Materials technology has always been a very important area in the planning of the scientific and technological development of countries around the world. Together with information technology, biotechnology and energy technology, they are recognized as high-level technologies that are the general position of mankind in modern society and for many years ahead of technology. High-tech materials are also the key technology of modern industry that supports today's human civilization, as well as the most important material basis of the country's national defense forces. The national defense industry is often a priority consumer of new advances in materials technology, and the research and development of new materials technologies plays a critical role in the development of the national defense industry and weapons.
The strategic importance of new military materials
New military materials are the material basis of a new generation of weapons and equipment, as well as key technologies in the military sphere in the modern world. Military technology of new materials - the technology of new materials used in the military sphere is the key to the creation of modern sophisticated weapons and equipment and an important part of high military technologies. Countries around the world attach great importance to the development of new technologies for military materials, and accelerating the development of new technologies for military materials is an important prerequisite for maintaining military leadership.
Status of application of new military materials
According to their application, new military materials can be divided into two categories: structural materials and functional materials, which are mainly used in the aviation, aerospace, military and shipbuilding industries.
Aluminum alloys have always been the most widely used metal construction materials in the military industry. Aluminum alloy has the characteristics of low density, high strength and good processing performance. As a structural material, due to its excellent processing performance, it can be made into profiles, pipes, high strength plates, etc. Rigidity, strength. Therefore, aluminum alloy is the preferred lightweight construction material for light weapons.
In the aviation industry, aluminum alloys are mainly used for the manufacture of aircraft skins, bulkheads, long beams and honing stones; in the aerospace industry, aluminum alloys are important materials for the structural parts of launch vehicles and spacecraft. Alloys are successfully used in infantry fighting vehicles and armored personnel carriers, and newly developed howitzers also use a large number of new aluminum alloy materials.
In recent years, the use of aluminum alloy in the aerospace industry has declined, but it still remains one of the main structural materials in the military industry. The development trend of aluminum alloys is the pursuit of high purity, high strength, high toughness and high temperature resistance. Aluminum alloys used in the military industry mainly include aluminum-lithium alloys, aluminum-copper alloys (2000 series) and aluminum-zinc alloys. -magnesium alloys (series 7000).
A new type of aluminum-lithium alloy is used in the aviation industry, and it is predicted that the weight of the aircraft will be reduced by 8-15%; aluminum-lithium alloy will also become a candidate as a structural material for aerospace vehicles. and thin-walled missiles. With the rapid development of the aerospace industry, Al-Li alloy research is still focused on solving the problems of poor thickness toughness and cost reduction.
As the lightest structural metal material, magnesium alloy has a number of unique properties, such as low specific gravity, high specific strength and specific rigidity, good damping and thermal conductivity, strong electromagnetic shielding ability, and good vibration damping performance. meets the needs of the aerospace industry, modern weapons and other military areas.
Magnesium alloys are widely used in military equipment, such as tank seat frame, vehicle commander's mirror, gunner's mirror, gearbox housing, engine filter seat, water inlet and outlet pipes, air distributor seat, oil pump housing, housing water pump, oil heat exchanger, oil filter housing, covervalve chamber, respirator and other machine parts; cockpit section and aileron skin, wall plate, reinforcing frame, rudder, tactical air defense missile baffle Frames and other parts of missiles; fighters, bombers, helicopters, transport aircraft, airborne radars, anti-aircraft missiles, launch vehicles, artificial satellites and other spacecraft and aircraft components. Magnesium alloy has the characteristics of light weight, good specific strength and rigidity, good vibration damping performance, strong electromagnetic interference and strong shielding ability, which can meet the requirements of military products for weight reduction, noise absorption, shock absorption and radiation protection. . It occupies a very important place in the aerospace and national defense industries and is a key structural material required for aircraft, satellites, missiles, fighter jets and tanks.
Titanium alloy has high tensile strength (441~1470MPa), low density (4.5g/cm³), excellent corrosion resistance, and a certain resistance to high temperature and very high temperature at 300~550℃ Good toughness at low temperatures is an ideal lightweight construction material. Titanium alloy has the functional characteristics of superplasticity. By using superplastic form diffusion welding technology, the alloy can be formed into complex shapes and precise dimensions with very little energy and material consumption.
The use of titanium alloys in the aviation industry is mainly in the manufacture of structural parts of the aircraft fuselage, landing gear, support beams, engine compressor disks, blades and joints; In the aerospace industry, titanium alloys are mainly used to make bearing components, frames, gas cylinders, pressure vessels, turbo pump housings, solid fuel engine housings and nozzles and other components. In the early 1950s, some military aircraft began using commercially pure titanium for structural parts such as heat shields, tailplanes, and tail fuselage speed brakes; in the 1960s, the use of titanium alloys in aircraft structures was expanded to include sliding rolling of flaps In major stressed structures such as structural bulkheads and landing gear beams, the use of titanium alloys in military aircraft and engines has increased rapidly since the 1970s , from fighter jets to large military bombers and transport aircraft. used in F14 and F15 aircraft The amount of titanium alloy is 25% of the structure weight, while the amount used in F100 and TF39 engines reaches 25% and 33% respectively; after the 1980s, titanium alloy materials and technologies have been further developed, and the B1B aircraft requires 90402 kg of titnew materials. Among the existing aerospace titanium alloys, the most widespread is the universal Ti-6Al-4V type a+b alloy. In recent years, two new types of titanium alloys have been consistently developed in the West and in Russia: high-strength, high-strength, weldable and formable titanium alloys and heat-resistant, high-strength, non-combustible titanium alloys. advanced titanium alloys in the future will be used in the aerospace industry, have good application prospects.
With the development of modern warfare, the army needs a multifunctional advanced howitzer system with high power, long range, high accuracy and fast response. One of the key technologies of the advanced howitzer system is the technology of new materials. The lightness of materials for self-propelled artillery turrets, assemblies and armored vehicles made of light metals is an inevitable trend in the development of weapons. In order to provide dynamics and protection, titanium alloys are widely used in military weapons. The use of titanium alloy for the brake of the 155 gun can not only reduce the weight, but also reduce the deformation of the gun barrel under the action of gravity, effectively improving the shooting accuracy; some complex shapes on the main battle tank and anti-tank helicopter multi-purpose missile Components can be made of titanium alloy, which can not only meet the product performance requirements, but also reduce the cost of parts processing.
For a long time, the use of titanium alloys was severely limited due to the high cost of production. In recent years, countries around the world have been actively developing low-cost titanium alloys, while reducing costs, they should also improve the performance of titanium alloys. In our country, the production cost of titanium alloy is still relatively high, and with the gradual increase in the amount of titanium alloy, the tendency to seek lower production costs to develop titanium alloy is inevitable.
4.1 Resin composites
Resin-based composite materials have good formability, high specific strength, high specific modulus, low density, fatigue resistance, shock absorption, chemical corrosion resistance, good dielectric property, low thermal conductivity and other characteristics, widely used in the military industry. . Resin-based composites can be divided into two categories: thermoset and thermoplastic. Thermosetting resin composite materials are a type of composite material composed of various thermosetting resins as a matrix and with the addition of various reinforcing fibers; thermoplastic resins are a type of linear polymer compounds that can dissolve in solvents or soften and melt in them, turning into a viscous liquid when heated andhardens on cooling. Resin-based composite materials have excellent comprehensive properties, simple preparation process, and abundant raw materials. In the aviation industry, resin-based composite materials are used to make aircraft wings, fuselages, nose fins, fins, and engine air ducts; In the aerospace field, resin-based composite materials are used for more than just rudders, radars, and air intakes. In addition, it can be used to make the heat-insulating shell of the solid propellant rocket engine combustion chamber, and can also be used as an ablative heat-resistant material for the engine nozzle. New cyanate resin composite materials developed in recent years have the advantages of high moisture resistance, good microwave dielectric properties and good dimensional stability. They are widely used in the production of aerospace structural parts, primary and secondary aircraft structural structural parts. and radar radomes.
4.2 Metal matrix composites
Metal matrix composites have high specific strength, high specific modulus, good high temperature performance, low thermal expansion coefficient, good dimensional stability, excellent electrical and thermal conductivity, and are widely used in the military industry. Aluminum, magnesium, and titanium are the main matrices of metal matrix composites, and reinforcing materials can generally be divided into three categories: fibers, particles, and whiskers. Among them, particle-reinforced aluminum matrix composites have been model tested, such as used in F- 16, because the pelvic fin replaces the aluminum alloy, and its rigidity and service life are greatly improved. Composite materials based on aluminum and magnesium, reinforced with carbon fiber, not only have high specific strength, but also have a coefficient of thermal expansion close to zero and good dimensional stability, have been successfully applied to the manufacture of brackets for artificial satellites, L-band planar antennas, space telescopes and artificial satellites, parabolic antennas, etc., aluminum matrix composites reinforced with silicon carbide particles have good high temperature performance and wear resistance, and can be used for missiles, missile components, components of infrared and laser guidance systems, precision avionics, etc. d.; Titanium Matrix Reinforced with Silicon Carbide Fiber Composite materials have good thermal and oxidation resistance and are ideal structural materials for high thrust-to-weight ratio engines and have entered the trial run stage of advanced engines. In the field of weapons, composite materials based on metals can be usedDesigned for large caliber tail fins to stabilize APDS, anti-helicopter/anti-tank multi-purpose missile engine housings and other components, so how to reduce warhead mass and improve combat capabilities.
4.3 Ceramic Matrix Composites
Ceramic matrix composites are reinforced with fibers, whiskers, or particles. A general term for materials bonded to a ceramic matrix through a specific composite process. It can be seen that a ceramic matrix composite is a multi-phase material composed of a second phase component introduced into a ceramic matrix that overcomes the brittleness inherent in ceramic materials. , has become the most active aspect of current research in materials science. Ceramic matrix composites have low density, high specific strength, good thermomechanical properties and heat resistance, and are one of the key auxiliary materials for the future development of the military industry. Although ceramic materials perform well at high temperatures, they are brittle. Methods for improving the brittleness of ceramic materials include phase transformation hardening, microcrack hardening, metal dispersion hardening, and continuous fiber hardening, etc. Ceramic matrix composites are mainly used to make nozzle valves of aircraft gas turbine engines, which play an important role in improving engine thrust-to-weight ratio and reducing fuel consumption.
4.4 Carbon-carbon composite
Carbon-carbon composite material is a composite material consisting of a reinforcing carbon fiber and a carbon matrix. Carbon-carbon composite materials have a number of advantages such as high specific strength, good thermal shock resistance, high ablation resistance and structural performance. The development of carbon-carbon composite materials is closely related to the stringent requirements of aerospace engineering. Since the 1980s, research into carbon-carbon composite materials has entered a stage of performance improvement and expansion of applications. In the military industry, the most notable application of carbon-carbon composites is the anti-oxidation carbon-carbon nose cone cover and the leading edge of the wing of the Space Shuttle, and the largest number of carbon-carbon products is the brake pads of supersonic aircraft. . Carbon-carbon composite materials are mainly used as ablative materials and thermal structural materials in the aerospace industry, in particular, they are used as nose cones for intercontinental missile warheads, rocket solid propellant nozzles, and spacecraft wing leading edges. Current advanced carbon-carbonthe material for the nozzles has a density of 1.87–1.97 g/cm3 and an ultimate tensile strength in ring tension of 75–115 MPa. Nearly all recently developed long-range ICBM end caps use carbon-carbon composite materials.
With the development of modern aviation technology, the weight of aircraft loading increases, the speed of flight and landing increases, which puts forward higher requirements for emergency braking of aircraft. Carbon-carbon composite materials are light in weight, resistant to high temperatures, have large energy absorption and good frictional performance. They are widely used in high-speed military aircraft for brake pads.
Ultra high strength steel
Ultra-high strength steel is steel whose yield strength and tensile strength exceed 1200 MPa and 1400 MPa, respectively. It has been researched and developed to meet the requirements for high strength-to-weight ratio materials in aircraft structures. Due to the expansion of the use of titanium alloys and composite materials in aviation technology, the amount of steel used in aviation technology has decreased, but the main bearing elements of aviation technology are still made of ultra-high strength steel. At present, 300M low-alloy ultra high-strength steel is a typical steel for aircraft landing gear. In addition, D6AC low-alloy ultra high-strength steel is a typical solid fuel engine case material. The development trend of ultra-high strength steel is to continuously improve toughness and stress corrosion resistance while achieving ultra-high strength.
Superalloys are key materials for aerospace power systems. Superalloys—alloys that withstand a certain stress at a high temperature of 600~1200°C and are resistant to oxidation and corrosion—are the preferred material for aerospace turbine discs. According to the different matrix components, superalloys are divided into three categories: iron-based, nickel-based, and cobalt-based. Engine turbine disks were made from forged heat-resistant alloys until the 1960s. Typical grades are A286 and Inconel 718. In the 1970s, GE in the USA used Rene95 fast-hardening alloy powder to make turbine disks for the CFM56 engine, which greatly increased its thrust-to-weight ratio. , the use temperature is greatly increased. Since then, powder metallurgy turbine discs have developed rapidly. Recently, the superalloy turbine disc, made by rapid spray curing in the United States, has a simpler process, lower cost, and good forging performance than powdered superalloys. It is a preparation technology with great development potential.
The melting point of tungsten is the highest among metals. Its outstanding advantage is that its high melting point ensures good heat resistance and corrosion resistance of the material, and it shows excellent performance in the military industry, especially in the production of weapons. In the arms industry, warheads for various armor-piercing projectiles are mainly made from it. Tungsten alloy refines material grains and lengthens grain orientation through powder pre-treatment technology and high strain hardening technology to improve material strength, toughness and penetrating power. The tungsten core of the 125Ⅱ armor-piercing projectile of the main battle tank developed in our country is W-Ni-Fe, which uses the variable density compact sintering process. indicator 2000 m. Penetration range of homogeneous steel armor 600 mm thick. At present, tungsten alloy is widely used in large aspect ratio armor-piercing shells of the main battle tank, small and medium caliber anti-aircraft armor-piercing shells, and ultra-high-speed kinetic energy armor-piercing shells, which makes it possible to create a variety of armor-piercing shells. sub-caliber projectiles have a more powerful penetrating ability.
Intermetallic compounds have a long-range superlattice structure that maintains a strong metallic bond, so they have many special physical, chemical and mechanical properties. Intermetallic compounds have excellent thermal strength and have become important new high-temperature structural materials, which have been actively studied at home and abroad in recent years. In the military industry, intermetallic compounds have been used to make parts subjected to thermal stress, for example, the American company Puao made the blades of the JT90 gas turbine engine, the US Air Force used titanium aluminum to make the main rotor blades of small aircraft engines, etc., and Russia used titanium. The aluminum intermetallic compound replaces the heat-resistant alloy as the piston crown, greatly improving engine performance. In the field of military industry, the material of the tank engine supercharger turbine is K18 nickel-based superalloy, which affects the accelerating characteristics of the tank due to its high specificity and large starting inertia. fight. In addition, intermetallic compounds can also be used in various heat-resistant components to reduce weight and improve reliability and combat technicalindicators.
Ceramic materials are today the fastest growing high-tech materials in the world. They have gone from single-phase ceramics to multi-phase composite ceramics. Structural ceramic materials have good application prospects in the military industry due to their excellent properties such as high temperature resistance, low density, wear resistance and low coefficient of thermal expansion.
In recent years, a wide range of research and development work has been carried out at home and abroad on structural ceramics for military engines, such as small-sized turbines for engine superchargers, in the United States, ceramic plates are embedded in the top of the pistons, which greatly increases the service life of the pistons, and also improves the thermal efficiency of the engine. Ceramic components inlaid in Germany in the outlet to improve the efficiency of the outlet. The piston sleeve and cylinder sleeve of the miniature Stirling refrigerator on foreign infrared thermal imagers are made of ceramic materials, and their service life reaches 2000 hours, the power of the rocket gyroscope is provided by powder gas, and the residue of the powder into the gas has a negative serious damage to eliminate the residue in the gas and improve accuracy rocket hit, it is necessary to study the ceramic filter material suitable for rocket propellant gas operating at 2000 ℃. In the military industry, structural ceramics are widely used in main battle tank supercharger turbines, piston heads, exhaust port mosaics, etc., and are a key material for new weapons and equipment. At present, the requirements for radio frequencies of 20-30 mm machine guns reach more than 1200 rounds per minute, which makes the drift of the gun barrel extremely serious. The high melting point and high temperature chemical stability of ceramics can effectively suppress strong barrel ablation. Ceramic materials have high compressive strength and creep properties. Through thoughtful design, ceramic materials can be kept in a three-dimensional compression state to overcome their brittleness. to ensure the safe use of ceramic inlays.
Photovoltaic functional materials
Optoelectronic functional materials refer to materials used in optoelectronic technologies that can transmit and process information in combination with optoelectronics and are an important part of modern information technology. Photovoltaic functional materials are widely used in the military industry. Mercury-cadmium telluride and indium antimonide are important materials for infrared detectors; zinc sulfide, zinc selenide and gallium arsenide are mainly used for windows, hoods and fairingsinfrared detection systems for aircraft, missiles and ground weapons and equipment. Magnesium fluoride has high transmittance, high rain erosion resistance and erosion resistance, and is a material with better infrared transmission. Laser crystals and laser glasses are materials for high-power and high-energy solid-state lasers. Typical laser materials include ruby crystals, Nd-doped yttrium aluminum garnet, and materials for semiconductor lasers.
Hydrogen storage material
Some transition cluster metals, alloys and intermetallic compounds, due to the special lattice structure, hydrogen atoms more easily penetrate into the tetrahedron or octahedron of the metal lattice. A metal hydride is formed in the gap, and this material is called a hydrogen storage material.
In the weapons industry, lead-acid batteries used in tank trucks need to be recharged frequently due to their low capacity and high self-discharge rate, which is very inconvenient to maintain and transport. Discharge output power is easily affected by battery life, state of charge, and temperature. In cold weather conditions, the starting speed of the tank will be greatly reduced or even not start, which will affect the tank's combat capability. . Hydrogen alloy batteries have the advantages of high energy density, recharging resistance, shock resistance, good low temperature performance and long service life, and have broad application prospects in the development of main battle tank batteries in the future.
Damping cushioning material
Attenuation refers to the phenomenon in which the mechanical properties of a freely vibrating solid body are converted into thermal energy, even if it is completely isolated from the outside world. The purpose of using materials with a high damping function is to reduce shock and noise. Therefore, damping and shock-absorbing materials are of great importance in the military industry.
The use of metal damping materials in foreign countries is mainly concentrated in industries such as shipbuilding, aviation and aerospace. The US Navy has used a high-damping Mn-Cu alloy for the production of submarine propellers, which provides an obvious damping effect. In the West, much attention is paid to research on the application of damping materials and technologies in weapons, and in some developed countries research institutes have been established to deal with the application of damping materials in weapons and equipment. After the 1980s, foreign damping, cushioning, and noise reduction technologies have achieved more development. Through CAD/CAM, when applying noise reduction technology, they have combined design-material-process-testing and performed damping of the overall design.Rugged and noise-absorbing design. In the 1970s, my country did research on damping, cushioning and noise reduction materials and achieved certain results, but there is still a certain gap compared to developed countries. In the aerospace field, damping materials are mainly used to make rockets, rockets, and other control panels or gyroscope shells; Vibration and noise generated by the collision of surfaces during the engagement of mechanical parts. In the weapons industry, the vibration of the transmission part of the tank (reducer, reducer) is a complex vibration with a wide frequency range. The use of highly efficient damping zinc-aluminum alloys and vibration-damping wear-resistant cladding materials The technology significantly reduces the main vibration and noise generated by the transmission part of a battle tank.
The development of modern offensive weapons, especially the emergence of high-precision strike weapons, has greatly threatened the survivability of weapons and equipment. Simply relying on strengthening the protective capabilities of weapons is no longer appropriate. The use of stealth technologies disables enemy detection, guidance and reconnaissance systems, thereby concealing oneself as much as possible and seizing the initiative on the battlefield. The detection and destruction of the enemy was the first to become an important direction in the development of modern weapon protection. The most effective means of stealth technology is the use of stealth materials. Research on foreign stealth technologies and materials began during World War II, originated in Germany, developed in the United States and spread to the UK, France, Russia and other advanced countries. The United States is currently at the forefront of stealth technology and materials research. In the field of aviation, many countries have successfully applied stealth technologies for stealth aircraft, in terms of conventional weapons, the United States has also done a lot of work on the stealth of tanks and missiles, and have found application in technology, such as the American M1A1 tank. Radar and infrared stealth materials are used, and the former the Soviet T-80 tank is also covered in stealth materials.
Stealth materials include materials that absorb millimeter wave patterns, rubber materials that absorb millimeter waves, and multifunctional absorbent coatings. Compatible with visible light, near-infrared camouflage, and mid- and far-infrared thermal camouflage effects.
In recent years, foreign countries have been devoting themselves to researching various new materials, improving and improving the traditional stealth materials. Whisker materials, nanomaterials, ceramic materials, chiral materials, conductive polymer materials, etc. are gradually applied to radar and infrared invisible materials, making the coating thinner and lighter.where. Because of its excellent wave absorption performance, nanomaterials have the characteristics of broadband, good compatibility and small thickness, developed countries have researched and developed nanomaterials as a new generation of invisible materials; domestic invisible materials of the millimeter range. 1980s, and research units mainly focused on the weapon system. After many years of hard work, preliminary research work has made significant progress. This technology can be used to camouflage and stealth various ground weapon systems, such as main battle tanks, 155mm advanced howitzer systems, and amphibious tanks.
The fourth generation supersonic fighter is currently being developed in the world. Composite materials, wing-body alloy and wave-absorbing coatings are used in its hull design, which makes it truly inconspicuous. Coatings that absorb electromagnetic waves, electromagnetic shielding Typical coatings began to be drawn on stealth aircraft, U.S. and Russian surface-to-air missiles use lightweight, broadband, and heat-resistant stealth materials. It can be predicted that the study and application of stealth technologies has become one of the most important topics of national defense technology in all countries of the world.
Trends in the development of new military materials in my country
All new materials used in the military industry are of high technical content, so the rate of industrialization of new military materials is generally relatively slow. New military materials around the world are developing in the direction of functionalization, ultra-high energy, composite light weight and intelligence. From this point of view, titanium alloys, composite materials and nanomaterials have very good prospects for industrialization in the military industry.
1. Titanium Alloy
Titanium is a metal with excellent performance and rich resources, developed in the 1950s. Due to the increasing demand of the military industry for high-strength materials with low density, the process of industrialization of titanium alloys has accelerated significantly. In foreign countries, the weight of titanium materials on promising aircraft has reached 30-35% of the total weight of the aircraft structure. During the "Ninth Five-Year Plan" in my country, to meet the needs of aviation, aerospace, naval ships and other departments, the country considers titanium alloys as one of the priorities for the development of new materials. The "Tenth Five Year Plan" will be a period of rapid development of new titanium alloy materials and new processes in China.
2. Composite materials
The development of high military technologies requires that materials cease to be a single structural material. Under such conditions, my country has made great strides in the development and application of advanced composite materials. There will be morenoticeable. The direction of development of composite materials in the 21st century is low cost, high performance, versatility and intelligence.
Nanotechnology is a product of the combination of modern science and technology, it not only covers all existing fundamental areas of science and technology, but also has broad prospects for application in the military industry. With a sharp increase in the surprise of future wars, various methods of detection are being improved more and more. To meet the needs of modern warfare, stealth technology occupies a very important place in the military field. Nanomaterials have a high rate of absorption of radar waves, which provides a material basis for the development of technologies for stealth weapons.