ASTM B733-84 - 1.1.1984
 
1. Scope

1.1 This specification covers requirements for autocatalytic ( electroless) nickel-phosphorus coatings applied to metallic products for engineering (functional) uses from acid-aqueous solutions.

1.2 The coatings are alloys of nickel and phosphorus produced by autocatalytic chemical reduction with hypophosphite. Because the nickel deposited is a catalyst for the reaction, the process is self-sustaining. The chemical and physical properties of the deposit vary primarily with its phosphorus content and subsequent heat treatment. The chemical makeup of the plating bath can also affect the porosity and corrosion resistance of the deposit. For more details, see ASTM STP 265 (1)2 and Refs (2) and (3), also refer to Figs. XI. I, X 1.2, and X 1.3 in the Appendix of Guide 8656.

1.3 The coatings are generally deposited from baths operating at pH 4.3 to 5.3 and 85 to 95C.

1.4 The process produces coatings of uniform thickness on irregular-shaped parts, provided the plating solution circulates freely over their surfaces.

1.5 The coatings have multifunctional properties, such as hardness, heat hardenability, abrasion, wear and corrosion resistance, magnetics, and solderability. They are also used for the salvage of worn or mismachined parts.

1.6 This standard may involve hazardous materials. operations. and equipment. This standard does not purport to address al/ of the safety problems associated with its use. It is the responsibility qf whoever uses this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior lo use.

1.7 The values stated in SI units are to be regarded as standard.

 
2. Referenced Documents

B374-24

Standard Terminology Relating to Electroplating

B380-97(2023)

Standard Test Method for Corrosion Testing of Decorative Electrodeposited Coatings by the Corrodkote Procedure

B487-24

Standard Test Method for Measurement of Metal and Oxide Coating Thickness by Microscopical Examination of Cross Section

B368-21

Standard Test Method for Copper-Accelerated Acetic Acid-Salt Spray (Fog) Testing (CASS Test)

B499-09(2026)

Standard Test Method for Measurement of Coating Thicknesses by the Magnetic Method: Nonmagnetic Coatings on Magnetic Basis Metals

B849-02(2023)

Standard Specification for Pre-Treatments of Iron or Steel for Reducing Risk of Hydrogen Embrittlement

B504-90(2023)

Standard Test Method for Measurement of Thickness of Metallic Coatings by the Coulometric Method

B762-21

Standard Guide of Variables Sampling of Metallic and Inorganic Coatings

B537-22

Standard Practice for Rating of Electroplated Panels Subjected to Atmospheric Exposure

B567-98(2021)

Standard Test Method for Measurement of Coating Thickness by the Beta Backscatter Method

B678-25

Standard Test Method for Solderability of Metallic-Coated Products

B697-88(2021)

Standard Guide for Selection of Sampling Plans for Inspection of Electrodeposited Metallic and Inorganic Coatings

B850-98(2022)

Standard Guide for Post-Coating Treatments of Steel for Reducing the Risk of Hydrogen Embrittlement

B851-04(2020)

Standard Specification for Automated Controlled Shot Peening of Metallic Articles Prior to Nickel, Autocatalytic Nickel, or Chromium Plating, or as Final Finish

D1193-24

Standard Specification for Reagent Water

D2670-25

Standard Test Method for Measuring Wear Properties of Fluid Lubricants (Falex Pin and Vee Block Method)

D2714-24

Standard Test Method for Calibration and Operation of the Falex Block-on-Ring Friction and Wear Testing Machine

D3951-18(2023)

Standard Practice for Commercial Packaging

D4060-25

Standard Test Method for Abrasion Resistance of Organic Coatings by the Taber Abraser

E60-11(2022)e1

Standard Practice for Analysis of Metals, Ores, and Related Materials by Spectrophotometry (Includes all amendments and changes 6/29/2022).

E140-12B(2019)e1

Standard Hardness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness, Scleroscope Hardness, and Leeb Hardness (Includes all amendments and changes 5/7/2019).

E156-88

Method for Determination of Phosphorus in High-Phosphorus Brazing Alloys (Photometric Method) (Withdrawn 1993)

E352-23

Standard Test Methods for Chemical Analysis of Tool Steels and Other Similar Medium- and High-Alloy Steels

F519-23

Standard Test Method for Mechanical Hydrogen Embrittlement Evaluation of Plating/Coating Processes and Service Environments

G5-14(2021)

Standard Reference Test Method for Making Potentiodynamic Anodic Polarization Measurements

G31-21(2025)

Standard Guide for Laboratory Immersion Corrosion Testing of Metals

G59-23

Standard Test Method for Conducting Potentiodynamic Polarization Resistance Measurements

G85-19

Standard Practice for Modified Salt Spray (Fog) Testing

MIL-R-81841

Rotary Flap Peening of Metal Parts Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700 Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.

MIL-STD-105

Sampling Procedures and Tables for Inspection by Attribute

ISO 4527

Autocatalytic Nickel-Phosphorus Coatings--Specification and Test Methods Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.

B568-98(2021)

Standard Test Method for Measurement of Coating Thickness by X-Ray Spectrometry

B571-23

Standard Practice for Qualitative Adhesion Testing of Metallic Coatings

B578-21

Standard Test Method for Microindentation Hardness of Electroplated Coatings

B602-21

Standard Guide for Attribute Sampling of Metallic and Inorganic Coatings

B667-97(2024)

Standard Practice for Construction and Use of a Probe for Measuring Electrical Contact Resistance