In recent years, along with the development of nanometer material and technology, it is raising the upsurge of researching the craft of electroless composite plating with nanometer particles in domestic and foreign. However the nanometer material because its big relative surface proportion, the increase of superficial atomicity, insufficient of atomic coordinate, and the high surface energy, make these superficial atoms to have the higher activeness, they are extremely unstable and very easy to

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... reunite with each other and become the big reunion body with some connection interfaces. Therefore, in order to make the nanometer particles suspend evenly in the bath to obtain the composite coating of symmetrical distribution of nanometer particles, the question of dispersion of nanometer particles appears important especially. The orthogonal test method has been used to study the effects of the concentration of SiC, the speed of mixing, the temperature and the surfactants on depositing rate and micro-hardness, and obtained the optimized technological scheme and fine Ni-P-SiC composite coating. The results showed that using citric acid-acetic acid as complexing agents can obtain high speed of depositing and homogeneous coating with SiC well-distributed. Among the technological parameters, the effects of temperature on depositing rate is biggest, and the surfactants is next; the effects of the concentration of SiC particles on micro-hardness is biggest, and the surfactants is next. Give consideration to depositing rate and stability of the liquid, the temperature should be controlled at 82±2℃, the concentration of SiC particles and surfactants should be controlled in 4g/L and 60mg/L. The influence to micro-hardness value of coating with ultrasonic disperser craft also has been studied.