Date of Award

12-2000

Degree Name

Master of Science

Department

Industrial and Manufacturing Engineering

First Advisor

Dr. Pnina Ari-Gur

Second Advisor

Dr. Daniel Kujawski

Third Advisor

Dr. Michael E. McCarville

Access Setting

Masters Thesis-Open Access

Abstract

Nickel reinforced with nanoparticles of γ−Al2O3 have been successfully codeposited on 2024-T3 cold rolled aluminum alloy by electrodeposition with direct current. The effects of current density, particle concentration in the nickel sulfamate bath, air agitation, and coating time on Ni/γ−Al2O3 composite have been investigated. The residual stresses and wear resistance of the Ni/γ−Al2O3 composite have been measured using X-ray diffractometer and pin-on-disk techniques respectively. The residual stress and wear resistance behavior of the composite were compared with those of nickel-only deposits. An annealed ground nickel, which was mechanically removed from the plated specimens, was used as a reference. Taguchi methods were used to design the coating conditions. The results of residual stresses studies revealed that higher compressive residual stresses, from –110 to –235 MPa, were possible by operating the bath containing 22 g l-1 of γ−Al2O3 particles in suspension at 20.7 A/dm2, for 20 minutes at 55±3°C. The results showed that the magnitude and sign of the residual stresses vary with directions. The wear resistance of the composites was found to be higher than those of nickel only. Particle concentration of γ−Al2O3 in the coating bath showed a strong relation with the wear resistance and coating thickness. Particle content in the coating bath, current density, coating time, and agitation were found to be important factors in controlling the amount of embedded γ−Al2O3 particles into the deposit.

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