Influence of reflected radiation of high velocity oxy-fuel spraying torch on long wavelength IR pyrometry temperature measurement

High velocity oxy-fuel (HVOF) torch radiations were measured in the 8-14 μm spectral band as a function of successively oxygen and methane (CH4) flow rates. Experienced flow rates were varied respectively from 250 to 450 Nl/min for oxygen and from 100 to 150 Nl/min for methane. Prediction about the effects of the reflected HVOF torch radiation on the measured temperature was detailed. Extraneous radiant energy coming from the HVOF torch was found to have drastic effects on temperature measurement under some special input conditions. In such a case, a correction of the measured temperature for reflected HVOF radiant energy has to be performed for low target temperature or low target emissivity.