1、Designation: B994/B994M 15Standard Specification forNickel-Cobalt Alloy Coating1This standard is issued under the fixed designation B994/B994M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year of last revision. A number in
2、parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification describes the requirements forcorrosion-resistant coatings of electrodeposited nickel-cobalton metallic substrates and electro
3、deposited nickel-cobalt usedfor electroforming.NOTE 1The nickel-cobalt alloy is principally deposited as a coatingon steel products. It can also be electrodeposited on iron, stainless steel,aluminum, titanium and any other metal substrate.NOTE 2The nickel-cobalt alloy coating has a low coefficient o
4、ffriction of 0.08 that provides a dry lubricant on part surfaces that are incontact with each other and are subject to galling.1.2 This specification incorporates an accelerated exposuretest method to evaluate the effects of corrosion and galling onthe coating, and incorporates a means of reporting
5、the results tothe purchaser.1.3 The specification incorporates a classification schemethat establishes service conditions for thickness, classes ofdeposits based on the level of monitoring, and type based onsupplemental coatings used after deposition.1.4 The coating thickness ranges from 5 to 30 m,
6、and itcan be applied to machined parts, springs, latches, threadedparts, fasteners, etc. The deposit can also be used to electro-form parts requiring high strength with the alloy being main-tained at 50% nickel-cobalt.1.5 The nickel-cobalt alloy is used to protect ferrous metalsin contact with corro
7、sive environments such as: oil and gasproduction facilities, costal marine, andACQ (Alkaline CopperQuaternary) treatments for wood treatments.1.6 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equiva
8、lents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of
9、this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.8 This standard has been revised to comply with theRestriction of Hazardous Substances RoHS Requirements thatseek to limit the exposure of workers and the pub
10、lic to toxicmetals. The nickel-cobalt alloy does not contain any of the sixRestricted Hazardous Substances.2. Referenced Documents2.1 ASTM Standards:2A193/A193M Specification for Alloy-Steel and StainlessSteel Bolting for High Temperature or High PressureService and Other Special Purpose Application
11、sA194/A194M Specification for Carbon and Alloy Steel Nutsfor Bolts for High Pressure or High Temperature Service,or BothA681 Specification for Tool Steels AlloyB117 Practice for Operating Salt Spray (Fog) ApparatusB183 Practice for Preparation of Low-Carbon Steel forElectroplatingB242 Guide for Prep
12、aration of High-Carbon Steel for Elec-troplatingB254 Practice for Preparation of and Electroplating onStainless SteelB320 Practice for Preparation of Iron Castings for Electro-platingB322 Guide for Cleaning Metals Prior to ElectroplatingB368 Test Method for Copper-Accelerated Acetic Acid-SaltSpray (
13、Fog) Testing (CASS Test)B374 Terminology Relating to ElectroplatingB568 Test Method for Measurement of Coating Thicknessby X-Ray SpectrometryB571 Practice for Qualitative Adhesion Testing of MetallicCoatingsB602 Test Method for Attribute Sampling of Metallic andInorganic CoatingsB697 Guide for Selec
14、tion of Sampling Plans for Inspectionof Electrodeposited Metallic and Inorganic CoatingsB762 Test Method of Variables Sampling of Metallic andInorganic Coatings1This test method is under the jurisdiction ofASTM Committee B08 on Metallicand Inorganic Coatings and is the direct responsibility of Subco
15、mmittee B08.03 onEngineering Coatings.Current edition approved March 1, 2015. Published March 2015. DOI: 10.1520/B0994_B0994M15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informatio
16、n, 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 States1B849 Specification for Pre-Treatments of Iron or Steel forReducing Risk of Hydrogen EmbrittlementB850 Guide for Post-Co
17、ating Treatments of Steel for Reduc-ing the Risk of Hydrogen EmbrittlementD1193 Specification for Reagent WaterE2465 Test Method for Analysis of Ni-Base Alloys byWavelength Dispersive X-Ray Fluorescence SpectrometryF519 Test Method for Mechanical Hydrogen EmbrittlementEvaluation of Plating/Coating P
18、rocesses and Service En-vironmentsF1470 Practice for Fastener Sampling for Specified Me-chanical Properties and Performance InspectionG59 Test Method for Conducting Potentiodynamic Polariza-tion Resistance MeasurementsG85 Practice for Modified Salt Spray (Fog) TestingG102 Practice for Calculation of
19、 Corrosion Rates and Re-lated Information from Electrochemical MeasurementsG193 Terminology and Acronyms Relating to Corrosion2.2 ISO Standard:3ISO/IEC 17025:2005 General Requirements for the Compe-tence of Testing and Calibration Laboratories3. Terminology3.1 DefinitionsDefinitions of terms used in
20、 this specifica-tion are in accordance with Terminologies B374 and G193.4. Classification4.1 The coatings of nickel-cobalt have been classified asfollows: service condition by thickness, class by test methodsrequired, and type by secondary treatments.4.2 Service Condition (SC)This number signifies t
21、hethickness requirement based on the type of environment anddesired mechanical properties.NOTE 3The 50% NiCo alloy produces a high strength alloy that isused in electroforming to manufacture parts. These deposits can be usedat various thicknesses ranging from 1 m to hundreds of microns.4.2.1 SC5 sig
22、nifies that the application is slightly corrosiveand that a minimum 5 m of coating is sufficient for protectionand to provide the mechanical properties.4.2.2 SC12 signifies that the application is mildly corrosiveand that a minimum 12 m of coating is sufficient to protectagainst corrosion and provid
23、e the mechanical properties.4.2.3 SC18 signifies that the application is corrosive andthat a minimum of 18 m of coating is sufficient to protectagainst corrosion and provide the mechanical properties.4.2.4 SC25 signifies that the application is corrosive andthat a minimum 25 m of coating is sufficie
24、nt to protect againstcorrosion and provide the mechanical properties.4.3 ClassThis number signifies the type and frequency oftesting and monitoring programs that are used to control theprocess.4.3.1 Class 1Incorporates these standard tests: Galling(see Appendix X1) , Composition (see 9.3), Test Meth
25、ods F519and B368, and Practices B117 and G85.4.3.2 Class 2Incorporates these standard tests: Composi-tion (see 9.3), Test Methods F519 and B368, and PracticesB117 and G85.4.3.3 Class 3Incorporates these standard tests: Composi-tion (see 9.3) and Practice B117.4.3.4 Class 4Incorporates the standard t
26、est of composition(see 9.3).4.4 TypeThis number signifies the type of secondarytreatment applied after the coating to modify the surfaceproperties.NOTE 4The type classification is used to identify supplementalcoating that enhances the performance in various applications. Forqualification test purpos
27、es, if a supplemental coating is not used, that isType 0. Type 1 supplemental coatings are used to lock the threads ormetal-to-metal contact points to increase the amount of energy needed todisassemble the junction. Type 2 supplemental coatings are used to reducethe friction and aid in disassembly.
28、Materials like gold, thallium, andPTFE can be used to provide lubricity and reduce the break torque.4.4.1 Type 0 coatings are not treated with any supplementalcoatings.4.4.2 Type 1 coatings are treated with a material to securethe coating to itself.4.4.3 Type 2 coatings are treated with a material t
29、o reducethe friction between coated surfaces.5. Ordering Information5.1 The purchaser shall specify the following when orderingthis coating:5.1.1 The specification number and revision year,5.1.2 The service condition, class, and type,5.1.3 The significant surface on the part as identified on adrawin
30、g,5.1.4 The base metal alloy designation under ASTM stan-dard or equivalent,5.1.5 The tensile strength of the base metal in MPa,5.1.6 Any supplemental requirements including Type 1 andType 2 secondary treatments,5.1.7 Any exception to stress relief prior to coating (seesection 7.3),5.1.8 Any excepti
31、ons to post anneal heat treatments (seesection 7.4),5.1.9 Any exceptions to tests specified in the acceptancetests (see section 8), and5.1.10 Any exceptions to tests specified in the qualificationstests (see section 9).5.1.11 Any special requirements of shot peening or locationof rack or wire in the
32、 coating process, or both, should bespecified by the purchaser. Otherwise refer to 7.2.3 and 7.3.6. Coating Requirements6.1 The coatings shall be nickel-cobalt alloy produced byelectrodeposition.6.2 The nickel shall be in the range of 43 to 61% and thecobalt shall be in the range of 39 to 57%.6.3 Th
33、is coating shall be applied to the significant surface tothe desired minimum thickness of the service condition.6.4 The coating shall meet all applicable requirements asestablished in the purchase order in accordance with Section 5.3Available from International Organization for Standardization (ISO)
34、, 1, ch. dela Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland, http:/www.iso.org.B994/B994M 1527. Materials and Manufacture7.1 SubstrateDefects in the surface of the basis metal suchas scratches, porosity, pits, inclusions, roll and die marks, laps,cracks, burrs, cold shuts, and roughness may adv
35、ersely affectthe appearance and performance of the deposit, despite theobservance 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 c
36、onditions of themetal, if these conditions have been brought to the attention ofthe purchaser.7.2 The substrate may be subjected to such polishing orbuffing operations as are necessary to yield deposits with thedesired final performance and appearance.7.2.1 PeeningPeening prior to plating may be req
37、uired onhigh-strength steel parts to induce residual compressivestresses in the surface, which can reduce loss of strength andimprove stress corrosion resistance after plating.7.2.2 Steel parts that are designed for unlimited life underdynamic loads shall be shot peened or rotary flap peened.NOTE 5C
38、ontrolled shot peening is the preferred method because thereare geometries where rotary flap peening is not effective.7.2.3 Unless otherwise specified, the shot peening shall beaccomplished on all surfaces for which the coating is requiredand all immediate adjacent surfaces when they contain notches
39、,fillets, or other abrupt changes of section size where stresseswill be concentrated.7.3 RackingParts should be positioned so as to minimizetrapping of hydrogen gas in cavities and holes, allowing freecirculation of solution over all surfaces to obtain uniformcoating thickness. The location of rack
40、or wire marks in thecoating shall be agreed upon between the producer andpurchaser.7.4 Cleaning of Basis MetalProper preparatory proce-dures and thorough cleaning of the basis metal are essential toensure satisfactory adhesion and corrosion resistance perfor-mance of the coating. It is recommended t
41、hat the followingappropriate standards be used: Practices B183, B254, andB320, and Guides B242 and B322.7.5 PretreatmentA suitable method shall activate the sur-face and remove oxide and foreign materials, which may causepoor adhesion and coating porosity.7.6 Pretreatment of Iron or Steel for the Pu
42、rpose of Reduc-ing the Risk of Hydrogen EmbrittlementAll steel parts havingan ultimate tensile strength greater than 1000 MPa (31 HRC)and that have been machined, ground, cold formed, or coldstraightened, shall be heat treated for stress relief to reduce therisk of hydrogen embrittlement in the part
43、 before clean andelectroplate processes. If these heat treatments are not required,the purchaser shall specify in the ordering information SR-0. Ifthe purchaser does not specify an SR-0 exception to heattreatment, then the plater shall use Table 1 in SpecificationB849 to determine the appropriate he
44、at treatment for the steelbased on its tensile strength.7.7 Post-Coating Treatments of Iron and Steel for thePurpose of Reducing the Risk of Hydrogen EmbrittlementAllelectroplated steel parts having a tensile strength greater than1000 MPa (31 HRC) as well as surface-hardened parts, shall bebaked to
45、reduce the risk of hydrogen embrittlement. If theseheat treatments are not required, the purchaser shall specify inthe ordering information ER-0. If the purchaser does notspecify an ER-0 exception to heat treatment, then the producershall use Guide B850 to determine the appropriate heattreatment for
46、 the steel based on its tensile strength.8. Acceptance Tests8.1 These tests are performed on the article that has beencoated and can be performed by the producer prior to deliveryand by the purchaser upon delivery.8.2 AppearanceThe surface of the article shall be uniformin appearance, free of visibl
47、e coating defects, such as blisters,pits, roughness, nodules, burning, cracks, or unplated areas,and other defects that will affect the function of the coating.8.3 AdhesionThe adhesion of the coating shall be suchthat when examined by one of the test methods described inPractice B571 it shall not sh
48、ow separation from the basis metal.8.4 Coating ThicknessCoating thickness shall meet theminimum as specified in the purchase order by service condi-tion. Use an appropriate method for the part. Test Method B568provides a rapid measurement of the mass per unit area of thedeposit.9. Qualification Test
49、s9.1 These tests are performed on the process to ensure thesystem is capable of meeting the coating requirements by class.These tests shall be performed on SC25, Type 0 coupons at afrequency established in subsection 9.8 based on the class.9.2 Galling TestThe producer shall perform the gallingtest in accordance with the procedures established in AppendixX1. The producer shall prepare the finishing lot galling reportand shall demonstrate that loaded specimens will pass 608 daysof evaluation with the torque ration of less than 2.5.9.3 Chemical Composition
