Preparation method of hard alloy or metal ceramic

Abstract

The invention provides a preparation method of hard alloy or metal ceramic. The method comprises the steps that grinding is conducted by means of a grinding body, a density of the grinding body is 5 g / cm<3> to 13 g / cm<3>, and a hardness of the grinding body is 84 HRa to94 HRa. The hard alloy with the density being 5 g / cm<3> to 13 g / cm<3> and the hardness being 84 HRa to 94 HRa is used as the grinding body, the density is small, grinding kinetic energy in a grinding process is small, impact kinetic energy in the grinding process is reduced, flexible grinding and efficient mixing of materials can be achieved, machining strain and lattice distortion of powder can be relieved, subgrain defects are reduced, a complete shape of hard alloy grains is kept, mixture quality is improved, and alloy performance is improved.

Description

technical field [0001] The invention relates to the technical field of hard alloy manufacturing, in particular to a method for preparing hard alloy or cermet. Background technique [0002] Cemented carbide or cermet is usually prepared by powder metallurgy process, including the basic process of mixture preparation, press molding, sintering and so on. The preparation of the mixture is the process of putting WC, Co, Ti(C,N) and other component powders into the grinder and using the grinding body for grinding and mixing. A reasonable grinding process is the key to preparing a mixture with good forming and sintering properties, and it is also the main determinant of the final structure and properties of the alloy. Now the use of WC-Co cemented carbide as the grinding body has become the standard for the preparation of cemented carbide mixtures, and high hardness, wear-resistant fine grains or ultrafine grains with low Co content (6wt%-8wt%) should be selected To avoid excessi...

AI Technical Summary

Problems solved by technology

However, due to the high density of WC-Co cemented carbide grinding body (generally greater than 14.5g / cm 3 ), single weight, large impact kinetic energy during grinding, which will lead to great processing strain of WC and other powders, which will lead to serious lattice distortion of WC grains, significantly increase intragranular defects, and affect the performance of the final alloy

[0003] Especially when preparing coarse-grained or ultra-coarse-grained cemented carbide mixtures, excessive impact kinetic energy can easily break the coarse WC single crystal in the raw material powder, destroy the integrity of WC grains, induce processing strain, and ultimately lead to failure Coarse-grained or ultra-coarse-grained alloys with complete crystal form and few defects in the crystal can be obtained; when preparing fine-grained or ultra-fine-grained cemented carbide mixtures, due to the long grinding time required, the grinding kinetic energy is large, and the powder processing strain is serious. It will lead to poor formability of the mixture and high sintering activity, which will lead to serious abnormal grain growth and eventually affect the properties of the alloy.

At the same time, since the preparation of fine-grained or ultra-fine-grained hard alloys needs to add a small amount (usually 5-15% of Co weight) of Cr 3 C 2 , VC, TiC, TaC and other grain growth inhibitors (Grain Growth Inhibitor, hereinafter referred to as GGI), it is difficult to add a small amount of Cr 3 C 2 , VC, TiC, TaC and other GGIs are evenly dispersed, and the problem of abnormal growth of grains in areas lacking GGIs is prone to occur during sintering

In addition, when grinding Ti(C,N) cermet materials, due to the higher hardness of Ti(C,N) and other powders, the WC-Co cemented carbide grinding body wears a lot, and a large amount of grinding debris (powder) enters the material, which will obviously Change the composition ratio of the material

[0004] Patent CN106000566A discloses a new ball milling method used in the magnetic material industry, which controls the density of the ceramic grinding body at 3.0-6.0g / cm 3 , hardness 7-9, in order to reduce the energy consumption of ball milling and improve the grinding efficiency, but the ceramic grinding body in this patent is used for grinding magnetic materials, not suitable for grinding of cemented carbide powder, because the ceramic grinding body is brought into the Inorganic non-metallic impurities are incompatible with cemented carbide, which will cause the structure of cemented carbide to be dirty, form pores (holes), and seriously deteriorate the performance of the alloy

Images