ASTM_B_733_-_15.pdf

Designation:B73315Standard Specification forAutocatalytic(Electroless)Nickel-Phosphorus Coatings onMetal1This standard is issued under the fixed designation B733;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This specification covers requirements for autocatalytic(electroless)nickel-phosphorus coatings applied from aqueoussolutions to metallic products for engineering(functional)uses.1.2 The coatings are alloys of nickel and phosphorus pro-duced by autocatalytic chemical reduction with hypophosphite.Because the deposited nickel alloy is a catalyst for the reaction,the process is self-sustaining.The chemical and physicalproperties of the deposit vary primarily with its phosphoruscontent and subsequent heat treatment.The chemical makeupof the plating solution and the use of the solution can affect theporosity and corrosion resistance of the deposit.For moredetails,see ASTM STP 265(1)2and Refs(2)(3)(4)and(5).1.3 The coatings are generally deposited from acidic solu-tions operating at elevated temperatures.1.4 The process produces coatings of uniform thickness onirregularly shaped parts,provided the plating solution circu-lates freely over their surfaces.1.5 The coatings have multifunctional properties,such ashardness,heat hardenability,abrasion,wear and corrosionresistance,magnetics,electrical conductivity provide diffusionbarrier,and solderability.They are also used for the salvage ofworn or mismachined parts.1.6 The low phosphorus(2 to 4%P)coatings are microc-rystalline and possess high as-plated hardness(620 to 750 HK100).These coatings are used in applications requiring abra-sion and wear resistance.1.7 Lower phosphorus deposits in the range between 1 and3%phosphorus are also microcrystalline.These coatings areused in electronic applications providing solderability,bondability,increased electrical conductivity,and resistance tostrong alkali solutions.1.8 The medium phosphorous coatings(5 to 9%P)are mostwidely used to meet the general purpose requirements of wearand corrosion resistance.1.9 The high phosphorous(more than 10%P)coatingshave superior salt-spray and acid resistance in a wide range ofapplications.They are used on beryllium and titanium parts forlow stress properties.Coatings with phosphorus contentsgreater than 11.2%P are not considered to be ferromagnetic.1.10 The values stated in SI units are to be regarded asstandard.1.11 The following precautionary statement pertains only tothe test method portion,Section 9,of this specification.Thisstandard does not purport to address all of the safety concerns,if any,associated with its use.It is the responsibility of the userof this standard to establish appropriate safety and healthpractices and determine the applicability of regulatory limita-tions prior to use.2.Referenced Documents2.1 ASTM Standards:3B368 Test Method for Copper-Accelerated Acetic Acid-SaltSpray(Fog)Testing(CASS Test)B374 Terminology Relating to ElectroplatingB380 Test Method for Corrosion Testing of DecorativeElectrodeposited Coatings by the Corrodkote ProcedureB487 Test Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examination ofCross SectionB499 Test Method for Measurement of Coating Thicknessesby the Magnetic Method:Nonmagnetic Coatings onMagnetic Basis MetalsB504 Test Method for Measurement of Thickness of Metal-lic Coatings by the Coulometric Method1This specification is under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and is the direct responsibility of SubcommitteeB08.03 on Engineering Coatings.Current edition approved Nov.1,2015.Published November 2015.Originallyapproved in 1984.Last previous edition approved in 2014 as B733 09(2014).DOI:10.1520/B0733-15.2The boldface numbers given in parentheses refer to a list of references at theend of the text.3For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 B537 Practice for Rating of Electroplated Panels Subjectedto Atmospheric ExposureB567 Test Method for Measurement of Coating Thicknessby the Beta Backscatter MethodB568 Test Method for Measurement of Coating Thicknessby X-Ray SpectrometryB571 Practice for Qualitative Adhesion Testing of MetallicCoatingsB578 Test Method for Microhardness of Electroplated Coat-ingsB602 Test Method for Attribute Sampling of Metallic andInorganic CoatingsB667 Practice for Construction and Use of a Probe forMeasuring Elect