Electrodeposition of Ni-Co Alloys and Their Mechanical Properties by Micro-Vickers Hardness Test

Nanocrystalline Ni-Co alloy deposits with grain sizes less than 30 nm were produced by electrodeposition with a direct current in a sulfamate bath. Surfaces of the Ni-Co alloy deposits showed granular morphology. The size of the granular particles and the Co content decreased when a lower current density was applied. Addition of NiBr2 and a surface brightener (NSF-E) into the bath resulted in the grain refinement effect and an increase of Co content in the deposit. The grain size reached roughly 14 nm and 60 at.% of Co content in Ni-Co alloys electrodeposited with the bath containing the two additives. Ni-Co alloys obtained in this study showed higher microhardnesses than those of pure Ni and Co deposits prepared under the same condition, which revealed the solid solution strengthening effect. With a decrease in the grain size, the microhardness further increased, and this trend followed the Hall–Petch relationship well. The maximum microhardness value of 862.2 Hv was obtained owing to both the grain boundary and solid solution strengthening effects.

Effect of Current Density on Properties Of Nickel-Silicon Carbide Composites

Nickel-Silicon Carbide (Ni-SiC) composite coating has been prepared by two electrode electrochemical co-deposition technique in nickel sulfamate bath. The Cetyltrimethylammonium bromide (CTAB) was added in bath as cationic surfactant whereas saccharine as a grain modifier. The effect of current density during deposition was systematically studied and optimized to get homogeneous surface texture with utmost microhardness and deprived coefficient of friction. The result revealed that 60 mA/cm2 current density was found to be the optimum current density which showed the highest microhardness of 590 ± 10 Hv and lowest coefficient of friction with regular surface morphology.Journal of Institute of Science and TechnologyVol. 21, No. 1, 2016, Page : 82-85

EFFECT OF STIRRING RATE ON ELECTROCHEMICAL CODEPOSITION OF Ni-SiC COMPOSITE

Nickel-Silicon Carbide (Ni-SiC) composite has been prepared by electrochemical codeposition technique. Nickel sulfamate bath was used along with grain modifier saccharine and cationic surfactant cetyltrimetylammonium bromide (CTAB). The effect of stirring rate was systematically studied and optimized to get well dispersed SiC particles in appropriate amount. Mixed crystalline phase with reinforced [2 1 1] crystal orientation was obtained by XRD analysis. The result revealed that, 250 revolutions per minute (rpm) is optimum stirring rate for the electrochemical codeposition of Ni–SiC. Coating prepared at 250 rpm showed highest microhardness and lowest coefficient of friction with better surface morphology and well distributed nano SiC particles.Scientific World, Vol. 12, No. 12, September 2014, page 30-33

High Tensile Ductility in Electrodeposited Bulk Nanocrystalline Ni–W Alloys

Bulk nanocrystalline Ni–W alloys were electrodeposited from a sulfamate bath that contained saccharin sodium as a gloss agent, and propionic acid and sodium gluconate as a complexing agent (SPG bath) to understand the tensile behavior. SPG bath with 1.0 and 5.0 g/L saccharin sodium at 45 ºC produced the bulk specimens with W content of 3.4 and 1.5 at.%, respectively. The electrodeposited alloys had a nanocrystalline structure with grain sizes of approximately 20 nm and a stronger (111) texture. The bulk nanocrystalline Ni–3.4 at.%W alloys deposited from an SPG bath with 1.0 g/L saccharin sodium exhibited a tensile strength of 1.6 GPa and tensile ductility of 1.8%. The bulk nanocrystalline Ni–1.5 at.%W alloys deposited from an SPG bath with 5.0 g/L saccharin sodium exhibited a tensile strength of 1.4 GPa and tensile ductility of 1.7%. The bulk nanocrystalline Ni–W alloys with a stronger (111) texture showed high strength and low plasticity.