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Method for preparing spherical nano tungsten powder

A nano-tungsten powder, spherical technology, applied in the field of powder metallurgy powder making, can solve the problems of arc extinguishing and plasma arc reduction, and achieve the effect of full cylinder, improved production efficiency and short process flow

Inactive Publication Date: 2013-01-02
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

DC Ar+H 2 Plasma can provide highly reactive H, H , H + and other particles, which promote the forward progress of the reduction reaction, but adding H to the pure Ar plasma 2 It will cause the plasma arc to shrink or even arc extinguished

Method used

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  • Method for preparing spherical nano tungsten powder
  • Method for preparing spherical nano tungsten powder
  • Method for preparing spherical nano tungsten powder

Examples

Experimental program
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Effect test

Embodiment 1

[0022] By adjusting the plasma parameters, the output power of the high-frequency machine is 30KW, both the middle gas and the side gas use Ar, and the flow rate of the middle gas is 1m 3 / h, the edge air flow is 4m 3 / h, H 2 The flow rate is 0.3m 3 / h, NH 3 The flow rate is 1.2m 3 / h, to establish a stable high frequency Ar+NH 3 +H 2 Mixed gas plasma, using NH 3 and H 2 As the carrier gas, the raw material APT is added to the plasma arc in stable operation. The particle size of APT is 10μm, and the feeding amount is 3g / min. The stainless steel casing of the cooling chamber is passed through reverse cooling water, and the upper part of the cooling chamber is cooled by tangential cooling through the ventilation flange. Gas, the cooling water inlet temperature is 10°C, the cooling gas is inert gas Ar, and the flow rate is 2m 3 / h. The reaction time is 2 hours. After the reduction, pass Ar for half an hour to protect the product. After the reactor is cooled, the material...

Embodiment 2

[0024] By adjusting the plasma parameters, the output power of the high-frequency machine is 33KW, both the middle gas and the edge gas use Ar, and the flow rate of the middle gas is 2m 3 / h, edge air flow is 5m 3 / h, H 2 The flow rate is 0.8m 3 / h, NH 3 The flow rate is 0.8m 3 / h, to establish a stable high frequency Ar+NH 3 +H 2 Mixed gas plasma, using NH 3 and H 2 As the carrier gas, the raw material APT is added to the plasma arc in stable operation. The particle size of APT is 100μm, and the feeding amount is 20g / min. The stainless steel casing of the cooling chamber is passed through reverse cooling water, and the upper part of the cooling chamber is cooled by tangential cooling through the ventilation flange. Gas, the cooling water inlet temperature is 15°C, the cooling gas is inert gas Ar, and the flow rate is 6m 3 / h. The reaction time was 3 hours, and the product was protected by passing Ar for half an hour after the reduction. After the reactor is cooled, ...

Embodiment 3

[0026] By adjusting the plasma parameters, the output power of the high-frequency machine is 35KW, both the middle gas and the edge gas use Ar, and the flow rate of the middle gas is 4m 3 / h, the edge air flow rate is 6m 3 / h, H 2 The flow rate is 1.2m 3 / h, NH 3 The flow rate is 0.3m 3 / h, to establish a stable high frequency Ar+NH 3 +H 2 Mixed gas plasma, using NH 3 and H 2 As the carrier gas, the raw material APT is added to the plasma arc in stable operation. The particle size of APT is 150μm, and the feeding amount is 50g / min. The stainless steel casing of the cooling chamber is passed through reverse cooling water, and the upper part of the cooling chamber is cooled by tangential cooling through the ventilation flange. Gas, the cooling water inlet temperature is 15°C, the cooling gas is inert gas Ar, and the flow rate is 8m 3 / h. After the reduction, pass Ar for half an hour to protect the product. After the reactor is cooled, the material is collected in the r...

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Abstract

The invention discloses a method for preparing the spherical nano tungsten powder by using high frequency Ar+NH3+H2 mixed gas plasma to reduce ammonium paratungstate (APT) directly. In a high frequency plasma device, central gas and side gas uses Ar, carrier gas uses NH3and H2, and stably and continuously operating high frequency Ar+NH3+H2 mixed gas plasma is built. Material APT is added into the plasma by the drive of the carrier gas through a feeder and is further reduced to metal tungsten under the atmosphere of high reactivity high frequency Ar+NH3+H2 mixed gas plasma, and the metal tungsten is subjected to subsequent cooling and collection to obtain the spherical nano tungsten powder. The frequency Ar+NH3+H2 mixed gas plasma has the advantages that arc cylinders are long and thick, the cylinders are full, exhaust plume has no gap, problems of defects in arc cylinder contraction and exhaust plume and short reaction time of ordinary high frequency Ar+ H2 plasma are overcome, dwell time of materials in plasma arcs is prolonged, an ATP reduction process is strengthened, and the spherical nano tungsten powder is obtained. The spherical nano tungsten powder can be used in fields of electric vacuum cathode materials, thermal spraying and powder metallurgy.

Description

technical field [0001] The invention belongs to a preparation method of spherical nano-tungsten powder in the field of powder metallurgy powder making, in particular to a high-frequency Ar+NH powder that adopts continuous and stable operation. 3 +H 2 The mixed gas plasma arc directly reduces ammonium paratungstate to prepare spherical nano-tungsten powder. This preparation method does not require calcination and other intermediate processes, and the spherical nano-tungsten powder is directly prepared in the plasma. Background technique [0002] Tungsten (W), a metal with high melting point and high hardness, is an important strategic material, which is widely used in tungsten carbide tools, electric filaments, tool steel additives, rockets, spacecraft, nuclear reactors and other fields. With the development of science and technology, new special requirements are constantly put forward for the raw material tungsten powder, such as spherical tungsten powder is required for el...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F9/28
Inventor 袁方利张海宝白柳杨尹春雷
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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