Abstract: To solve the serious high-temperature water vapor corrosion of SiC based refractories used in waste incinerators,SiC particles and powders were adopted as main raw materials,silica sol as the binder,and Y₂O₃ as the additive to prepare strip samples of 140 mm×25 mm×25 mm under the pressure of 150 MPa.The strip samples were fired at 1 400 ℃ for 3 h to fabricate Y₂Si₂O₇ reinforced SiC based refractories,and then the SiC based refractories were corroded under a water vapor atmosphere at 1 000 ℃ for 100 h.The effect of the Y₂O₃ addition (0,1.5%,3.0%,4.5%,by mass) on properties,phase composition,microstructure of the fired and water vapor corroded samples were investigated.The results show that:the addition of Y₂O₃ increases the apparent porosity of SiC based refractories and decreases the cold modulus of rupture;however,with the increase of the Y₂O₃ addition,the bulk density and cold modulus of rupture of the samples after water vapor corrosion at 1 000 ℃ for 100 h increase,and the cold modulus of rupture increases after 5 water-cooled thermal shock cycles.This is because of the enhanced phase Y₂Si₂O₇ formed by the in-situ reaction between Y₂O₃ and SiO₂ during firing at 1 400 ℃.It tightly bonds with SiC matrix,performs good stability in high-temperature water vapor,and has an approximate thermal expansion coefficient to SiC,which can improve the high-temperature water vapor corrosion resistance of the SiC based refractories.

Key words: SiC based refractories, Y₂Si₂O₇, water vapor corrosion, thermal shock resistance

摘要： 为解决高温水蒸气对垃圾焚烧炉用SiC质耐火材料产生的严重腐蚀,以SiC颗粒和细粉为主原料,硅溶胶为结合剂,Y₂O₃粉为添加剂,在150 MPa的压力下压制成140 mm×25 mm×25 mm的长条试样,经 1 400 ℃保温3 h烧成制备Y₂Si₂O₇增强SiC质耐火材料,再经1 000 ℃保温100 h水蒸气腐蚀。研究Y₂O₃粉的添加量(添加质量分数分别为0、1.5%、3.0%、4.5%)对烧后试样和水蒸气腐蚀后试样的性能、物相组成和显微结构的影响。结果表明:添加Y₂O₃会造成烧后SiC质耐火材料的显气孔率上升,常温抗折强度下降;但是随着Y₂O₃添加量的增加,经1 000 ℃保温100 h水蒸气腐蚀后试样的体积密度和常温抗折强度增加,水冷热震5次后的常温抗折强度增加,因为1 400 ℃高温烧成过程中Y₂O₃和SiO₂原位反应生成Y₂Si₂O₇增强相,其与SiC基体结合紧密,且Y₂Si₂O₇在高温水蒸气条件下稳定性好,与SiC基体热膨胀系数接近,能够提高SiC质耐火材料的抗高温水蒸气腐蚀性能。

关键词: SiC质耐火材料, Y₂Si₂O₇, 水蒸气腐蚀, 抗热震性