Nano SiC Particles In-situ Growth Via Laser Irradiation

Laser, as a heater, had been used to preparate for nano- materials in the past years, because of its instant output of energy and speedy heat up the materials that were irradiated by laser beam. When the laser irradiated the nano-materials, the energy density took on gauss distributing in the facula of laser bean, and made the materials be in the graded temperature field, thus the preparation of the materials had an essential condition.The growth mechanism of the SiC nano particles via laser irradiation was studied in this dissertation. When SiC nano-particles (precursor) are irradiated by laser (heat source), SiC nano-whiskers in-situ growth was studied. The main work accomplished and conclusions gotten in this dissertation are presented as follows:1. Analyzing the sintering theory of nano material and the heat conduction theory of laser machining, the mathematic model of grain size growth of nano material in laser irradiation was built. The growth trends of grain size were simulated under different laser technological parameters.2. According to the characteristics of laser,the experimentations had two steps: the laser and surface irradiated are paralleled and upright.The phase and microstructures of the sample gotten by laser irradiation were studied in detail with X-ray diffraction and scanning electron microscopy in these two types.3. The microstructures irradiated by laser had nano and micro whiskers. These whiskers show mainly three shapes: floccule, reticulation and claviform. The growth theory of the three whiskers was studied. Because there was no catalyzers in the test,the whiskers had high purity. The X-ray diffraction showed that the whiskers were pure SiC.