Fast heat treatment methods for al slurry diffusion coatings on alloy 800 prepared in air

In the present study aluminum diffusion coatings were prepared on alloy 800H within a few minutes in air using several surface heating methods: induction heating, a natural gas burner, and a heating mat. All such methods are highly relevant for on-site applications, because they are commonly known from post welding heat-treatments. The very short (3 or 5 min) dwell times at temperatures between 700 and 1000 °C were sufficient to produce continuous diffusion coatings with all heat treatment methods. With the heating mat more of the Al-poor (Fe, Cr, Ni)Al phase is formed during diffusion treatment at 1000 °C due to the slower heating and cooling rates in comparison to the other techniques.