Hideyuki Arikawa

ZrO2 and Cu functionally gradient materials prepared by a dynamic ion mixing process

Abstract ZrO2-Cu films have been prepared as functionally gradient materials (FGM) which change continuously from Cu to ZrO2. Partially stabilized ZrO2 (PSZ) and the PSZ-Cu FGM films were prepared on a Cu substrate by a dynamic ion mixing process. Oxygen ion irradiation was essential for the FGM formation of the PSZ-Cu films, because films deposited without oxygen ion irradiation were easily peeled from the substrate during the deposition steps. The electron beam deposition rates of Cu and ZrO2 were individually controlled. The FGM structures were analysed by X-ray photoelectron spectroscopy and transmission electron microscopy. Cu and PSZ crystal grains were finely mixed in the FGM layers. The thermal resistance of the FGMs was examined by a heat test in which the film surface was heated by an Ar + H2 plasma jet. No cracks were observed on the PSZ-Cu FGM surfaces after the test. However, for PSZ film (without the FGM layer) on the Cu substrate, cracks were seen.

304 The Influence of Long Term Operation on Delamination Behavior of Thermal Barrier Coatings under Thermo-mechanical Fatigue.

1 緒 言 燃料価格の上昇および環境問題などから,発電効率の 向上が強く求められている.ガスタービンの高効率化に は高温化が効果的であるものの,クリープ強度に対する 材料の制限から,遠心力が作用するタービン動翼の信頼 性を維持するべく,冷却の強化を図る必要がある. 近年,冷却強化の手法の一つとして,熱伝導率の低い セラミック皮膜を動翼表面に施工することで,内部冷却 翼の温度を低減する熱遮蔽コーティング (TBC, Thermal Barrier Coatings) の適用が主流となりつつある. TBCはすでに運用中の翼に施工することも可能であ り,耐食耐酸化性向上も期待できることから,その適用 範囲は今後さらに拡大することが予想される.しかしな がら,TBCの損傷挙動を定量的に評価するには,まだ不 透明な点も多い.1) 従来 TBCに関する研究は,皮膜の性質に関する内容 とはく離強度に関する内容に大別されてきた.膜質につ いて Fujiiらは,高温曝露に伴う焼結によりセラミック層 の気孔率が減少するとともに熱伝導率が増加する挙動を LMP (Larson-Miller Parameter) を用いて整理する手法を 提案している.2)TomimatsuらはEB-PVD (Electron Beam Enhanced Physical Vapor Deposition) により製膜した TBCを対象として,レーザー光を用いた皮膜内の残留応 力測定手法を提案するとともに,高温曝露に伴い残留応 力の値が増加することを報告している.3)また脇らはセラ ミック層の残留応力を応力開放法により求めるとともに, 繰り返し負荷下での皮膜の変形特性を示している.4), 5) 一方強度については,西野らが TBCの施工により等 温下での低サイクル疲労寿命が低温で短寿命,高温で長 寿命となることを示し,これはボンド層の延性の温度依 存性に起因すると説明している.6)しかしながらガスター ビンの高温部品には,Fig. 1に示すように起動・停止に 熱機械疲労下における熱遮蔽コーティングのはく離挙動 吉 竹 茂 飯 尾 哲 史 船 尾 淳 喜 関 原 傑 有 川 秀 行 市 川 国 弘 Delamination Behavior of Thermal Barrier Coatings under Thermo-Mechanical Fatigue

Experimental Investigation of High Temperature Wear Resistant Coatings for Industrial Gas Turbine

In the contact section of industrial gas turbine parts, wear can be observed after normal operations. Especially, in the contact area of combustors and their fittings, such as a transition piece and a seal plate, the severe wear may occur owing to combustion vibration under high temperature. If such severe wear occurs, some inspections or repair of the combustor parts may be needed. The short cycle of inspection and repair will decrease the performance of the gas turbine. Though combustors and their fittings are subjected to high temperature condition without any lubricant, any relevant prevention has not been developed yet. In this paper, wear resistance of ceramic hard coating materials, i.e. titanium nitride (TiN), titanium aluminum nitride (TiaAIN), chromium nitride (CrN), titanium carbide (TiC), silicon carbide (SiC), aluminum oxide (Al2 O3 ) against various metals was tested under the condition similar to that in a gas turbines. These coatings were deposited by physical vapor deposition (PVD) or chemical vapor deposition (CVD) processes. It was concluded that, the combination of Al2 O3 coating and stellite #6B had excellent high temperature wear resistance.© 2003 ASME