16 New Military Materials

New military materials are the material basis for a new generation of weapons and equipment, and are also key technologies in the military field in today's world. Military new material technology is a new material technology used in the military field. It is the key to modern sophisticated weapons and equipment and an important part of military high technology. Countries around the world attach great importance to the development of new military material technology. Accelerating the development of new military material technology is an important prerequisite for maintaining military leadership.

Application status of new military materials

New military materials can be divided into two categories: structural materials and functional materials according to their uses. They are mainly used in the aviation industry, aerospace industry, weapons industry and shipbuilding industry.

Aluminum alloy

Aluminum alloy has always been the most widely used metal structural material 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-reinforced plates, etc. of various cross-sections to fully utilize the potential of the material and improve components. Rigidity and strength. Therefore, aluminum alloy is the preferred lightweight structural material for lightweight weapons.

In the aviation industry, aluminum alloys are mainly used to manufacture aircraft skins, partitions, long beams, and trim bars. In the aerospace industry, aluminum alloys are important materials for structural parts of launch vehicles and spacecraft. In the field of weapons, aluminum alloys have been successfully used. It is widely used in infantry fighting vehicles and armored transport vehicles. The recently developed howitzer mount also uses a large number of new aluminum alloy materials.

The use of aluminum alloys in the aerospace industry has decreased in recent years, but it 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. The aluminum alloys used in the military industry mainly include aluminum-lithium alloys, aluminum-copper alloys (2000 series) and aluminum-zinc-magnesium alloys (7000 series).

New aluminum-lithium alloys are used in the aviation industry, and it is predicted that the weight of aircraft will decrease by 8 to 15%; aluminum-lithium alloys will also become candidate structural materials for aerospace vehicles and thin-walled missile casings. With the rapid development of the aerospace industry, the research focus of aluminum-lithium alloys is still on solving the problems of poor toughness in the thickness direction and reducing costs.

Magnesium alloy

As the lightest engineering metal material, magnesium alloy has a series of unique properties such as light specific gravity, high specific strength and specific stiffness, good damping and thermal conductivity, strong electromagnetic shielding ability, and good vibration damping properties, which greatly meets the needs of The needs of aerospace, modern weapons and equipment and other military fields.

Magnesium alloys have many applications in military equipment, such as tank seat frames, commander's mirrors, gunner's mirrors, gearbox cases, engine filter seats, water inlet and outlet pipes, air distributor seats, oil pump housings, water pump housings , oil heat exchangers, oil filter housings, valve covers, respirators and other vehicle parts; tactical air defense missile support compartments and aileron skins, wall panels, reinforced frames, rudder plates, partition frames and other ammunition Arrow parts; fighter aircraft, bombers, helicopters, transport aircraft, airborne radars, surface-to-air missiles, launch vehicles, artificial satellites and other spacecraft components. Magnesium alloys are light in weight, have good specific strength and stiffness, good vibration damping performance, strong electromagnetic interference, and strong shielding capabilities, which can meet the requirements of military products for weight reduction, noise absorption, shock absorption, and radiation protection. It occupies a very important position in aerospace and national defense construction and is a key structural material required for weapons and equipment such as aircraft, satellites, missiles, and fighter jets and tanks.

Titanium alloy

Titanium alloy has high tensile strength (441~1470MPa), low density (4.5g/cm³), excellent corrosion resistance and certain high-temperature durable strength and good low-temperature resistance at 300~550℃. Impact toughness, it is an ideal lightweight structural material. Titanium alloy has the functional characteristics of superplasticity. Using superplastic forming-diffusion joining technology, the alloy can be made into products with complex shapes and precise dimensions with very little energy consumption and material consumption.

The application of titanium alloys in the aviation industry is mainly to make aircraft fuselage structural parts, landing gear, support beams, engine compressor disks, blades and joints; in the aerospace industry, titanium alloys are mainly used to make load-bearing components and frames. , gas bottles, pressure vessels, turbo pump casings, solid rocket motor casings and nozzles and other parts. In the early 1950s, industrial pure titanium began to be used on some military aircraft to manufacture structural parts such as rear fuselage heat shields, tail cowls, and speed brakes; in the 1960s, the application of titanium alloys in aircraft structures expanded to include sliding-rolled flaps. , load-bearing bulkheads, landing gear beams and other major stress-bearing structures; since the 1970s, the use of titanium alloys in military aircraft and engines has increased rapidly, expanding from fighter jets to large military bombers and transport aircraft. It is used on F14 and F15 aircraft. The usage accounts for 25% of the structural weight, and the usage on the F100 and TF39 engines reaches 25% and 33% respectively; after the 1980s, titanium alloy materials and process technology have reached further development, and a B1B aircraft requires 90,402 kilograms of titanium. Among the existing aerospace titanium alloys, the most widely used is the multi-purpose a+b type Ti-6Al-4V alloy. In recent years, the West and Russia have successively developed two new types of titanium alloys. They are titanium alloys with high strength, high toughness, weldability and good formability, and titanium alloys with high temperature, high strength and flame retardancy. These two advanced titanium alloys will play an important role in the future aerospace industry. has good application prospects.

With the development of modern warfare, the army needs a multi-functional advanced howitzer system with high power, long range, high accuracy and rapid response capabilities. One of the key technologies of the advanced howitzer system is new material technology. The lightweighting of materials for self-propelled artillery turrets, components, and light metal armored vehicles is an inevitable trend in the development of weapons. On the premise of ensuring dynamics and protection, titanium alloys are widely used in army weapons. The use of titanium alloy for the 155 artillery muzzle brake can not only reduce weight, but also reduce the deformation of the artillery barrel caused by gravity, effectively improving the shooting accuracy; some complex shapes on main battle tanks and helicopter-anti-tank multi-purpose missiles The components can be made of titanium alloy, which can not only meet the performance requirements of the product but also reduce the processing cost of the parts.

For a long time in the past, the application of titanium alloys has been greatly limited due to high manufacturing costs. In recent years, countries around the world are actively developing low-cost titanium alloys to reduce costs while improving the performance of titanium alloys. In my country, the manufacturing cost of titanium alloys is still relatively high. As the amount of titanium alloys gradually increases, seeking lower manufacturing costs is an inevitable trend in the development of titanium alloys.

Composite materials

4.1 Resin-based composite materials

Resin-based composite materials have good molding processability, high specific strength, high specific modulus, low density, fatigue resistance, shock absorption, chemical corrosion resistance, good dielectric properties, and low thermal conductivity. High efficiency and other characteristics, it is widely used in the military industry. Resin-based composite materials can be divided into two categories: thermoset and thermoplastic. Thermosetting resin-based composite materials are a type of composite materials that use various thermosetting resins as the matrix and add various reinforcing fibers; while thermoplastic resins are a type of linear polymer compounds that can be dissolved in solvents or in It softens and melts into a viscous liquid when heated and hardens into a solid when cooled. Resin-based composite materials have excellent comprehensive properties, the preparation process is easy to implement, and the raw materials are abundant. In the aviation industry, resin-based composite materials are used to manufacture aircraft wings, fuselages, canards, horizontal tails, and engine outer ducts; in the aerospace field, resin-based composite materials are not only important materials for rudders, radars, and air intakes, but also Moreover, it can be used to manufacture the insulating shell of the solid rocket motor combustion chamber, and can also be used as the ablation heat-proof material for the engine nozzle. The new cyanate resin composite materials developed in recent years have the advantages of strong moisture resistance, good microwave dielectric properties, and good dimensional stability. They are widely used in the production of aerospace structural parts, primary and secondary load-bearing structural parts of aircraft, and radar radomes.

4.2 Metal matrix composites

Metal matrix composite materials have high specific strength, high specific modulus, good high temperature performance, low thermal expansion coefficient, good dimensional stability, and excellent electrical and thermal conductivity and have been widely used in the military industry. Aluminum, magnesium, and titanium are the main matrices of metal matrix composites. Reinforcement materials can generally be divided into three categories: fibers, particles, and whiskers. Among them, particle-reinforced aluminum matrix composites have entered model verification, such as used in F-16 fighter jets. The ventral fin replaces aluminum alloy, and its stiffness and lifespan are greatly improved. Carbon fiber reinforced aluminum and magnesium-based composite materials not only have high specific strength, but also have a thermal expansion coefficient close to zero and good dimensional stability. They have been successfully used to make artificial satellite brackets, L-band planar antennas, space telescopes, and artificial satellites. Parabolic antennas, etc.; silicon carbide particle reinforced aluminum matrix composite materials have good high temperature performance and anti-wear characteristics, and can be used to make rocket and missile components, infrared and laser guidance system components, precision avionics devices, 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. They have now entered the testing stage of advanced engines. In the field of weapons industry, metal matrix composite materials can be used in large-caliber tail-stabilized armor-piercing sabots, anti-helicopter/anti-tank multi-purpose missile solid engine casings and other components to reduce the weight of the warhead and improve combat capabilities.

4.3 Ceramic matrix composites

Ceramic matrix composite materials are a general term for materials that use fibers, whiskers or particles as reinforcements and are combined with a ceramic matrix through a certain composite process. It can be seen that ceramic matrix composite materials introduce a second phase into the ceramic matrix. Multiphase materials composed of components overcome the inherent brittleness of ceramic materials and have become the most active aspect in current materials science research. Ceramic matrix composite materials 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 future development of military industry. Although ceramic materials have good high-temperature properties, they are also brittle. Methods to improve the brittleness of ceramic materials include phase change toughening, microcrack toughening, dispersed metal toughening, and continuous fiber toughening. Ceramic matrix composite materials are mainly used to make aircraft gas turbine engine nozzle valves, which play an important role in improving the engine's thrust-to-weight ratio and reducing fuel consumption.

4.4 Carbon-carbon composites

Carbon-carbon composite materials are composite materials 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. The development of carbon-carbon composite materials is closely related to the demanding requirements of aerospace technology. Since the 1980s, research on carbon-carbon composite materials has entered a stage of improving performance and expanding applications. In the military industry, the most eye-catching applications of carbon-carbon composite materials are the anti-oxidation carbon-carbon nose cone caps and wing leading edges of space shuttles. The largest carbon-carbon product is the brake pads of supersonic aircraft. Carbon-carbon composite materials are mainly used as ablative materials and thermal structural materials in aerospace. Specifically, they are used as nose cone caps for intercontinental missile warheads, solid rocket nozzles, and space shuttle wing leading edges. The current density of advanced carbon-carbon nozzle materials is 1.87~1.97 g/cm3, and the hoop tensile strength is 75~115 MPa. The end caps of recently developed long-range intercontinental missiles almost all use carbon-carbon composite materials.

With the development of modern aviation technology, the loading mass of aircraft continues to increase, and the flight landing speed continues to increase, which puts forward higher requirements for the emergency braking of aircraft. Carbon-carbon composite materials are light in weight, resistant to high temperatures, absorb large amounts of energy, and have good friction properties. They are widely used in high-speed military aircraft to make brake pads.

ultra high strength steel

Ultra-high strength steel is steel with a yield strength and tensile strength exceeding 1200 MPa and 1400 MPa respectively. It is researched and developed to meet the requirements of high specific strength materials for aircraft structures. Due to the expansion of the use of titanium alloys and composite materials in aircraft, the amount of steel used in aircraft has decreased, but key load-bearing components on aircraft are still made of ultra-high-strength steel. At present, the internationally representative low-alloy ultra-high-strength steel 300M is a typical steel for aircraft landing gear. In addition, low-alloy ultra-high-strength steel D6AC is a typical solid rocket motor casing material. The development trend of ultra-high strength steel is to continuously improve toughness and stress corrosion resistance while ensuring ultra-high strength.

Advanced High Temperature Alloys

High-temperature alloys are key materials for aerospace power systems. High-temperature alloys are alloys that can withstand certain stress at high temperatures of 600~1200°C and have anti-oxidation and anti-corrosion capabilities. They are the preferred materials for aerospace engine turbine disks. According to the different matrix components, high-temperature alloys are divided into three categories: iron-based, nickel-based and cobalt-based. Engine turbine discs were made of forged high-temperature alloys until the 1960s. Typical grades include A286 and Inconel 718. In the 1970s, the American GE Company used rapidly solidifying powder Rene95 alloy to make the CFM56 engine turbine disc, which greatly increased its thrust-to-weight ratio. , the operating temperature is significantly increased. Since then, powder metallurgy turbine discs have developed rapidly. Recently, the United States has adopted a spray deposition rapid solidification process to manufacture high-temperature alloy turbine disks. Compared with powdered high-temperature alloys, the process is simple, the cost is reduced, and it has good forging processing performance. It is a preparation technology with great development potential.

Tungsten alloy

Tungsten has the highest melting point among metals. Its outstanding advantage is that its high melting point brings good high-temperature strength and corrosion resistance to the material. It has shown excellent characteristics in the military industry, especially in weapons manufacturing. In the weapons industry, it is mainly used to make the warheads of various armor-piercing projectiles. Tungsten alloy uses powder pretreatment technology and large deformation strengthening technology to refine the material's grains and elongate the grain orientation, thereby improving the material's strength, toughness and penetration power. The tungsten core material of the Type 125 II armor-piercing projectile developed by our country is W-Ni-Fe, which adopts a variable density compact sintering process. Its average performance reaches a tensile strength of 1,200 MPa, an elongation of more than 15%, and a combat technical index of 2,000 meters. Distance penetrates 600 mm thick homogeneous steel armor. At present, tungsten alloy is widely used as the core material for main battle tank large aspect ratio armor-piercing projectiles, small and medium-caliber anti-aircraft armor-piercing projectiles and ultra-high-speed kinetic energy armor-piercing projectiles, which makes various armor-piercing projectiles have more powerful penetration power.

intermetallic compounds

Intermetallic compounds have long-range ordered superlattice structures and maintain strong metallic bonds, giving them many special physical, chemical and mechanical properties. Intermetallic compounds have excellent thermal strength and have become important new high-temperature structural materials actively studied at home and abroad in recent years. In the military industry, intermetallic compounds have been used to manufacture parts that withstand thermal loads. For example, the U.S.-based Puau Company manufactures JT90 gas turbine engine blades, the U.S. Air Force uses titanium-aluminum to make small aircraft engine rotor blades, etc., and Russia uses titanium Aluminum intermetallic compounds replace heat-resistant alloys as piston crowns, greatly improving engine performance. In the field of weapons industry, the tank engine supercharger turbine material is K18 nickel-based high-temperature alloy, which affects the acceleration performance of the tank due to its large specific gravity and starting inertia. Titanium-aluminum intermetallic compounds and their components are made of alumina and silicon carbide fibers. The enhanced composite lightweight and heat-resistant new material can greatly improve the tank's starting performance and improve its survivability on the battlefield. In addition, intermetallic compounds can also be used in a variety of heat-resistant components to reduce weight and improve reliability and combat performance indicators.

structural ceramics

Ceramic materials are the fastest growing high-tech materials in the world today. They have developed from single-phase ceramics to multi-phase composite ceramics. Structural ceramic materials have good application prospects in the military industry due to their many excellent properties such as high temperature resistance, low density, wear resistance and low thermal expansion coefficient.

In recent years, extensive research work has been conducted on structural ceramics for military engines at home and abroad. For example, small turbines for engine superchargers have been put into practical use; the United States has embedded ceramic plates on the top of the piston, which has greatly increased the service life of the piston and also Improved engine thermal efficiency. Germany inlays ceramic components in the exhaust port to improve the efficiency of the exhaust port. The piston liner and cylinder liner of the miniature Stirling refrigerator on foreign infrared thermal imaging cameras are made of ceramic materials, with a lifespan of up to 2,000 hours; the power of the missile gyroscope is supplied by gunpowder gas, but the gunpowder residue in the gas has a negative impact on the gyroscope. Severe damage. In order to eliminate residues in the gas and improve the hit accuracy of the missile, it is necessary to study ceramic filter materials suitable for missile gunpowder gas working at 2000°C. In the field of weapons industry, structural ceramics are widely used in main battle tank engine supercharger turbines, piston tops, exhaust port inlays, etc., and are key materials for new weapons and equipment. At present, the radio frequency requirement of 20-30 mm caliber machine guns reaches more than 1,200 rounds per minute, which makes the ablation of the barrel extremely serious. The high melting point and high-temperature chemical stability of ceramics are used to effectively suppress severe barrel ablation. Ceramic materials have high compression resistance and creep resistance. Through reasonable design, ceramic materials can maintain a three-dimensional compression state and overcome their brittleness. , to ensure the safe use of ceramic liners.