TriStar Plastics Corp. » deflection http://www.tstar.com/blog Tech Talk Blog Tue, 27 Sep 2011 14:29:51 +0000 http://wordpress.org/?v=2.8.4 en hourly 1 Coating Mismatch Effect http://www.tstar.com/blog/index.php/2009/10/coating-mismatch-effect/ http://www.tstar.com/blog/index.php/2009/10/coating-mismatch-effect/#comments Tue, 27 Oct 2009 14:57:30 +0000 fhild http://www.tstar.com/blog/?p=127 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.

  convex

Case 1.  The coating has a higher coefficient of thermal expansion vs. the substrate:

 concave

Case 2.  The coating has a lower coefficient of thermal expansion vs. the substrate:

fracture

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.

 

 
Share/Bookmark]]> http://www.tstar.com/blog/index.php/2009/10/coating-mismatch-effect/feed/ 0