Study On Accelerating Characteristics Of Nano-particles In Electrostatic-force-assisted Cold Gas Dynamic Spraying Process

Electrostatic-force assisted vacuum cold gas dynamic spraying technology is a new surface engineering technology based on the vacuum cold spraying technology and electrostatic-force assisted cold spraying technology, it aiming at solving the technical problem that nano-particle is difficult to realize effective deposition in the traditional cold spraying environment caused by the influence of the bow shock before the substrate. The article takes air as carrier gas and Cu particles as spraying particles, bases on the critical velocity of 500 m/s, uses numerical analysis method to research and explore the elements influencing on the nano-particle impact velocities in electrostatic-force assisted vacuum cold gas dynamic spraying. The main research content is as follows:Firstly, the article researches the effect of inlet pressure, particle size and electric field on the particle impact velocity in the electrostatic-force assisted cold spraying. The results show that the inlet pressure too high or too low are bad for the particle motion, for the specific spraying system need to choose the best inlet pressure; Optimal particle size range is dp?0.15 ?m in electrostatic-force assisted cold spraying process; Electric field force can't influence the particle movement inside the nozzle, accelerates charged particles in the area of the jet.Then, the article studies the effect of the vacuum degree(ambient pressure), spraying distance and particle size on particle impact velocity in vacuum cold spraying. The results show that the influence of ambient pressure on particle impact velocity is opposite to the inlet pressure; Smaller spraying distance causes a strong bow shock in front of the substrate; Optimal particle size range is 0.8 ?m?dp?1 ?m in the vacuum cold spraying process.Finally, the article researches the effect of the particle charge, substrate voltage and spraying distance on the particle impact velocity in electrostatic-force assisted vacuum cold spraying, and further discusses it whether can realize that nano-particle effective deposition with normal pressure and temperature and using air as carrier gas. Results show it can be realized the effective deposition of micron and nano-particles by improving the particle charge or substrate voltage; The influence law of the spraying distance on electrostatic-force assisted vacuum cold spraying is same as vacuum cold spraying; It can be realized that the effective deposition of nano-particles with normal pressure and temperature by reducing the vacuum degree, improving the particle charge or substrate voltage.The above research results show that the electrostatic-force assisted vacuum cold spraying technology can realize the nano-scale and sub-micron particles effectively spraying with normal pressure and temperature and using air as carrier gas. The technology enlarged the range of spraying particle size, reduced the cost of the spraying, it worthy of popularization and application.