Experimental Investigation on the Reliability of Thermal Wave Interferometry in the Thermophysical Characterization of Plasma Sprayed Coatings

Tokamak active laser pyrometry for tungsten deposited layer characterisation

“…The calculations were performed with the developed 3D numerical model. The properties obtained for the W-layer (Table 1) differ significantly from those of metallic tungsten and those of W-layer in [21]. This difference may be attributed to high porosity and complex morphology of our layer.…”

Potential of Modulated IR Radiometry for the On-Line Control of Coatings

“…Such deviations from the coating's homogeneity and the effects of transparency, e.g., IR transparency in the case of plasma‐sprayed coatings,12 often are the origin for larger errors obtained in the modulated IR radiometry of coatings 13,14. Comparing the measurement and interpretation method proposed here with former work on thermal wave interferometry of layer systems and coatings, e.g., ref 1,8,10,15,.…”

Comment on “Photothermal radiometry parametric identifiability theory for reliable and unique nondestructive coating thickness and thermophysical measurements” [J. Appl. Phys. 121, 095101 (2017)]

“…A significant number of papers have already addressed the problem of identifiability regarding the parameters of a coating in the course of a photothermal measurement, with periodic excitation [2][3][4][5] , pulsed excitation [6][7][8][9][10][11][12] or both 13 . Of benefit are also some works on the thermal characterization of a given layer in a multilayer stacking [14][15][16] .…”

“…This is exactly what is encountered with the combination of parameters { 2 L , 2  , 2  } because they are fully correlated. The conditions of identifiability of 2 Q and 2 P (or related parameters) were analysed in many instances [2][3][4][5][6][7][8][9][10][11][12][13] (in particular, 2…”

“…This corresponds to one of the pathological cases described by one of the authors in Ref. 4:"the best way to make an inversion problem effective is to use only experimental data in the regions where the sensitivity coefficients are high, not proportional, nor almost proportional, nor, in general, constitute a linear combination".…”