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Carbonitriding method for metal surface

A metal surface, carbonitriding technology, applied in metal material coating process, electrolytic inorganic material coating, coating, etc., can solve problems such as improper air pressure adjustment, unreasonable air flow in the furnace, uneven hardness and permeation layer, etc. , to achieve the effect of promoting the diffusion

Active Publication Date: 2014-12-24
CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in the process of gas carbonitriding, due to improper adjustment of air pressure, uneven temperature or unreasonable air flow in the furnace, etc., the hardness and inhomogeneity of the carburized layer are often caused.

Method used

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  • Carbonitriding method for metal surface

Examples

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Effect test

Embodiment 1

[0022] A method for metal surface carbonitriding treatment of the present invention, comprising the following steps:

[0023] (1) Argon arc welding was used to weld Fe-Cr wire with a diameter of 1mm to the surface of polished 304 stainless steel as electrode lead wires, cleaned with acetone and ethanol successively, and dried for use.

[0024] (2) Preparation of LiCl-KCl-KNO 2 Mixed salt, based on mole fraction, LiCl is 49.3mol%, KCl is 50.2mol%, KNO 2 0.5 mol%. LiCl-KCl-KNO 2 The mixed salt was placed in a muffle furnace and dried at 200 °C for 48 h under the protection of argon.

[0025] (3) The dried LiCl-KCl-KNO 2 The mixed salt is placed in a high-temperature well-type furnace, and under the protection of argon, it is first heated to 550°C and kept at this temperature, so that the mixed salt is in a molten state and forms LiCl-KCl-KNO 2 Molten salt, then the 304 stainless steel with the electrode lead prepared by step (1) is used as the cathode, and the carbon rod is...

Embodiment 2

[0028] A method for metal surface carbonitriding treatment of the present invention, comprising the following steps:

[0029] (1) Argon arc welding was used to weld Fe-Cr wire with a diameter of 1 mm to the surface of polished 316L stainless steel as electrode lead wires. After cleaning with acetone and ethanol successively, dry it for use.

[0030] (2) Preparation of LiCl-KCl-KNO 2 Mixed salt, based on mole fraction, LiCl is 48.8mol%, KCl is 50.2mol%, KNO 2 1 mol%. LiCl-KCl-KNO 2 The mixed salt was placed in a muffle furnace and dried at 200 °C for 48 h under the protection of argon.

[0031] (3) The dried LiCl-KCl-KNO 2 The mixed salt is placed in a high-temperature well-type furnace, and under the protection of argon, it is first heated to 550°C and kept at this temperature, so that the mixed salt is in a molten state and forms LiCl-KCl-KNO 2 Molten salt, then the 316L stainless steel with the electrode lead prepared in step (1) is used as the cathode, and the carbon r...

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Abstract

The invention discloses a carbonitriding method for a metal surface. The method comprises the following steps of: welding an electrode lead on the metal surface, then preparing LiCl-KCl-KNO2 mixed salt, drying the LiCl-KCl-KNO2 mixed salt under the protection of an inert gas, then under the protection of the inert gas, heating the dried LiCl-KCl-KNO2 mixed salt to the temperature of 450 to 650 DEG C and keeping the temperature all the time, facilitating the mixed salt in a molten state to form LiCl-KCl-KNO2 molten salt, taking metal with the electrode lead as a cathode, and a carbon rod as an anode, placing in the LiCl-KCl-KNO2 molten salt and carrying out electrochemical carbo-nitridation on the metal surface to form a carbonitriding layer on the metal surface. The carbonitriding method for the metal surface disclosed by the invention has the advantages of short treatment time, low temperature, and controllable compositions and thicknesses of a permeation layer.

Description

technical field [0001] The invention relates to a method for carbonitriding (ie nitrocarburizing) on ​​a metal surface, in particular to a method for carbonitriding a metal surface by using an electrochemical method in a molten salt system. Background technique [0002] Carbonitriding is a chemical heat treatment method that is widely used on metal surfaces. Its process is to simultaneously infiltrate carbon and nitrogen into the surface of the metal to improve the strength or hardness of the metal surface. At present, there are mainly two methods of liquid carbonitriding and gas carbonitriding. The liquid carbonitriding method is gradually replaced by gas carbonitriding because the medium used is a highly toxic cyanide salt, which pollutes the environment. However, in the process of gas carbonitriding, due to improper adjustment of air pressure, uneven temperature or unreasonable air flow in the furnace, etc., the hardness and inhomogeneity of the carburized layer are ofte...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C25D9/08C23C8/54
Inventor 任延杰陈荐文雯陈建林何建军邱玮
Owner CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY