Gaseous products of dimethylamine borane oxidation in chemically catalyzed deposition of nickel-rhenium-boron coatings

Abstract

The gaseous products of the oxidation of hydride hydrogen of the dimethylamine borane (DMAB) (CH₃)₂NH · BH₃ reducer used for depositing Ni-Re-B coatings and hydrolysis of DMAB on them were studied by mass spectrometry of the isotope composition of the gas. The oxidation level of hydride hydrogen of the DMAB reducer was found to depend on the catalytic activity of the Ni-Re-B alloy, on which heterogeneous hydrolysis takes place. For Ni-Re-B alloys with low rhenium concentrations (0–13 at %), the heterogeneous hydrolysis of DMAB proceeds with hydride hydrogen oxidation to the atomic state, as it does in the deposition of the Ni-B alloy. In contrast, at high rhenium concentrations (40–46 at %), the oxidation proceeds to the proton H⁺, leading to an antibatic dependence of the hydrolysis and alloy reduction rates. An analysis of the partial rates of the process and isotope composition of the evolved gas revealed two different mechanisms of the chemical-catalytic reduction of Ni-Re-B alloys at concentrations of potassium perrhenate of 0–4 and 4–16 mM in solution.