阅读说明：本技术 一种铜碳化钨金刚石复合电触头材料及其制备方法 (Copper tungsten carbide diamond composite electrical contact material and preparation method thereof ) 是由 兰岚 宋振阳 孔欣 赵阿强 崔永刚 王达武 陈松扬 于 2020-03-03 设计创作，主要内容包括：本发明公开一种铜碳化钨金刚石复合电触头材料及其制备方法,包括有以下组分：碳化钨粉的平均粒度为0.5～5μm,质量比为55～70wt％；金刚石粉末的平均粒度为0.1～10μm,质量比为0.01～2wt％；钴粉的平均粒度为1～5μm质量比为：1～4wt％。本发明能够实现用液相烧结工艺制备高致密度的铜碳化钨金刚石材料,解决触头内部孔隙度高的问题,全面提高触头材料的抗熔焊性和耐电磨损性。(The invention discloses a copper tungsten carbide diamond composite electrical contact material and a preparation method thereof, wherein the copper tungsten carbide diamond composite electrical contact material comprises the following components: the average particle size of the tungsten carbide powder is 0.5-5 mu m, and the mass ratio is 55-70 wt%; the average particle size of the diamond powder is 0.1-10 mu m, and the mass ratio is 0.01-2 wt%; the average particle size of the cobalt powder is 1-5 μm by mass: 1 to 4 wt%. The invention can realize the preparation of the high-density copper tungsten carbide diamond material by using a liquid phase sintering process, solves the problem of high porosity inside the contact, and comprehensively improves the fusion welding resistance and the electric wear resistance of the contact material.)

1. The copper-tungsten carbide-diamond composite electrical contact material is characterized by comprising the following components:

the average particle size of the tungsten carbide powder is 0.5-5 mu m, and the mass ratio is 55-70 wt%;

the average particle size of the diamond powder is 0.1-10 μm, and the mass ratio is 0.01-2 wt%;

the average particle size of the cobalt powder is 1-5 μm according to the mass ratio: 1 to 4 wt% of a catalyst,

the balance being copper.

2. A method of making a copper tungsten carbide diamond composite electrical contact material according to claim 1, comprising the steps of:

(1) mixing and grinding, namely uniformly mixing tungsten carbide powder, diamond powder and cobalt powder, then mechanically grinding the mixed powder, and diffusing the cobalt dispersed and distributed in the mixed powder on the surfaces of the tungsten carbide and the diamond;

(2) reduction and diffusion: in a reducing atmosphere, sintering the mixed powder treated in the step (1) at the temperature of 800-950 ℃ for 2-5 hours in a heat preservation manner, reducing an oxide film on the surface of the powder to diffuse cobalt on the surfaces of tungsten carbide and diamond, and then crushing and sieving the reduced mixed powder;

(3) and (3) granulating powder: adding the powder treated in the step (2) into a granulator, and adding a forming agent for granulation;

(4) molding and pre-sintering: carrying out compression molding on the powder treated in the step (3), preparing a skeleton pressed compact with the skeleton porosity of 35-50%, removing a forming agent through sectional heating of the skeleton pressed compact in a reducing atmosphere, and carrying out skeleton pre-sintering on the skeleton pressed compact, wherein the diamond particles coated with cobalt on the surface and tungsten carbide particles are sintered into an integral skeleton under the bonding action of cobalt in the pre-sintering;

(5) and (3) skeleton infiltration: and (3) stacking the pre-sintered skeleton pressed compact and the copper sheet in a reducing atmosphere, putting the stacked skeleton pressed compact and the copper sheet into an infiltration furnace, carrying out infiltration at 1150-1200 ℃, and cooling and discharging to obtain the copper tungsten carbide diamond composite contact material.

3. The method of making a copper tungsten carbide diamond composite electrical contact material according to claim 1, wherein: and (2) mixing the powder in the step (1) by filling the powder into a mixer for mixing for 1-4 hours.

4. The method of making a copper tungsten carbide diamond composite electrical contact material according to claim 1, wherein: and (2) in the mechanical grinding in the step (1), the mixed powder is filled into a ball milling tank, alloy balls are added, and mechanical grinding treatment is carried out for 10-24 hours.

5. The method of making a copper tungsten carbide diamond composite electrical contact material according to claim 1, wherein: the forming agent in the step (3) is paraffin or stearic acid, and the addition amount of the forming agent is 1-5% of the mass ratio of the forming agent to the mixed powder of tungsten carbide powder, diamond powder and cobalt powder.

6. The method of making a copper tungsten carbide diamond composite electrical contact material according to claim 1, wherein: the reducing atmosphere in the steps (4) and (5) is a hydrogen atmosphere or an ammonia decomposition atmosphere.

Technical Field

The invention belongs to the field of electric contact material manufacturing processes, and particularly relates to a liquid-phase sintered copper-tungsten carbide-diamond composite electric contact material and a preparation method thereof.

Background

Copper tungsten carbide is a pseudo alloy composed of tungsten carbide having a high melting point and a high hardness and copper having a high electric conductivity and a high thermal conductivity, and is widely used as an electric contact material, such as an electric resistance welding material, an electric discharge machining material, and a plasma electrode material. Under large and medium currents, the contact resistance of the copper tungsten carbide material is gradually increased along with the increase of the on-off times, and the temperature rise is also gradually increased, so that the fusion welding risk and the arc corrosion speed of the contact are also continuously increased. The welding resistance and the electric wear resistance of the contact can be further improved by adding the diamond component particles with high melting point and high hardness into the copper tungsten carbide material, so that the service life and the safety of an electric appliance are improved.

The content of tungsten carbide in a copper tungsten carbide material used for the electrical contact is generally 50-70 wt%, and due to the characteristics of high hardness and high strength of tungsten carbide, the material cannot be produced in a sintering, re-pressing and extrusion rolling mode, and a high-density material can be obtained only in a liquid phase sintering (infiltration) mode.

The liquid phase sintering process has higher requirements on the wettability between the framework and the infiltration metal and the smoothness of an infiltration channel in the framework. The atomic structure of diamond causes the interface energy between the diamond and the general metal liquid to be relatively higher than the surface energy of the diamond, so that the diamond is not infiltrated by the general metal and alloy melt. The wetting angle of diamond and copper at 1150 ℃ is 145 degrees, the wetting property of the diamond and the copper is poor, diamond is added into a tungsten carbide framework, due to the poor wetting property, the diamond cannot be completely wetted by copper solution, holes are formed at the edges of diamond particles, and the framework cannot be completely penetrated. And diamond proportion is lighter, can float in the copper melt, and the diamond of suspension can constantly block the infiltration passageway of the copper melt in the skeleton base along with the flow of copper melt, leads to the infiltration process to go on smoothly. The sintered compact thus has a large amount of pores left therein which are not filled with the copper melt. To achieve infiltration of such materials, the problems of poor wetting between the materials and free floating of the additive in the molten metal must be solved.

Through retrieval, in the prior art:

chinese patent publication No. CN1124353C discloses a copper tungsten carbide contact material and its application in low-voltage leakage switches, the material contains the following components by weight percent: 8-10% of tungsten carbide, 0.8-2% of graphite, 0.01-0.1% of zinc, 0.01-0.1% of nickel, 0.05-0.1% of lanthanide series element of III family and the balance of copper.

Chinese patent publication No. CN02129979.X A copper-based material for contacts is characterized in that the copper-based material comprises (by weight) tungsten carbide 0-10%, yttrium or zirconium or a mixture of the two 0.1-1%, lanthanum 0.01-2%, and the balance copper.

Chinese patent publication No. CN201710728339.7 discloses a boron-containing tungsten carbide copper alloy and a preparation method thereof, wherein the material components comprise 49.97-80% of tungsten carbide, 19.97-50% of copper and 0.01-0.03% of boron, and the specific processing mode comprises mixing, cladding, pressing, sintering and infiltration.

The above patents all relate to the problems of poor wettability between the materials and free floating of the additive in the molten metal to be solved by the present application. There is therefore a need for improvement.

Disclosure of Invention

In order to solve the problems and the defects in the prior art, the invention aims to provide a copper-tungsten carbide diamond composite electrical contact material and a preparation method thereof.

In order to achieve the purpose, the technical scheme of the invention is that the copper tungsten carbide diamond composite electrical contact material comprises the following components:

the average particle size of the tungsten carbide powder is 0.5-5 mu m, and the mass ratio is 55-70 wt%;

the average particle size of the diamond powder is 0.1-10 mu m, and the mass ratio is 0.01-2 wt%;

the average particle size of the cobalt powder is 1-5 mu m, and the mass ratio is as follows: 1 to 4 wt% of a catalyst,

the balance being copper.

A second object of the present invention is to provide a method for preparing a copper tungsten carbide diamond composite electrical contact material according to claim 1, comprising the steps of:

(1) mixing and grinding, namely uniformly mixing tungsten carbide powder, diamond powder and cobalt powder, then mechanically grinding the mixed powder, and diffusing the cobalt dispersed and distributed in the mixed powder on the surfaces of the tungsten carbide and the diamond;

(2) reduction and diffusion: under the reducing atmosphere, the mixed powder treated in the step (1) is heated to 800-950 DEG C

Sintering for 2-5 hours under heat preservation, reducing the oxide film on the surface of the powder to diffuse cobalt on the surfaces of tungsten carbide and diamond, and then crushing and sieving the reduced mixed powder;

(3) and (3) granulating powder: adding the powder treated in the step (2) into a granulator, and adding a forming agent for granulation;

(4) molding and pre-sintering: carrying out compression molding on the powder treated in the step (3), preparing a skeleton pressed compact with the skeleton porosity of 35-50%, removing a forming agent through sectional heating of the skeleton pressed compact in a reducing atmosphere, and carrying out skeleton pre-sintering on the skeleton pressed compact, wherein the diamond particles coated with cobalt on the surface and tungsten carbide particles are sintered into an integral skeleton under the bonding action of cobalt in the pre-sintering;

(5) and (3) skeleton infiltration: and (3) stacking the pre-sintered skeleton pressed compact and the copper sheet in a reducing atmosphere, putting the stacked skeleton pressed compact and the copper sheet into an infiltration furnace, carrying out infiltration at 1150-1200 ℃, and cooling and discharging to obtain the copper tungsten carbide diamond composite contact material.

And further setting that the powder mixing in the step (1) is carried out by filling the powder into a mixer for mixing for 1-4 hours.

Further setting the mechanical grinding in the step (1) as that the mixed powder is filled into a ball milling tank, alloy balls are added, and mechanical grinding treatment is carried out for 10-24 hours.

And (3) further setting that the forming agent in the step (3) is paraffin or stearic acid, and the adding amount of the forming agent is 1-5% of the mass ratio of the forming agent to the mixed powder of the tungsten carbide powder, the diamond powder and the cobalt powder.

It is further provided that the reducing atmosphere in the steps (4) and (5) is a hydrogen atmosphere or an ammonia decomposition atmosphere.

The invention has the advantages that:

the mixed powder is treated mainly in a mechanical grinding mode, and the tungsten carbide powder, the diamond powder and the cobalt powder are ground for a long time, so that the powder particles are repeatedly broken and deformed in the mechanical grinding process, and further refinement, homogenization of components and dispersion distribution of additives of the powder particles are promoted. And (3) carrying out high-temperature treatment on the mixed powder in a reducing atmosphere, reducing an oxide film on the surface of the powder, diffusing cobalt dispersed and distributed in the mixed powder on the surfaces of tungsten carbide and diamond, and eliminating the processing stress generated in the powder grinding process. During high-temperature presintering, the diamond particles coated with cobalt on the surface and tungsten carbide particles are sintered into an integral framework under the bonding action of the cobalt, so that the problem that the infiltration is influenced by the suspension of the independent diamond particles in the copper melt is solved. Meanwhile, the surface of the diamond particles is coated with cobalt, so that the wettability of the diamond particles with copper is greatly improved, the copper melt can smoothly permeate the whole framework, and the high-density copper tungsten carbide diamond composite contact material is finally obtained. The invention can realize the preparation of the high-density copper tungsten carbide diamond material by using a liquid phase sintering process, solves the problem of high porosity inside the contact, and comprehensively improves the fusion welding resistance and the electric wear resistance of the contact material.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is within the scope of the present invention for those skilled in the art to obtain other drawings based on the drawings without inventive exercise.

FIG. 1 is a cross-sectional scan of a copper tungsten carbide diamond composite electrical contact material made in accordance with a first embodiment of the present invention;

FIG. 2 is a magnified 1000 (x) metallographic view of a copper tungsten carbide diamond composite electrical contact material prepared according to a first embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings.