Memory is not exclusively human. Do you believe that some metals have memories?

In an experiment, Buehler, the metallurgy man of American Navy Ordnance Laboratory, needed a nickel-titanium alloy and had only a few twisted nickel-titanium wires at hand, so the researchers straighten the alloy wire out for the convenience of the experiment. But when the experimental temperature reached a certain point, all of these straightened strands suddenly returned to a zigzagged shape, and the results are the same no matter how you repeat the experiment. Scientists call this the shape memory effect, which means that the nickel-titanium alloy is unconscious when the temperature of the environment changes, once the temperature of the environment reached a temperature change, the memory of the nickel-titanium alloy was aroused and restored to its original appearance.

The memory capacity of some metals is determined by the inherent variation of the microstructure inside the alloy. In a solid metal alloy, atoms are arranged in a certain order, and the arrangement of atoms will change when the ambient temperature changes. Once you get back to the original temperature, the atoms in the alloy go back to the original arrangement.

Not all alloys have "memory", and only metals with special structures have memory. In recent years, the human has found many "memory" of the alloy, nickel-titanium alloy such as titanium-nickel-copper, titanium-nickel-niobium, an aluminum alloy such as copper-zinc-aluminum, and iron series alloy such as copper-nickel-aluminum, iron- platinum, iron-palladium alloy, etc.

Nitinol is a nickel-titanium alloy with superelasticity and shape memory properties. Shape memory refers to the ability of Nitinol to undergo deformation at one temperature and then recover its original, under-formed shape upon heating above its transformation temperature. Superelasticity occurs at a narrow temperature range just above its transformation temperature; in this case, no heating is necessary to cause the under formed shape to recover, and the material exhibits enormous elasticity, some 10-30 times that of ordinary metal.

Memory metal is widely used in tooth orthodontics, female bra, bone plate, artificial heart, aerospace, nuclear industry, and other fields. Researchers will also explore ways to make memory metals serve better for production and human life.

SAM is a trusted manufacturer of Nitinol Memory Wire and Nitinol Rod with competitive pricing and great lead times. Please visit http://www.samaterials.com for more information.

Oznake: Nitinol Memory Wire, Nitinol Rod

Introduction to the solid lubricant

When it comes to lubrication, you may first think of the lubricants, which play an important role in the operation of mechanical equipment. However, with the development of science and technology, especially high-end manufacturing, national defense technology, aerospace, and other industries have the higher requirements for lubricant, such as the high-temperature resistance, high speed, heavy load, corrosion resistance, etc.

With the development of solid lubricants, graphite and molybdenum disulfide are commonly used, while boron nitride powder, as a new solid lubricant, has unique and excellent properties and has become a hot material for current and future development.

Application in modified lubricating oil

Boron nitride, graphite, molybdenum disulfide, and fluorine fossil ink were added to paraffin base mineral oil (VG15) and lithium base grease, and then the test was carried out on the ring-roller friction and wear test machine. During the test, the ring specimen rotates with the rotating shaft, and sliding friction is generated between the roller specimen and the ring specimen. The ring specimen is made of bearing steel (SUJ2), and its lubrication effect is compared. The addition of boron nitride was milky white, while the addition of fatwas lights yellow, and the addition of the other three solid lubricants was black and gray.

Application in improving friction materials

Silicon nitride (Si3N4) ceramics have high strength, hardness, heat resistance, wear resistance and excellent chemical stability, so they are widely used in sealing parts, key parts of the engine, high-speed cutting tools and other fields, and become one of the best choices for wear-resistant parts. However, Si3N ­ ceramic itself has high dry friction coefficient and wear rate, and cannot meet the request of tribological materials engineering application. Adding the solid lubricant hexagonal boron nitride (h - BN) can improve Si ­ N4 interchange tribological properties of ceramics.

The addition of h-BN can significantly improve the friction and wear performance of Si3N4. With the increase of h-BN content, the friction factor is 0.3 ~ 0.4 goes down to 0.01. Si3n4-20% h-BN composite ceramics have the best friction and wear performance, and the wear rate is close to 0. The h-BN has a good application in reducing wear amount, stabilizing friction coefficient and reducing sensitivity to speed, pressure and high temperature for other abrasive resistance materials and other self-lubricating functional materials.

Application of demolding agent in die casting, metallurgy and glass mold

Compared with the traditional release agent carbon black and graphite, boron nitride has excellent lubrication performance and high-temperature stability. It improves the efficiency of the mold, prolongs the service life of the mold, and improves the qualified rate of the product. In addition, boron nitride has excellent environmental protection materials, which can significantly improve the working environment of the factory and the cleanliness of the final product by reducing environmental pollution in the process of use.

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Oznake: Boron Nitride Powder

Liquid oxygen-kerosene is a typical hydrocarbon propellant. In the type of propellant of a rocket, whether liquid oxygen or liquid hydrogen or hydrazine, they cannot be separated from an important material -- a catalyst. Nano tungsten carbide is a kind of catalyst material with high performance, low cost and most promising to replace platinum.

The engine of a car, an airplane, or a ship needs not only fuel but also oxygen to helping to combust. The launch vehicle would have to be much faster than an airplane to overcome gravity to get into space, and the efficiency of fuel work would have to be very high. It also has to work at very high altitudes, even in outer space, so there's not enough oxygen in the atmosphere. Therefore, the rocket has to carry an oxidizer and a catalyst in addition to the fuel.

Liquid oxygen-kerosene is a typical hydrocarbon propellant and is the main rocket fuel studied in recent years. Compared with liquid hydrogen fuel, the disadvantage of liquid oxygen-kerosene is relatively low specific washing and regenerative cooling capacity and easy carbon deposition and coking. However, the combination of liquid oxygen/hydrocarbon propellant has many advantages, such as wide source, low cost, high combination density, high specific impulse performance, non-toxic, environmental protection and good storage resistance. It is understood that the efficiency of using liquid oxygen-kerosene is 15-20% higher than that of liquid hydrogen, which can greatly reduce the fuel carrying and the weight and volume of the rocket. Besides that, the price of kerosene is lower, saving more than 1 million dollars per launch. Unlike previous rocket engines that produced highly toxic pollution, neither kerosene nor liquid oxygen is toxic, and only water and carbon dioxide are produced during combustion.

The space industry has always used platinum metal as catalysts, which is not only expensive but also toxic in the process of catalysis. However, the development of nanometer technology has opened up new application fields for many materials, among which tungsten carbide is the best one. The presence of carbon in nano tungsten carbide not only alters the electronic properties of the surface of tungsten, giving it properties similar to platinum but also prevents the generation of toxic by-products.

It was found that the catalytic activity of tungsten carbide on the surface of pure tungsten carbide was mainly reflected in the reaction of carbon chain fracture, and the conversion rate of catalytic active reactants increased with the increase of reaction temperature. When the oxygen is introduced, the catalytic activity of tungsten carbide decreases, but its selectivity to the isomerization of reactant increases. At this time, isomerization is the main reaction, which indicates that tungsten carbide also has a good catalytic effect on liquid oxygen-kerosene, and it's surface composition has a direct influence on its catalytic activity and selectivity, and it needs to be doped with other elements appropriately to enhance the effect. In conclusion, as the most active transition metal carbides, tungsten carbide has Pt-like characteristics in the isomerization of catalytic hydrocarbons.

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Oznake: Tungsten Carbide, Nano Tungsten Carbide

Aerospace field

*Gyro rotor material

The gyroscope is the brain of the navigation and control systems of aircraft, satellites, various missiles and the nuclear submarine of the spaceship. The stability of gyroscope is improved with the weight of gyroscope increasing, and the stability and control accuracy of the gyroscope can be greatly improved by using high-density alloy as the gyro rotor.

*The inertial rotating element on an airplane

*All kinds of instruments and balancing weight components on the engine

For example, the counterweight element used in the Sibe engine and the counterweight element which controls the oil separation fJ and can adjust the oil quantity under the high-speed operation. In addition, it is widely used in the static and dynamic balancing weight of ailerons and steering rudder and the balancing weight of rotary blades of a helicopter.

Military industry

*The W-Ni-Fe alloy with high density, strength, plasticity, and hardness is a key material in the military industry. It is used as the small arrow of cluster bolt in gunshot, shrapnel, cluster bomb, screen bomb and penetrator bomb, which has great killing power.

*In a missile, it is used as a gyroscope for navigation, a counterweight screw, a TAB, and a high-density alloy missile body weighing several tens of kilograms.

*It is used in tank engines as a counterweight in the governor.

*It is used in nuclear submarines as a counterweight and reactor shielding material.

Electrical industry

Tungsten heavy alloy has good high-temperature strength, hardness, conductivity, and corrosion resistance, so it has a wide application prospect in electrothermal processing. Tungsten heavy alloy is used as rootstock material for electric heating and upsetting, riveting material for electric riveting, electrode material for EDM, spot welding material and contact material for high voltage switch are very suitable.

Mechanical manufacturing and pressure casting

Tungsten alloys are used as balanced components in the manufacturing of machinery and instruments. For example, the installation of high-density alloy counterweights on the drill pipe of oil drilling rig can greatly improve the verticality of drilling and improve the efficiency of oil drilling. Tungsten alloy is a good tool for die-casting due to its high-temperature performance.

Medical device industry

Due to its strong X-ray attenuation capacity, tungsten alloy is an ideal material to be used as a shielding element or vessel for various radioactive sources. It is used in medicine as a shield against radiation and Y-ray knife.

Other industries

Tungsten alloy is used as vibrator material in BP machine and mobile phone in the electronic communication industry. In addition, it is widely used in fishing for falling fish and so on.

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Oznake: Tungsten alloy, Tungsten heavy alloy