電析Ｎｉ‐Ｐ，Ｃｏ‐ＰおよびＮｉ‐Ｃｏ‐Ｐ合金の作製とその特性

Abstract

Ni-P, Co-P, and Ni-Co-P alloys (0≤P≤16wt%) were electrodeposited from Watts-type plating bath containing phosphorous acid. Effects of bath temperature, current density, content of phosphorous acid in the bath, and molar ratio of metal ions in the bath on the deposition rate and the composition of the deposited alloys were studied. The relation between Vicker's hardness and phosphorous content in the deposited Ni-P and Co-P alloys were also discussed. Moreover, for better understandings of the conformation or the nature of the chemical state of phosphorous, its properties and stability in the deposited Co-P alloys, the differential scanning calorimetry, the small angle X-ray scattering, and the P-Kβ X-ray spectroscopy were measured on the alloys. The results are summerized as follows; (1) The deposition rate and composition of the deposited alloys are greatly influenced by the plating conditions, that is, temperature of the bath, current density, and composition of electrolytes in the bath. (2) The Ni-P, Co-P, and Ni-P, Co-P deposited alloys containing more than 5 wt% phosphorous exhibited the hardness of 600-800Hv. (3) Phosphorous in the Co-P alloys as deposited is bonded to cobalt by metallic bond, and it is suggested that phosphorous in the alloy is neither at the elementary state (red or white) nor constitutes stoichiometric cobalt-phosphides such as CoP, Co1.6 P, and that the deposits are at the state of a super-saturated solid-solution of phosphorous in hcp Co (P<-5wt%) and an amorphous solid (P>-5wt%).