Design Of The Pulse Power Source For Plasma Spraying

Recently, the plasma technology has been developed so much that the spraying equipment based on plasma technology has been designed. With the spraying equipment based on plasma technology, the quality of the spraying coating has been improved significantly to lengthen the life of the product. However, there exist some drawbacks of the plasma spraying technology. For instance, the temperature during the spraying process is high so much that the sprayed objects are deformed. The percents of the oxygen is large in the jet stream and the speed of the particles in the jet stream is slow so that the spraying coating does not combined to the objects well and the spraying coating is not homogenous. Furthermore, the current plasma spraying technology mainly employs the DC voltage as well as pulse to absorb power. The methods to absorb power lead to large energy consumption and low efficiency. In order to improve the efficiency and lessen the power consumption, a new type of power source based on pulse is of importance for the application of the plasma technology to the spraying.This thesis is focused on the pulse power source for the plasma spraying. At first,we analyze the principle of the spraying and the mechanism of the plasma and give the context of the design of the pulse power source. Our pulse power source innovatively combines the high voltage pulse and high voltage DC to obtain the new pulse. Such a pulse demonstrates a lot of good properties including the high amplitude, steep front,narrow width, large power, and high voltage DC. Our pulse power source is presented with a conclusive hardware design based module and give design of the high voltage DC circuit, high voltage pulse circuit, control circuit. The simulation has been made to test the reliability and feasibility. This pulse power source has good properties of high reliability, adjustable amplitude, adjustable frequency and we choose the IGBT as the switch elements and SG3525 as the control unit.We contribute to the design of the sample of the pulse power source and make tests of the components of the source to obtain the practical properties. With tests, the pulse power source can provide pulse with amplitude of 48 kV and frequency of 100 Hz.Additionally, through several tests, we determined the optimal duty cycle for the spraying. In the application, the plasma spraying with our pulse power source demonstrates better spraying efficiency than the traditional plasma spraying.