Effects of CaO additions( 0,0. 5%,1. 0%,1. 5%,2. 0%,3. 5%,5. 0% and 7. 0%,in mass) on phase composition and properties of zirconia products were studied using CaO partially stabilized ZrO 2 and commercial ZrO 2 as starting materials. The results show that adding CaO has obvious effects on phase composition; as CaO addition increases,ZrO 2 stability degree increases,density and thermal shock resist- ance decline; when CaO addition is 1. 5%,the specimen has the highest strength. The stress forms on the interfaces between monoclinic phase and stabilized ZrO 2 because of their different thermal expansion coef- ficients,and results in the abnormal thermal shock resistance of specimens with less stabilized ZrO 2.

To prepare uniform zirconia spherical particles with excellent flowability by spray drying process,CaO partly stabilized ZrO2 was used as the main raw materials.The spherical particles with loose density of 1.945 g/cm3with excellent flowability were obtained.The results show that suspensions and spray-dried operating conditions have great influence on the properties of zirconia particles.When the atomizer frequency varies from 100 to 110 Hz and the rotate speed of pump varies from 15 to 20 r/min,the uniform particles have excellent flowability and little defects.

In order to prepare zirconia spray granulated slurry with good flow ability and stability,influences of STPP,SHPP,PAA and PEG2000 on their rheological behavior were discussed. It is found that the best dispersant for zirconia slurry is PAA. Then an orthogonal test was designed based on the results. The average viscosity and subsidence of slurry were used as indexes and the appropriate amounts of solid phase,binder PVA and dispersant PAA were optimized. In this experiment,zirconia slurry with good properties was prepared with 85% solid,8% PVA,and 0.5% PAA.

Based on analysis to micro structure and mine phase of used zirconia nozzle brick,it is considered that damage of the brick is because of the stabilizer in zirconia getting precipitated,instable and decomposed caused by corrosion of molten steel and slag,and furthermore the corrosion is speeded up by the more permeation of steel through the micro cracks brought by thermal stress.

在板状刚玉细粉中添加粘土或Al2O3微粉和不同种类的SiO2微粉制成刚玉-莫来石试样,分别于1200℃、1400℃和1600℃保温5 h烧成后,测定试样的体积密度、显气孔率和烧后线收缩率,利用XRD分析了试样在不同温度段的莫来石生成量,研究了添加Al2O3微粉和不同种类的SiO2微粉对材料的烧结性能和莫来石化的影响,并利用SEM观察了试样的显微结构.结果表明:(1)加入Al2O3微粉和SiO2微粉均有利于材料的烧结;加入SiO2微粉的纯度和晶形不同,对试样莫来石化的影响也不同,无定形态SiO2微粉(即硅灰)的纯度越高,试样的莫来石生成量也越高.(2)加粘土的试样,其显微结构中柱状莫来石的晶体特征比较明显;而加入SiO2微粉的试样,其莫来石晶体和刚玉晶体相互交错,晶粒较小.