HEAT TREATING METHOD FOR IMPROVING THE WEAR-RESISTANCE AND CORROSION-RESISTANCE OF CHROMIUM PLATINGS
PURPOSE: A heat treatment method is provided to overcome deterioration of corrosion resistance caused by micro cracks of the chromium plating layer and improve hardness of trivalent chromium plating layer to improve wear resistance thereof by heat treating chromium plating layer plated in an iron ba...
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Zusammenfassung: | PURPOSE: A heat treatment method is provided to overcome deterioration of corrosion resistance caused by micro cracks of the chromium plating layer and improve hardness of trivalent chromium plating layer to improve wear resistance thereof by heat treating chromium plating layer plated in an iron based matrix metal under the proper conditions. CONSTITUTION: The heat treatment method for improving corrosion resistance and wear resistance of chromium plating layer(1) comprises the process of heating a work to be plated the surface of iron based matrix(2) of which is exposed by cracks(3) penetrating chromium plating layer plated on the surface of an iron based matrix metal at an oxidative gas atmosphere having an atmospheric pressure or more, thereby forming an oxidation layer(2a) containing magnetite (Fe3O4) on the surface of the work to be plated, wherein the process of forming the oxidation layer is performed by heating the work to be plated to the temperature range of 180 to 570 deg.C at an oxidative gas atmosphere for 10 to 600 minutes, wherein the oxidation layer formed by heating the work to be plated at an oxidative gas atmosphere is an oxidation layer containing 60 wt.% or more of magnetite (Fe3O4), wherein the oxidative gas is steam, carbon dioxide, air or a mixture thereof, and wherein the heat treatment method further comprises the process of performing nitro-carburizing before the process of forming the oxidation layer by heating the work to be plated at the oxidative gas atmosphere, thereby forming -phase (Fe2-3N) iron nitride on the surface of an iron based matrix exposed by cracks.
본 발명은 철계 기지금속에 도금된 크롬도금층을 적정한 조건으로 열처리하여 크롬도금층의 미세크랙으로 인하여 발생하는 내식성 저하를 극복하고, 3가 크롬도금층의 경도를 향상시켜 내마모성을 향상시키기 위한 크롬도금층의 내식성 및 내마모성을 향상시키는 열처리방법에 관한 것이다. 이를 위하여, 본 발명은 철계 기지금속의 표면에 도금된 크롬도금층을 관통하는 크랙으로 인하여 철계기지 표면이 노출된 도금재를 대기압 이상의 산화성가스 분위기에서 가열하여 그 표면에 마그네타이트(Magnetite; FeO)를 함유하는 산화층이 형성되도록 하는 것을 특징으로 하는 크롬도금층의 내식성 및 내마모성을 향상시키는 열처리방법을 제공한다. 이와 같이, 본 발명은 도금 후 간단한 열처리공정을 통해 우수한 크롬도금층의 내식성 및 내마모 특성을 얻을 수 있고, 크롬도금 적용 제품의 불량률을 대폭 줄일 수 있으며, 제조원가를 절감하고, 또한 수명을 크게 향상시킬 수 있다. |
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