Laser Induced Thermal Stresses in Brittle Materials
This paper presented the theoretical and experimental background for understanding of opaque and transparent brittle materials subjected to continuous wave laser irradiation. At irradiations above ~ 1 kw/cm2, the time to failure of opaque materials was proportional to the thickness squared and inversely proportional to the thermal diffusivity. The time to fracture of transparent materials was nearly independent of thickness but was highly dependent on the absorption coefficient. The burnthrough time of both opaque and transparent materials was proportional to the thickness and thermodynamic parameters and inversely proportional to the irradiance.
Laser irradiation can be used to rank the thermal stress resistance of opaque brittle materials. This ranking was the same as that obtained from thermal quenching into water, as long as the thickness, wavelength, and heating rates were equivalent. The reason for the similarity was that the analytical expressions describing both behaviors were similar.
KeywordsLaser Irradiation Thermal Stress Thermal Diffusivity Brittle Material High Power Density
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