1、Designation: B 607 91 (Reapproved 2003)Standard Specification forAutocatalytic Nickel Boron Coatings for Engineering Use1This standard is issued under the fixed designation B 607; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、 year of last 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 Nickel boron coatings are p
3、roduced by autocatalytic(electroless) deposition from aqueous solutions. These solu-tions contain either an alkylamineborane or sodium borohy-dride as a reducing agent, a source of nickel ions, a buffer,complexant, and control chemicals.1.2 This standard describes the requirements for coatings ofaut
4、ocatalytic nickel boron deposited from aqueous solutionsonto substrates for engineering use. The specification classifiesthese coatings into two types:1.2.1 Type 1 coatings have a boron content of 0.1 to lessthan 3.5 mass percent with the balance nickel.1.2.2 Type 2 coatings have a boron content of
5、3.5 to 6 masspercent and a minimum of 90 mass percent nickel.1.3 The coatings are hard and uniform in thickness, even onirregular shaped parts, and used in a wide range of applications.1.4 Process solutions formulated with an alkylamineboraneusually produce coatings that contain 0.1 to 3.5 % boron.
6、Thincoatings of this type provide bondability and solderability onelectronic components such as lead frames, electrical contacts,and headers. To maintain solderability, these coatings aregenerally not heat treated.1.5 Process solutions formulated with sodium borohydrideare strongly alkaline and are
7、frequently used to plate steel andtitanium parts to impart surface hardness and wear resistanceproperties. Deposits produced from these processes can contain3 to 5 % boron and thallium or other metals which are used tostabilize the plating solution and modify the coating properties.1.6 The physical
8、and mechanical properties of these depos-its such as density, hardness, stress, and melting point will varywith the boron content. The variation of boron content alsoaffects the quantity and structure of nickel boride precipitatedduring heat treatment. In the as-plated condition the depositconsists
9、of a predominantly amorphous mixture of nickel andboron with a hardness of about 700 HKN. When the deposit isheated above 300C the nickel crystallizes, forming nickelclusters of Ni (111) and boron precipitates as nickel boride,Ni3B (211) and (311), increasing the hardness to greater than1000 HK100fo
10、r Type 2 coatings.1.7 The nickel boron coatings are microporous and offerlimited corrosion protection. Their columnar structure, how-ever, is beneficial in reducing wear because it provides a meansof trapping lubricants within the surface of the coated part.1.8 This document describes only autocatal
11、ytic nickel boroncoatings that have been produced without use of externalelectric sources.1.9 The following hazards caveat pertains only to the TestMethods section of this specification: This standard does notpurport to address the safety problems associated with its use.It is the responsibility of
12、the user of this standard to establishappropriate safety and health practices and determine theapplicability of regulatory limitations prior to use.NOTE 1The following AMS standards are not requirements. They arereferenced for information only: AMS 2399 and AMS 2433.2. Referenced Documents2.1 ASTM S
13、tandards:B 374 Terminology Relating to Electroplating2B 487 Test Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examination of aCross Section2B 567 Test Method for Measurement of Coating Thicknessby Beta Backscatter Method2B 568 Test Method for Measurement of Coating Thi
14、cknessby X-Ray Spectrometry2B 571 Practice for Qualitative Adhesion Testing of MetallicCoatings2B 578 Test Method for Microhardness of ElectroplatedCoatings2B 602 Test Method for Attribute Sampling of Metallic andInorganic Coatings2B 656 Guide for Autocatalytic (Electroless) Nickel-Phosphorus Deposi
15、tion on Metals for Engineering Use2B 667 Practice for Construction and Use of a Probe forMeasuring Electrical Contact Resistance3B 678 Test Method for Solderability of Metallic-CoatedProducts21This specification is under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and is
16、 the direct responsibility of SubcommitteeB08.08.01 on Engineering Coatings.Current edition approved Sept. 10, 2003. Published Sept. 2003. Originallyapproved in 1991. Last previous edition approved in 1998 as B 607 91 (1998).2Annual Book of ASTM Standards, Vol 02.05.3Annual Book of ASTM Standards, V
17、ol 03.04.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.B 697 Guide for Selection of Sampling Plans for Inspectionof Electrodeposited Metallic and Inorganic Coatings2B 762 Test Method of Variables Sampling of Metallic andInorganic C
18、oatings2D 2670 Test Method for Measuring Wear Properties ofFluid Lubricants (Falex Pin and Vee Block Method)4D 2714 Test Method for Calibration and Operation of theFalex Block-on-Ring Friction and Wear Testing Machine4E 39 Test Methods for Chemical Analysis of Nickel5F 519 Test Method for Mechanical
19、 Hydrogen Embrittle-ment Evaluation of Plating Processes and Service Environ-ments62.2 Aerospace Materials Specifications:AMS 2399 Electroless Nickel-Boron Plating7AMS 2433 Electroless Nickel-Thallium-Boron Plating72.3 U.S. Government Standards:MIL-STD-105 Sampling Procedures and Tables for Inspec-t
20、ion by Attributes8MIL-STD-13165 Shot Peening of Metal Parts83. Terminology3.1 DefinitionsMany terms used in this standard aredefined in Terminology B 374.3.2 Definitions of Terms Specific to This Standard:3.2.1 cold shuta void on the surface which has beenclosed by machining and then partially opene
21、d through clean-ing.3.2.2 hot halide stress-corrosion crackinga type of me-chanical failure produced by halogenated solvents that havebeen absorbed onto titanium and then in the presence of heatcause microcracking, and the loss of mechanical strength.3.2.3 lap cracksa surface imperfection caused by
22、coldworking of steels producing a void which can be duplicated inthe deposit.3.2.4 significant surfacethose substrate surfaces whichthe coating must protect and that are essential to the appear-ance.4. Classification4.1 The classification by type of these coatings establishesthe amount of boron in t
23、he alloy.4.1.1 Type 1Coatings shall contain 0.1 to less than 3.5mass percent boron with the balance nickel.4.1.2 Type 2Coatings shall contain 3.5 to 6 mass percentboron and a minimum of 90 mass percent nickel.4.2 The classification by class of these coatings establishesthe post treatment to be perfo
24、rmed on the part(s). The posttreatment steps are designed to reduce the potential forhydrogen embrittlement, increase the adhesion of the coatingto the substrate, improve the fatigue properties of the part(s),and increase the wear resistance and hardness of the coating:4.2.1 Class 1Parts are supplie
25、d as plated with no post heattreatment.4.2.2 Class 2Parts are heat treated after plating to increasehardness. The coating is heat treated at 365 to 385C for 90min (see 7.2.4).4.2.3 Class 3Parts are heat treated after plating at 180 to200C for 2 to 23 h to improve coating adhesion on steel andfor hyd
26、rogen embrittlement relief of steels (see 7.2.4).4.2.4 Class 4Parts are heat treated after plating at 120 to130C for a minimum of1htoimprove adhesion onheat-treatable (age-hardened) aluminum alloys and carburizedsteels (see 7.2.4).4.2.5 Class 5Parts are heat treated after plating at 365 to375C for a
27、 minimum of4htoimprove adhesion on titaniumand titanium alloys (see 7.2.4).4.3 The classification by grade establishes the minimumthickness of the coating:4.3.1 Grade AParts are plated to a minimum coatingthickness of 0.5 m.4.3.2 Grade BParts are plated to a minimum coatingthickness of 12 m.4.3.3 Gr
28、ade CParts are plated to a minimum coatingthickness of 25 m.4.3.4 Grade DParts are plated to a minimum coatingthickness of 75 m.5. Ordering Information5.1 The purchaser should be aware of several processingconsiderations or options available to the processor and whenordering should supply the inform
29、ation described in 5.1.1through 5.1.15 in the purchase order and drawings.5.1.1 Title, ASTM designation, and year of issue of thisspecification.5.1.2 Composition and metallurgical condition of the basismetal, assemblies of dissimilar materials must be identified.5.1.3 Classification of the coating:
30、type, class, and grade forthis specification (see Section 4).5.1.4 Minimum thickness required on the significant sur-face, and any maximum dimensions or tolerance requirements,if any (see 7.2.2).5.1.5 Method of adhesion testing from Test Method B 571to be used in acceptance requirements (see 8.3).5.
31、1.6 Requirements for certification and test reports (seeSection 11).5.1.7 Requirements for heat treatment of the part(s) forstress relief prior to plating (see 7.2.4).5.1.8 Optional sampling plan for lot inspection of the part(s)(see 9.1 and 13.1).5.1.9 Increased sampling frequency, if any, for qual
32、ificationtests (see 7.3).5.1.10 Supplemental requirements for shot peening of thepart(s) (see 12.1).5.1.11 Supplemental requirements for wear testing (see 12.2and 12.3).5.1.12 Supplemental requirements for heat treatment invacuum or inert or reducing atmosphere (see 7.2.1 see 1994 Annual Book of AST
33、M Standards, Vol 03.05.6Annual Book of ASTM Standards, Vol 15.03.7Available from Society of Automotive Engineers, Inc. (SAE), 400 Common-wealth Drive, Warrendale, PA 15096.8Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPO
34、DS.B 607 91 (2003)25.1.15 Supplemental U.S. Government requirements, if any(see Section 13).6. Materials and Manufacture6.1 PretreatmentParts can be processed in accordancewith Practice B 656.6.1.1 A suitable method should be used to remove surfaceoxides and foreign materials which can cause poor ad
35、hesionand increased porosity.6.1.2 A suitable method should be used to condition andactivate the surface so that an adherent coating will beproduced.6.2 Basis Material and Workmanship Nickel boron coat-ings will replicate the surface finish of the basis material.Imperfections in the surface of the b
36、asis material includingscratches, porosity, pits, inclusions, roll and die marks, lapcrack, burrs, cold shuts, and surface roughness that couldadversely affect the coating should be brought to the attentionof the purchaser prior to processing (see 7.2.1).6.3 Stress ReliefSurface-hardened parts can r
37、equire stressrelief before plating. The stress relief heat treatment can reducethe hardness of some alloys and should therefore be reviewedby all parties before processing (see 5.1.7 and 7.2.4). Shortertimes and higher temperature can be used if the resulting lossof surface hardness is acceptable to
38、 the purchaser.6.4 Hydrogen Embrittlement Relief Hydrogen embrittle-ment of high strength steels can be initiated by several differentprocessing operations. Exposure of the parts to hydrogensources will generally induce the condition. Care must beexercised whenever high strength steel is processed t
39、o ensureminimal exposure and timely relief treatment.6.5 Stress-Corrosion CrackingTitanium and titanium al-loys are subject to stress-corrosion cracking after processing.Pretreatment solutions including rinses should not containmethanol, halogenated hydrocarbon, or more than 50 ppmchlorides, all of
40、which can cause subsequent stress-corrosioncracking when the parts are heated to 260C or higher.7. Requirements7.1 ProcessThe nickel boron coatings shall be producedby autocatalytic nickel deposition from aqueous solutions.7.2 Acceptance RequirementsThe acceptance require-ments in 7.2.1 through 7.2.
41、4 are required for all lots of part(s).Each lot of part(s) shall be sampled with the recommendedprocedure described in Section 9 of this specification.7.2.1 AppearanceThe coating shall have a uniform ap-pearance without visible imperfections such as blisters, pits,pimples, and cracks.7.2.1.1 Imperfe
42、ctions that arise from the surface conditionof the basis metal and that cannot be removed using conven-tional metal finishing techniques and that persist in the coatingshall not be cause for rejection.7.2.1.2 Discoloration caused by heat treatment shall not because for rejection unless specified in
43、the ordering information(see 5.1.12 and 12.4).7.2.2 ThicknessThe coating thickness shall be measuredand conform to the specified grade.7.2.3 AdhesionThe coating shall pass the adhesion test ofTest Method B 571 as specified in the ordering information(see 5.1.15).7.2.4 Heat Treatment:7.2.4.1 All stee
44、l part(s) with a tensile strength of 1000 MPaor greater shall be heat treated at 190 6 15C for stress reliefin accordance with Table 1 before plating and baked within 3h after plating for hydrogen embrittlement relief.7.2.4.2 Class 2 coated part(s) shall be heat treated afterplating in accordance wi
45、th Table 2 for precipitation hardeningof the deposit.7.2.4.3 Heat treatment for Class 3 coated steel part(s) shallbe in accordance with Table 1.7.2.4.4 Heat treatment for Class 4 and 5 coated part(s) otherthan steel basis material shall be in accordance with Table 3.7.3 Qualification RequirementsCoa
46、ting and process at-tributes that require testing on a monthly basis, or morefrequently when specified in the ordering information by thepurchaser. A test specimen or part, processed in a manner thatduplicates the characteristics of production parts, shall beproduced and used in these tests.7.3.1 Ha
47、rdnessThe hardness of the Type 2, Class 2, GradeC and D coating shall be not less than 1000 HK100as measuredby Test Method B 578.7.3.2 CompositionThe coating composition producedfrom the process shall be analyzed for nickel and boron. Thealloy produced shall be within the range specified for thecoat
48、ing type.7.3.3 Hydrogen EmbrittlementThe process and coatingshall be evaluated for freedom from hydrogen embrittlementand pass requirements of Test Method F 519.8. Test Methods8.1 Test Specimens:8.1.1 When separate test specimens are required, the num-ber to be used, the material from which they are
49、 to be made,and their shape and size shall be specified by the purchaser.8.1.2 When separate test specimens are used for acceptanceor qualification testing of the coating, the specimens shall bemade of the same material as the part(s), have the samemetallurgical condition as the part(s), and be processed withthe part(s).8.2 ThicknessThe thickness shall be measured at anyplace on the significant surface designated by the purchaser,and the measurement shall be made with an accuracy of betterthan 10 % by a method selected by the purchaser. Fig. X
