Abstract To take full advantage of the excellent properties of CA6 present in calcium alumino-titanate (CAT) and reduce the formation of the low melting point phase (anorthite), CAT-bauxite-SiC composite refractories were fabricated under buried sintering in order to achieve low thermal expansion, superior high-temperature performance, and increased alkali resistance. Furthermore, the corrosion mechanism of K vapor was investigated by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results show that CA6 present in CAT can be partially retained and the hot strength of CAT-bauxite-SiC composites slowly decreases when the amount of CAT added is less than 21.6 wt%. The cold strength and bulk density decrease with the CAT content, and the residual ratio of MOR firstly decreases and subsequently increases with the CAT content. For the specimens with CAT additions, 43.2 wt% CAT results in the highest volume expansion at high temperatures. It is proposed that the corrosion mechanism of CAT aggregates under buried sintering is as follows: 1) K vapors penetrate into the CAT with high CA6 content through the lamellar CA6 gap and deposit on the inner regions of CAT; and 2) K vapors react with corundum and anorthite present in CAT and cause the microstructural destruction of CAT due to a decrease in the amount of the Al2O3-CaO-SiO2 liquid phase in the CAT. The alkali resistance of the CAT-bauxite-SiC composites decreases as the CAT content increases, which is attributed to poor sintering densification and high apparent porosity.

中文翻译：

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还原气氛下反应键合铝钛酸钙铝土矿-SiC复合耐火材料的合成与表征

摘要 为充分利用钛酸钙（CAT）中存在的 CA6 的优异性能，减少低熔点相（钙长石）的形成，采用埋地烧结法制备 CAT-铝土矿-SiC 复合耐火材料，以达到低热膨胀、优越的高温性能和增加的耐碱性。此外，通过X射线衍射（XRD）和扫描电子显微镜（SEM）研究了K蒸气的腐蚀机理。结果表明，当CAT加入量小于21.6wt%时，CAT中存在的CA6可以部分保留，CAT-铝土矿-SiC复合材料的热强度缓慢下降。冷强度和堆积密度随CAT含量的增加而降低，MOR残留率随CAT含量的增加先降低后升高。对于添加 CAT 的样品，43.2 wt% CAT 导致高温下的最大体积膨胀。提出埋藏烧结下CAT聚集体的腐蚀机理如下：1）K蒸气通过层状CA6间隙渗入具有高CA6含量的CAT并沉积在CAT内部区域；2) K 蒸气与 CAT 中的刚玉和钙长石反应，由于 CAT 中 Al2O3-CaO-SiO2 液相量的减少，导致 CAT 的微观结构破坏。CAT-铝土矿-SiC复合材料的耐碱性随着CAT含量的增加而降低，这是由于烧结致密化差和表观孔隙率高。提出埋藏烧结下CAT聚集体的腐蚀机理如下：1）K蒸气通过层状CA6间隙渗入具有高CA6含量的CAT并沉积在CAT内部区域；2) K 蒸气与 CAT 中的刚玉和钙长石反应，由于 CAT 中 Al2O3-CaO-SiO2 液相量的减少，导致 CAT 的微观结构破坏。CAT-铝土矿-SiC复合材料的耐碱性随着CAT含量的增加而降低，这是由于烧结致密化差和表观孔隙率高。提出埋藏烧结下CAT聚集体的腐蚀机理如下：1）K蒸气通过层状CA6间隙渗入具有高CA6含量的CAT并沉积在CAT内部区域；2) K 蒸气与 CAT 中的刚玉和钙长石反应，由于 CAT 中 Al2O3-CaO-SiO2 液相量的减少，导致 CAT 的微观结构破坏。CAT-铝土矿-SiC复合材料的耐碱性随着CAT含量的增加而降低，这是由于烧结致密化差和表观孔隙率高。2) K 蒸气与 CAT 中的刚玉和钙长石反应，由于 CAT 中 Al2O3-CaO-SiO2 液相量的减少，导致 CAT 的微观结构破坏。CAT-铝土矿-SiC复合材料的耐碱性随着CAT含量的增加而降低，这是由于烧结致密化差和表观孔隙率高。2) K 蒸气与 CAT 中的刚玉和钙长石反应，由于 CAT 中 Al2O3-CaO-SiO2 液相量的减少，导致 CAT 的微观结构破坏。CAT-铝土矿-SiC复合材料的耐碱性随着CAT含量的增加而降低，这是由于烧结致密化差和表观孔隙率高。