Silica-alumina refractories are materials that are composed of a mixture of silica (SiO2) and alumina (Al2O3). These refractories possess several important properties that make them suitable for various applications. One of the key properties of silica-alumina refractories is their high thermal stability. They can withstand extremely high temperatures, making them ideal for use in industries such as glass, cement, and steel. They have a low thermal expansion coefficient, which means they do not undergo significant dimensional changes when exposed to heat, ensuring stability and durability. Another important property is their excellent resistance to chemical attack. Silica-alumina refractories are highly resistant to acidic and basic environments, making them suitable for applications in aggressive chemical processes. They can withstand corrosive substances such as molten metals, slag, and gases, making them indispensable in the metallurgical industry. Additionally, silica-alumina refractories have good mechanical strength and abrasion resistance. They can withstand mechanical stresses and are resistant to physical wear and tear, ensuring long-lasting performance. This property makes them suitable for applications in furnaces, kilns, and reactors where they are subjected to mechanical forces and abrasion. The applications of silica-alumina refractories are diverse. They are widely used in the production of glass, where they are used to line glass tanks, furnaces, and ladles. In the cement industry, these refractories are utilized in kilns and preheaters due to their high-temperature stability. They are also employed in the steel industry for the lining of blast furnaces, ladles, and tundishes. In summary, silica-alumina refractories possess properties such as high thermal stability, chemical resistance, and mechanical strength, making them well-suited for applications in industries such as glass, cement, and steel. Their ability to withstand extreme temperatures and corrosive environments makes them vital materials in various industrial processes.

Lanthanum oxide enhances the performance of refractory materials by improving their thermal and chemical stability. It acts as a fluxing agent, reducing the melting point of the refractory material and increasing its resistance to high temperatures. Lanthanum oxide also enhances the mechanical strength and corrosion resistance of refractories, making them more durable and suitable for demanding industrial applications.

Raw materials play a crucial role in determining the resistance to alkali attack of refractory products. The selection and composition of raw materials directly affect the overall chemical and physical properties of the refractory product. Certain raw materials, such as high-alumina content materials, have excellent resistance to alkali attack due to their ability to form a protective barrier against alkalis. Additionally, the presence of certain minerals or additives in raw materials can enhance the refractory's resistance to alkali attack by minimizing reactions with alkalis and reducing the formation of harmful compounds. Therefore, careful consideration and proper selection of raw materials are essential in ensuring the desired resistance to alkali attack in refractory products.

Different types of serpentine vary in their performance in refractory applications. Chrysotile serpentine, also known as white asbestos, has historically been widely used due to its high heat resistance and flexibility. However, due to health concerns associated with asbestos, its use has been significantly reduced. Other types of serpentine, such as antigorite and lizardite, have been explored as alternatives. While they may not possess the same level of heat resistance as chrysotile, they still offer good refractory properties and can be effective in certain applications. Overall, the choice of serpentine for refractory purposes depends on specific requirements, balancing performance, and health and safety considerations.