ASTM-B994 › Standard Specification for Nickel-Cobalt Alloy Coating
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This specification outlines the requirements for corrosion-resistant coatings of electrodeposited nickel-cobalt on metallic substrates and electrodeposited nickel-cobalt used for electroforming. It includes an accelerated exposure test method to evaluate the effects of corrosion and galling on the nickel-cobalt alloy coating, as well as a means of reporting the results to the purchaser.
This specification incorporates a classification scheme that establishes service condition by thickness, classes of deposits based on the level of monitoring, and type based on supplemental coatings used after deposition. It also provides requirements for materials and manufacture; acceptance tests in terms of appearance, adhesion, and coating thickness, qualification tests (galling test, chemical composition, hydrogen embrittlement test, corrosion testing, environmental testing, third party reports, frequency of qualification tests); sampling; rejection; and certification.
1.1 This specification describes the requirements for corrosion-resistant coatings of electrodeposited nickel-cobalt on metallic substrates and electrodeposited nickel-cobalt used for electroforming.
Note 1: The nickel-cobalt alloy is principally deposited as a coating on steel products. It can also be electrodeposited on iron, stainless steel, aluminum, titanium and any other metal substrate.
Note 2: The nickel-cobalt alloy coating has a low coefficient of friction of 0.08 that provides a dry lubricant on part surfaces that are in contact with each other and are subject to galling.
1.2 This specification incorporates an accelerated exposure test method to evaluate the effects of corrosion and galling on the coating, and incorporates a means of reporting the results to the purchaser.
1.3 The specification incorporates a classification scheme that establishes service conditions for thickness, classes of deposits based on the level of monitoring, and type based on supplemental coatings used after deposition.
1.4 The coating thickness ranges from 5 to >30 μm, and it can be applied to machined parts, springs, latches, threaded parts, fasteners, etc. The deposit can also be used to electroform parts requiring high strength with the alloy being maintained at 50% nickel-cobalt.
1.5 The nickel-cobalt alloy is used to protect ferrous metals in contact with corrosive environments such as: oil and gas production facilities, costal marine, and ACQ (Alkaline Copper Quaternary) treatments for wood treatments.
1.6 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1.8 This standard has been revised to comply with the Restriction of Hazardous Substances RoHS Requirements that seek to limit the exposure of workers and the public to toxic metals. The nickel-cobalt alloy does not contain any of the six Restricted Hazardous Substances.
alloy; coating; cobalt; corrosion; corrosion in threaded articles; corrosion rate; dismantle; electrochemical testing; metal coating; nickel; nickel-cobalt alloy; performance; protective coating; salt spray (fog) chamber; torque ratio;; ICS Number Code 25.220.40 (Metallic coatings)
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March 15, 2015