I. Application of ceramics in automotive engines
New ceramics are inorganic nonmetals such as silicon carbide and silicon nitride sintered together. Compared with the previous use of alumina ceramics, strength is more than three times, can withstand more than 1000 degrees Celsius high temperature, the new material to promote the development of new uses on the car. For example, to reduce the combustion cost of diesel engines by more than 30%, it can be said that the new ceramic is an indispensable material. Now in the gasoline engine, about 78% of the combustion energy is lost in the heat and heat transfer, the diesel engine thermal efficiency of 33%, compared with the gasoline engine has been very superior, however, there are still more than 60% of the heat energy loss.
Therefore, in order to reduce this part of the loss, the thermal insulation of the combustion chamber surrounded by ceramic materials with good thermal insulation properties, and then the exhaust gas turbocharger and power turbine to recover the exhaust energy, there are tests to prove that this can increase the thermal efficiency to 48%. At the same time, thanks to the new ceramics, instantaneous fast starting of diesel engines will become possible. The turbocharger with the new ceramic, which has superior heat resistance than today's super heat resistant alloys, while the specific gravity is only about one-third of the metal turbine.Thus, new ceramic turbines can compensate for the low dynamic response of metal turbines. Other ongoing research includes moving parts such as piston pins and piston rings with new ceramics. Due to the weight reduction, the engine efficiency is expected to improve.
II, special sensitive ceramics in automotive sensors on the application
The requirements for automotive sensors are long-lasting application in the harsh environment specific to automobiles (high temperature, low temperature, vibration, acceleration, humidity, noise, exhaust gas), and should have a small and lightweight, good reusability, a wide range of output and other characteristics. Ceramic heat, corrosion, wear and its potential excellent electromagnetic, optical function, with the progress of manufacturing technology in recent years has been fully utilized, sensitive ceramic materials made of sensors can fully meet the above requirements.
III. Application of ceramics in automotive brakes
Ceramic brakes are manufactured on the basis of carbon fiber brakes. A carbon fiber brake disc initially consists of carbon fiber and resin, which is pressed into shape by a machine and then heated, carbonized, heated and cooled in several processes to make a ceramic brake. The hardness of the surface of the carbon silicon compound of the ceramic brake is close to that of a diamond, and the carbon fiber structure inside the disc makes it strong and impact resistant and corrosion resistant, making the disc extremely wear resistant. At present, this kind of technology is not only applied in F1 cars, but also involved in super civil sports cars, such as the CL55 AMG of Mercedes-Benz.
IV, the application of ceramics in automotive dampers
Advanced car damping device is a comprehensive use of sensitive ceramic positive piezoelectric effect, inverse piezoelectric effect and electrostrictive effect of the successful development of intelligent dampers. As a result of the use of high-sensitivity ceramic components, this damper has the recognition of the road and can do self-adjustment function, the car can be caused by rough road vibration to a minimum.
V. Application of ceramic materials in automotive spray technology
In recent years, the ceramic film spraying technology widely used in aerospace technology began to be applied to the car. The advantages of this technology is good thermal insulation, can withstand high temperature and high pressure, mature technology, stable quality. To achieve the goal of low heat dissipation, the engine combustion chamber components can be ceramic sprayed, such as zirconia sprayed on the top of the piston and zirconia sprayed on the cylinder liner. After this treatment of the engine can reduce heat loss, reduce the mass of the engine itself, reduce the size of the engine, reduce fuel consumption.
VI. Smart ceramic materials in automotive applications
Smart ceramic materials, which are classified as special ceramic products, including materials sensitive to the environment and responsive to environmental changes used in automotive manufacturing, have become the focus of research in the field of materials science and engineering.
Smart ceramic products used in automobiles include smart material systems or structures that combine functional materials, drive systems, and feedback systems. Due to its comprehensive function, it can make the automotive products sense and respond to changes in the external environment while driving, so that the automotive products have many properties such as self-checking, self-measurement, self-diagnosis, self-repair and self-adaptation. Currently some functional ceramic products already have intelligent functions, such as semiconductor barium titanate positive temperature coefficient thermal resistors and zinc oxide varistors, which have their own diagnostic, standby protection and self-repair functions for temperature and voltage, which can make the material itself have the ability to resist sudden changes in the environment and can be used repeatedly. Among smart ceramic systems, piezoelectric ceramics are the most important category.
The following piezoelectric smart ceramic products and material systems have been popularly used and are being developed:
Automotive shock absorbers: Intelligent shock absorbers developed by using the positive piezoelectric effect and inverse piezoelectric effect of intelligent ceramic products have the function of recognizing the road surface and self-adjusting, which can reduce the vibration formed by the rough road surface to a minimum, and the whole process of sensing and adjusting takes only 20 seconds. In addition, the damping device made of intelligent ceramic materials can also be promoted in areas other than automotive products, such as the use of a stable work platform to precision machining.
Intelligent wipers for automobiles: Using the piezoresistive effect of barium titanate ceramics to make intelligent ceramic wipers, they can automatically sense the amount of rain and automatically adjust the wipers to the best speed.
Active anechoic ceramic materials for automobiles: Active anechoic ceramic materials consisting of piezoelectric ceramic pickups, resonators, analog sound coils and digital signal processing integrated circuits can reduce the vibration frequency of automobiles to below 500 Hz.
In addition, intelligent ceramic materials can be used to develop intelligent safety systems and intelligent transmission systems, such as in airbags, where intelligent ceramic components are also used. The development of modern intelligent ceramic materials research and market, has been in the flourishing period, while its application has not only been limited to the automotive industry, and shipbuilding, construction, machinery, home appliances, aerospace, national defense and other industrial fields have an important impact, will greatly improve the level of intelligence and automation of various types of machinery and electronic products.
In short, special ceramics is a ceramic material products are being developed, but the production of raw materials, material evaluation and the use of technology and many other aspects have yet to be resolved. At present, special ceramics in the automotive application is not widespread, the main reasons are: manufacturing process is complex and demanding; because of special ceramics on the raw material requirements are relatively strict, the process is difficult to master, making it difficult to maintain uniform performance of the batch of products; higher cost, poor processability, brittleness, use of poor reliability. However, people have good reason to believe that, with the rapid development of science and technology, in the future of the automotive manufacturing industry will have more special ceramics, intelligent ceramic products are introduced and adopted into the car, and will certainly be widely used in the production of automobiles.