Material technology is the most important material foundation of a country's defense force. The defense industry is often the preferred user of new material technology achievements. The research and development of new materials technology plays a decisive role in the development of the defense industry and weaponry.
The strategic significance of new military materials
New military materials are the material basis for a new generation of weapons and equipment, as well as a key technology in the military field of the world today. The military new material technology is the new material technology used in the military field, the key to modern sophisticated weapons and equipment, and an important part of military high technology. Countries around the world have attached great importance to the development of new military materials and technologies. Accelerating the development of new military materials and technologies is an important prerequisite for maintaining military leadership.
The development status of military composite materials
Advanced composite materials are new materials with higher comprehensive performance than general composite materials. They include resin-based composite materials, metal-based composite materials, ceramic-based composite materials, and carbon-based composite materials. It plays a decisive role in the development of the military industry. The role of.
Advanced composite materials have a series of advantages such as high specific strength, high specific modulus, ablation resistance, corrosion resistance, nuclear resistance, particle cloud resistance, wave penetration, wave absorption, stealth, and high-speed impact resistance. The most important type of engineering material.
1. Carbon-carbon composite material
Carbon-carbon composite material is a composite material composed of carbon fiber reinforcement and carbon matrix. Carbon-carbon composite materials have a series of advantages such as high specific strength, good thermal shock resistance, strong ablation resistance, and designable performance.
In the military industry, the most eye-catching application of carbon-carbon composite materials is the anti-oxidation carbon-carbon nose cone caps and wing leading edges of space shuttles. The most used carbon-carbon product is the brake pads of supersonic aircraft.
Carbon-carbon composites are mainly used as ablation materials and thermal structural materials in aerospace. Specifically, they are used as the nose cone caps of intercontinental missile warheads, solid rocket nozzles and the leading edges of space shuttle wings. The current advanced carbon-carbon nozzle material has a density of 1.87~1.97 g/cm3, and a ring tensile strength of 75~115 MPa. The end caps of the recently developed long-range intercontinental missiles almost all use carbon-carbon composite materials.
With the development of modern aviation technology, the loading quality of aircraft continues to increase, and the landing speed continues to increase, which puts forward higher requirements for the emergency braking of aircraft. Carbon-carbon composite material has light weight, high temperature resistance, high energy absorption and good friction performance. It is widely used in high-speed military aircraft to make brake pads.
2. Ceramic Matrix Composite
Ceramic matrix composite material is a general term for materials composed of fibers, whiskers or particles as reinforcements and combined with ceramic matrix through a certain composite process. It can be seen that ceramic matrix composite materials introduce the second phase into the ceramic matrix. The multiphase material composed of components overcomes the inherent brittleness of ceramic materials and has become the most active aspect of current materials science research.
Ceramic matrix composites have the characteristics of low density, high specific strength, good thermomechanical properties and thermal shock resistance. They are one of the key supporting materials for the development of the military industry in the future.
Although the high temperature performance of ceramic materials is good, it is brittle. Methods to improve the brittleness of ceramic materials include phase change toughening, micro-crack toughening, dispersed metal toughening and continuous fiber toughening.
Ceramic-based composite materials are mainly used to make nozzle valves of aircraft gas turbine engines, which play an important role in improving the thrust-to-weight ratio of the engine and reducing fuel consumption.
3. Resin Matrix Composite
Resin matrix composites have good forming processability, high specific strength, high specific modulus, low density, fatigue resistance, shock absorption, chemical corrosion resistance, good dielectric properties, and low thermal conductivity The characteristics such as high efficiency are widely used in the military industry.
Resin-based composite materials can be divided into two categories: thermoset and thermoplastic. Thermosetting resin-based composite material is a type of composite material composed of various thermosetting resins as the matrix and adding various reinforcing fibers; while thermoplastic resin is a type of linear polymer compound, which can be dissolved in a solvent or in a It softens and melts into a viscous liquid when heated, and hardens into a solid after cooling.
The resin matrix composite material has excellent comprehensive properties, the preparation process is easy to realize, and the raw materials are abundant. In the aviation industry, resin-based composite materials are used to manufacture aircraft wings, fuselages, canards, flat tails, and engine outer ducts; in the aerospace field, resin-based composite materials are not only important materials for rudders, radars, and air intakes. Moreover, it can be used to manufacture the heat-insulating shell of the combustion chamber of the solid rocket motor, and can also be used as the ablation and heat-proof material of the engine nozzle. The new cyanate resin composite material developed in recent years has the advantages of strong moisture resistance, good microwave dielectric properties, and good dimensional stability. It is widely used in the production of aerospace structural parts, primary and secondary bearing structural parts of aircraft and radomes.
4. Metal matrix composites
Metal matrix composites with high specific strength, high specific modulus, good high temperature performance, low thermal expansion coefficient, good dimensional stability, and excellent electrical and thermal conductivity have been widely used in the military industry.
Aluminum, magnesium, and titanium are the main substrates of metal matrix composite materials, and reinforcement materials can generally be divided into three types: fiber, particle and whisker. Particle-reinforced aluminum matrix composite material has entered the type verification, such as used in F-16 fighter jets. The pelvic fin replaces aluminum alloy, and its rigidity and life are greatly improved.
Carbon fiber reinforced aluminum and magnesium-based composite materials have high specific strength, close to zero thermal expansion coefficient and good dimensional stability, and have been successfully used to make artificial satellite supports, L-band planar antennas, space telescopes, and artificial satellites. Parabolic antennas, etc.; silicon carbide particle-reinforced aluminum-based composites have good high-temperature performance and wear resistance, and can be used to make rockets, missile components, infrared and laser guidance system components, precision avionics, etc.; silicon carbide fiber reinforced titanium matrix Composite materials have good high temperature resistance and oxidation resistance, and are ideal structural materials for engines with high thrust-to-weight ratio. At present, they have entered the trial stage of advanced engines.
In the ordnance industry, metal-based composite materials can be used for large-caliber tail stabilized armor-piercing projectiles, anti-helicopter/anti-tank multi-purpose missile solid engine shells and other parts, so as to reduce the weight of the warhead and improve combat capabilities.