Physical And Chemical Changes Of MgO-CaO-TiO₂-ZrO₂ Materials During Sintering Process

Because of its high temperature resistance, Refractory material which has been favored by the high temperature industry is widely used in high-temperature equipment lining. But with the development of industry, refractory material is not limited to its high temperature, when it is applied in the high temperature industry.After a long period of development and research, many properties of refractory materials have been developed, such as slag resistance, thermal shock resistance,hydration resistance, purification of steel liquid and so on. At present, the steel industry is developing rapidly, so the requirement of steel making technology is getting higher and higher, and the demand for clean steel is increasing. Because of its high temperature resistance, good slag resistance and purifying molten steel performance, Calcium magnesium series refractory has been widely concerned by iron and steel, nonferrous metallurgy and cement industry, which is the first choice of refractory material for smelting clean steel.Calcium magnesium series refractory have many excellent properties, which is widely used in iron and steel industry and cement industry, but it also has many disadvantages and problems, one of the most disadvantages is the f-CaO hydration which seriously hinders the application of refractory materials. At present, there are many researchs about calcium magnesium series refractory in order to improve the hydration resistance. After years of research, methods of improving the hydration resistance basically have the following three types: a is sintering process; b is adding admixtures; c is the surface treatment. Sintering process mainly adopts two-step calcining or improving the sintering temperature, and adding admixtures commonly have Fe₂O₃, Al₂O₃, SiO₂, TiO₂, ZrO₂, Cr₂O₃, etc. In the study of improving the hydration resistance of calcium magnesium series refractory, it used a combination of various methods which can greater improve the hydration resistance, but not a single method.This subject uses light burned dolomite as the main raw material, the titanium dioxide and zirconia as additives, which were calcined at different temperatures. We will study compactness, hydration resistance and phase composition of samples bychanging of the content of admixtures and adjusting temperature. The research of this topic is divided into four aspects:（1） We will study compactness, hydration resistance and phase composition of samples which is MgO-CaO-TiO₂ refractories by introducing separately titanium dioxide.（2） We will study compactness, hydration resistance and phase composition of samples which are MgO-CaO-ZrO₂ refractories by introducing separately zirconia.（3） We will study compactness, hydration resistance and phase composition of samples which are MgO-CaO-TiO₂-ZrO₂ refractories by introducing titanium dioxide and zirconia.（4） On the basis of the former three groups of tests, we will study compactness, hydration resistance and phase composition of samples which are prepared by introducing quartz into three formula of DMT₃, DMZ₃ and DMTZ₄. The experiment results show that:（1） The influence of refractory material’ compactness and hydration resistance by introducing admixtures and improving sintered temperature is appear. The compactness and hydration resistance of samples is best when w（TiO₂） is 4% and sintering temperature is 1450℃; The compactness and hydration resistance of samples is best when w（ZrO₂）is 20% and sintering temperature is 1550 ℃; The compactness and hydration resistance of samples is best when w（TiO₂） is 4% and w（ZrO₂） is 16% and sintering temperature is 1450℃.（2） When introduced additives of TiO₂ and ZrO₂, the sample produced a new phase of CaTiO3 and CaZrO₃.It promoted the grain growth and more uniform by improving the sintering temperature.（3） After added SiO₂ in three formulations, the sample’ which are MgO-CaO-TiO₂-ZrO₂ refractories compactness and hydration resistance did not improve, the volume density decreased and the apparent porosity and water weight gain rate increased.