The,element,synthesis,metal,bo business, insurance The element synthesis of metal borides
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Someone had been prepared molybdenum boride in a molybdenum crucible, thetemperature is 1300~2050. Someone also preparedmolybdenum boride in graphite crucible and hydrogen, the temperature is 1500 ~1700.With a purity of 99% molybdenum powder and 83% to 85% boron powder can be obtained a purity of 96% to 98 % product, most of theimpurities removed by evaporation while sintering. Some people preparedmolybdenum boride and europium boride using the method that: in an evacuatedquartz tube heating a mixture of boron and metal to 1200and heat preservation for 48h, or in vacuo heated the same mixture in 1500-1600MgO crucible for a few minutes. Prepare chromium boride is invacuum induction furnace heated to above 1600to smelt a mixture of chromium and boron, or sintering thepowder mixture in the 1150evacuatedquartz tube for 48 ~ 72h.When the 1150sintered time increasing to 20 days, can obtain single crystal, the rawmaterial is 99.4% electrolytic chromium and 98%-99% boron powder. This boronpowder is obtained by used hydrogen reduce boron tribromide in the quartz tube,the reduction temperature is 750 ~ 800.Preparationof zirconium boride is melted the element in a vacuum induction furnace;zirconium boride is hard gray crystals, there are three components that is, zirconiumboride, zirconium diboride, three zirconium boride, only zirconium diboride ina very wide temperature range is stable. Industrial production is mainly thezirconium diboride. Zirconium diboride is hexagonal crystal, gray crystal orpowder, relative density is 5.8, melting point is 3040.Thermostability, the strength under normal and high temperature are very high. Goodthermal shock resistance, low resistance, high temperature oxidation. Thetemperature is about 3000,with metallic luster, have metallicity, resistance is slightly lower than themetal zirconium, after heating in a wide temperature range is stability. Althoughmelting point is high, but can be sintered at lower temperature. Prepared by themixture of metal zirconium, boron carbide, boron nitride heated to 2000in argon. It can be used as aerospace high temperaturematerials, wear-resistant smooth solid materials, cutting tools, temperaturethermocouple protection tubes and the electrode materials of electrolysis moltencompound, particularly suitable for using as the ball bearing surface.Preparationof boride powder is vacuum sintering the mixed powder under 1800 ~ 1900for 0.5h, or at 1150vacuumquartz tube sintered 100 ~ 150h; the manganese boride prepared is at 1100 ~ 1200sintered 48 ~ 72h, if you need to get a single crystal should heat preservation7 to 10 days. Directly at 2850hot-press the mixture of metal powder and boron powder, can beobtained the boride components with the same dense as hot-press boride powder.Denseboride components and boride coatings were able to through restore or thermaldecomposition of boron halide and a metal halide vapor in the hot surface toobtain, or in the hot metal surfaces to restore or replace boron halides, and makethe boron diffused into the metal matrix, of course, the latter method may be formedeutectic on the metal boron substrate. Some eutectics melting point is lowerthe pure boride or metal, thereby reducing the heat resistance of the obtain coating.Source:http://www.mhcmp.com
The,element,synthesis,metal,bo