EFFECT OF HEAT-TREATMENT ON THE MECHANICAL PROPERTIES OF AIN/SICw(Y_2O_3+SiO_2)COMPOSITE

In the paper, the effect of heat-treatment on thestrength and toughness of AlN-SiC whisker composites with Y_2O_3+SiO_2 additives have been studied. When the sample contining 10wt%Y_2O_3+SiO_2(Y_2O_3/SiO_2=1/0. 66) was treated at 1330℃ in air for 140hours,the flexural strength of composites was raised from 481 MPa to784 MPa the toughness was also enhanced slightly. The phase composi-tion microstructure and grain boundary phase structure have been char-acterized by combining XDR, SEM, TEM/EDXA and HREM tech-niques. reinforcenent and toughening mechanism of the composites re-sults from the crystallization of glass phase in the grain boundary atthe high temperature oxidizing atmosphere to form the crossing struc-ture of 2H°sialon fibrous phase and SiC whisker     

SiC WHISKER-TOUGHENED ALUMINIUM NITRIDE CERAMICS

Aluminium nitride ceramics containing 15-30 w/o of SiC whiskers can be sintered tofull density(by hot pressing at 1800℃)using2-3 w/o of Y_2O_3,additions.The whiskersincrease the toughness and strength of thecomposite,K_(10) increasing from 2.8 to about5.0 and flexural strength increasing by 30-50%.However,the whiskers must be welldispersed and if the dispersion is notsatisfactory,toughness may increase but thestrength decreases.The hot-pressingtemperature can be reduced by up to 100℃ ifY(NO_3)_3 .5H_20 is used as the sinteringadditive instead of Y_2O_3,but some oxidation ofthe AIN occurs during heating.Isopropan-2-01 is a better dispersing agent thancyclohexane,but again some oxidation of theAIN does occur.The best sample prepared during this work contained 20 w/o of SiC whiskers and 2 w/oY_2O_3 added as Y(NO_3)_3. 5H_2O and mixed inisopropanol.This exhibited a mean strength of453MPa(maximum 522MPa,measured bydisc flexure)and a fracture toughness of5.5MPam~(1/2).     

多功能高分子添加剂在高压注浆中的作用

在简单介绍高压注浆的特点、多功能高分子添加剂的特性和对陶瓷泥浆的作用后，通过小型高压注浆试验，将加有几种多功能高分子添加剂的泥浆与加传统无机添加剂泥浆的高压注浆性能进行对比，证明了多功能高分子添加剂在高压注浆中的重要作用。     

含硅白云石质釉面砖反应机理的研究

本文研究了湖北省襄阳县的含硅白云石制造釉面砖的反应过程。研究表明该矿石除白云石外还含有部分滑石和石英及少量其他矿物。以它为主要原料制造釉面砖时的反应机理是：白云石中的ＣａＣＯ３、ＭｇＣＯ３与由粘土、滑石脱水而来的非晶态ＳｉＯ２、Ａｌ２Ｏ３、ＭｇＯ以及石英类原料产生固相反应，生成钙长石（Ｃａ，Ｎａ）（Ｓｉ、Ａｌ）４Ｏ８）和普通辉石（Ｃａ（Ｍｇ，Ａｌ）（Ｓｉ，Ａｌ）２Ｏ６），即将碳酸盐转变为架状和链状     

Zn2+掺加的包覆型Fe2O3/SiO2颜料的制备及其呈色性能

包覆型Fe₂O₃/SiO₂颜料由于包覆完整性并不理想,该颜料高于800 ℃时呈色会产生变黑、变暗的问题。采用溶胶-凝胶法制备包覆型Fe₂O₃/SiO₂颜料,研究催化剂浓度、反应温度、硅/铁质量比等因素对包覆型Fe₂O₃/SiO₂颜料呈色性能的影响。在此基础上,通过掺加Zn²⁺,进行了Zn²⁺掺加的包覆型Fe₂O₃/SiO₂颜料的呈色性能研究。研究表明,当催化剂(氨水)浓度为0.75 mol/L,反应温度为40 ℃,硅/铁质量比m(SiO₂)/m(Fe₂O₃)为0.20,铁/锌摩尔比n(Fe)/n(Zn)为4时,制备得到的Zn²⁺掺加的包覆型Fe₂O₃/SiO₂颜料的呈色耐热性能获得明显提升,样品在850 ℃煅烧后仍然呈现出明亮的红橙色色调。     

AlN微粉表面结合状态的XPS研究

通过X射线光电子能谱 (XPS)分析研究了碳热还原氮化法制备的AlN微粉的表面结合状态。结果表明 :AlN微粉的表面有明显的氧化层存在 ;AlN微粉表面结合状态为Al—O和Al—N复合型结合 ;杂质元素W主要是由球磨介质中的WC引入的 ,并以WO2 - 4形式分布于AlN微粉表面。     

异丙醇钇〔Y(OC_3H7)_3〕合成的研究

本文采用 Ｉ２ 及 Ｈｇ Ｃｌ２ 为催化剂,用金属钇和异丙醇直接反应合成了异丙醇钇,产率可达８３ ％ 以上,而反应时间只需５ 个小时左右,超过了已有文献的报道。     

利用长江淤泥制砖的调查分析

通过对长江淤泥进行化学分析、矿物分析及物理性能测定,对长江淤泥的性能及分布进行全面的评价。由此可以肯定,通过合理地利用,长江淤泥用于制造砖瓦是可行的。     

黑色软质粘土的组成分析及其使用特点

本文通过对几种粘土的化学组成和矿相分析比较，探讨粘土矿物组成与宏观特性的相互关系，及其在陶瓷生产中使用的可能性。