CN109266939B

CN109266939B - Preparation method of high-density WC-WB-Co spherical powder hard-face material

Info

Publication number: CN109266939B
Application number: CN201811483646.4A
Authority: CN
Inventors: 刘宝刚; 余晓坤; 陈彪; 马遥
Original assignee: Zhuzhou Jiangwu Boda Hard Surface Material Co ltd
Current assignee: Zhuzhou Jiangwu Boda Hard Surface Material Co ltd
Priority date: 2018-12-05
Filing date: 2018-12-05
Publication date: 2020-07-24
Anticipated expiration: 2038-12-05
Also published as: CN109266939A

Abstract

The invention relates to a high-density WC-WB-Co spherical powder hard-surface material and a preparation method thereof, wherein the formula ratio is as follows by mass percent: 50% -75% of WC powder; 15% -38% of WB powder; 8% -12% of Co powder; 1.0 to 4.0 percent of PEG adhesive. Has the advantages that: WB is introduced into a material system design, and the WB can react with a metal phase Co in a powder sintering process to generate ternary-phase CoWB which has higher microhardness and better corrosion resistance than WC, so that the wear resistance and corrosion resistance of the material can be obviously improved after the WB is added, the microhardness HV0.3 of a coating is improved to more than 1900, the corrosion resistance of the material is improved by more than 2 times, the powder can be rapidly heated and melted by a high-temperature spheroidizing production process, powder particles are solidified into spheres in a very short time under the action of surface tension, the sphericity and the solidity of single powder can be greatly improved, the apparent density of a final product of the powder is more than 7.5g/cm3, the flow rate of the powder is less than 10s/50g, and the porosity of the coating is less than 0.5%.

Description

Preparation method of high-density WC-WB-Co spherical powder hard-face material

Technical Field

The invention relates to the technical field of new materials, in particular to a preparation method of a high-density WC-WB-Co spherical powder hard-face material.

Background

In recent years, with rapid progress of science and technology and continuous improvement of modern industrial technology level, the requirements of modern mechanical equipment on the surface properties of important parts are more and more strict. The surface abrasion and corrosion of the workpiece are always important factors for restricting the service life of modern mechanical equipment, and particularly under severe conditions of high temperature, high pressure, heavy load, corrosion and the like, the whole set of equipment often fails due to the surface abrasion and corrosion of the workpiece.

The hard surface material is coated on the surface of a workpiece by means of a supersonic flame spraying technology, a plasma surfacing technology, a laser cladding technology, a plasma spraying technology and the like, so that the performances of wear resistance, corrosion resistance, high temperature resistance and the like of the material can be obviously improved.

The WC-Co coating material has the characteristics of high hardness of WC and good toughness of Co, wear resistance, corrosion resistance and the like, and is considered as the most widely applied metal ceramic material in hard surface materials. However, with the rapid development of engineering technology, the surface engineering field puts higher requirements on the wear resistance and corrosion resistance of the coating, and the single WC-Co hard surface material cannot meet the performance requirements of high-end application fields on the material. The characteristics of the friction component and the bonding interface of the friction component and a base body are main factors influencing the wear resistance and the corrosion resistance of the material, WB has an extremely important position in modern industry, and has higher microhardness and better corrosion resistance than WC.

The spherical powder hard surface material has the advantages of good fluidity, high apparent density, small porosity of prepared coating, excellent wear resistance and corrosion resistance of the coating and the like, and the advantages are more obvious when the density of the spherical powder is higher, so that researchers at home and abroad always aim to prepare the powder hard surface material into a high-density sphere. The research reports about the preparation of WC-WB-Co spherical powder hard-face materials are rarely seen in the existing documents and patent searches, and the invention patent CN105463283A applied by Shiyaoyeng Jinlu cemented carbide tool Co., Ltd discloses a preparation method and application of a tungsten boride thermal spraying coating material, wherein the main technical process of the method is as follows:

(1) WC powder, WBn powder (n is 0.5, 1, 2, 2.5 or 0.5 is not less than n and not more than 2.5) and metal M powder (M is Co, Ni or Ni-Cr alloy) are used as raw material ingredients;

(2) deionized water or alcohol is used as a ball milling medium, the prepared materials are placed in a ball milling tank for wet milling, and then the slurry is granulated by adopting a centrifugal spray drying tower;

(3) placing the powder after spray drying in a graphite crucible, and sintering at the temperature of 1000-1500 ℃ by using a vacuum furnace;

(4) and crushing the powder after sintering, and finally screening. The microscopic morphology of the tungsten boride thermal spraying powder prepared by the method is hollow sphere-like, the surface roughness of the powder is larger, and the apparent density of the powder is lower; in addition, the powder prepared by the method is in a hollow sphere-like shape, so that the porosity of the coating is higher after thermal spraying, and the wear resistance, corrosion resistance and other properties of the coating are further influenced. Therefore, the preparation of the high-density WC-WB-Co spherical powder is particularly necessary.

Disclosure of Invention

The invention aims to solve the technical problem of providing a high-density WC-WB-Co spherical powder hard-surface coating material to prevent failure caused by abrasion and corrosion of the surface of a workpiece.

The invention relates to a high-density WC-WB-Co spherical powder hard-face material, which comprises the following components in percentage by mass: 15 to 38 percent of WB powder, 8 to 12 percent of Co powder, 1.0 to 4.0 percent of PEG binder and 50 to 75 percent of WC powder.

The preparation method of the high-density WC-WB-Co spherical powder hard-face material comprises the following process steps:

(1) preparing materials: mixing materials according to the mass percentage, wherein the adding proportion of WC powder is 50-75%, the adding proportion of WB powder is 15-38%, the adding proportion of metal Co powder is 8-12%, PEG is selected as a binder, and the adding amount of PEG is 1.0-4.0% of the total mass;

(2) wet grinding: placing the prepared materials into a ball milling tank, and taking deionized water or edible alcohol as a ball milling medium, wherein the ball milling time is 20-72 h, and the ball milling mass ratio is controlled within the range of 2:1-5: 1;

(3) spray drying: carrying out spray drying on the WC-WB-Co slurry subjected to wet grinding by using a pressure type spray drying tower to prepare a spare mixed material;

(4) pressing: placing the powder after spray drying in a powder press, and pressing under the pressure of 40-200 MPa to form a block-shaped blank for later use;

(5) and (3) sintering: placing the pressed blocky WC-WB-Co blank on a graphite plate coated with 92% ZrO 2-8% Y2O3 on the surface, and sintering at the temperature of 1300-1480 ℃ by using a vacuum furnace for 1-4 h;

(6) mechanical crushing: crushing the sintered blocky WC-WB-Co alloy by using a double-roll crusher, wherein the double rolls are made of WC-6Co hard alloy materials in order to avoid doping of other impurities;

(7) primary sieving: screening the irregular powder after mechanical crushing by using a three-dimensional rotary vibration screen, entering the next process step when the size of the powder is less than 125 microns, and returning the powder with the size of the powder more than 125 microns to the step (6) for mechanical crushing again;

(8) and (3) high-temperature spheroidizing: feeding the powder after one sieving at a feeding speed of 30-270 g/min from top to bottom

The powder is rapidly heated and melted through a vertical tubular high-temperature spheroidizing furnace, the molten particles form liquid drops with high sphericity under the action of surface tension and are solidified into spheres in a very short time, and the temperature of the high-temperature spheroidizing furnace is controlled within the range of 2980-3600 ℃;

(9) and (3) secondary sieving: sieving the powder spheroidized at high temperature by using an ultrasonic sieving machine or a three-dimensional rotary vibration sieve, wherein the powder with the particle size of less than 45 mu m is used for supersonic flame spraying, and the powder with the particle size of between 45 mu m and 125 mu m is used for laser cladding, plasma surfacing and plasma spraying;

the mass percentage purity of the WC powder, the WB powder and the Co powder in the step (1) is more than 99.8%; the Fisher granularity of WC powder is 0.6-20 μm, the Fisher granularity of WB powder is 0.8-8 μm, and the Fisher granularity of Co powder is 0.8-2 μm;

the ball mill used in the step (2) is a rolling tiltable ball mill, and the ball grinding balls are WC-8Co hard alloy balls;

the temperature of spray drying in the step (3) is 180-260 ℃;

and (3) the heating mode of the tubular high-temperature spheroidizing furnace in the step (8) is intermediate-frequency heating or plasma heating.

The invention has the beneficial effects that:

(1) according to the invention, WB is introduced into the material system design, and as WB reacts with a metal phase Co in the powder sintering process to generate ternary phase CoWB which has higher microhardness and better corrosion resistance than WC, the microhardness HV0.3 of the coating can be increased to more than 1900 after WB is added, and the corrosion resistance of the material is increased by more than 2 times;

(2) the high-strength long-time wet grinding process ensures that the powder raw materials are fully mixed and crushed, improves the uniformity, the toughness and the surface energy of the powder raw materials, and is beneficial to improving the microhardness, the wear resistance and the corrosion resistance of the final powder product;

(3) the ball grinding balls and the pair rollers adopted in the wet grinding and mechanical crushing process are made of WC-Co hard alloy materials, so that impurity elements can be effectively prevented from being doped into a WC-WB-Co powder system, and the purity of a final powder product is guaranteed;

(4) according to the invention, the graphite plate is coated with the 92% ZrO 2-8% Y2O3 coating in the sintering process, so that the C element of the graphite plate can be effectively prevented from diffusing into a WC-WB-Co material system, and the high hardness of the material system is ensured;

(5) the production process of high-temperature spheroidization can rapidly heat and melt the powder, and the melted powder particles are solidified into spheres in a very short time under the action of surface tension, so that the sphericity and the solidity of single powder can be greatly improved, the apparent density of a final powder product can reach more than 7.5g/cm3, the flow rate of the powder is less than 10s/50g, and the porosity of a coating is less than 0.5%;

(6) the method has strong target property, controllable process, safety and reliability, and the produced high-density WC-WB-Co spherical powder hard-face material and the preparation method thereof are suitable for coating preparation methods such as supersonic flame spraying, plasma surfacing, laser cladding and the like.

Drawings

FIG. 1 is an SEM image of 60WC-30WB-10Co spherical powder in example 1 of the present invention;

FIG. 2 is an SEM image of 50WC-38WB-12Co spherical powder in example 2 of the invention;

FIG. 3 is an SEM image of 75WC-17WB-8Co spherical powder in example 3 of the invention;

FIG. 4 shows a 70WC-20WB-10Co spherical powder cross-sectional metallographic phase in example 4 of the present invention;

FIG. 5 shows the metallographic phase of the cross section of 60WC-28WB-12Co spherical powder in example 5 of the present invention;

FIG. 6 is an SEM image of 67WC-25WB-8Co spherical powder in example 6 of the present invention;

FIG. 7 is an SEM image of 75WC-15WB-10Co spherical powder in example 7 of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure more apparent, the technical solutions of the embodiments of the present disclosure will be described clearly and completely with reference to the drawings of the embodiments of the present disclosure. It is to be understood that the described embodiments are only a few embodiments of the present disclosure, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the disclosure without any inventive step, are within the scope of protection of the disclosure.

The invention relates to a high-density WC-WB-Co spherical powder hard-face material, which comprises the following components in percentage by mass: 15 to 38 percent of WB powder, 8 to 12 percent of Co powder, 1.0 to 4.0 percent of PEG binder and 50 to 75 percent of WC powder. The preparation method of the high-density WC-WB-Co spherical powder hard-face material comprises the following process steps:

(4) pressing: placing the powder after spray drying in a powder press, and pressing into a block-shaped blank under the pressure of 40-200 MPa for later use;

(8) and (3) high-temperature spheroidizing: passing the powder after primary sieving through a vertical tubular high-temperature spheroidizing furnace from top to bottom at a feeding speed of 30-270 g/min, rapidly heating and melting the powder, forming liquid drops with high sphericity by the molten particles under the action of surface tension, solidifying and changing the liquid drops into spheres in a very short time, and controlling the temperature of the high-temperature spheroidizing furnace to be within the range of 2980-3600 ℃;

the temperature of spray drying in the step (3) is 180-260 ℃;

The invention will be described in detail below with reference to specific examples, electron microscope image detection data, and performance detection data of the spherical powder prepared by the method of the invention in each example:

example 1, fig. 1 is an SEM electron microscope image of 60WC-30WB-10Co spherical powder, in which the addition ratio of WC powder is 60%, the addition ratio of WB powder is 30%, and the addition ratio of metal Co powder is 10% are taken as examples:

(1) preparing materials: batching according to the mass percentage, wherein the adding proportion of WC powder is 60%, the adding proportion of WB powder is 30%, the adding proportion of metal Co powder is 10%, PEG is selected as a binder, and the adding amount of PEG is 2.0% of the total mass;

(2) wet grinding: placing the prepared materials in a ball milling tank, taking deionized water as a ball milling medium, wherein the mass ratio of ball materials is 4:1, and the ball milling time is 48 hours;

(3) spray drying: carrying out spray drying on the slurry subjected to wet grinding by using a pressure type spray drying tower to prepare a spare mixed material;

(4) pressing: putting the powder after spray drying into a powder press, and pressing into a block-shaped blank for later use under the pressure of 120 MPa;

(5) and (3) sintering: placing the pressed block blank on a graphite plate coated with 92% ZrO 2-8% Y2O3 on the surface, and sintering at 1360 ℃ by using a vacuum furnace for 2 h;

(6) mechanical crushing: crushing the sintered blocky alloy by using a double-roll crusher, wherein the double roll is made of WC-6Co hard alloy materials in order to avoid impurity doping;

(7) primary sieving: screening the irregular powder after mechanical crushing by using a three-dimensional rotary vibration screen, entering the next process step when the size of the powder is less than 125 microns, and returning the powder with the size of more than 125 microns to the mechanical crushing step for crushing again;

(8) and (3) high-temperature spheroidizing: passing the primarily sieved powder through a vertical tubular high-temperature spheroidizing furnace from top to bottom at a blanking speed of 60g/min, rapidly heating and melting the powder, forming liquid drops with high sphericity under the action of surface tension of the melted particles, and solidifying and changing the liquid drops into spheres in a very short time, wherein the temperature of the high-temperature spheroidizing furnace is set at 3100 ℃;

(9) and (3) secondary sieving: sieving the powder spheroidized at high temperature by using an ultrasonic sieving machine, wherein the powder with the diameter of less than 45 mu m is used for supersonic flame spraying, and the powder with the diameter of between 45 mu m and 125 mu m is used for laser cladding, plasma surfacing and plasma spraying.

Example 2, fig. 2 is an SEM electron microscope image of 50WC-38WB-12Co spherical powder, in which the addition ratio of WC powder is 50%, the addition ratio of WB powder is 38%, and the addition ratio of metal Co powder is 12% are taken as examples:

(1) preparing materials: proportioning according to mass percent, wherein the adding proportion of WC powder is 50%, the adding proportion of WB powder is 38%, the adding proportion of metal Co powder is 12%, PEG is selected as a binder, and the adding amount of PEG is 2.2% of the total mass;

(2) wet grinding: placing the prepared materials in a ball milling tank, taking deionized water as a ball milling medium, wherein the mass ratio of ball materials is 3.5:1, and the ball milling time is 60 hours;

(4) pressing: putting the powder after spray drying into a powder press, and pressing into a block-shaped blank under the pressure of 100MPa for later use;

(5) and (3) sintering: placing the pressed block blank on a graphite plate coated with 92% ZrO 2-8% Y2O3 on the surface, and sintering at 1340 ℃ by using a vacuum furnace for 1 h;

(8) and (3) high-temperature spheroidizing: passing the primarily sieved powder through a vertical tubular high-temperature spheroidizing furnace from top to bottom at a blanking speed of 270g/min, rapidly heating the powder to melt, forming liquid drops with high sphericity under the action of surface tension of the molten particles, solidifying the liquid drops into a spherical shape in a very short time, and setting the temperature of the high-temperature spheroidizing furnace at 2980 ℃;

(9) and (3) secondary sieving: and screening the powder spheroidized at high temperature by using a three-dimensional rotary vibration screen, wherein the powder with the diameter of less than 45 mu m is used for supersonic flame spraying, and the powder with the diameter of between 45 mu m and 125 mu m is used for laser cladding, plasma surfacing and plasma spraying.

Example 3, fig. 3 is an SEM electron microscope image of 75WC-17WB-8Co spherical powder, in which the addition ratio of WC powder is 75%, the addition ratio of WB powder is 17%, and the addition ratio of metal Co powder is 8% are taken as examples:

(1) preparing materials: proportioning according to mass percent, wherein the adding proportion of WC powder is 75%, the adding proportion of WB powder is 17%, the adding proportion of metal Co powder is 8%, PEG is selected as a binder, and the adding amount of PEG is 4.0% of the total mass;

(2) wet grinding: placing the prepared materials in a ball milling tank, taking edible alcohol as a ball milling medium, wherein the ball-material mass ratio is 5:1, and the ball milling time is 20 hours;

(4) pressing: putting the powder after spray drying into a powder press, and pressing into a block-shaped blank under the pressure of 200MPa for later use;

(5) and (3) sintering: placing the pressed block blank on a graphite plate coated with 92% ZrO 2-8% Y2O3 on the surface, and sintering at 1480 ℃ by using a vacuum furnace for 4 hours;

(8) and (3) high-temperature spheroidizing: passing the primarily sieved powder through a vertical tubular high-temperature spheroidizing furnace from top to bottom at a feeding speed of 30g/min, rapidly heating and melting the powder, forming liquid drops with high sphericity under the action of surface tension of the melted particles, and solidifying and changing the liquid drops into spheres in a very short time, wherein the temperature of the high-temperature spheroidizing furnace is set at 3600 ℃;

Example 4, a 70WC-20WB-10Co spherical powder cross-section metallographic phase, wherein the addition ratio of WC powder is 70%, the addition ratio of WB powder is 20%, and the addition ratio of metal Co powder is 10% are taken as examples:

(1) preparing materials: proportioning according to mass percent, wherein the adding proportion of WC powder is 70 percent, the adding proportion of WB powder is 20 percent, the adding proportion of metal Co powder is 10 percent, PEG is selected as a binder, and the adding amount of PEG is 1.0 percent of the total mass;

(2) wet grinding: placing the prepared materials in a ball milling tank, taking edible alcohol as a ball milling medium, wherein the ball-material mass ratio is 2:1, and the ball milling time is 72 hours;

(4) pressing: placing the powder after spray drying in a powder press, and pressing into a block-shaped blank under the pressure of 80MPa for later use;

(5) and (3) sintering: placing the pressed block blank on a graphite plate coated with 92% ZrO 2-8% Y2O3 on the surface, and sintering at 1400 ℃ by using a vacuum furnace for 3 hours;

(8) and (3) high-temperature spheroidizing: passing the primarily sieved powder through a vertical tubular high-temperature spheroidizing furnace from top to bottom at a blanking speed of 100g/min, rapidly heating and melting the powder, forming liquid drops with high sphericity under the action of surface tension of the melted particles, and solidifying and changing the liquid drops into spheres within a very short time, wherein the temperature of the high-temperature spheroidizing furnace is set to 3200 ℃;

Example 5, fig. 5 shows a 60WC-28WB-12Co spherical powder cross-sectional metallographic phase, taking an example in which the addition ratio of WC powder is 60%, the addition ratio of WB powder is 28%, and the addition ratio of metallic Co powder is 12%:

(1) preparing materials: batching according to the mass percentage, wherein the adding proportion of WC powder is 60%, the adding proportion of WB powder is 28%, the adding proportion of metal Co powder is 12%, PEG is selected as a binder, and the adding amount of PEG is 2.5% of the total mass;

(2) wet grinding: placing the prepared materials in a ball milling tank, taking deionized water as a ball milling medium, wherein the mass ratio of ball materials is 3:1, and the ball milling time is 36 hours;

(4) pressing: putting the powder after spray drying into a powder press, and pressing into a block-shaped blank under the pressure of 40MPa for later use;

(5) and (3) sintering: placing the pressed block blank on a graphite plate coated with 92% ZrO 2-8% Y2O3 on the surface, and sintering at 1300 ℃ by using a vacuum furnace for 2.5 h;

(8) and (3) high-temperature spheroidizing: passing the primarily sieved powder through a vertical tubular high-temperature spheroidizing furnace from top to bottom at a blanking speed of 120g/min, rapidly heating and melting the powder, forming liquid drops with high sphericity under the action of surface tension of the melted particles, and solidifying and changing the liquid drops into spheres in a very short time, wherein the temperature of the high-temperature spheroidizing furnace is set at 3150 ℃;

Example 6, fig. 6 is a SEM electron microscope image of 67WC-25WB-8Co spherical powder, in which the addition ratio of WC powder is 67%, the addition ratio of WB powder is 25%, and the addition ratio of metal Co powder is 8% are taken as examples:

(1) preparing materials: proportioning according to mass percent, wherein the adding proportion of WC powder is 67 percent, the adding proportion of WB powder is 25 percent, the adding proportion of metal Co powder is 8 percent, PEG is selected as a binder, and the adding proportion of PEG is 3 percent of the total mass;

(2) wet grinding: placing the prepared materials in a ball milling tank, taking deionized water as a ball milling medium, wherein the mass ratio of ball materials is 4:1, and the ball milling time is 24 hours;

(4) pressing: putting the powder after spray drying into a powder press, and pressing into a block-shaped blank under the pressure of 160MPa for later use;

(5) and (3) sintering: placing the pressed block blank on a graphite plate coated with 92% ZrO 2-8% Y2O3 on the surface, and sintering at 1440 ℃ by using a vacuum furnace for 3 h;

(8) and (3) high-temperature spheroidizing: passing the primarily sieved powder through a vertical tubular high-temperature spheroidizing furnace from top to bottom at a blanking speed of 180g/min, rapidly heating the powder to melt, forming liquid drops with high sphericity under the action of surface tension of the molten particles, and solidifying the liquid drops into spheres in a very short time, wherein the temperature of the high-temperature spheroidizing furnace is set at 3400 ℃;

Example 7, fig. 7 is an SEM electron microscope image of 75WC-15WB-10Co spherical powder, in which the addition ratio of WC powder is 75%, the addition ratio of WB powder is 15%, and the addition ratio of metal Co powder is 10% are taken as examples:

(1) preparing materials: proportioning according to mass percent, wherein the adding proportion of WC powder is 75 percent, the adding proportion of WB powder is 15 percent, the adding proportion of metal Co powder is 10 percent, PEG is selected as a binder, and the adding amount of PEG is 3.5 percent of the total mass;

(2) wet grinding: placing the prepared materials in a ball milling tank, taking deionized water as a ball milling medium, wherein the mass ratio of ball materials is 4:1, and the ball milling time is 30 hours;

(4) pressing: putting the powder after spray drying into a powder press, and pressing into a block-shaped blank under the pressure of 180MPa for later use;

(5) and (3) sintering: placing the pressed block blank on a graphite plate coated with 92% ZrO 2-8% Y2O3 on the surface, and sintering at 1450 ℃ by using a vacuum furnace for 3.5 h;

(8) and (3) high-temperature spheroidizing: passing the primarily sieved powder through a vertical tubular high-temperature spheroidizing furnace from top to bottom at a blanking speed of 90g/min, rapidly heating and melting the powder, forming liquid drops with high sphericity under the action of surface tension of the melted particles, and solidifying and changing the liquid drops into spheres in a very short time, wherein the temperature of the high-temperature spheroidizing furnace is set at 3480 ℃;

(9) and (3) secondary sieving: sieving the powder spheroidized at high temperature by using an ultrasonic sieving machine, wherein the powder with the diameter of less than 45 mu m is used for supersonic flame spraying, and the powder with the diameter of between 45 mu m and 125 mu m is used for laser cladding, plasma surfacing and plasma spraying. It should be noted that: as can be seen from the SEM image of the spherical powder shown in the attached drawing of the specification of the invention, the prepared powder has very high sphericity and very small surface roughness; as can be seen from the attached figure, the cross section metallographic phase of the spherical powder prepared by the method has no pores inside the powder and shows high compactness.

Table 1 shows the data of the performance tests of the spherical powders prepared in the examples of the process of the invention.

Claims

1. The preparation method of the high-density WC-WB-Co spherical powder hard-surface material is characterized in that the formula proportion of the high-density WC-WB-Co spherical powder hard-surface material is as follows by mass percent:

15% -38% of WB powder;

8% -12% of Co powder;

1.0 to 4.0 percent of PEG binder;

50% -75% of WC powder;

the temperature of spray drying in the step (3) is 180-260 ℃;