Abstract
Flattening ratio of thermal sprayed particle on a flat substrate has been of great concern in the thermal spraying research. To clarify the flattening ratio experimentally, accurate information on the flying particle, such as velocity and temperature, is essential. In flight measured values for the thermal sprayed particles will play a significant role to understand the flattening behavior of the particle on a substrate. Most of the studies relating to the particle's flattening, however, has applied some assumed values as for the particle's characters in flying, because in-situ measurement for them is somewhat difficult at the present condition.
In this study, DPV-2000 system, which is a revolutionary optical sensing device with on-line monitoring of the individual particle in thermal spray flame, was introduced to establish the in flight measurement of the particle's characters. The purpose of the study is to investigate the relationship between spraying parameters and particle's characters, and clarify the flattening behavior of the particle on a substrate based on the measured data.
From the measurement results of the particle's characters obtained by changing each spraying parameter, i.e. spray distance, arc current and operating gas flow rate, it was found that the spray distance had the strongest effect on the particle's character. The flattening ratio based on the measured data increased with the particle's Re number. In comparison with experimental flattening ratio and theoretical values, Mostaghimi's curve agreed well to the experimental data.
