Preparation of metal powders and application of ancient origin. Ancient times have used gold, silver, copper, bronze and some of its oxide powder to make paint for pottery, jewelry and other apparatus coloring, decoration. Early 20th century, Americans Kuli Ji (WDCoolidge) with hydrogen reduction of tungsten oxide to tungsten powder production Preparation of tungsten wire, is the beginning of modern metal powder production. After Preparation by chemical reduction of copper, cobalt, silicon powder, iron, tungsten carbide and other powder metallurgy products for the early (porous oil-bearing, porous filters, carbide, etc.) development; also invented at this time Preparation method for carbonyl iron and nickel powder. 30 years, first with the vortex grinding method to take iron, and later with the production of solid carbon reduction iron, low cost. The early 1930s there was even a molten metal atomization. This method first used for extracting low melting point metals such as tin, lead, aluminum powder, to the early 1940s developed into a system with high pressure air atomized iron powder obtained. 50's with high pressure water spray system to take a variety of alloy steel and alloy powder. 60 years developed a variety of high-alloy powder aerosol produced to promote the development of high-performance powder metallurgy products. Since the 1970s there has been a variety of physical and chemical reactions in gas and liquid phase methods, the system has an important purpose to take powder and ultrafine powder coated.
Metal powder-like material is loose, the performance of a comprehensive reflection of the nature of the metal itself and the individual particle properties and particle swarm features. The performance of the metal powder is generally divided into chemical properties, physical properties and process performance. Chemical properties is the metal content and impurities. Physical properties, including powder, nickel powder the average particle size and particle size distribution, powder surface area and true density, particle shape, surface morphology and internal microstructure. Process performance is a combination of properties including powder flow, bulk density, tap density, compressibility, forming and sintering size changes. In addition, for certain special purposes also requires powder with other chemical and physical properties, such as catalytic, electrochemical activity and corrosion resistance, magnetic properties, internal friction coefficient. Performance of metal powder production depends largely on the powder method and system access process. The basic properties of powder-specific standard test methods can be used determined. Determination of powder size and its distribution in many ways, generally with the sieve analysis (> 44?m), sedimentation analysis (0. rock drill bits 5 ~ 100?m), gas permeation method, the microscope method. Ultra-fine powder (<0.5?m) using electron microscopy and X-ray small-angle scattering method. Customary metal powder into meal, medium pink, powder, fine powder and fine powder of five levels.https://jimadelaid.insanejournal.com/53113.html

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