Several new ceramic materials are mainly introduced.
1. Engineering ceramics
Engineering ceramics, it is mainly used in high temperature, also known as high temperature structural ceramics. This kind of ceramic takes alumina as the main raw material, which has the advantages of high strength, high hardness, high oxidation resistance, corrosion resistance, wear resistance, ablative resistance and so on under high temperature. It can withstand the high temperature of 1980℃ in the air. It is an important material in space technology, military technology, atomic energy, industrial and chemical equipment and other fields. There are many kinds of engineering ceramics, but at present, the most studied materials in the world are silicon chloride, silicon carbide and toughened oxide.
Semiconductor ceramic is a kind of ceramic whose electrical conductivity is between conductive ceramic and insulator ceramic, and its resistivity is between. Generally, one or more metal oxides are polycrystalline semiconductor materials made by ceramic preparation process. There are thermal – sensitive ceramics, pressure – sensitive ceramics, gas – sensitive ceramics, light – sensitive ceramics, wet – sensitive ceramics and other types.
Cermet has excellent mechanical properties, mainly referring to titanium nitride ceramics. This kind of metal ceramic is wear-resisting and bending resistant, with golden luster and good decorative effect. It has the characteristics of high conductivity and superconductivity, high strength, its function has covered most of the use of hard alloy, applied in the military field can save the use of rare metals. Due to its unique performance, the field of use is expanding.
Nanoceramics are a new type of structural ceramics developed in recent decades. Nanoceramics refer to ceramic materials with nanoscale (0.1-100nm) phase in microstructures. Ceramic is a kind of polycrystalline material, which is a sintered body composed of grains and grain boundaries. Nanometer ceramic material improves the grain size to nanometer level and greatly optimizes the performance of ceramic material. The characteristics of nanoceramics mainly include: high strength, the strength of nanoceramics after pressing and sintering is 4-5 times higher than that of ordinary ceramic materials; Increased toughness and low temperature plasticity, the refinement of grain makes the material not easy to fracture, and helps to improve the plasticity of the material. Diffusion and sintering properties, the sintering temperature of nanoceramics is about 600 lower than that of traditional ceramics, and the sintering process is greatly shortened. In addition, the high magnetic susceptibility, low magnetic loss and special light absorption effect of nanoceramics have opened up a new application field for the new ceramics
Bioferamics, which are burned at high temperatures, have strong atomic binding forces such as ionic bonds and covalent bonds, so the solubility is generally very small and the chemical properties are stable. They will not dissolve or expand in the body and do not need to worry about being eaten by macrophages and phagocytes. Biomedical ceramics and the physiological environment of the human body more biocompatibility, not easy to occur in the human body chemical changes, cheap, very attractive. With corrosion resistance, wear resistance, anti – thrombosis, strength matching, sterilization, adaptability. Generally divided into three categories: biological inert ceramics, including alumina ceramics, zirconia ceramics, glass, glass ceramics and various carbon products; Bioactive ceramics, which can be combined with human tissues, including active glass, active glass ceramics, hydroxyapatite ceramics; Ceramic materials that can be absorbed by human tissues, i.e. bioabsorbable ceramics, including calcium sulfate, tricalcium phosphate and calcium phosphate ceramics.
Piezoceramics are functional ceramics that convert pressure into electrical energy. Even small pressures like acoustic vibrations can cause them to deform, thus electrifying the surface. Using piezoelectric ceramic column instead of ordinary flint made of gas electronic lighter, can fire for tens of thousands of times.
6. Transparent ceramics
The main components of transparent ceramics are magnesium oxide, calcium oxide, calcium fluoride and so on. Transparent ceramics not only penetrate light, but also have high mechanical strength and hardness. Transparent ceramics are a good transparent bulletproof material, and can also be used to make high-speed cutting tools on lathes, parts for jet engines, and even replace stainless steel.
7. High strength ceramics
Silicon nitride high strength ceramics are known for their high strength, which can be used in the manufacture of gas turbine burners, blades, turbines, etc.
8. Precision ceramics
Precision ceramic ammoniation silicon instead of heat resistant metal manufacturing engine parts, the workpiece temperature can be greatly improved, thus improve the thermal efficiency, reduce the fuel consumption, save energy and reduce the volume and weight of the engine, and replaces the important metal materials such as nickel, chromium, such as sodium, so, is seen by some as a revolution of the engine. Silicon nitride can be prepared by a variety of methods. In industry, high purity silicon and pure nitrogen are generally obtained after reaction at 1600K:
Main application areas
Aerospace, the use of high temperature structural ceramics, ceramic turbine engine research.
In the field of machinery, the use of ceramic bearings has greatly increased the service life and limit speed of bearings, and provided basic parts for the development of high-speed and ultra-high-speed and ultra-precision machine tools.
The field of vehicles, car shock absorption device, intelligent ceramic wipers, engine control system have a special ceramic figure.
Military field, because of the special performance of new ceramic materials, so there are many USES in the military field. Special ceramics are widely used in bulletproof armor, ceramic thermal insulation tiles, missile control systems, radar and other military weapons, and thermal insulation materials on missiles.
In the field of medicine, prosthetics (such as various joints) that can be used for surgical correction, dental implants, middle ear bone implants, artificial heart valves, bone defect fillers, artificial tendons and ligaments, etc.