氮化硅陶瓷的烧结

氮化硅陶瓷广泛用作高温结构材料,是很有前途的陶瓷材料之一。本文研究了氮化硅陶瓷烧结动力学,分析了影响氮化硅陶瓷烧结的因素,为氮化硅陶瓷烧结提供了依据     

氮化硅陶瓷烧的烧结

氮化硅陶瓷广泛用作高温结构材料,是很有前途的陶瓷材料之一。本文研究了氮化硅硅瓷烧结动力学,分析了影响氮化硅陶瓷烧结的因素,为氮化硅陶瓷结提供了依据。     

陶瓷材料微波烧结工艺与机理研究现状

微波烧结作为一种新型材料烧结技术,在陶瓷材料制备领域受到越来越多的关注.与传统烧结技术相比,微波烧结具有快速高效、节能环保以及改善材料微观结构,提高材料性能的优点.本文介绍了传统烧结和微波烧结的特点,对比了传统烧结和微波烧结陶瓷材料的烧结工艺和力学性能;列举了运用微波烧结法制备的典型结构陶瓷的烧结工艺及其力学性能;全面综述了陶瓷材料微波烧结机理;最后提出了微波烧结在未来发展中亟待解决的问题.     

常压烧结制备多孔氮化硅陶瓷研究

选用Al2O3、Y2O3、Lu2O3三种氧化物作为烧结助剂,采用凝胶注模成型和气氛保护常压烧结工艺,成功制备了具有高强度和高气孔率的多孔氮化硅陶瓷材料.本文研究了三种烧结助剂对多孔氮化硅的力学性能、介电性能和微观结构的影响,以及对氮化硅陶瓷的烧结促进作用,结果表明Y2O3具有最佳的烧结活性促进作用,其微观结构表明β-Si3N4棒状晶粒搭接结构是使多孔氮化硅陶瓷材料具有较好力学性能的重要原因.     

微波烧结在陶瓷材料中的应用

微波烧结作为一种陶瓷材料烧结的新方法,近年来得到飞速发展。本文介绍了微波烧结的原理,阐述了微波烧结在陶瓷 材料中的应用,并分析了微波烧结存在的问题及其解决途径。     

超低温烧结微波介质陶瓷研究进展EI北大核心CSCD

超低温烧结微波介质陶瓷作为无源集成技术的主要介质材料,可广泛应用于无线通讯、可穿戴电子、物联网和全球定位系统等领域,其相关研究具有重要的应用价值和理论指导意义,是目前功能材料领域的研究热点之一。本文综合介绍了超低温烧结微波介质陶瓷材料的应用背景和主要的材料体系,以及主要材料体系的介电性能和优缺点,探讨了材料组分、介电常数、Qf值、频率温度系数之间的关系,阐述了超低温烧结陶瓷材料的性能调控手段,并指出了今后超低温烧结微波介质陶瓷材料的主要发展前景和研究方向。钼酸盐基超低温烧结陶瓷兼具超低烧结温度、系列化介电常数和低损耗等优点,有望实现在超低温共烧技术中的应用。离子取代和多相复合是有效调控材料微波介电性能的方法,使材料更利于应用。     

先进陶瓷材料快速烧结技术发展现状及趋势

快速烧结技术在节省时间和能源方面的巨大优势使其成为一直以来的研究热点。近几十年来,快速烧结技术(如火花等离子烧结、闪电烧结、选区激光烧结、感应烧结、微波烧结和传统烧结装置中的快速烧结等)的发展,使陶瓷材料的快速烧结成为可能。本文综述了近20年来先进陶瓷领域中的快速烧结技术和烧结机理,并对火花等离子烧结中直流脉冲电流和机械压力对微观结构、材料性能和烧结机理的影响进行了深入分析和总结。同时指出,快速烧结技术今后的发展一方面是对烧结机理的进一步研究并应用到先进陶瓷材料的制备中,另一方面是解决快速烧结技术工业化生产中大尺寸、大批量生产的难题。     

微波烧结制备陶瓷材料的研究进展

微波烧结是一种新型的利用微波加热来对材料进行烧结的方法,它是一种快速制备高质量新型材料和使传统材料具有新的性能的技术手段。简要介绍了微波烧结的发展史、基本原理、制备陶瓷材料的研究进展、微波烧结技术存在的一些问题,并对微波烧结技术的前景进行了展望。     

添加Mg-Al-Si体系烧结助剂的氮化硅陶瓷的无压烧结

以MgO-Al2O3-SiO2体系作为烧结助剂,研究了氮化硅陶瓷的无压烧结。着重考察了烧结温度、保温时间以及烧结助剂用量等工艺因素对氮化硅陶瓷材料力学性能和显微结构的影响,通过工艺调整来设计材料微观结构以提高材料的力学性能。在烧结助剂质量分数为3.2％的情况下,经1 780℃,3 h无压烧结,氮化硅大都呈现长柱状β-Si3N4晶粒,具有较大的长径比,显微结构均匀。样品的相对密度达99%,抗弯强度为956.8 MPa,硬度HRA为93,断裂韧性为6.1 MPa·m1/3。具有较大长径比晶粒构成的显微结构是该材料表现较高力学性能的原因。     

β-氮化硅陶瓷烧结致密化的研究

以β-Si3N4粉末为原料,MgAl2O4为烧结助剂,通过气氛压力烧结(GPS)制备出致密的β-氮化硅陶瓷材料,探讨了β-氮化硅陶瓷烧结机制,系统研究了烧结助剂质量分数、烧结温度以及保温时间对材料致密化的影响.     

陶瓷材料的微波连续化烧结系统研究

陶瓷材料烧结通常需要整体在窑炉内烧结,以保证材料性能.本文利用微波烧结的特性,研究了混合场的模型,设计了微波连续化烧结系统,并在该系统上成功地实现了Φ40×2400mm的陶瓷辊棒的微波连续化烧结.结果表明,微波烧结陶瓷辊棒的抗热震性能及抗弯强度均有较大幅度提高.本研究对微波烧结的实用化具有较大的推动作用.     

α-β Sialon Ceramics Made from Different Silicon Nitride Powders

The present work is concerned with the sintering of an α-β sialon ceramic using five different silicon nitride powders from a single source. The parameters varied in the silicon nitride were the amount of "free' silicon, iron content, α:β ratio, and grain size as measured by BET surface. The sintering atmosphere was varied by use of protective powder beds with passive (boron nitride) and active (SiO-generating) properties. Five sintering temperatures between 1600° and 1800°C were used. Microstructural characterization as well as density, hardness, and fracture toughness measurements were carried out. The sintering conditions were found to be critical for obtaining fully dense materials and low weight change. The optimum sintering temperature was 1750°C. The silicon nitride powder with a high content of free silicon resulted in a material which was more susceptible to the sintering atmosphere conditions. An α-β sialon made from a silicon nitride powder with a high β-α phase ratio resulted in a higher β-α ratio in the sintered material.     

Electrical resistivity of silicon nitride produced by various methods

It has been shown that the grain growth and amount of the glass phase influence the electrical resistivity of pressureless sintered and spark plasma sintered silicon nitride. Sintering additives strongly affect the impurity conductivity of pressureless sintered silicon nitride and slightly influence the intrinsic conductivity due to the longer sintering process as compared with the spark plasma sintering. It was demonstrated that Al₂O₃-Y₂O₃ lead to decrease in the electrical resistivity of SPSed silicon nitride due to increase in the band gap width as opposed to Al₂O₃-MgO. Effect of the sintering additive on the impurity conductivity is practically absent but there is a strong dependence of the sintering temperature for reported spark plasma sintered silicon nitride. However, intrinsic conductivity of SPSed silicon nitride is affected by both sintering temperature and sintering additive. It was also shown that electrical resistivity of produced ceramics is linearly depends on the content of β-Si₃N₄ and microhardness. Electrical resistivity of manufactured silicon nitride varied from 3.16·10⁹ to 1.73·10¹¹ Ω?m. It has been observed strong influence of the sintering additive and sintering temperature on the electrical properties of SPSed and pressureless sintered silicon nitride.     

Rapid densification of SiC ceramic rollers by microwave sintering

Ultralarge silicon carbide (SiC) ceramic rollers are successfully prepared in a microwave multimode cavity at 2·45 GHz. The length of the rollers is 1220 mm with outer diameter of 62 mm and thickness of 7 mm. The optimised sintering temperature of microwave sintering is ～980°C, which is ～400°C lower than that of conventional sintering. Mullite was detected within microwave sintered samples, rather than conventional sintered ones, which preferentially appeared around SiC as well as inside the residual pores. This might be attributed to the unique features of microwave sintering of ‘hot spot effect’, plasma behaviour and high frequency electromagnetic fields.     

微波烧结AlN陶瓷的初步研究

采用微波高温烧结工艺,制备了致密的AlN陶瓷,并初步探讨了微波烧成环境对烧结体性能的影响.结果表明:利用微波烧结AlN陶瓷,虽然在节能省时方面效果显著,但是微波烧成环境对AlN陶瓷的烧成影响比较复杂,本文着重指出烧成环境中的碳热还原气氛能极大地加快AlN陶瓷的致密化速率,但容易在AlN陶瓷晶界相内部产生气孔,使AlN陶瓷的热导率降低.     

In situ synthesis of three-dimensional nanofiber-knitted ceramic foams via reactive sintering silicon foams

Three-dimensional ceramic nanofiber-assembled materials with large specific surface area and excellent thermal insulation properties are attracting increasing interests for their unique structure and promising applications. In this paper, we propose a facile methodology to fabricate three-dimensional silicon nitride nanofiber-knitted ceramic foams via in situ reactive synthesis from silicon foams. Silicon particle-stabilized foams are fabricated for the first time using long-chain surfactant cetyltrimethyl ammonium bromide as a hydrophobic modifier. First, the fabrication and stability of silicon foams are investigated. Based on the stable silicon foams, silicon nitride-based nanofiber-knitted ceramic foams are synthesized via in situ reactive sintering in nitrogen atmosphere. The novel ceramic foam materials consist of three-dimensional nanofiber-assembled strut wall and nanofiber-spheres in the pores. The diameter of obtained silicon nitride nanofibers ranges from 15 to 100 nm. The unique nanofiber-knitted foams may have potential applications in specific fields, including catalysis, adsorption, separation, and thermal insulation.     

AIN陶瓷烧结技术研究进展

氮化铝（AIN）因其具有高热导率，作为基片材料在电子元器件中得到日益重视。本文主要论述了氮化铝陶瓷制备过程中各种烧结参数，包括烧结助剂、烧结气氛、保温时间、常压烧结、热压烧结、微波烧结和等离子烧结等对氮化铝陶瓷性能的影响。并指出可通过合适的AIN粉体制备技术，结合快速烧结方法可得到具有晶粒细小、结构均匀、高致密度和高导热率的AIN陶瓷。     

烧结技术与氯化硅陶瓷显微结构研究

本文以编号为SPN氨化硅与编号为M(20)、M(50)的Sialon材料为例在无压烧结、气压烧结和热等静压烧结等工艺条件下进行烧结，测试了材料性能，用SEM、EM和X折射等分析手段观察材料的显微结构和相组成，及其对材料性能的影响进行了讨论。     

无压烧结氮化硅陶瓷的物理性能研究

以α-Si₃N₄粉末为原料,Y₂O₃和MgAl₂O₄体系为烧结助剂,采用无压烧结方式,研究了烧结温度、保温时间、烧结助剂含量以及各组分配比对氮化硅致密化及力学性能的影响。结果表明:以Y₂O₃和MgAl₂O₄为烧结助剂体系,氮化硅陶瓷在烧结温度为1 600 ℃,保温时间为4 h,烧结助剂含量为12.5%(质量分数),Y₂O₃和MgAl₂O₄质量比为1∶1时,综合性能最好;氮化硅陶瓷显气孔率为0.21%,相对密度为98.10%,抗弯强度为598 MPa,维氏硬度为15.55 GPa。