A new electrothermal chemical method for metals carbides and ceramics hard coating. Experiment and theory

Summary form only given. A new method and an experimental device for powders of metals, carbides and ceramics coating of various substrates are presented. The powder-particles are accelerated and heated by a mixture of plasma and gases resulted from the burning of an energetic material (propellant). The operating prototype already allows one to obtain coatings of metals, carbides and ceramics. Some of the coatings obtained, especially those by carbide powders, indicate (even at the present stage of research) properties (such as hardness and porosity) which are comparable to those provided by the presently industrial methods in use. The accelerating heating agent in our device (the plasma-gas mixture) is characterized by very high densities (up to 120 kg/m/sup 3/), temperatures (up to 7,0000 K) and velocities (more than 1500 m/s). Due to these characteristics, the powder particles are accelerated to velocities significantly higher than those reached in other coating devices such as, for example, the detonation gun. Some preliminary experimental data show that the accelerated particle can reach velocities higher than 1000 m/s. In parallel, in order to better understand the phenomena taking place inside the device and to determine the optimal process parameters leading to high quality coatings, an appropriate theoretical model was developed. The model is able to describe the complex processes of plasma-gas-propellant interaction, gas flow and powder particle heating and acceleration.