The effect of hydrodynamics and temperature on the electrodeposition of Fe-Ni alloys has been investigated with dc, pulse, and pulse-reverse electrodeposition techniques. Strong mass-transfer effects in the co-deposition of Fe on rotating cylindrical cathodes were indicated at high current densities. Many features of the present deposition process are shown to be consistent with the Hessami and Tobias model. A comparison of the polarization behavior of single-metal and alloy deposition clearly demonstrate the lower rate of Ni co-deposition in accord with previous reports of anomalous co-deposition of Fe-Ni alloys. X-ray diffraction studies indicate that the crystalline phases (fcc, bcc, and mixed fcc +bec) in the electrodeposited alloys depend on alloy composition and deposition conditions. Thermal expansion coefficients of electroformed cylinders of near-Invar compositions ranged from 7.7-10.9 • I0-6/~ for unannealed alloys to 4-5 • 10-~/~ for alloys annealed at 680~ Average internal stress of deposits increased with increasing Fe content.
Detailed friction load-displacement response of four distinct metallic surfaces [one beaded porous metal (CTR) and three cast Co-Cr alloy ingrowth mesh surfaces, nonplanar mesh (INX), cast mesh 1 (CM1), and cast mesh 2 (CM2)] on poly-urethane and cancellous bone specimens of six tibiae were measured under different normal stresses (0.1, 0.15, or 0.025 MPa). Bone cubes were obtained from different proximal regions of resurfaced cadaveric tibiae. Both monotonic and cyclic fatigue loadings of up to 4000 cycles at 1 Hz were considered. Comparison of measured results indicated that the friction coefficient was not affected by the magnitude of normal stress and the bone excision site (medial, lateral, anterior, posterior, and central). The CM2 surface showed significantly greater resistance with friction coefficients of more than 0.9 for the bone and 0.8 for the polyurethane. The INX surface yielded the second largest resistance followed by CM1 and CTR surfaces. NO significant difference was found between these latter two surfaces. Fatigue tests of up to 4000 loading-unloading cycles showed about 10% reduction in friction coefficient for CTR and INX surfaces, while negligible reduction was found for CM1 and CM2 surfaces.
Binary iron group ͑IG͒-rare earth ͑RE͒ and ternary IG-RE-B alloys were codeposited from aqueous chloride and sulfamate solutions containing glycine as the complexing agent. The effects of solution composition and deposition conditions on deposit composition, coercivity, and morphology were investigated using dc and pulse current electrodeposition, resulting in nanocrystalline deposits approaching amorphism ͑grain size, ϳ5 nm͒. Continuing research indicates substantially increased RE deposit contents have been achieved with modifications in solution composition and ratios of IG and RE to glycine with applied current density у 300 mA cm Ϫ2 and vigorous agitation; e.g., CoSm deposits containing 15-18 atom % Sm have been obtained. A mechanism for the codeposition of the alloys is proposed. It involves hetero-nuclear glycinato coordination complexes as a result of the zwitterionic characteristics of glycine. The complexes adsorbed on the cathode provide step-wise reduction of the depositing metals with surface adsorbed H atoms and/or direct electron transfer, resulting in alloy deposits.
The effects of dc, pulse, and pulse reverse current waveforms on deposition of Fe-Ni alloys have been studied in unagitated solutions and with a rotating cylindrical electrode. A nickel sulfamate/ferrous chloride electrolyte system at pH 2 with additives was used. Pulse plating resulted in an increase in iron content of deposits, especially at current densities less than 2 A/dm 2. Pulse reverse plating led to a decrease in anomalous deposition at low current densities. Rotating cylindrical electrodes indicated significant mass transfer effects at high current densities. During pulse reverse plating an increase in anodic pulse magnitude decreased anomalous deposition; pulse frequency had its greatest effect in reducing anomalous deposition between 100 and 300 Hz.
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