Application of Cordierite
2.1 Application of ceramics and refractory materials
Cordierite was originally used as a packaging material for ceramic firing, known as saggar. Due to the low expansibility of Cordierite, the saggar made of it has a longer service life than the saggar made of other materials - clay materials. Subsequently, the shed plate and support materials made of it were used in the tunnel kiln, which greatly accelerated the production cycle.
However, Cordierite also has certain shortcomings, namely, its poor high-temperature load bearing performance, which has led to the emergence of composites of cordierite with other materials to improve its performance, such as cordierite mullite, cordierite sillimanite, cordierite spinel, and other composite materials. Although this composite can overcome the disadvantage of poor loading performance of a single cordierite, due to the lack of specific theoretical support and the existence of process and equipment problems, it often fails to achieve ideal results.
Lightweight cordierite materials have been developed successively, such as thermal insulation products with a unit weight of 0.8 to 1.0 g/cm 'and a temperature of up to 1350' C. Due to its light weight, low thermal conductivity, and relatively high operating temperature, this material is directly used on the flame surface, achieving efficient and energy-saving effects. Some are also used on heat exchangers with high cold and heat exchange rates, such as durable hot pots for cooking or frying, heat-resistant porcelain for gas stoves, and honeycomb stoves.
2.2 Ceramic catalyst carrier
As a catalyst carrier, cordierite ceramics are mainly used in automotive exhaust purification. Tail gas purification requires that the catalyst be able to fully contact harmful gases to increase its reaction area. Therefore, it is required that the catalyst carrier not only have sufficient strength, but also have a large surface area. The crystal structure of cordierite is characterized by strong adsorption and low thermal expansion, which is conducive to the preparation of honeycomb carriers with low thermal expansion. It can make the products have the characteristics of thin pore walls and fast temperature rise, and can quickly reach the activation temperature of the catalyst, achieving good results. Due to the loose crystal structure of Cordierite, the volume of the product can also be made smaller, occupying less space, and it is the main catalyst carrier used in automobiles for a period of time in the future.
In addition, cordierite can also be used as a carrier for enzymatic reactions. During enzymatic reactions, the reaction is generally required to be continuous. The porous nature of cordierite structure allows microorganisms to adsorb onto its surface. This will cause the proliferation of microorganisms, while also immobilizing the microorganisms on the carrier to maintain the activity of active enzymes at a certain level, improving production continuity.
2.3 Make foam ceramics
Cordierite foam ceramics are mainly used to absorb the heat released by the exhaust gas in the exhaust gas channel of automobile combustion, "Then, in the form of thermal radiation, it is transmitted to other heat recovery devices around it. This is due to: (1) Cordierite material is a heat resistant material, which has a higher operating temperature than metal materials. Although it does not have better thermal shock resistance compared to metal materials, its corrosion resistance is better than metal materials." Cordierite has excellent thermal radiation properties. In addition, it can also filter carbon black in vehicle exhaust, thereby achieving the effect of purifying the environment. The carbon black collected through filtration can be treated regularly. (3) It can also be used as a porous sound-absorbing material as a muffler for exhaust emissions from automobiles and motorcycles.
Cordierite foam ceramics can also be used in the investment casting industry. For example, precision casting of aluminum products is used to filter impurities in aluminum liquid and make the internal structure of aluminum castings uniform and free of impurities.
2.4 Use as infrared radiation material
Due to the existence of voids surrounded by hexagonal rings in the parallel c-axis direction in the crystal structure of cordierite, its size is sufficient to accommodate water molecules. Therefore, its structure is not compact, and oxides of transition elements can be solidly dissolved in it and cause lattice distortion, further reducing the symmetry of lattice vibrations. This structural characteristic determines that cordierite has a high infrared emissivity, especially in the infrared region.
