An Elucidation On Adhesive Strength Of Al2o3 And Zro25cao Composite Coatings Applied On Al-6061 & Ci Substrates

Abstract

In this study, the adhesion strength of atmospheric plasma sprayed coatings on cast iron and Al-6061substrates were carried out. Alumina and calcia stabilized zirconia in 50:50 proportion by weight were blended in a ball mill and applied as a top coat. The top coat thickness was varied as 100 µm, 200 µm, and 300µm. Adhesion test was conducted as per ASTM C633 standard and a comparative analysis was done. SEM micrographs revealed that the weakest link was formed between the top coat/bond coat interfaces in all the coating systems. Relatively higher adhesion strength was found due to the excellent metallurgical bonding between Al2O3 -ZrO2 ·5CaO topcoat and Ni-Al bond coat in the case of the cast iron 300µm coating system. An attempt has been made to bring out an insight into the principal causes of adhesion failure for the above coating combinations.