Abstract
A thermal wave technique for the non-destructive examination of plasma-sprayed coatings is described. Measurements of molybdenum NiAl and aluminium coatings are presented to demonstrate that the technique can be used for defect detection, coating thickness determination and thermal property evaluation. The effects observed are shown to be attributable to thermal wave interference in the coating material. A semiquantitative model of the coating microstructure is presented to compare its effects on the propagation of ultrasonic and thermal waves. The model predicts the coating material's very high attenuation of ultrasonic waves and a very low attenuation for thermal waves. This is taken to explain the success of thermal waves, and the failure of ultrasonic waves, in producing measurable interference effects in plasma-sprayed coatings.
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References
R. C. Tucker Jr, in “Deposition technologies for films and coatings”, edited by R. F. Bunshah (Noyes Publication, New Jersey, USA, 1982).
R. L. Cox, D. P. Almond andH. Reiter,Ultrasonics 19 (1981) 17.
D. R. Green,J. Appl. Phys. 37 (1966) 3095.
M. V. Luukkala, “Scanned image microscopy”, edited by E. A. Ash (Academic Press, London, 1980) p. 273.
G. Busse andP. Eyerer,Appl. Phys. Lett. 43 (1983) 535.
N. N. Ault,J. Amer. Ceram. Soc. 40 (1957) 69.
T. B. Buzovkina, T. V. Sokolova, A. P. Obukhov, R. I. Uspenskaga andM. G. Degen,High Temp. (USA) 10 (1972) 345.
S. Safai andH. Herman, Proceedings of the International Conference on Advances in Surface Coatings Technology, February 13–15, 1978, London (The Welding Institute, 1978) Paper 5.
R. Mcpherson andB. V. Shafer,Thin Solid Films 97 (1982) 201.
V. Wilms andH. Herman,ibid. 39 (1976) 251.
S. Safai andH. Herman,ibid. 45 (1977) 295.
J. B. Kinney andR. H. Staley,Ann. Rev. Mat. Sci. 12 (1982) 295.
Y. H. Wong, in “Scanned image microscopy”, edited by E. A. Ash (Academic Press, London, 1980) p. 247.
A. J. Angstrom,Ann. Phys. (Leipzig) 114 (1861) 513.
L. Vereni andA. Santucci,Il Nuovo Cimento B (Italy) 62B Ser 2 (1981) 399.
H. S. Carslaw andJ. C. Jaeger, “Conduction of heat in solids” (Clarendon Press, Oxford, 1959) pp. 64–9.
D. R. Green,Mat. Eval. (USA) 25 (1967) 231.
J. Ospal andA. Rosencwaig,J. Appl. Phys. 53 (1962) 4240.
F. Alan Mcdonald,Amer. J. Phys. 48 (1980) 41.
C. A. Bennet Jr andR. R. Pattey,Appl. Opt. 21 (1982) 45.
R. L. Thomas, L. D. Favro, K. R. Grice, L. J. Inglehart, P. K. Kuo, J. Lhota andG. Busse,IEEE Ultrasonics Symp. 2 (1982) 586.
M. Luukkala, A. Letho, J. Jahrinen andM. Jokinen,ibid. 2 (1982) 591.
P.-E. Nordal andS. O. Kanstad,Phys. Scr. 20 (1979) 659.
G. Busse,Infrared Phys. 20 (1980) 419.
R. L. Cox, MSc thesis, University of Bath (1979) unpublished.
J. Daniault, J. de Goer andG. Schnedeker, Preprints of 8th International Thermal Spraying Conference, September, 1976, Florida, USA (American Welding Society) p. 310.
R. L. Thomas et al., J. Appl. Phys. 51 (1980) 1152.
G. Busse andA. Rosencwaig,Appl. Phys. Lett. 36 (1980) 815.
W. W. Seto, “Theory and problems in acoustics”, Schaum's outline series (McGraw Hill, 1971) p. 99.
R. L. Cox, D. P. Almond andH. Reiter,NDT Int. 13 (1980) 291.
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Patel, P.M., Almond, D.P. Thermal wave testing of plasma-sprayed coatings and a comparison of the effects of coating microstructure on the propagation of thermal and ultrasonic waves. J Mater Sci 20, 955–966 (1985). https://doi.org/10.1007/BF00585740
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DOI: https://doi.org/10.1007/BF00585740