Study On Combustion Characteristic And Paticles Behavior Of HVOF Spraying

Combining with the experiment and calculating method, the effect which is caused by combustion characteristic and particle behavior of coating's properties are studied in this letter. Based on computational fluid dynamics, a computational framework is developed to calculate the combustion characteristic and particle behavior of HVOF Spraying using the commercial software Fluent. The result shows that the temperature of flame is decided by equivalence ratio of fuel and oxidant gas. When the equivalence ratio is closer to theoretical value, the maximum temperature of flame is higher. The velocity of flame is decided by the pressure of combustion chamber which is affected by the flow rate. It also shows that the particle behavior of HVOF is affected by Combustion Characteristic and self-Characteristic. Both particle velocity and temperature are affected by Combustion Characteristic. Moreover, both particle velocity and temperature at impact are strongly dependent on particle size. The larger the particle size is, the smaller effect the flame has. Even particle size is large enough to lead to undeposition. Result shows that the particle size between 20 m to 40 m is available.The coatings are prepared with CH-2000 HVOF system under the condition of different particle behaviors when oxygen is the oxidant gas and the performance of these coatings are tested. The relationship between particle behavior and coating performance is studied. The result shows obviously that coating performance is depended on particle behavior. When particle temperature fixed, the higher the particle velocity is, the smaller the coating porosity is. In addition, the deposition mechanism is changed when particle velocity is higher than a critical value which is different for different particle temperature. And also, when particle velocity is higher than the critical value, the higher the particle velocity is, the better the coating erosion resistance is. When particle velocity is fixed, the compactness and porosity of coating is depended on particle temperature. And also, the erosion resistance of coating is much affected by particle temperature.