タングステン繊維のニッケル拡散防止多層被覆(<特集>複合材料)

概要

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Attempts have been made to develop multi-layer ceramic barrier coatings over the reinforcing wire in tungsten wire reinforced nickel-base superalloys suitable for their fabrication by a casting technique. Using the processing of chemical vapor deposition, the wire was first coated with a 1μm thick layer of TiN, then with a 5μm thick layer of TiC or TiN or Al_2O_3, and finally with a 1μm thick layer of Al_2O_3. It was found that none of these multi-layer coatings was damaged during the composite fabrication by casting. The most favorable in terms of the barrier effect was the Al_2O_3-based coating (TiN-Al_2O_3/Al_2O_3), which completely inhibitted the nickel-induced recrystallization of tungsten wire even after 1000h exposure at 1200℃. The TiC-based coating (TiN/TiC/Al_2O_3) was unfavorable because complicated chemical interactions occured especially between TiC and TiN. While the TiN-based coating (TiN/TiN/Al_2O_3) was structurally similar to the Al_2O_3-based coating, results were somewhat different since the constituent layers, TiN and Al_2O_3, had different thickness. The superiority of the Al_2O_3-based coating was also confirmed by the composite creep-rupture testing.
社団法人日本鉄鋼協会の論文
1989-09-01