1、Designation: B 733 04Standard Specification forAutocatalytic (Electroless) Nickel-Phosphorus Coatings onMetal1This standard is issued under the fixed designation B 733; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This specification covers requirements
3、 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
4、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 resistan
5、ce 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 ci
6、rcu-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
7、 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 microcryst
8、alline. These coatings areused in electronic applications providing solderability, bond-ability, 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 corros
9、ion 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 ferr
10、omagnetic.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
11、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:3B 368 Test Method for Copper-Accelerated Acetic Acid-Salt Spray (Fog) Testing (CASS Te
12、sting)B 374 Terminology Relating to ElectroplatingB 380 Test Method of Corrosion Testing of DecorativeElectrodeposited Coatings by the Corrodkote ProcedureB 487 Test Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examination of aCross SectionB 499 Test Method for Measure
13、ment of Coating Thick-nesses by the Magnetic Method: Nonmagnetic Coatings onMagnetic Basis MetalsB 504 Test Method for Measurement of Thickness of Me-tallic Coatings by the Coulometric MethodB 537 Practice for Rating of Electroplated Panels Subjectedto Atmospheric Exposure1This specification is unde
14、r the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and is the direct responsibility of SubcommitteeB08.08.01 on Engineering Coatings.Current edition approved Aug. 1, 2004. Published August 2004. Originallyapproved in 1984. Last previous edition approved in 1997 as B 733 97.2T
15、he 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
16、Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.B 567 Test Method for Measurement of Coating Thicknessby the Beta Backscatter MethodB 568 Test Method for Measurement of Coating Thicknessby X-Ray Spectr
17、ometryB 571 Practice for Qualitative Adhesion Testing of MetallicCoatingsB 578 Test Method for Microhardness of ElectroplatedCoatingsB 602 Test Method for Attribute Sampling of Metallic andInorganic CoatingB 667 Practice for Construction and Use of a Probe forMeasuring Electrical Contact ResistanceB
18、 678 Test Method for Solderability of Metallic-CoatedProductsB 697 Guide for Selection of Sampling Plans for Inspectionof Electrodeposited Metallic and Inorganic CoatingsB 762 Test Method of Variables Sampling of Metallic andInorganic CoatingsB 849 Specification for Pre-Treatments of Iron or Steel f
19、orReducing Risk of Hydrogen EmbrittlementB 850 Guide for Post-Coating Treatments of Steel for Re-ducing the Risk of Hydrogen EmbrittlementB 851 Specification for Automated Controlled Shot Peeningof Metallic Articles Prior to Nickel, Autocatalytic Nickel,Chromium, or As A Final FinishD 1193 Specifica
20、tion for Reagent WaterD 2670 Test Method for Measuring Wear Properties ofFluid Lubricants (Falex Pin and Vee Block Method)D 2714 Test Method for Calibration and Operation of theFalex Block-on-Ring Friction and Wear Testing MachineD 3951 Practice for Commercial PackagingD 4060 Test Method for Abrasio
21、n Resistance of OrganicCoatings by the Taber AbraserE 60 Practice for Analysis of Metals, Ores, and RelatedMaterials by Molecular Absorption SpectrometryE 140 Hardness Conversion Tables for Metals RelationshipAmong Brinell Hardness, Vickers Hardness, RockwellHardness, Superficial Hardness, Knoop Har
22、dness, andScleroscope HardnessE 156 Test Method for Determination of Phosphorus inHigh-Phosphorus Brazing Alloys (Photometric Method)4E 352 Test Methods for Chemical Analysis of Tool Steelsand Other Similar Medium-and High-Alloy SteelF 519 Test Method for Mechanical Hydrogen Embrittle-ment Evaluatio
23、n of Plating Processes and Service Environ-mentsG 5 Reference Test Method for Making Potentiostatic andPotentiodynamic Anodic Polarization MeasurementsG 31 Practice for Laboratory Immersion Corrosion Testingof MetalsG 59 Practice for Conducting Potentiodynamic PolarizationResistance MeasurementsG 85
24、 Practice for Modified Salt Spray (Fog) Testing2.2 Military Standards:MIL-R-81841 Rotary Flap Peening of Metal Parts5MIL-S-13165 Shot Peening of Metal Parts5MIL-STD-105 Sampling Procedures and Tables for Inspec-tion by Attribute52.3 ISO Standards:ISO 4527 Autocatalytic Nickel-Phosphorus CoatingsSpec
25、ification and Test Methods63. Terminology3.1 Definition:3.1.1 significant surfacesthose substrate surfaces whichthe coating must protect from corrosion or wear, or both, andthat are essential to the performance.3.2 Other DefinitionsTerminology B 374 defines most ofthe technical terms used in this sp
26、ecification.4. Coating Classification4.1 The coating classification system provides for a schemeto select an electroless nickel coating to meet specific perfor-mance requirements based on alloy composition, thickness andhardness.4.1.1 TYPE describes the general composition of the de-posit with respe
27、ct to the phosphorus content and is divided intofive categories which establish deposit properties (see Table 1).NOTE 1Due to the precision of some phosphorus analysis methods adeviation of 0.5 % has been designed into this classification scheme.Rounding of the test results due to the precision of t
28、he limits provides foran effective limit of 4.5 and 9.5 % respectively. For example, coating witha test result for phosphorus of 9.7 % would have a classification of TYPEV, see Appendix X5, Alloy TYPEs.4.2 Service Condition Based on Thickness:4.2.1 Service condition numbers are based on the severity
29、 ofthe exposure in which the coating is intended to perform andminimum coating thickness to provide satisfactory perfor-mance (see Table 2).4Withdrawn.5Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.6Available from Am
30、erican National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.TABLE 1 Deposit Alloy TypesType Phosphorus % wtI No Requirement for PhosphorusII 1to3III 2to4IV 5to9V 10 and aboveTABLE 2 Service ConditionsCoating Thickness RequirementsService ConditionMinimum CoatingThickness
31、Specificationm in.SC0 Minimum Thickness 0.1 0.000004SC1 Light Service 5 0.0002SC2 Mild Service 13 0.0005SC3 Moderate Service 25 0.001SC4 Severe Service 75 0.003B7330424.2.2 SC0 Minimum Service, 0.1 mThis is defined by aminimum coating thickness to provide specific material prop-erties and extend the
32、 life of a part or its function. Applicationsinclude requirements for diffusion barrier, undercoat, electricalconductivity and wear and corrosion protection in specializedenvironments.4.2.3 SC1 Light Service, 5 mThis is defined by aminimum coating thickness of 5 m for extending the life ofthe part.
33、Typical environments include light-load lubricatedwear, indoor corrosion protection to prevent rusting, and forsoldering and mild abrasive wear.4.2.4 SC2 Mild Service, 13 mThis is defined by mildcorrosion and wear environments. It is characterized by indus-trial atmosphere exposure on steel substrat
34、es in dry or oiledenvironments.4.2.5 SC3 Moderate Service, 25 mThis is defined bymoderate environments such as non marine outdoor exposure,alkali salts at elevated temperature, and moderate wear.4.2.6 SC4 Severe Service, 75 mThis is defined by a veryaggressive environment. Typical environments would
35、 includeacid solutions, elevated temperature and pressure, hydrogensulfide and carbon dioxide oil service, high-temperature chlo-ride systems, very severe wear, and marine immersion.NOTE 2The performance of the autocatalytic nickel coating dependsto a large extent on the surface finish of the articl
36、e to be plated and howit was pretreated. Rough, non uniform surfaces require thicker coatingsthan smooth surfaces to achieve maximum corrosion resistance andminimum porosity.4.3 Post Heat Treatment ClassThe nickel-phosphoruscoatings shall be classified by heat treatment after plating toincrease coat
37、ing adhesion and or hardness (see Table 3).4.3.1 Class 1As-deposited, no heat treatment.4.3.2 Class 2Heat treatment at 260 to 400C to produce aminimum hardness of 850 HK100.4.3.3 Class 3Heat treatment at 180 to 200C for 2 to 4 hto improve coating adhesion on steel and to provide forhydrogen embrittl
38、ement relief (see section 6.6).4.3.4 Class 4Heat treatment at 120 to 130C for at least 1h to increase adhesion of heat-treatable (age-hardened) alumi-num alloys and carburized steel (see Note 3).4.3.5 Class 5Heat treatment at 140 to 150C for at least 1h to improve coating adhesion for aluminum, non
39、age-hardened aluminum alloys, copper, copper alloys and beryl-lium.4.3.6 Class 6Heat treatment at 300 to 320C for at least 1h to improve coating adhesion for titanium alloys.NOTE 3Heat-treatable aluminum alloys such as Type 7075 canundergo microstructural changes and lose strength when heated to ove
40、r130C.5. Ordering Information5.1 The following information shall be supplied by thepurchaser in either the purchase order or on the engineeringdrawing of the part to be plated:5.1.1 Title, ASTM designation number, and year of issue ofthis specification.5.1.2 Classification of the deposit by type, se
41、rvice condi-tion, class, (see 4.1, 4.2 and 4.3).5.1.3 Specify maximum dimension and tolerance require-ments, if any.5.1.4 Peening, if required (see 6.5).5.1.5 The tensile strength of the material in MPa (see 6.3.1and 6.6).5.1.6 Stress relief heat treatment before plating, (see 6.3).5.1.7 Hydrogen Em
42、brittlement Relief after plating, (see6.6).5.1.8 Significant surfaces and surfaces not to be plated mustbe indicated on drawings or sample.5.1.9 Supplemental or Special Government Requirementssuch as, specific phosphorus content, abrasion wear or corro-sion resistance of the coating, solderability,
43、contact resistanceand packaging selected from Supplemental Requirements.5.1.10 Requirement for a vacuum, inert or reducing atmo-sphere for heat treatment above 260C to prevent surfaceoxidation of the coating (see S3).5.1.11 Test methods for coating adhesion, composition,thickness, porosity, wear and
44、 corrosion resistance, if required,selected from those found in Section 9 and SupplementalRequirements.5.1.12 Requirements for sampling (see Section 8).NOTE 4The purchaser should furnish separate test specimens orcoupons of the basis metal for test purposes to be plated concurrently withthe articles
45、 to be plated (see 8.4).6. Materials and Manufacture6.1 SubstrateDefects in the surface of the basis metalsuch as scratches, porosity, pits, inclusions, roll and die marks,laps, cracks, burrs, cold shuts, and roughness may adverselyaffect the appearance and performance of the deposit, despitethe obs
46、ervance of the best plating practice. Any such defects onsignificant surfaces shall be brought to the attention of thepurchaser before plating. The producer shall not be responsiblefor coatings defects resulting from surface conditions of themetal, if these conditions have been brought to the attent
47、ion ofthe purchaser.6.2 PretreatmentA suitable method shall activate thesurface and remove oxide and foreign materials, which maycause poor adhesion and coating porosity.TABLE 3 Classification of Post Heat TreatmentCLASS DescriptionTemperature(C)Time (h)1 No Heat Treatment, As Plated2 Heat Treatment
48、 for Maximum HardnessTYPE I 260 20285 16320 8400 1TYPE II 350 to 380 1TYPE III 360 to 390 1TYPE IV 365 to 400 1TYPE V 375 to 400 13 Adhesion on Steel 180 to 200 2 to 44 Adhesion, Carburized Steel andAge Hardened Aluminum120 to 130 1 to 65 Adhesion on Beryllium andAluminum140 to 150 1 to 26 Adhesion
49、on Titanium 300320 14B733043NOTE 5Heat treatment of the base material may effect its metallur-gical properties. An example is leaded steel which may exhibit liquid orsolid embrittlement after heat treatment. Careful selection of the pre andpost heat treatments are recommended.6.3 Stress Relief:6.3.1 Pretreatment of Iron and Steel for Reducing the Risk ofHydrogen EmbrittlementParts that are made of steel withultimate tensile strength of greater than 1000 MPa (hardness of31 HRC), that have been machined, ground, cold formed, orcold straightened s
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