α－Al_2O_3与CaO－Al_2O_3－B_2O_3系玻璃复合材料的等速升温

用ＤＴＡ、ＸＲＤ及压汞方法研究了α－Ａｌ２Ｏ３与ＣａＯ－Ａｌ２Ｏ３－ＳｉＯ２－Ｂ２Ｏ３系玻璃复合材料的等速升温烧结与相组成．实验表明：在７０－９００℃时烧结快速进行．９００℃后由于闭气孔大量生成使致密化速度减慢．钙长石是由玻璃析晶及α－Ａｌ２Ｏ３与玻璃在＞７００℃反应生成．     

Effect of CuO Addition on the Sintering Behavior and Electrical Conductivity of 3Y-TZP

Yttria stabilized tetragonal zirconia polycrystals （3Y-TZP） doped with CuO was prepared, to get two compositions, 0.3 and 1 mole fraction CuO, respectively. The dilatometric study of the samples showed sintering to be improved for the samples doped with 0.3 mole fraction CuO, and to be deteriorated for the samples doped with 1 mole fraction CuO. The 1 mole fraction CuO doped 3Y-TZP showed higher tetragonal/monoclinic phase transformation which was accompanied by grain growth. The electrical conductivity decreased with the addition of CuO.     

Substituent Influence of Yttria by Gadolinia on the Tetragonal Phase Stability for Y_2O_3-Ta_2O_5-ZrO_2 Ceramics at 1300℃

The influences of equimolar substitution of yttria by gadolinia on the phase constituent and stability for Y_2O_3—Ta_2O_5—ZrO_2 ceramics have been investigated.The ceramics with the Gd content lower than 8 nnol%exhibit pure tetragonal phase as well as high tetragonal phase stability.However,the high Gd containing ceramics consist of t-ZrO_2,m-ZrO_2 and monoclinic GdTaO_4 and show complicated phase evolution behaviors.The fractions of monoclinic ZrO_2 and GdTaO_4 increase with increasing Gd content,indicating that the excessive substitution of Gd for Y results in a reduction in the tetragonal phase stability.In addition,the lower Gd containing ceramics show an almost invariable tetragonality,while the higher Gd containing ceramics reveal a composition-dependent tetragonality.Accordingly,an association of the tetragonal phase stability and tetragonality with the Gd concentration is established,which provides us a clue to understand the phase stability of these ceramics.     

Effect of the AL2O3 and BaO Addition on the Thermal and Physical Properties of Ternary Glass System （B2O3-BaO-AL2O3）

In borate glasses, the main structural units are the [BO3] triangles and [BO4] tetradral which form different superstructural units like; boroxol rings, metaborate rings and chains, pentaborate, diborate, triborate and pyroborate. In this work, the Barium aluminoborate glasses were prepared. Some of properties were investigated by measure like density and chemical durability and the other by calculs. The dilatometric curves were determined and they revealed that the temperature of transition （Tg） and softening （Ts） and the dilatation coefficient increase by addition of Al2O3 and BaO content.     

热压烧结制备Ti3Al/TiC+ZrO2陶瓷复合材料

采用机械合金化和热压烧结制备了Ti3Al/TiC ZrO2复合材料.研究了不同烧结温度(1500,1550℃)及Ti3Al在TiC基体中不同的添加方式对烧结体力学性能的影响,并对烧结体的断口进行了SEM分析.结果表明:在Ti3Al和ZrO2协同增韧补强的作用下,得到的烧结体具有良好的力学性能,其断裂以穿晶和沿晶相结合方式进行,并且出现了内晶.     

TiC-TiB2复相陶瓷的氧化行为研究

对自蔓延高温合成法制备的TiC-TiB2复相陶瓷的氧化行为及机理进行了研究.结果表明:在低于1000℃范围内,随氧化温度和时间的增加,氧化增重符合抛物线规律;在600℃时,TiB2首先被氧化成TiO2,在1000℃时TiB2、TiC均被氧化成TiO2,表面形成致密的TiO2氧化膜,阻止内部继续发生氧化,这表明该材料具有较好的高温抗氧化能力.     

放电等离子烧结NdFeB磁体的氧化和腐蚀行为

采用放电等离子烧结技术制备了新型NdFeB磁体,研究了NdFeB磁体在湿热环境下的氧化行为和在电解质溶液中的电化学特性.在扫描电子显微镜下分析了磁体的显微组织结构和成分.结果表明,与传统烧结NdFeB磁体相比,新型磁体的显微组织特征为:主相Nd2Fe14B晶粒细小、均匀,富钕相在主相晶粒边界上分布较少,主要集中在三角晶界处.这种组织结构有效抑制了磁体沿富钕相发生的晶间腐蚀的过程,使磁体具有良好的耐腐蚀性能.