ZrO_2加入量对刚玉-尖晶石浇注料性能的影响

Effect of ZrO_2 addition on properties of alumina-spinel castables

以板状刚玉颗粒（6～3、3～1和≤1mm）为骨料，电熔白刚玉粉（≤0．088和≤0．044mm）、电熔尖晶石细粉（≤0．044mm）、α-Al2O3微粉（≤5μm，d50=1．2μm）、纯铝酸钙水泥、单斜氧化锆（≤15μm，d50=6．2μm）为基质，按骨料与基质质量比为70：30配料，基质中纯铝酸钙水泥的加入量（质量分数，下同）为3％、α-Al2O3微粉为6％、电熔尖晶石细粉为10％，用单斜氧化锆等量替代电熔白刚玉细粉，其加入量分别为0、2％、4％、6％和8％，加水混匀后振动浇注成25mm×25mm×125mm的试样，于室温下养护24h后脱模，经110℃24h烘干后，分别经1100、1500、1600℃热处理3h。对各温度热处理后试样进行了常温物理性能、热态抗折强度、抗热震性能检测，并利用SEM对部分试样于1400℃高温抗折强度试验后的断口形貌进行了分析。结果表明：（1）随ZrO2加入量的增加，刚玉-尖晶石浇注料于1500和1600℃处理后的常温抗折强度降低，显气孔率升高，故ZrO2的加入对材料的烧结性略有负面影响。（2）随ZrO2加入量的增加，1600℃处理后试样的热态抗折强度下降，但热态抗折强度在1000℃以前变化较小，1000℃以后明显降低。（3）ZrO2的加入改善了试样的抗热震性能，其质量分数为2％时，1100℃水冷1次和3次后的强度保持率和残余强度最大。（4）本试验范围内ZrO2的最佳加入量为2％。

Alumina-spinel castables were prepared by using tabular alumina（6- 3,3 -1, ≤1 mm） as aggregates, fused white corundum fines （ 〈0.088, 〈0.044 mm）, fused spinel fines （ 〈0. 044 mm）, ultra-fine alumina （≤5 μm,d50 = 1. 2 μm）, calcium aluminate cement （Secar 71） and monoclinic zirconia fines （〈15 μm, d50 =6.2 μm）as matrix. The mass ratio of aggregates and matrix is 70：30. The content（mass percent） of calcium aluminate cement,ultra-fine alumina,fused spinel in the matrix is 3% ,6%, 10%, respectively. Based on formula,0,2% ,4% ,6% and 8% monoclinic zirconia substituted the corresponding content of fused white corundum fines,respectively. The castables were mixed with water and cast into 25 mm × 25 mm × 125 mm moulds,cured in air at ambient temperature for 24 h,dried at 110 ℃ for 24 h,and then firing at 1 100,1500 and 1 600 ℃ for 3 h. Physical properties of the specimens heated at different temperatures were measured. Hot modulus of rupture（HMOR） at different temperatures was tested by three-point bending method. Thermal shock resistance（TSR） of specimens after firing at 1 600℃ for 3 h was conducted by quenching it into water. Morphology of fractural surface of specimens after HMOR test at 1 400 ℃ was examined by SEM. The results show that cold modulus of rupture decreases,apparent porosity increases with ZrO2 fines addition,indicating that sintered properties of castables slightly deteriorate. Hot modulus of rupture of specimens noticeably decreases at 1 000 - 1400 ℃ and decreases with the increase of ZrO2 content. Thermal shock resistance of the specimens is improved with ZrO2 addition. The residual strength and strength ratio of specimen with 2% ZrO2 fines are the maximum value. The optimum content of ZrO2 is 2% in this experiment.