Method for preparing gradient cemented carbide with cubic carbide free layer

A cemented carbide and cemented carbide substrate technology is applied in the field of preparation of beta layer gradient cemented carbide, which can solve the problems of increasing production process and cost, difficult to form cemented carbide, and low nitrogen activity.

CN101974713AInactive Publication Date: 2011-02-16UNIV OF SCI & TECH BEIJING +2
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2011-02-16
Estimated Expiration
Not applicable · inactive patent

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Abstract

The invention relates to a process for preparing gradient cemented carbide with a cubic carbide free layer, which is generally used for preparing a coated cemented carbide substrate. The process is characterized in that: an initial component adopts a nitrogen-free cemented carbide raw material, and is prepared into a blade or a sample green compact by a standard cemented carbide preparation process; and a sintering process adopts a one-step sintering method comprising the following steps of: performing sintering by adopting normal dewaxing and deoxidizing processes, introducing micro-pressure nitrogen to react the nitrogen with carbides in the cemented carbide substrate to synthesize a nitrogen-containing cubic phase, evacuating the nitrogen at gradient sintering temperature and switching to sintering in a denitriding atmosphere like vacuum to form a surface layer into a cubic phase-free and cobalt layer-rich structure, namely, the cubic carbide free layer. The process is characterized in that: a nitrogen-containing phase is not added into the cemented carbide raw material, so the increasing of alloy porosity caused by the early decomposition of the nitrogen-containing phase can be avoided; the reaction nitrogen-addition of the cemented carbide substrate is realized by controlling the reaction between the sintering atmosphere and the cemented carbide substrate, so the gradient cemented carbide with the cubic carbide free layer also can be prepared under the condition of not adding the nitrogen-containing phase into the initial component; due to the adoption of the one-step sintering method, the sintering process can be simplified and the production cost can be reduced; and the prepared gradient cemented carbide comprises the cubic carbide free layer with the thickness of 10 to 40 microns, and has high compactness and bending resistance.
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Description

technical field

[0001] The invention relates to a preparation process of a beta layer-removed gradient cemented carbide. Background technique

[0002] Cemented carbide has been widely used in the field of metal cutting because of its high strength, high hardness, wear resistance, corrosion resistance and other advantages. In recent years, the development of modern manufacturing industry has put forward higher and higher requirements on the performance of cemented carbide cutting tools. Good impact resistance, cemented carbide with traditional homogeneous structure usually cannot meet this requirement. For this reason, one or more layers of wear-resistant coatings, such as TiN, Ti(C,N), Al 2 o 3 Wait. Since the deposition temperature of general CVD technology may be as high as 800-1000 ° C, and there is a difference in thermal expansion coefficient between the coating and the substrate, a large thermal stress will inevitably be generated at the interface between the coati...

Examples

Embodiment 1

[0020] First weigh several raw material powders with medium particle size (about 2 microns), and their mass fractions are: WC powder: 83.7%; (Ti, W) C solid solution powder: 8%, the mass ratio of WC and TiC in the solid solution 5:5; Co powder: 8%; carbon black: 0.3%; mix the raw material powder and pour it into a ball mill barrel equipped with cemented carbide balls for wet grinding, the ball-to-material ratio is 4:1, and the ball milling medium is Alcohol, the ball milling time is 36 hours, the ball milling process is to make the raw material powder fully homogenized; the slurry after ball milling is dried in a vacuum oven, crushed and sieved, then added 2wt% paraffin gasoline solution, dried and broken again 1. After sieving, the mixed material is obtained. The purpose of adding paraffin is to improve the fluidity of the mixed material and improve the molding ability; then the mixed material is molded into a knife or a sample compact on a press with a pressure of 200MPa; fin...

Embodiment 2

[0022] Using raw material powder with the same composition and particle size as in Example 1, carry out wet milling after mixing, add powdered paraffin wax after wet milling for 30 hours, continue to spray dry the slurry after ball milling to obtain a mixture, and then press, The sintering process is the same as in Example 1. The density of the beta-removed gradient cemented carbide produced by this process reaches 97%, the hardness value is 90.4HRA, the thickness of the beta-removed layer is 32 microns, and the overall bending strength is 1890N / mm 2 .

[0023] The preparation process is the same as that of Example 1, but the examples using other alloy initial components and gradient sintering process are shown in the table below.

[0024]