Study on atmospheric plasma spraying of Al2O3 using on-line particle monitoring

In recent years, the interest in on-line diagnostic methods for thermal spraying has been increasing. The particle in-flight properties can be determined using such methods. One of the methods is on-line particle monitoring. In this investigation, study of atmospheric plasma spraying of Al2O3 was done using a DPV-2000 system (TECNAR, Canada). The influence of some spray parameters and the noise factor ‘wear of electrodes’ on the particle in-flight properties was investigated. It was found that the argon flow rate was the most influential factor for the particle velocity. The hydrogen flow rate influenced mainly the particle surface temperature. Increasing the electric current led to an increase in the particle velocity as well as in the particle surface temperature. The melting behaviour of the powder was significantly influenced by the particle velocity. The higher particle velocity resulted in a worse melting behaviour of the powder due to the shorter dwell time, leading to a lower deposition efficiency of the powder during spraying.