Method for producing a chromium coating on a metal substrate

A metal substrate and coating technology, applied in the direction of metal material coating process, coating, superimposed layer plating, etc. And corrosion resistance is not enough to meet industrial needs and other problems, to achieve the effect of excellent corrosion resistance, safety and toxicity
CN104995339AActive Publication Date: 2015-10-21SAVROC
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
SAVROC
Publication Date
2015-10-21

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Abstract

In the method for producing a trivalent chromium based coating on a metal substrate,a layer of nickel phosphorus alloy is deposited on a metal substrateanda trivalent chromium layer is electroplated on the Ni-P layer. The coated metal substrate is subjected to one or more heat treatments to harden the coating and to produce multiphase layers including at least one layer containing crystalline Ni and crystalline Ni 3 P, and at least one layer containing crystalline Cr and crystal- line CrNi.By using this method it is possible to pro- duce coatings having a Vickers microhardness value higher than 2000 HV.
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Description

technical field

[0001] The present invention relates to a method for producing trivalent chromium-based coatings on metal substrates. The invention also relates to a coated article produced by said method. Background technique

[0002] Chromium coatings are widely used as surface coatings for metal articles due to their high hardness values, attractive appearance, and excellent wear and corrosion resistance. Traditionally, Cr deposition is accomplished by electroplating from an electrolytic bath containing hexavalent Cr ions. The process is highly toxic in nature. Many efforts have been made to develop alternative coatings and coating processes to replace hexavalent Cr in electroplating. Among these alternative processes, trivalent Cr plating is attractive due to its low cost, ease of fabrication by using environmentally friendly and non-toxic chemicals, and ability to produce bright Cr deposits. However, there is still a lack of an industrial-scale process that imparts ...

Claims

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