What Are Acid Refractories

Acid refractories are a kind of refractory that is composed principally of silica and reacts at high temperatures with bases such as lime, alkalies, and basic oxides. They usually contains a certain amount of silica. 

The main characteristic of acid refractories is good resistance to acid substances. However, it is easy to react with alkalis (basic slags). Acid refractories usually include silica brick, fireclay brick, and semi-siliceous refractories. Silicon carbide refractories and zirconia refractories also belong to this group because they can generate SiO2. 

 

Silica brick contains more than 93% SiO2. It is the strongest acid refractory and has great resistance to acid slags. It has high softening temperature under load. Its volume does not shrink after repeated firing. However, it is easily corroded by alkali slags and has bad thermal shock. 

 

Fireclay brick contains 30%-46% SiO2. It is a type of slight acid refractory. It has good thermal shock and finds a wide application in many industries. 

 

Zirconia refractory is a kind of special acid refractory. It has a strong resistance to alkali slags. It has low thermal expansion coefficient, high softening temperature under load, good wear resistance and good thermal shock resistance. 

 

Silicon carbide refractory is a type of refractory with SiC as the main raw material. It contains 72%-99% SiC. It has high thermal conductivity, good wear resistance, thermal shock resistance, and corrosion resistance. It can be used for the aluminum reduction cell lining, the molten aluminum tubes and ceramic kiln furniture, the lower part of blast furnace, aluminum refining furnace lining, and zinc retorts lining.

 

These are used in areas where slag and atmosphere are acidic. They are mainly used for coke oven, glass melting furnace, steel-making furnaces and other acidic thermal equipment.