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Spherical powder and its preparation

A powder and spherical technology, which is applied in the field of spherical powder and its preparation, can solve problems such as insufficient strength of tungsten carbide alloys, and achieve the effects of uniform composition and structure, reduced heat loss, and increased grain yield

Inactive Publication Date: 2013-04-24
美塔斯菲尔技术公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0011] Tungsten carbide alloys manufactured using traditional processes such as post-melt crushing have insufficient strength due to the presence of microcracks

Method used

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  • Spherical powder and its preparation
  • Spherical powder and its preparation
  • Spherical powder and its preparation

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0077] Tungsten with a melting point of 3380° C. was atomized on a centrifugal atomization device equipped and not equipped with the device of the invention described herein. Nebulization was performed under pure nitrogen atmosphere. Crucibles were used with and without the lining according to the invention. The diameter of the opening edge of the crucible is 60mm. The rotation speed of the crucible was 5000 rpm. The current of the plasma arc alternates within the limits of 800 to 1500A, and the arc voltage is 70 to 85V. The gravel is preheated by bringing the moving raw gravel into contact with the face of a tungsten trough surrounded by tubular heaters. The heater is made of carbon-carbon composite material, and the heater is heated to 2500°C by passing electric current from an automatic power supply. The outlet temperature of the grit flowing out of the heater is 1850-1950°C. The atomization results are shown in Table 1. Using the method to atomize tungsten on the dev...

example 2

[0081] Sintered tungsten carbide (tungsten carbide eutectic mixture WC-W 2 C) Nebulize. Crushed sintered tungsten carbide grit with a particle size of less than 1 mm is used for atomization. The carbon content in the original gravel is 4.0% of its mass, and the average microhardness of crushed and sintered tungsten carbide is Hμ-1800HV. The current of the plasma arc alternates within the limits of 800 to 1500A, and the arc voltage is 70 to 85V. Cemented tungsten carbide grit is preheated by bringing moving raw grit into contact with the inner surface of a tubular heater. The heater is made of carbon-carbon composite material, and the heater is heated to 2200°C by passing electric current from an automatic power supply. The outlet temperature of the grit flowing out of the heater is 1850-1900°C. Atomization was performed in a pure nitrogen atmosphere using a crucible with an open edge diameter of 62 mm. A comparative atomization of cemented tungsten carbide grit was also c...

example 3

[0085] Example 3 (comparison)

[0086] The particle size range of the prepared powder is 50 to 800 microns. The microhardness of the molten tungsten carbide powder produced by the method is 3400-3550kgf / mm 2 In the range. This is 1.25-1.27 times the microhardness value of tungsten carbide powder produced in an argon atmosphere. The increase of microhardness significantly enhances the wear resistance of the material.

[0087] The apparent density of the obtained powder is 8.5-10.0g / cm 3 In the range of , this apparent density value indirectly indicates its internal porosity and deviation from a perfect sphere.

[0088] Using high currents slightly improves the hardness and strength properties of the product. However, due to the impact of high-intensity current, the electrodes are easily damaged, and the electrodes must be replaced frequently. In addition, the edges of the crucible are severely worn when high currents are used. This causes instability in the atomization...

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Abstract

A spherical tungsten carbide powder is characterized by that the material has a microhardness higher than 3600 kgf / mm2, and that the powder has an apparent density from 9.80 to 11.56 g / cm3. A method for the manufacture of a powder comprises the steps: a) providing a chamber comprising a rotatable crucible, b) adding material into said rotatable crucible, c) melting the material using a plasma arc discharge, d) rotating the crucible to atomize the molten material to form liquid droplets, with subsequent cooling of the droplets to obtain a powder, wherein the material added into said rotatable crucible is heated to a temperature above 40% of the melting temperature of the material before it enters the crucible. It is possible to reduce the current required for melting the stock. Heat losses are decreased, and the spherical powder obtained during atomization becomes more homogeneous in its composition and structure. The cost is reduced.

Description

technical field [0001] The present invention generally relates to a process for the preparation of powders by thermal centrifugal atomization. The invention also relates to a spherical tungsten carbide powder. The invention further relates to a device for carrying out the method. Background technique [0002] The wear resistance of composites depends on factors such as reinforcing particle concentration and particle size, as well as matrix properties. Under the same conditions, an additional increase in wear resistance can be achieved by improving the properties of the particles in the composite. Preparation of pellets by crushing ingots can lead to cracks, reed marks and other defects in the pellets as a broken seat under the influence of load. Therefore, there is a need in the art to improve the microstructure of the particles, thereby improving their mechanical properties. [0003] The former Soviet patent document SU1802466 discloses a method for preparing refractory...

Claims

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Application Information

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IPC IPC(8): C01B31/34C22C29/08B01J2/14B22F9/00C01B32/949
CPCB22F9/00B01J2/18B01J2/14C22C29/08B01J2/04C01B31/34C01P2006/10C01P2004/60C01P2004/61C01B32/949
Inventor 鲁斯兰·阿列克谢耶维奇·舍甫琴科安德瑞·帕夫洛维奇·丘卡诺夫伯里斯·弗拉基米罗维奇·萨夫罗诺夫尤里·詹那迪维奇·纳杰日金亚历山德拉·尤里维奇·瓦赫鲁申
Owner 美塔斯菲尔技术公司
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