热处理温度对刚玉基耐火材料组织和微粒脱落的影响EI北大核心CSCD

为研究温度对刚玉基耐火材料组织和微粒脱落的影响,对粉末冶金高温合金粉末制备用刚玉基(Al_(2)O_(3))耐火材料进行950~1350℃不同温度保温60 min处理。采用XRD分析热处理前后耐火材料的结构,采用扫描电镜对各样品进行微观形貌观察和微区成分测定,并用黏附实验评价不同温度处理后耐火材料颗粒脱落性的改善情况,探索加热保温处理对减少颗粒脱落的机理。采用热冲击测试评价不同温度处理后耐火材料耐热冲击性,并测试耐火材料的显气孔率与体积密度。结果表明:随着加热温度升高,耐火材料中的铝酸钙黏结剂成分将逐步从CaAl_(2)O_(4)(CA)转化为CaAl_(4)O_(7)(CA_(2)),一方面耐火材料中细小的陶瓷颗粒逐步烧结在一起,直至形成相互连接的稳定网状结构;另一方面逐步在大颗粒骨料上润湿铺展并相互连接,最后形成对大颗粒的包覆,同时耐火材料微粒黏附力将随着加热温度的升高逐渐增强。采用预热处理对于耐火材料的显气孔率、体积密度以及整体的耐热冲击性影响不大,但是随着温度升高,对于耐火材料表面在热冲击测试中的局部脱落程度和质量损失率有较明显改善。在保温60 min的条件下,加热温度在1150~1350℃时微粒脱落明显减少,其中1250~1350℃为较优预热温度段。

Effect of heat treatment temperature on microstructure and particle shedding of corundum-based refractory materials

Corundum-based (Al₂O₃) refractory materials prepared by powder metallurgy superalloy powder were heat treated at 950-1350 ℃ for 60 min in order to study the effect of temperature on the microstructure and particle shedding of corundum-based refractory materials. The phase structure of the refractory materials before and after heat treatment was analyzed by XRD. Scanning electron microscopy (SEM) with energy dispersive spectrum (EDS) was used to characterize the microstructure and phase composition of the refractory samples. In addition, the adhesion experiment was used to evaluate the particle shedding of the refractory materials after heat treatment at different temperatures, and explore the mechanism of pre-heating treatment reducing the possibility of particle shedding. Thermal shock test was used to evaluate the thermal shock resistance of refractory materials after heat treatment at different temperatures. The apparent porosity and bulk density were measured. The results show that with the increase of preheating temperature, the composition of calcium aluminate cement binder in refractories is gradually changed from CaAl₂O₄ (CA) to CaAl₄O₇ (CA₂), and the fine ceramic particles in refractories are sintered together until the interconnected network structure is formed. With the increase of preheating temperature, the fine refractory particles in the refractory are gradually wet and spread on the large particles as aggregated and connected to form a network structure, and finally the large particles are coated. The particle adhesion of refractory gradually increases with the increase of heating temperature. The heat treatment has minor effect on the apparent porosity, bulk density and heat shock resistance of the refractory materials. However, with the increase of heating temperature, the local peeling degree of the refractory surface and mass loss rate in the thermal shock test are significantly improved. The particle shedding is obviously reduced whereas preheating for 60 min at 1150-1350 ℃, and the relative suitable preheating temperature is in the range of 1250-1350 ℃.