Powder metallurgy: is a research and manufacture of various metal powders, alloy powders, metal compound powders and using the powders as raw materials, through compression molding, sintering and necessary subsequent processing The science and technology of producing metal materials, composite materials and their products.
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Critical speed: refers to the rotation speed of the barrel when the ball in the ball mill barrel moves along the cylinder wall to pass the vertex position without falling.
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Strength of the compact: refers to the ability of the compact to resist external forces to keep its geometric shape and size unchanged.
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Relative density: The relative density is the ratio of the mass per unit volume of an object to the mass per unit volume of water at 4℃.
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Bulk density: The mass of powder per unit volume when the powder sample is naturally filled with the specified volume.
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Formability: refers to the ability of the compact to maintain a predetermined shape after powder compaction.
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Compressibility: The ability of powder to be compressed during the pressing process.
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Fluidity: The time required for 50g powder to flow out of a standard flow funnel.
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Atomized powder: The method of directly crushing liquid metal or alloy by high-speed fluid or other methods to obtain metal powder with a size of less than 150μm.
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Mixing: refers to the process of mixing two or more powders with different ingredients.
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Admixture: The process of adding forming agent to the mixture powder to make it evenly mixed.
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Combined batch: Mix powders with the same composition but different particle sizes.
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Forming: is to process loose powder into compacts with a certain shape, size, density and strength.
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Elastic aftereffect:In the pressing process, but after the pressing pressure is removed and the powder compact is pressed out of the pressing film, due to the relaxation of the elastic internal stress, the powder The blank will expand elastically. This phenomenon is called elastic aftereffect. (After the green compact is released from the mold, the phenomenon that the green compact expands is called the elastic aftereffect)
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Arch bridge effect: Due to the overlapping of powder particles when they are freely piled, large holes that are many times larger than the particles are caused, this phenomenon is called the arch bridge effect.
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Sintering:Powder or compact is heated at a temperature lower than the melting point of the main component to increase the strength by bonding between particles.
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Liquid phase sintering: Powder sintering is carried out in the presence of two or more components of metal powder or powder compact in the same state of liquid and solid.
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Dissolution and analysis:In powder liquid sintering, after the liquid phase appears, the protrusions and corners of fine powder and coarse particles dissolve and disappear in the liquid phase. To dissolve; while dissolving, there will be precipitated particles on the surface of coarse particles, which is precipitation.
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Densification: The total volume of voids in the melt decreases, the distance between particles decreases, the sintering volume shrinks, and the density increases.
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Dipping: The powder compact is in contact with liquid metal or immersed in the liquid metal, so that the pores in the compact are filled with liquid metal, and the compact material is obtained by cooling down Or parts, this process is called immersion or infiltration.
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Mechanical alloying: A high-energy ball milling method, this method can be used to produce composite metal powder with controllable fine microstructure
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Sintering atmosphere: can prevent or reduce the harmful reaction of the surrounding environment to the sintered body. Divided into reducing atmosphere, vacuum atmosphere, and controllable carbon potential atmosphere.
