TiAl合金表面搪瓷基復合涂層與多弧離子鍍NiCrAlY涂層的抗熱腐蝕行為對比研究

TiAl合金表面搪瓷基復合涂層與多弧離子鍍NiCrAlY涂層的抗熱腐蝕行為對比研究Comparative Study of Hot Corrosion Behavior of the Arc Ion Plating NiCrAlY and the Enamel Based Composite Coatings

本文以Ti-45Al-2Mn-2Nb合金為基體，采用多弧離子鍍制備NiCrAlY涂層、噴涂-燒結法制備搪瓷基復合涂層，對比研究了2種涂層以及合金基體的熱腐蝕行為。熱腐蝕實驗溫度為850 ℃，選用飽和鹽溶液溶質成分為75%Na2SO4+25%NaCl (質量分數，%)，涂鹽量為1.5~2.5 mg/cm2。研究結果表明，合金基體完全不具備抗熱腐蝕能力，表面形成的氧化膜疏松多孔，且極易剝落；NiCrAlY涂層表面生成的保護性Al2O3膜提高了合金的抗熱腐蝕能力，然而涂層與基體間嚴重的互擴散及Al2O3膜與熔鹽的堿性溶解使得NiCrAlY涂層逐漸失效，熱腐蝕60h即出現氧化膜的剝落；而搪瓷基復合涂層在熔鹽環境中只發生了輕微的物理溶解，具有極高的熱穩定性及較低的熱腐蝕速率，有效地阻隔了腐蝕性離子的入侵，抗熱腐蝕性能優異。

TiAl intermetallic alloys have attracted great attention for its potential application in preparing low pressure turbine blades in aircraft engine. However, its poor oxidation and corrosion resistance becomes a challenge at temperatures above 800 ℃, which leads to the developing of protective coatings. Enamel coating is considered as one of the candidates that match the TiAl alloy well, meanwhile provide corrosion protection. Enamel coating has many advantages such as high thermochemical stability, adjustable thermal expansion coefficient and simple preparation process. This study comparatively investigates hot corrosion behavior of the Ti-45Al-2Mn-2Nb alloy, the traditional NiCrAlY coating and the enamel based composite coating in (75% Na2SO4+25% NaCl, mass fraction) melted salt. Results indicate that after 80h of hot corrosion, the bare alloy has completely destroyed. For the NiCrAlY coating, it protects the underlying alloy well by forming a protective Al2O3 scale initially. However, serious interdiffusion between coating and substrate results in the degeneration of the coating as well as the scale. At the same time, the basic dissolution of Al2O3 film accelerates corrosion. So obvious spallation takes place after 60h corrosion. The enamel based composite coating shows excellent thermal stability and low corrosion rate. During the whole hot corrosion test, it still retains its original blue glazing color and luster. Furthermore, the enamel coating suppresses the inward diffusion of oxygen and corrosive ions into the alloy substrate, and thus, it protects the TiAl alloy well from corrosion of the molten (75% Na2SO4+25% NaCl, mass fraction) salt.

全文下載：https://pan.baidu.com/s/1BvmxCaA8dD4QJH3sNY9WSg?

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