Study On Application Of Alumina In High-Purity Andalusite Based Refractory

Abstract

Effects of some kinds of alumina on physical properties of high-purity andalusite based refractory were studied, and, effects of type and amount of added alumina on phase composition and microstructure of the refractory were investigated by XRD and SEM. The results revealed that the sintering property of the refractory sample without added alumina was better than that of one with added alumina, whereas the effect of a selected sample of added alumina on the sintering property of the high-purity andalusite based refractory was related to the purity and activity of the added alumina sample. The SiO 2 glass phase originated from the decomposed andalusite aggregate cannot wholly react with added alumina to form secondary mullite. Moreover, when the quantity of added alumina amounted to about 15% (mass percent), more extensive secondary mullitization and greater expansion will be observed in the experimental sample.

Substitution of antioxidant Si by andalusite fine powder in Al2O3‐SiC‐C castables

“…The formation of secondary mullite is accompanied by a volume expansion of about 8%-10%. 20,21 Therefore, a decrease in linear expansion is produced when the Si content is decreased. However, Figure 6 shows that, even when the Si content is reduced to 0%, the linear expansion of the sample containing andalusite fine powder (A0) is still significantly higher than that of the samples (M) without andalusite but with 1.5 wt% Si.…”

“…Si can react with oxygen to produce SiO 2 , which then combines with Al 2 O 3 in the matrixes to form secondary mullite in the castables. The formation of secondary mullite is accompanied by a volume expansion of about 8%–10% 20,21 . Therefore, a decrease in linear expansion is produced when the Si content is decreased.…”

Enhancing the Oxidation Resistance of Al2O3-SiC-C Castables via Introducing Micronized Andalusite

“…Based on our previous study, adopting 19 wt% andalusite aggregates could significantly promote the antioxidation of ASC castables [8][9][10][11], as the high-temperature heating prompts the transformation of andalusite into mullite and silica-rich glass. This silica-rich glass obstructs the pore channels and impedes oxygen diffusion into the castable interior [15][16][17].…”

“…Moreover, the substitution of high-density and low-porosity brown fused alumina would deteriorate the slag corrosion resistance of the castables [18,19]. Maintaining a low content of andalusite to enhance the oxidation resistance is important for corrosion resistance.…”

Model for Periodic Analysis of the Quantity of Water Evaporated during Thermo-processing of Clay Designated for Production of Oven Refractory

“…It has been shown [2] that clays of alumino-silicate minerals have excellent high temperature volume stability, mechanical strength, thermal shock resistance and creep resistance. Refractories and kiln linings made from these alumino-silicate materials have found application in industrial fields, such as metallurgical and building materials industries [2].…”