Aviation Brake Disc
With the rapid development of aviation science and technology and industry, the landing speed and quality of the aircraft is increasing, the landing speed of modern advanced aircraft has exceeded 350km/h, the take-off weight has reached 600t, the kinetic energy absorbed by the aircraft of a landing braking device has reached 1000-1300MJ. When landing brake, the friction surface temperature of the brake disc instantly reaches more than 1000℃, and at the same time, there is a large temperature gradient in the surface layer of the brake disc, which generates high thermal stress and is in the state of violent thermal shock.In the narrow space of the wheel, it is a difficult engineering problem to design a braking device with thermal load capacity, great braking power, stable braking performance and good heat dissipation. In order to make the braking device meet several design and use requirements, the performance of the brake disc friction material is crucial.Carbon-carbon composites have the outstanding features of low density, excellent friction and wear properties, long service life, no melting and bonding under high energy braking conditions, excellent thermal conductivity and large specific heat capacity, good dimensional stability, high fracture toughness, and designability of general composite materials.
For example, carbon-carbon composite materials used as brake discs, due to the small density, the use of carbon-carbon composite brake discs can make the aircraft weight greatly reduced. Not only that, carbon-carbon composites excellent high temperature performance is also very compelling, aircraft braking friction caused by temperature rise of 500 ℃ or more, especially the most demanding abort take-off emergency braking caused by the temperature rise of more than 1,000 ℃, at this time the carbon carbon materials of high temperature performance shows a great superiority.In addition, carbon-carbon brake discs have a suitable friction factor and very good wear resistance, which leads to a substantial increase in service life, the replacement cycle is greatly extended. One cycle can reach 1500-3000 landings and takeoffs, which increases the life span by 5-6 times.
Aero-engine High-temperature Hot-end Components
The rapid development of the aviation industry puts forward higher and higher requirements for aero-engine thrust-to-weight ratio, and the key to improve the thrust-to-weight ratio of the new engine is to improve the thermal efficiency, which is realized by increasing the air compression ratio and increasing the turbine inlet temperature. Therefore, the increase in thrust-to-weight ratio will lead to a significant increase in the turbine inlet temperature of aero-turbine engines and industrial turbine engines. For example, the new generation of high-performance aero-engines will have an operating temperature of more than 1800°C, and there are higher requirements for material strength and resistance to gas washout. Except for carbon-carbon composites, other materials are unable to meet the service requirements of this harsh environment, which is mainly attributed to the following special features of carbon-carbon composites:
1 Above 1600 ℃ can still maintain the strength does not reduce, can work at higher temperatures, improve the thermal efficiency of the engine
2 Low specific gravity, can reduce the weight of the engine, improve the thrust-to-weight ratio, reduce cold air consumption, improve engine efficiency.
All the developed countries in the world are studying the new generation of high thrust-to-weight ratio aero-engine, and all of them are taking the carbon-carbon composite materials as the key materials for high-temperature consideration. It can be said that which country can completely solve the problem of carbon-carbon composite materials, which country enjoys the initiative to develop high-performance engines.