| Al diffusion to Inconel 713C by pack commentation in Ar gas with FeAl₂, Al＋Fe and Al powders has been investigated for the purpose of improvement of hot corrosion resistance. The main results are as follows. 1. Al diffusion coating was possible with only Al powder without activator (NH₄Cl). 2. The thickness of diffused layer increased with increasing of holding time, but the coated layer was the thickest when it was treated for 15 hours at 1000℃ in Ar. 3. The diffused layer by FeAl₂(or Al＋Fe) powder was thicker than that by Al powder, and the thickness of coated layer by Al powder was thicker than that by FeAl₂(or Al＋Fe) powder under the same condition. 4. Hot corrosion resistance of the coated layer was good, for example, the specimens by FeAl₂( or Al＋Fe) powders endured 3-4 cycles, and those by Al powders endured more than 15 cycles in salt mixture of 75%Na₂SO₄＋25%NaCl for 20 hours at 900℃ per cycle. 5. Hot sulfuric corrosion attack of the coated specimens were progressed quickly when the coated layer was cracked from cyclic thermal shock, because of infiltration of melted salt through it. |
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