Preparation Of Nano-sic Powder And Ni-p-sic (nanometer) Composite Plating Study

The nanometer powder of SiC was preparation by two different ways . one is that the micrometer SiC powder was directly milled to nanometer size grain, another is that the mixed powder of micrometer Si and C with rare earth was milled to sythesize the nanometer SiC by MA(Machine Alloying).Namometer silicon carbide powder was prepared from industrial silicon carbide by high energy ball milling. Then the morphology and the phase structure of the milled powder were inspected by Y-4A XRD and Philips XL30 PEG SEM., the variational rules of milled SiC powder size were determined. Experimental results show that the grains were gradually triturated to namometer size with milling time and the grain size might be 30nm or so, but the grain size was not decreasing after the powder has been milled for 25 hours.The nano-sized SiC was synthesized by ball milling of Si and C mixed powders which rare earths as a additive was added to. And the morphology and the phase structure of the milled powder were inspected by Philips XL30 PEG SEM and Y-4A XRD. The results revealed that: by adding some rare earths to the mixture of Si and C powders, the rate of synthesizing SiC increased and the grinding rate quickened.On the basis of the technology of general Ni-P electroless coating, different quantity of nanometer SiC powder was put into Ni-P solution to prepare the nanostructure coatings. And how nanometer SiC particles and the concentration of SiC in the solution affect the coating rate and coating properties were discussed. The structure and the thickness of the coatings was inspected by the XJP-2 metallography microscope, the structure morphology was tested by Philips XL30 PEG SEM, and the adhesion between the foundation and the coating was examed by two methods: one is WS-92 sound-producing coating adhesion nick testing, another is bending. The hardness of coating was inspected by the MVK-H3 hardness test machine and the crystal process was tested on the DSC-TGA heat and weight ananysis machine. The gliding abration test was on the MPX-2000 friction and abration machine and the abration morphoy was tested by Philips XL30 PEG SEM. The results revealed thatcoating rate and film hardness increase much for putting proper nanometer SiC particles in the solution. When the nanometer SiC concentration is 4.5g/L, the rate can reach 68.4 m / h and the nanometer SiC concentration is 3.5g/L, the film hardness can reach 1650HV . The crystallizing progress is more slow and the temperature that Ni3P separate out postponed at 530 C or so. The wearability of the coating improved, the nanometer composite electroless coating was better than the Ni-P electroless coating and the micrometer composite electroless coating from the curve of the loss weight for abration.