Функціональні покриття тернарними сплавами кобальту з тугоплавкими металами

Abstract

Thesis for the Degree of Candidate of Technical sciences in specialty 05.17.03 – Technical Electrochemistry. – National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2017. The thesis is devoted to development of technologies for galvanic coatings synthesis of the ternary alloys cobalt-molybdenum-tungsten from poly-ligand electrolytes to produce materials with improved physical and mechanical properties. The constant instability and composition of mono- and bi-ligand complexes of cobalt are determined, and both citrate-diphosphate and ammonia-citrate systems suggested for the deposition of cobalt alloys with tungsten and molybdenum. The mechanism of alloy deposition is defined based on kinetic patterns analysis. Metals recovered by stages from hetero-nuclear complexes of composition [MO₄Со(P₂O₇)]⁴⁻ and mononuclear Со(Cit)₂⁴⁻ (where M = Mo, W) when deposited from citrate-diphosphate bath. Conjugate deposition of metals in alloy from ammonia-citrate electrolyte occurred from complexes [MO₄Со(Cit)]³⁻. The effect of electrolytes composition and deposition modes (stationary and pulse) on the components content, morphology, structure and functional properties of alloys as well as process efficiency are substantiated. A technological scheme for functional electrolytic cobalt alloy coatings deposition with molybdenum and tungsten is offered and relevant technological instructions are developed. It was established high corrosion resistance coatings, synergic growth of microhardness and catalytic activity compared with alloying components.