Cobalt alloy is added based on cobaltalloying elementFormed alloy.Common cobalt alloys includePlatinum cobalt alloy, samarium cobalt alloy, zirconium cobalt alloy, tungsten cobalt alloy, etc.Non magnetic cobalt alloys have high strength and excellent corrosion resistance, and have been proven to be compatible with medical implants.
Metal cobalt is mainly used to make alloys.Cobalt base alloyIt is a general term for alloys made of cobalt, chromium, tungsten, iron and nickel.The tool steel containing a certain amount of cobalt can significantly improve the wear resistance and cutting performance of the steel.Stellite cemented carbide containing more than 50% cobalt will not lose its original hardness even if heated to 1000 ℃. Now this cemented carbide has become the most important material used between gold cutting tools and aluminum.In this material, cobalt combines the grains of other metal carbides in the alloy composition to make the alloy have higher toughness and reduce the sensitivity to impact. Fusion welding of this alloy on the surface of parts can increase the life of parts by 3-7 times.Aerospace technologyThe most widely used alloy inNickel base alloyCobalt based alloys can also be used, but the "strength mechanism" of the two alloys is different.The high strength of the nickel base alloy containing titanium and aluminum is due to the formation of a phase enhancer composed of NiAl (Ti). When the operating temperature is high, the phase enhancer particles will transfer into the solid solution, and the alloy will soon lose strength.The heat resistance of cobalt base alloy is due to the formation of refractory carbides, which are not easy to be converted into solid solution and have low diffusion activity. When the temperature is above 1038 ℃, the advantages of cobalt base alloy are shown.This is just right for the manufacture of high efficiency high-temperature engines and cobalt based alloys.Cobalt base alloy containing 20% - 27% chromium is used as the structural material of aviation turbine, which can make the material reach high oxidation resistance without protective coating.The nuclear reactor provides heat with mercury so that the turbine generator with thermal medium can operate continuously for more than one year without maintenance.
It is reported that the generator boiler used in the US test is made of cobalt alloy.Cobalt is one of the few metals that can maintain its magnetism once magnetized.Under thermal action, the temperature of loss of magnetism is called the Curie point. The Curie point of iron is 769 ℃, that of nickel is 358 ℃, and that of cobalt is 1150 ℃.The coercivity of magnetic steel containing 60% cobalt is 2.5 times higher than that of general magnetic steel.Under vibration, magnetic steel generally loses about 1/3 of its magnetism, while cobalt steel only loses 2%~3.5% of its magnetism.Therefore, cobaltmagnetic material The advantages are obvious.Cobalt metal is also widely used in electroplating, glass, dyeing, medicine and medical treatment.Lithium cobalate made of lithium carbonate and cobalt oxide is the most widely used in modern timesHigh energy batteryPositive material.Cobalt may also be used to make nuclear weapons, a theoretical atomic bomb or hydrogen bomb, installed in the cobalt shell, which can turn cobalt into deadly radioactive dust after explosion.
Cobalt base alloyWidely used in production and life, the common cobalt base alloys arePlatinum cobalt alloy, samarium cobalt alloy, zirconium cobalt alloy, tungsten cobalt alloy, etc.
Platinum cobalt alloy
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Platinum cobalt alloy is a platinum alloy composed of platinum based cobalt.Below the solid phase line isContinuous solid solution；There are two ordered phases in the alloy system: PtCo and PtthreeCo，AuCu and CuthreeAu type structure, with order transition temperature of 833 ℃ and 750 ℃, has ferromagnetism.For single-phase solid solution, with the increase of cobalt content, the lattice constant of the alloy decreases, the strength properties and resistivity increase and reach the maximum value on the alloy containing about 30% cobalt (atomic fraction), the Curie temperature increases, and the resistance temperature coefficient decreases.Ordering treatment obviously affects various properties: increase the strength, magnetic coercivity (Hc）And maximum magnetic energy product (BrHc)；Reduce resistivity, Curie temperature and remanence value (Br)。The best magnetism is obtained on the partially ordered alloy and is attributed to the two-phase structure and largeMagnetocrystalline anisotropy。
Pt-50% Co (23.3% Co) alloy is an excellent permanent magnetic material.It not only has high coercivity, magnetic energy product and magnetic stability, but also has good processability and corrosion resistance.Main magnetic parameters: Br=0.70～0.79T，Hc=308～379KA/m，(BH)max=80～93.6kJ/m，Bd=0.34～0.5T，Hd=213～237KA/m，T=500℃。Although the magnetic properties are inferior to those containingrare earth elementPt Co alloy is the only permanent magnetic material that can meet the requirements of miniaturization, high reliability and corrosion resistance.Mainly used as hearing aid, magnetron, electronic clock, focusing equipment andMotor rotorEtc.[1]
Zirconium cobalt alloy
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A tritium storage alloy in AB type compounds.Among them, tritide UH of metallic uranium for tritium storagethreeThe biggest disadvantage is U and UHthreeAt room temperature, it will react strongly with air and burn, pulverize into ultra-fine powder and bring into the tritium process system.Zirconium cobalt hydride ZrCoHxIt is an excellent tritium storage material with the advantages of low equilibrium decompression at room temperature, difficult combustion and pulverization, high tritium storage density, and small release percentage of decayed helium-3.Mix high-purity zirconium powder and cobalt powder in proportion, and smelt them in an argon arc furnace without melting electrode. The blocks are homogenized and crushed (20~120 mesh) into powder. After 400 ℃ vacuum degassing in the chemical bed, 1 MPa high-purity hydrogen is charged at less than 10 Pa, and after 3~4 times of hydrogenation and dehydrogenation cycles, the hydrogen absorption is saturated, and ZrCo is fully activated.The hydrogen absorption capacity of ZrCo alloy is 205~224mol/g, and that of metallic uranium is only 140mol/g.ZrCoHthreeHydrogen absorption capacity reaches 1.83~1.97 at.%,After hydrogen absorption, the volume expands by 18%. There is a wide equilibrium platform pressure between 590 and 670 ℃, and the reaction enthalpy is 93.6kJ/molHtwo。When ZrCo powder rises to 60 ℃ and is cooled rapidly to room temperature, the stack color has no obvious change.ZrCOHtwoThe powder burns slowly 5 minutes after contacting the air, and then slowly cools to room temperature without burning after the room temperature rises by 100 ℃.[2]
Palladium silver cobalt alloy
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A kind of palladium alloy.The commonly used PdAgCo35-15 alloy is PdAgCo35-15, which is a single-phase solid solution with hardness of HB192 and resistivity of 38 Ω· mm/m.AndSilver copper alloyIn contrast, it has better corrosion resistance and oxidation resistance, and can be used as the elastic element contact in harsh environment.[3]
Tungsten carbide based carbide
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Tungsten carbide based cemented carbide is a kind of cemented carbide with tungsten carbide (WC) as the main component.It has the largest output and the widest use in cemented carbide.It can be divided into the following categories: (1) WC Co alloy, referred to as "tungsten cobalt alloy", contains 3~25% cobalt as the binder, code YG.It can be used as tools, dies, cobalt heads, nozzles, piercing tools, etc.(2) WC TiC Co alloy, referred to as "tungsten cobalt titanium alloy", contains 4-10% cobalt as binder, 5-30% TiC, and the rest is WC.Code YT.It is mainly used as a tool for cutting steel.(3) WC TiC TaC (NbC) - Co alloy, referred to as "general alloy", code YW, mainly used asCutting tool。(4) Tungsten carbide based corrosion resistant alloys, including three types of WC Ni, WC Ni Cr and WC CoCr, are mainly used as corrosion and wear resistant parts, such as sealing rings, cylinder liners, ball pen tips, etc.[3]
