陶瓷力学性能和介电性能的研究进展。考虑到高孔隙率氮化硅基多孔陶瓷力学性能难以提高,磷酸盐结合氮化硅基多孔陶瓷已经逐渐成为新的研究热点,因此,本文进一步对磷酸盐结合氮化硅基多孔陶瓷的制备技术、力学性能、介电性能、热学性能进行了综合评述,并对氮化硅基多孔陶瓷的应用前景进行了展望。     

氮化硅陶瓷的制备与应用

论述了氮化硅陶瓷在航天军工、机械工程、超细研磨、轴承制造、汽车配件等领域的应用,对氮化硅陶瓷的生产技术发展与市场应用进行了分析,展望了我国氮化硅行业的发展方向。     

牙科用氧化锆陶瓷的稳定性、制备工艺及临床应用研究进展

氧化锆牙科陶瓷凭借优异的力学性能、美学性能和生物相容性成为目前牙齿临床修复的首选对象,已被用作固定局部义齿和种植牙。然而在潮湿环境中氧化锆陶瓷的性能会发生低温劣化,稳定性显著降低,限制了其广泛的临床应用。介绍了氧化锆陶瓷发生低温劣化时t–m转变的变形机制,并着重从提高转变自由能势磊、阻止氧空位的耗散和调整残余应力方面提出抑制低温劣化的方法,阐述了目前牙科陶瓷的制备工艺及其临床应用稳定性和评估结果。最后对氧化锆牙科陶瓷的发展前景进行了展望。     

氮化硅多孔陶瓷制备国内专利技术综述

多孔氮化硅陶瓷材料因其能够充分发挥氮化硅陶瓷和多孔陶瓷两者的优异性能,广泛应用于机械、化工、海洋工程、航空航天等重要领域。制备孔隙率和孔隙结构可控、高强度、低介电常数的氮化硅多孔陶瓷是实现其应用的关键。本文在检索了大量国内专利文献的基础上,对氮化硅多孔陶瓷制备技术信息进行统计和分析,并对其未来技术发展进行了预测。     

Silicon Nitride and Related Materials

Silicon nitride has been researched intensively, largely in response to the challenge to develop internal combustion engines with hot-zone components made entirely from ceramics. The ceramic engine programs have had only partial success, but this research effort has succeeded in generating a degree of understanding of silicon nitride and of its processing and properties, which in many respects is more advanced than of more widely used technical ceramics. This review examines from the historical standpoint the development of silicon nitride and of its processing into a range of high-grade ceramic materials. The development of understanding of microstructure–property relationships in the silicon nitride materials is also surveyed. Because silicon nitride has close relationships with the SiAlON group of materials, it is impossible to discuss the one without some reference to the other, and a brief mention of the development of the SiAlONs is included for completeness.     

多孔氮化硅陶瓷透波材料研究进展

多孔氮化硅陶瓷透波材料具有优异的机械性能、耐热性能及介电性能,成为透波材料科学研究领域中的热点之一。本文介绍了多孔氮化硅陶瓷的主要制备技术,并对国内外多孔氮化硅陶瓷透波材料的应用研究进展进行了综述。     

氮化硅陶瓷的制备及性能研究进展

氮化硅陶瓷是一种具有广阔发展前景的高温、高强度结构陶瓷,它具有强度高、抗热震稳定性好、疲劳韧性高、室温抗弯强度高、耐磨、抗氧化、耐腐蚀性能好等高性能,已被广泛应用于各行业。本文介绍了氮化硅陶瓷的基本性质．综述了氮化硅陶瓷的制备工艺和提高其高温性能的方法以及增韧的途径,并展望了氮化硅陶瓷的发展前景。     

工业陶瓷超声辅助加工技术研究

陶瓷材料具有耐高温、硬度高、绝缘性好的优良性能,在航空航天、军事医疗、电子信息等领域具有广泛的应用。旋转超声辅助加工的刀具磨损小、材料去除率高、加工精度高,在工业陶瓷精密加工领域取得了较好的运用。本文以常用的石英陶瓷和氮化硅陶瓷为加工对象,进行了表面磨削及钻孔试验研究,通过宏观形貌观察、测量表面粗糙度值、工件及刀具微观形貌分析,确定了PCD砂轮结合超声辅助磨削加工,可以得到较好的表面加工质量。开展了石英陶瓷凹槽面、平面及过渡面的磨削加工试验,取得了较好的表面形貌;利用不同类型的砂轮加工氮化硅陶瓷孔,从而确定高强度的金刚石磨头是加工硬性材料的最优砂轮。     

氮化硅陶瓷的应用和酸腐蚀研究进展

综述了氮化硅陶瓷的三种工业应用,即氮化硅陶瓷轴承球、氮化硅涡轮转子、铝冶金氮化硅陶瓷部件,以及氮化硅在H2SO4,HN03,HCl,HF等酸溶液及高温SO2和HCl气体中的腐蚀行为,对其腐蚀机理进行总结,并提出今后提高氮化硅陶瓷抗腐蚀性能的研究重点。     

环保奇效优势凸显话陶瓷

陶瓷制品生产在中国历史悠久,经过长期的发展制造工艺得到不断发展。随着社会的发展和生活水平的提高,在生活中的应用范围越来越广。特种陶瓷又称高性能陶瓷先进陶瓷、精细陶瓷、高技术陶瓷等,是新材料的一个组成部分。本文分别介绍了氮化硅功能陶瓷,氮化铝陶瓷,电子陶瓷,生物陶瓷以及氧化锆陶瓷的组织结构,性能特点和应用领域,并同时指出了他们的发展前景和趋势。     

Effect of Powder Surface Modifications on the Properties of Silicon Nitride Ceramics

The effect of surface oxygen concentration of silicon nitride powders on the properties of resulting ceramics was studied. A high-purity silicon nitride powder was treated physically and chemically to modify its surface oxygen content. The resulting powders were hot-pressed into dense ceramics using 6 wt% yttria as a sintering aid. Strength and oxidation resistance of these ceramics were measured and correlated with the powder and ceramic compositions as well as the resulting intergranular phases. Results show that the phases developed in yttria-containing silicon nitride ceramics vary with slight changes in the initial powder oxygen content, as predicted, and that strength can be correlated to initial oxygen concentration. The mechanical strength vs oxygen content curve has a definite maximum; i.e., there is a small oxygen concentration range at which optimum ceramic strength is realized. Best results are obtained when the oxygen content is increased by thermal oxidation; other techniques such as chemical oxidation or addition of silica are not as effective, particularly in attaining high strength at elevated temperatures.     

Highly porous silica foams prepared via direct foaming with mixed surfactants and their sound absorption characteristics

The highly porous silica ceramics were fabricated by direct foaming with mixed surfactants and the influence of silicon nitride addition and solid content on the microstructures and properties were investigated. The results showed that silicon nitride can impede the formation of cristobalite and facilitates the sintering of silica ceramics. When the addition of silicon nitride powders reached 15 wt%, the highest compressive strength of silica ceramic foams could be obtained. The porosity of silica ceramic foams was tailored in the range of 84.61%–91.35% by adjusting the solid content, and the compressive strength of the obtained ceramic foams ranged from 5.89 MPa to 0.94 MPa. Sound absorption characteristics of silica ceramics foams were investigated. With the porosity of ceramic foams increased from 84.61% to 91.35%, the sound absorption coefficients in the entire sound wave frequency were enhanced due to the reduction of flow resistances, besides, the sound absorption peak varied from 4200 Hz to 2300 Hz, and became more intense and sharper.     

Hierarchical Structure of Porous Silicon Nitride Ceramics with Aligned Pore Channels Prepared by Ice‐Templating and Nitridation of Silicon Powder

A unique hierarchical porous structure of silicon nitride ceramic with 76.5% porosity is fabricated by combining an ice‐templating method and nitridation for a silicon powder. The porous silicon nitride ceramics were composed of a lamellar structure with aligned pore channels and ceramic walls filled with fibrous whiskers. This study is focused on the influences of freezing rate on the microstructures and properties of the silicon nitride ceramics. The properties were characterized by compressive strength and gas permeability, which were shown to vary with controlled microstructure. The compressive strength and the permeability reached up to 32.2 MPa and 0.035^?12 m², respectively.