Coating Mismatch Effect
The expansion due to applied heat under ideal circumstances will occur in three dimensions, but with thin film flexible substrates, a mismatch in the coefficient of thermal expansion will result in interfacial stress causing curl.
Case 1. The coating has a higher coefficient of thermal expansion vs. the substrate:
Case 2. The coating has a lower coefficient of thermal expansion vs. the substrate:
Case 3. Coatings of relatively higher modulus may respond to interfacial stress to the extent that any substrate thermal expansion will cause cracking, crazing, and loss of adhesion. Such failure may not occur until the system has been repeatedly cycled through extremes of temperature.
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Tags: Coating, coatings, deflection, fracture, interfacial stress, thermal expansion
