Method for Activating Surface of Metal Member

Inactive Publication Date: 2007-09-06
PARKER NETSUSHORI KOGYO CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0025] A passivated film on a surface of a high-alloy steel member makes it difficult to apply diffusion treatment, such as gas nitriding or gas carburizing, that forms a nitrided layer, carburized layer or carbonitrided layer on the surface of the steel member. According to the present invention, an activating treatment method is provided for the surface of the metal member. This method is not accompanied by problems of conventional activation treatment with a halide, such as furnace deposits, furnace wall erosion and effluent gas detoxification treatment, and is useful as pretreatment for diffusion treatment. According to this method, the passivated surface of the high-alloy steel member can be activated by using a gas commonly employed in gas heat treatment, and forming HCN gas in a heating furnace while making use of catalytic action of the steel member or a surface of the furnace.
[0026] The present invention will next be described in more detail based on best modes for carrying out the invention.
[0027] According to Patent Document 2 referred to in the above, CH3. (methyl radicals) formed by the pyrolysis of acetone in the formula (1) reduce an oxide film on a surface of a metal member. The CO formed in the above-described formula (1) and (2) reacts with ammonia as atmosphere gas on the metal surface to form HCN. HCN acts on the metal oxide film in accordance with the above-described formula (5).
[0028] From a comparison between the formula (2) and the formula (5), the CH3. formed by the pyrolysis of acetone an

Problems solved by technology

Upon applying such treatment to a surface of a member made of alloy steel, especially high-alloy steel, the penetration and diffusion of nitrogen or carbon into the surface of the metal member is prevented by a passivated film (an oxide or the like) which exists on the surface of the member, thereby possibly resulting in the occurrence of poor treatment or uneven treatment of the member as a problem.
However, the surface activation of a metal member by such a chloride results in the erosion of a furnace wall made of bricks or a metal by HCl formed through decomposition, and in gas nitriding or gas softnitriding, HCl so formed reacts with ammonia as atmosphere gas to form ammonium chloride, which not only dep

Method used

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  • Method for Activating Surface of Metal Member
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  • Method for Activating Surface of Metal Member

Examples

Experimental program
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Effect test

example 1

[0051] Using the SUS310S Muffle furnace of 100-L internal capacity shown in FIG. 1, SUS304 plates were set in the furnace, NH3 gas and N2 gas were fed at flow rates of 200 L / H, respectively, and the furnace atmosphere was heated from room temperature to 550° C. in 75 minutes. At the time point that the atmosphere temperature had reached 100° C. in the course of the heating (at the 18th minute after the initiation of the heating), an injection of acetylene gas was initiated at 2 L / hr. After heated to 550° C., the atmosphere temperature was maintained for 2 hours. At that time point, the injection of acetylene gas was terminated and instead, NH3 gas and N2 gas were then fed at 550° C. for 4 hours to allow nitriding to proceed. Subsequently, the heating was stopped and N2 gas alone was continuously fed to cool down the furnace. When the atmosphere temperature had dropped to 100° C. or lower, the specimens were taken out of the furnace.

[0052] Effluent gas from the furnace was branched ...

example 2

[0053] SUS304 plates were set in the Muffle furnace employed in Example 1, NH3 gas and N2 gas were fed at flow rates of 200 L / H, respectively, and the furnace atmosphere was heated from room temperature to 550° C. in 75 minutes. At the time point that the atmosphere temperature had reached 100° C. in the course of the heating (at the 18th minute after the initiation of the heating), an injection of propane gas was tinitiated at 5 L / hr. After heated to 550° C., the atmosphere temperature was maintained for 2 hours. At that time point, the injection of propane gas was terminated and instead, NH3 gas and N2 gas were then fed at 550° C. for 4 hours to allow nitriding to proceed. Subsequently, the heating was stopped and N2 gas alone was continuously fed to cool down the furnace. When the atmosphere temperature had dropped to 100° C, or lower, the specimens were taken out of the furnace.

[0054] Effluent gas from the furnace was branched off to have a portion of the effluent gas absorbed ...

example 3

[0055] SUS304 plates were set in the Muffle furnace employed in Example 1, NH3 gas and N2 gas were fed at flow rates of 200 L / H, respectively, and the furnace atmosphere was heated from room temperature to 550° C. in 75 minutes. At the time point that the atmosphere temperature had reached 100° C. in the course of the heating (at the 18th minute after the initiation of the heating), an injection of CO gas was initiated at 5 L / hr. After heated to 550° C., the atmosphere temperature was maintained for 2 hours. At that time point, the injection of CO gas was terminated and instead, NH3 gas and N2 gas were then fed for 4 hours to allow nitriding to proceed. Subsequently, the heating was stopped and N2 gas alone was continuously fed at 550° C. to cool down the furnace. When the atmosphere temperature had dropped to 100° C. or lower, the specimens were taken out of the furnace.

[0056] Effluent gas from the furnace was branched off to have a portion of the effluent gas absorbed in a 2 wt. ...

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Abstract

A passivated film on a surface of a high-alloy steel member makes it difficult to apply diffusion treatment, such as gas nitriding or gas carburizing, that forms a nitrided layer, carburized layer or carbonitrided layer on the surface of the steel member. An activating treatment method is provided for the surface of the metal member. This method is not accompanied by problems of conventional activation treatment with a halide, such as furnace deposits, furnace wall erosion and effluent gas detoxification treatment, and is useful as pretreatment for diffusion treatment. According to this method, the passivated surface of the high-alloy steel member can be activated by using a gas commonly employed in gas heat treatment, and forming HCN gas in a heating furnace while making use of catalytic action of the steel member or a surface of the furnace.

Description

TECHNICAL FIELD [0001] The invention of the present application relates to a method for the pretreatment of a metal member to activate a surface of the metal member before applying diffusion treatment such as nitriding or carburizing to the metal member. BACKGROUND ART [0002] To improve mechanical properties such as abrasion resistance and fatigue strength, gas nitriding or gas carburizing that forms a nitrided layer or carburized layer in a surface of a metal member is widely applied primarily to members made of iron-based material. [0003] Upon applying such treatment to a surface of a member made of alloy steel, especially high-alloy steel, the penetration and diffusion of nitrogen or carbon into the surface of the metal member is prevented by a passivated film (an oxide or the like) which exists on the surface of the member, thereby possibly resulting in the occurrence of poor treatment or uneven treatment of the member as a problem. Before such diffusion treatment, activation tr...

Claims

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Application Information

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IPC IPC(8): C23C22/00C23C8/02
CPCC23C8/02C23C8/30C23C8/32
Inventor HOSHINO, KAORUMIYASHITA, MAKOTOKAWAMURA, TAKASHITOTSUKA, TOSHIKOEIRAKU, HIROSHIYASHIRO, KUNIJIKUROSAWA, TAKUMI
Owner PARKER NETSUSHORI KOGYO CO LTD
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