ASTM B656-91

1.1 This guide gives information about the deposition of autocatalytic nickel for engineering uses (Note 1). It is not intended to be a standardized procedure, but rather a guide for obtaining smooth, adherent, and uniform coatings of a nickel-phosphorus alloy from acid-plating solutions (Note 2).

1.2 Autocatalytic nickel deposits covered in this guide are alloys of nickel and phosphorus produced by autocatalytic chemical reduction with hypophosphite. Because the nickel deposit is a catalyst for the reaction, the process is self-sustaining.

1.3 The chemical and physical properties of the deposit vary with the pretreatment of the substrate, plating bath chemistry, phosphorus content, and subsequent heat treatment. For more details on such properties, see ASTM STP 265 (1) , (2), (3), (4), and (7). Also, refer to Figs. X1.1, X1.2, and X1.3 in the Appendix.

1.4 This guide covers the metal preparation and deposition process. The testing of autocatalytic nickel-phosphorus deposits is covered in Specification B733.

1.5 This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. See 8.11 and 8.13 for specific safety precautionary statements.