Special ceramics and automotive components

In the past 20-year period, in order to meet the requirements of automotive functional diversification, people gradually put more eyes on the special ceramics. From the earliest start automobile ceramic material insulating means, to produce spark plug insulators, but also extended to the purification of exhaust gas oxygen sensor, a honeycomb catalyst carrier, the catalyst used in the protection of the temperature sensor, knock sensor to improve the thermal efficiency of the heater and the valve used , pump mechanical seals, etc., showing the development trend of special ceramic products aggressive.

In recent years, peoples interest in research and development of ceramic engines unabated, has crossed a lot of science and technology gap with the problem, it is reported as the heart of a new generation of ceramic engines of automotive products, will soon be put into use. Special ceramics used in automotive parts and subassemblies will be further expanded, making it possible to form a broad range of products, causing a sudden change from a revolutionary ceramic industrial structure and product structure.

1, excellent mechanical properties

As we all know, the car is a use of the environment and working conditions extremely harsh products, so the composition of the various components of this monster must have very superior functionality. Over the years a variety of metal materials occupy this position very glory. However, since the metal material weakness, such as anti-poor fatigue performance, fast heat, abrasion and corrosion resistance and poor, severely restricted the development of the automotive industry. Special ceramics for its excellent performance, just to make up the shortage of the metal material, and thus began the auto accepted. As it has long-term patience 20G of vibration function; for combustion, exhaust system parts, you can long tolerate quench 50 ~ 60 ℃ / S of emergency heat; the mechanical performance and reliability, the failure rate is usually 10-5 or less; special ceramic and metal and other materials bonding property; can be mass, and low prices, to facilitate the formation of Industrial Management, etc. unique advantages.

In recent years, scientists have special ceramics international community through hard trials and research, developed a large number of cars with special ceramic products, through experiments and industrial applications show: superior mechanical properties of ceramic materials and high temperature chemical properties, has been far more than metal material components or other material. These are large-scale special ceramic products into more widespread use of the situation. Summarized as follows:

① Zirconia Oxygen Sensor

Zirconia ceramic quality of the oxygen sensor with high mechanical performance and reliability, as the exhaust gas purification unit, with its car exhaust gas measurement O2 concentration, then the measured value back to the engine to the air and fuel supply systems, to keep fuel in the combustion state. Because all of this ceramic material phase is complete cubic stabilized zirconia, partially stabilized zirconia tetragonal and monoclinic mixed, in the course of the mechanical properties is excellent, and can reduce the heat generated by friction.

② cordierite ceramic honeycomb catalyst carrier

Also known as a ceramic honeycomb. Honeycomb catalyst carrier was porous thin structure, material strength of 10kg / mm2. It is also in the same work with the oxygen sensor temperature and vibration environments, subjected to thermal stress of the ordeal. The catalyst is used for purifying automotive exhaust (exhaust), after the carrier in case of engine ignition, unburned exhaust gas can be burned in the carrier surface. Therefore, the temperature change is more severe than the oxygen sensor. After the material using cordierite ceramic quality, showing low inflation, so small on the carrier thermal stress generated oxygen sensor. Current automotive exhaust gas treatment apparatus mainly uses a cordierite honeycomb ceramic products, due to its excellent energy saving and purification, environmental protection function, there will be a substantial increase in its production. Japanese products currently dominate the international market.

③ ceramic heater valve

In order to start the engine when the complete combustion in the engine air intake. Side mounting a heating device, namely a valve heater to heat intake, the mixed fuel is completely evaporated. Inhale heated to control the temperature, improve the reliability of the device, while the barium titanate ceramic-based PTC (thermistor) is used as a valve heater. With ceramic valve heater, a launch that is in complete engine combustion state, so as to improve the thermal efficiency, energy saving and purifying exhaust and other effects. Valve heater system is made of special ceramic material.

④ knock sensor

To improve the combustion efficiency of automotive fuel, people want to knock in the engine stop occurs frequently set point on the piston. Using Piezoelectric knock sensor can still be resistance to fatigue under repeated use, longer life. Now car deflagration using PZT ceramic element is made, the use of performance remain stable over thousands of hours. The fracture toughness of 6.5MNm-3/2, the strength of 10kg / mm2, give full play to improve combustion efficiency.

⑤ ceramic engine

Special ceramics in automotive applications, and gained popularity and promotion of existing piston engines, there will be the secondary combustion chamber, the piston head, cylinder liner, cylinder head and turbocharger rotor and so on. These parts are considering using silicon nitride, silicon carbide, partially stabilized zirconia and other special ceramic materials. Mechanical strength requirements here: flexural strength of 50kg / mm2 or more, the thermal expansion coefficient of ≤3.5 × 10-6 ℃

The above materials are available to meet these requirements substantially, especially partially stabilized zirconia ceramic, not only the mechanical strength of up to 100kg / mm2, and thermal conductivity than other materials, only -0.04 / cmsc.

In terms of gas turbine engines, and diesel cars to achieve the same amount of fuel costs, the turbine inlet temperature to as high as 1350 ℃, can tolerate the high temperatures of only silicon carbide and silicon nitride ceramic material. Currently experts of their high hopes that the turbine rotor, a stator using the ceramic material is ideal. Future ceramic engine most likely to use a silicon nitride bonded silicon carbide ceramics or partially stabilized zirconia ceramic material.

⑥ various ceramic sensing elements

Limousine damping device, which is the use of sensitive ceramic piezoelectric effect, the inverse piezoelectric effect and the electrostrictive effect the successful development of intelligent integrated shock absorber. This smart shock absorber having an identification road and do a self-regulating function. Car shock rough road surface can be minimized, so that occupants feel comfortable.

Smart ceramic wipers: This wiper system made of pressure-sensitive effects of barium titanate ceramics. It can automatically sense the rain, the car windshield wipers and can automatically adjust to the optimal speed. Some other ceramic sensing elements, such as heat-sensitive, pressure-sensitive, humidity, component magnetic ceramic material, but also on temperature, humidity, condensation, frost and other exhibits sensitive display and automatic control and regulation.

In addition, many components, spare parts, small devices used on cars also are made of special ceramic material. An electronic buzzer, ultrasonic transducer, heat-absorbing glass, photovoltaic cells, oil ring, oil seals. Such vehicles by the new special ceramic material with products generally have a high physical and chemical properties, such as shock, abrasion, corrosion, high temperature, light weight, and ease of processing characteristics. So far, the international ceramics community confirmed dozens of automotive products ceramic material products have been or are applied, to take advantage of a large number of ceramic parts also includes includes: ① energy conservation, energy, speed; ② protect the environment, to prevent air pollution; reduce noise pollution, anti-magnetic interference; ③ reduce mechanical friction heat generated; ④ use of reliable performance, long life, light weight and so on.

21st Century automotive ceramic products, will form a broad market demand. In recent years, the development of Chinas automobile industry is also special ceramic industry put forward many new requirements, but also the formation of a large market, the need to import a lot of special ceramic components from abroad each year. Domestic special ceramic products, although some progress, but in the type, quantity, quality and technology, there is still a wide gap, therefore, that the next 20 years Chinas auto be a period of rapid growth with a special ceramic production will, which from enhance the technological content of the ceramic industry is also very beneficial.