| SM ISO690:2012|
BOBANOVA, Zh.; PETRENKO, Vladimir; VOLODINA, Galina; KROITORU, Dumitru; DIKUSAR, Aleksandr. Composition and properties of Сo-W alloys deposited from gluconate electrolyte. In: Materials Science and Condensed Matter Physics. Editia a 7-a, 16-19 septembrie 2014, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2014, p. 328.
|Materials Science and Condensed Matter Physics
Editia a 7-a, 2014
Conferința "Materials Science and Condensed Matter Physics" |
Chișinău, Moldova, 16-19 septembrie 2014
Recently Co-W covers which possess high wear - and the corrosion resistance, comparable to properties of chromiums deposited from gluconate electrolytes are of great interest . Such electrolyte is ecologically safety in comparison with chromium electrolyte. However conditions of Co-W alloys deposition from such electrolytes, as well as their properties are poorly understood. The influence of deposition conditions on structure of such alloys, their surface quality and mechanical characteristics were studied at wide range of deposition parameters variation. Electrolyte composition, M: CoSO4 ∙7Н2О - 0,053, sodium gluconate 0,5, Н3BO3 - 0,65, Na2WO4 ∙ 2H2O - 0,05, NaCl - 0,5. electrolyte рН – 5-8. Temperature 800С. Current efficiency, chemical composition of coating, a modification roughness and microhardness of alloys were determined in different conditions of electrolysis. Morphology and a composition studied by means of scanning electron microscope TESCAN VEGА and system of element analysis INGA Energy EDX. Deposit structure were determined by means of diffractometer ДРОН 3. Current efficiency (CE) and tungsten content in the covers received from said electrolyte depend on solution рН and current density. CE is 80-85 % and tungsten content is 23 %atomic at рН 6-7 and i = 1-2 A/dm2 The polycrystalline structure is characteristic for the covers deposited at current density 1 А/дм2 and at all рН in the range 5-7. At the same electrolyte рН, but with current densities 3-5 A/dm2 nanocristaline covers with the size of microcrystal - 2 nanometers are formed. Microhardness of the deposited alloys correlates with tungsten content, however in connection with deposit structural change at рН = 6.5, microhardness increased, attaining meaning Hv> 900 kg/mm2. The roughness slightly exceeded initial value practically at all mode of deposition unlike the covers deposited from citrate electrolytes. Friction factor k of Co-W alloys lay within the limits 0,114-0,132 for all рН band (5–7), that does not exceed the friction factor of chromium (~0,134) tested in simular friction conditions. k growth is only at рН 8 when in an electrolyte there are modifications in the complexing of main electrolyte components. Maximum deposition rates, tungsten content in covers, their microhardness and low friction factor are attained over the рН range 6-7. Presence of correlation between рН of gluconate electrolyte used for nanocrystaline Co-W alloys deposition, and deposition rate, coating content, their structure, microhardness and tribological properties may be explained as the result of formation of high-molecular complexes in electrolyte solution under corresponding conditions that is confirmed by means of gel filtration chromatography.