Combination Mechanism of Ni-Al Sprayed Coating under Median Temperature Sintering and Valid Evaluation for its Bonding Strength
After Ni-Al mixed powder is sprayed on surface of pure Fe using oxy-fuel spraying, the as-sprayed coatings are processed by median temperature sintering in hydrogen atmosphere. SEM image and element distributions cross the interface of sintering coating are characterized using scanning electron microscopy (SEM). The results show that the sintering coating have a good combinaton and there is a transition zones of about 10 μm in width with metallurgical binding cross the coating interface. Under the protection of hydrogen, the oxidation-reduction reaction of Fe, Ni and Al could be occurred cross the coating interface, and contribute to combination of the coating interface. In view of the low sterngth of glue, the high adhesion strength coating could not be evaluated by ASTM C633-79. As a result, a modified experimental method and corresponding finite element (FE) analysis was conducted to evaluate the adhesion strength of high-strength coating. The parallel testing between the new method and ASTM C633-79 on specimens with same condition for low adhesion strength coatings has been conducted and the valid is proved.
W. Zhou et al., "Combination Mechanism of Ni-Al Sprayed Coating under Median Temperature Sintering and Valid Evaluation for its Bonding Strength", Applied Mechanics and Materials, Vols. 29-32, pp. 537-542, 2010