Cite as:
Milcent E, Bénet S, Gervaise C, Nouals C, Serra J-J, 1998, "Microdiffusivity measurement on refractory metal coatings by photothermal microscopy" High Temperatures - High Pressures 30(1) 85 – 90

Microdiffusivity measurement on refractory metal coatings by photothermal microscopy

Emmanuel Milcent, Sauveur Bénet, Cédric Gervaise, Claude Nouals, Jean-Jacques Serra

Received 22 January 1997

Abstract. An experimental system for the analysis of thermal transfer on a mesoscopic scale is presented. The measurement technique is based on the photothermal effect. An argon-ion-laser modulated beam, focused by a microscope, produces a local (1 mm in diameter) thermal excitation. At a known distance (2 - 3 mm), a helium - neon laser is used to detect the diffusion of the thermal wave. The diffusivity is obtained on a 2 mm wide zone. With this high spatial resolution, the influence of grain boundaries and microcracks can also be studied. A one-dimensional model is presented, in which interfaces and microcracks are treated as thermal resistance. Data inversion allows the determination of the order of magnitude of these resistances. Results obtained on a chromium coating show the consequences of a strong heterogeneous mesostructure.

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