Application of zinc ash, a waste product of hot-dip galvanizing, in a powder composition for thermal diffusion galvanizing

The results of studies on the possibility of using zinc ash, a waste product of hot‑dip galvanizing, in a powder composition as an inexpensive substitute for the zinc‑containing and activating component are presented. It is shown that, during thermal diffusion galvanizing of steel specimens at a temperature of 450 °C for 4 h based on the zinc dust–Al2O3‑zinc ash system, the coating layers that form consist of the α, Γ, and δ phases, which are also characteristic of zinc layers in powder media based on the system of standard zinc powder–Al2O3 and an activator, for example, NH4Cl. It is established that the addition of zinc ash in an amount of 1.5 % to the saturating medium, consisting of 40 % zinc dust + 58.5 % Al2O3, made it possible to obtain the same values of the change in the dimensions and mass of the specimen as with the addition of 1 % of the activator NH4Cl.

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