Low expansion ceramic-Introduction and application of aluminum titanate ceramics

1. Overview of aluminum titanate ceramics

Aluminum titanate ceramics belong to the rhombic system of quasi - plate - titanium - type crystallization. The average thermal expansion coefficient 9.5X10^-6/℃, is a famous low thermal expansion coefficient of material, aluminum titanate in and will not appear in the process of long-term use repeatedly devitrification phenomenon, can be used under high temperature (1460 ℃), can also be very good to adapt to high temperature oxidation, therefore has broad application prospects, but its easy to crack when calcination, poor mechanical strength.

2. Manufacturing process of aluminum titanate ceramics

At present, there are three main synthesis methods of aluminum titanate:

(1) Al2O3 and TiO2 powder mixture, through high temperature calcination of solid phase reaction; (2) The liquid phase method of the solution product of metal alcohol salt or metal salt water; (3) Use the gas phase method of VCD, etc.

The synthesis and preparation process of solid phase method is simple and does not require special equipment. Although it cannot achieve high purity and ultrafine, it is a common preparation method; liquid phase method can produce ultrafine aluminum titanate powder with high purity, but the process is complicated;The powder obtained by gas phase method is characterized by high purity, less agglomeration, narrow particle size distribution range, and easy control of the atmosphere during chemical reaction, but requires a lot of energy and complex equipment.

3. Properties and applications of aluminum titanate

(1) The influence of process conditions on the properties of aluminum titanate

The properties, especially the strength, of aluminum titanate are very dependent on the sintering conditions and the characteristics of the initial powder. Generally, it can be found that the strength decreases with the increase of the sintering temperature.

The effect of sintering time on mechanical properties is faster than sintering temperature. At lower sintering temperatures of 1300°C, strength tends to increase with time, as density increases with the growth of fine grains. When the sintering temperature increases, grain growth dominates. The larger particle size leads to a decrease in strength with increasing sintering time.

The initial powder of aluminum titanate prepared by co-precipitation, sol-gel process and other chemical methods can be prepared with high strength without loss. Low expansion aluminum titanate sintered body. In addition, heat treatment of aluminum titanate sintered substance body can also significantly improve the properties of the material.

(2) Application of aluminum titanate ceramics.

Aluminum titanate ceramics as a characteristic of good thermal shock resistance, high fireproof inorganic non-metallic materials, widely used in metallurgy, thermal, mechanical, chemical and other areas, such as cars and other industrial waste gas with catalyst carrier, used under the high temperature of heat exchanger, thermowells, automobile exhaust pipe, high temperature fast kiln, water filling and moulds for the continuous casting of steel, in the crucible of molten alloy, etc

Aluminum titanate gate sleeve