Cyclic Corrosion Behavior of Pt/Ru-Modified Bond Coatings Exposed to NaCl Plus Water Vapor at 1050℃

In the present investigation,Pt/Ru-modified bond coating consisted of 2 μm Pt＋2 μm Ru was deposited on a nickel-based superalloy by electroplating method and followed by conventional Al pack cementation.The cyclic corrosion behavior of Pt/Ru-modified bond coating exposed to NaCl plus water vapor has been investigated under atmospheric pressure at 1050℃.The result shows that the cyclic corrosion life of Pt/Ru-modified bond coating is longer than that of the conventional Pt-modified aluminide coating in the presence of NaCl plus water vapor.The addition of Ru makes the coating possess the increased strength and suppress the rumpling behavior.The absence of rumpling may be responsible for the improved corrosion resistance of Pt/Ru-modified aluminide coating.

Cyclic-Oxidation Behavior of Multilayered Pt/Ru-Modified Aluminide Coating

Multilayered Pt/Ru modified aluminide coating for thermal barrier coating （TBC） systems has been investi- gated. 2μm Pt＋2 μm Ru＋2 μm Pt was first deposited on nickel-base superalloy DZ125 by electrodeposition, and then the coating was treated by annealing and a conventional pack-cementation aluminizing process. The cyclic oxidation tests were carried out at 1423 K in air. It was found that the thermal cyclic oxidation resistance of Pt/Ru-modified aluminide coating was comparable to that of Pt-modified aluminide coating, which was much better than simply aluminized DZ125. The addition of Ru to Pt-modified aluminide coating increased the resistance to rumpling. The microstructures and phase constitutions of the coating before and after oxidation were investigated.

Thermal cycling performance of La_(2)Ce_(2)O_(7)/YSZ TBCs with Pt/Dy co-doped NiAl bond coat on single crystal superalloy

Thermal barrier coatings(TBCs) consisting ofLa_(2)Ce_(2)O_(7)(LCO) and Y_(2)O_(3)-stabilized-ZrO_(2)(YSZ) doubleceramic layer and Dy/Pt co-doped NiAl bond coat were produced by electron beam physical vapor deposition(EBPVD). Thermal cyclic performance of the TBCs was evaluated by flame shock testing at 1300 ℃. For comparison, the TBCs with a undoped NiAl bond coat were also studied. The microstructural evolution and failure mechanisms of the above TBCs during thermal cycling were investigated. Spallation failure of the TBCs with the undoped bond coat occurs after around 500 cycles by cracking at the interface between YSZ ceramic layer and thermally grown oxides(TGO) layer. The TBCs with Pt/Dy modified bond coat reveal improved interface bonding even after 1200 thermal cycles, whereas some delamination cracks are presented in the LCO layer. On the other hand,the Pt/Dy modified bond coat effectively suppresses the formation of the needle-like topologically closed packed phases(TCP) in the single crystal superalloy.

铂改性铝化物涂层的热生长层内应力研究

研究了镍基高温合金热障涂层系统中铂改性铝化物粘结层在空气中非连续高温氧化生成的Al2O3层内应力状态及相应的粘结层微观结构。利用Raman光激发荧光谱技术,发现铂铝粘结层在900℃氧化初期生成了θ-和α-Al2O3,而在1100℃氧化时,表面则形成连续致密的α-Al2O3层。通过α-Al2O3的光激发荧光谱偏移量,计算得到了热障涂层中热生长层的内压应力略高于3.0GPa。铂改性铝化物涂层表面Al2O3"背脊"处的内应力相对较低,同时由于没有陶瓷层的压制,生成的Al2O3起伏较大,并发生局部的Al2O3脱落。随氧化时间延长,由于Al元素沿晶界扩散较快,导致更多的γ′-Ni3Al在粘结层晶界处形成,粘结层中基本相β-NiAl向γ′-Ni3Al转变,改变了粘结层本身的热膨胀系数,引起热生长层中内应力变化。