Effects of Silicon Carbide on the Hardness of Ni-SiC Composite Deposits

초록

The functional occulation depositions such as Ni-SiC ceramic composite deposits improve hardness and wear properties. Ni-SiC composite deposits are utilized for cylinder bores, piston, and piston rings. The effects of SiC particle size on occulation deposition surface and on the mechanical properties of Ni-SiC composite electrodeposits were investigated. And the effect of ultra-vibrational stirring speed( 0~60 Hz) on the fabrication of Ni-SiC composite electreodeposits was also discussed. The amount of SiC in deposits was increased with decreasing particle size. But the apparent area ratio of SiC on the coated surface was increased with increasing particle size. Irrespective of SiC particle size, all SiC particles are distributed uniformly in coated layer. The SiC particle content in the Ni-SiC composite deposit was increased with increasing ultra-vibrational stirring speed, and reached maximum value at an ultra-vibrational stirring speed of 45 Hz. Hardness was increased with decreasing particle size. Maximum hardness of 850 VHN was obtained under the conditions of SiC particle size of 1 μm and stirring speed of 45 Hz. SiC content and hardness were decreased more than strring speed of 45 Hz. The Vickers hardness of all Ni-SiC coatings was higher than that of pure electrodeposited nickel. The hardness and wear resistance of Ni-SiC deposits increased with increasing ultra- vibrational stirring speed and obtained maximum value at ultra-vibrational stirring speed of 45Hz. It could be concluded that synergy effects of dispersion-strengthening and particle-strengthening improve the mechanical properties of Ni-SiC composite deposits.