With the continuous development of industrial technology, the demand for materials with excellent high temperature resistance and thermal shock resistance in the production process is more and more urgent. Compared with polymer materials and metals, ceramic materials have a series of remarkable excellent properties such as high temperature resistance, high strength and corrosion resistance, and thermal expansion is also one of the main properties of ceramic materials. In the field of low thermal expansion ceramic materials, there are three very typical: fused quartz ceramics, cordierite ceramics and aluminum titanate ceramics. In this paper, aluminum titanate ceramics will be mainly introduced:
1. Basic properties of aluminum titanate ceramic materials
Aluminum titanate ceramics are characterized by high melting point, low thermal expansion coefficient, low thermal conductivity, and excellent thermal shock resistance and corrosion resistance. It is a complex oxide ceramic material with the best thermal shock resistance in low expansion ceramics. Its high temperature resistance is very excellent and can be used for a long time at 1400℃. The application is mainly in the special occasions of drastic temperature changes and strong corrosion, and the prospect is very broad.
At present, aluminum titanate ceramics is one of the best low-thermal expansion materials with high temperature resistance, but it also has defects: first, the anisotropy of the coefficient of thermal expansion causes a large number of micro cracks in its interior, which greatly reduces its own strength; The second is that it is easy to decompose and lose its low expansibility in the temperature range of 750~1300℃, but the key process parameters (such as sintering temperature) can be controlled by adding stabiliser (such as magnesium oxide, iron oxide, cerium oxide, silicon oxide, yttrium oxide, mullite powder, etc.) or the method of making composite materials can basically overcome these shortcomings, thereby extending the service life of the material.
3. Application direction of aluminum titanate ceramics:
Because aluminum titanate ceramics have a very low coefficient of thermal expansion, high melting point, excellent thermal shock resistance and thermal conductivity, as well as slag resistance, corrosion resistance, alkali resistance characteristics, and aluminum titanate ceramics and many metals (especially non-ferrous metals) melt and glass melt do not wetting, Can be widely used in chemical industry, metallurgy, ceramics, automotive and environmental protection in some of the fields of high temperature resistance, corrosion resistance and thermal shock and other harsh environment occasions.
① Low pressure casting aluminum alloy products: aluminum titanate as a relatively cheap high temperature resistance, low expansion, low thermal conductivity of ceramic materials, has excellent thermal shock resistance and non-stick with aluminum liquid, is the production of low die casting aluminum riser material of choice.
② Thermocouple protection: thermocouple aluminum titanate ceramic protection sleeve is used to measure the temperature of various kilns, frit pool kiln thermocouple protection, by which the thermocouple sleeve has normal temperature sensitivity and long service life. In particular, the thermocouple protection for measuring the temperature of metal melt and glass melt has advantages over similar products of other materials, because it can repeatedly enter and exit the environment under test without cracking and corrosion.
③ Used as insulation material for engine components: the excellent characteristics of aluminum titanate make it both excellent thermal shock resistance and heat insulation, and it is the ideal material for making engine exhaust pipes and supercharger turboshell insulation lining (especially military off-road vehicles and desert vehicles).
④ Other aspects: metal chute or crucible for smelting non-ferrous metals, amorphous refractory lining, inner wall coating of molten metal containers, catalyst carrier (honeycomb) for purifying automobile exhaust gas……
4. Conclusion
For the research of aluminum titanate ceramic materials, since the 1950s abroad, in the production of aluminum titanate ceramic products, a few developed countries such as Japan, the United States and Germany have mastered relatively excellent production technology, and aluminum titanate material products supply. The domestic research on aluminum titanate began in the 1980s, and the research is mainly limited to the basic and applied research of aluminum titanate ceramic materials, although there are some small batch production products, but compared with the international level, there is a certain gap in the level and quality of product development, the need to further increase research efforts.
