Preparation method for spherical monocrystal tungsten powder for thermal spraying

A thermal spraying, spherical technology, applied in the direction of single crystal growth, single crystal growth, chemical instruments and methods, etc., can solve the problems of high coating hardness, high energy consumption, high powder rate, and achieve simple process equipment and coating. The effect of high hardness and high production efficiency

Active Publication Date: 2016-11-09
LUOYANG GOLDEN EGRET GEOTOOLS
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AI Technical Summary

Problems solved by technology

In the field of spraying, dense spherical powder and adjustable particle size range are the basis for forming uniform coatings. Spherical thermal spraying single crystal tungsten powder not only has good fluidity, but also has complete crystallization, dense particles, high sphericity, good fluidity and high purity. The obtained coating has high hardness, high powder coating rate and low porosity
[0004] At present, it is reported that the preparation method of single crystal tungsten powder by high temperature reduction of tungsten oxide can prepare single crystal tungsten powder with a particle size of 5-50 μm, but its energy consumption is high and most of the particles are small particles aggregated to form large single crystals, which is not suitable for the thermal spray industry
It is also reported that adding lithium or sodium to APT to prepare single crystal tungsten powder, the particle size can be controlled at 15-150 μm, but its shape is irregular and its fluidity is poor, so it is not suitable for thermal spraying industry
It is also reported that irregular polygonal tungsten powder is oxidized, crushed, sieved, washed, and dried to obtain tungsten powder with good sphericity. , not suitable for use in the thermal spray industry
There is also the use of plasma spheroidization technology to prepare spherical tungsten powder. In this method, ordinary tungsten powder is added to the plasma jet to melt the surface or the whole of the tungsten powder particles to form molten droplets. The molten droplets shrink into a spherical shape due to surface tension, and then through rapid cooling, So as to obtain spherical tungsten powder, although the tungsten powder with high particle surface finish, increased density, reduced brittleness and good fluidity can be prepared by this method, but the equipment of this method is expensive, energy consumption is high, and the preparation cost is high. Crystalline tungsten powder, and tungsten powder is oxidized during the spheroidization process, it is difficult to realize industrial production and application

Method used

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Effect test

preparation example Construction

[0014] A preparation method of spherical single crystal tungsten powder for thermal spraying, comprising the following steps:

[0015] Weigh the ammonium tungstate solution with a mass concentration of 30%~40%, then add a mixture of lithium carbonate and sodium chloride to the weighed ammonium tungstate solution, mix evenly, dry and concentrate to obtain a precursor, and set aside; Wherein, the total addition amount of lithium carbonate and sodium chloride is 1g / L~5g / L, and the mass ratio of lithium carbonate and sodium chloride is 1:5~5:1;

[0016] Step 2. Select spherical tungsten powder with a grain size of 0.5-5 μm as the mother crystal, and add it to the precursor prepared in step 1 according to the mass ratio (0.1%-0.3%): 1, mix well and set aside;

[0017] Step 3. The mixture prepared in Step 2 is subjected to hydrogen reduction in a tubular reduction furnace, wherein the flow rate of hydrogen is 30-80ml / cm 3 min, the reduction temperature is 800-1100°C, the holding ti...

Embodiment 1

[0023] A preparation method of spherical single crystal tungsten powder for thermal spraying, comprising the following steps:

[0024] Step 1. Weigh an ammonium tungstate solution with a mass concentration of 33%, then add a mixture of lithium carbonate and sodium chloride to the weighed ammonium tungstate solution, mix well, dry and concentrate to obtain a precursor, and set aside; Wherein, the total addition of lithium carbonate and sodium chloride is 2g / L, and the mass ratio of lithium carbonate and sodium chloride is 1:3;

[0025] Step 2. Select spherical tungsten powder with a grain size of 1 μm as the mother crystal, and add it to the precursor prepared in step 1 according to the mass ratio of 0.1%:1, mix well and set aside;

[0026] Step 3, the mixture prepared in step 2 is subjected to hydrogen reduction in a tubular reduction furnace, wherein the flow rate of hydrogen is 40ml / cm 3 Min, the reduction temperature is 900°C, the holding time is 2 hours, after the reducti...

Embodiment 2

[0033] A preparation method of spherical single crystal tungsten powder for thermal spraying, comprising the following steps:

[0034] Step 1. Weigh an ammonium tungstate solution with a mass concentration of 37%, then add a mixture of lithium carbonate and sodium chloride to the weighed ammonium tungstate solution, mix well, dry and concentrate to obtain a precursor, and set aside; Wherein, the total addition of lithium carbonate and sodium chloride is 3g / L, and the mass ratio of lithium carbonate and sodium chloride is 2:3;

[0035] Step 2. Select spherical tungsten powder with a grain size of 3 μm as the mother crystal, and add it to the precursor prepared in step 1 according to the mass ratio of 0.3%:1, and mix it evenly for later use;

[0036] Step 3, the mixture prepared in step 2 is subjected to hydrogen reduction in a tubular reduction furnace, wherein the flow rate of hydrogen is 70ml / cm 3 Min, the reduction temperature is 1050°C, the holding time is 2 hours, after t...

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Abstract

The invention discloses a preparation method for a spherical monocrystal tungsten powder for thermal spraying. The preparation method comprises the following steps: firstly adding a certain amount of a mixture of lithium carbonate and sodium chloride in an ammonium tungstate solution as a mother solution, and concentrating to obtain a precursor through heating drying; then selecting a spherical tungsten powder as a mother crystal, adding the spherical tungsten powder in the precursor according to a certain ratio, uniformly mixing, and then placing the mixture in a tubular reduction furnace and carrying out hydrogen gas reduction, and then sequentially carrying out ultrasonic cleaning, vacuum drying and grinding spheroidization to prepare an intermediate; and carrying out airflow classification on the prepared intermediate to obtain the spherical monocrystal tungsten powder. The preparation method disclosed by the invention is simple in process equipment and high in production efficiency; and the prepared spherical monocrystal tungsten powder has a perfect crystal, compact particles, a high sphericity degree, high flowability, a high purity, a high coating hardness, a high powder-applying rate and a low porosity.

Description

technical field [0001] The invention relates to the technical fields of surface engineering and thermal spraying, in particular to a method for preparing spherical single crystal tungsten powder for thermal spraying. Background technique [0002] Thermal spraying technology is a rapidly developing surface strengthening technology. It uses special equipment to heat metal or non-metallic materials to a molten or semi-melted state by using a heat source, and sprays it onto the surface of the workpiece with a high-speed airflow to form a coating to improve the wear resistance and corrosion resistance of the workpiece. [0003] Tungsten has the advantages of high melting point, high hardness, low coefficient of thermal expansion, and strong ability to absorb rays, and is widely used in aviation, aerospace, military industry, and electronics industry. Among them, single crystal tungsten powder for thermal spraying is widely used in high-temperature wear-resistant coatings, sprayi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F9/22B22F1/00C30B29/02C30B1/10
CPCB22F1/0007B22F9/22C30B1/10C30B29/02
Inventor 谢屹峰杨跃刘宝刚张国锋郭望望
Owner LUOYANG GOLDEN EGRET GEOTOOLS
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