新型鈷基超合金的腐蝕特性

為了提升鈷基合金在高溫下的抗腐蝕能力，故在此研究中設計出一系列的合金。材料的研究主要分為兩種系列，第一系列是根據商用的UMCO50合金為基底並做進一步的合金成份改質；第二系列為含有γ′ 強化相的鈷基超合金(Co-Al-W-Ni-Si)系統。此兩系列合金皆是主要以改變鋁(Al)和矽(Si)的含量來探討其對材料性質的影響。實驗內容包含鑄造態的微結構分析、析出物熱性質、硬度、沖蝕等，且為了了解鈷基合金對於添加傾向形成氧化層元素的高溫表面穩定性，故測試了在900°C、1000°C、1100°C、1150°C時的恆溫氧化和900°C時的熱腐蝕，並利用XRD、SEM、EDS等儀器分析材料表面和氧化層的組成與厚度。實驗結果顯示，藉由矽或是鋁的添加而形成的連續氧化鋁保護層有助於提升材料在高溫下的表面穩定性，降低氧化增重的情形。另外，鎢含量的降低也能提升材料在高溫下形成氧化鋁保護層的能力。且經過預氧化處理的材料能有更卓越的抗氧化特性。在熱腐蝕方面，此研究中的合金與商用合金相較之下也有出色的表現。故根據實驗結果，此類型的材料具有在高溫環境下應用潛力的新型鈷基合金。

Keywords

鈷基超合金； γ′強化相；高溫氧化；熱腐蝕；硬度；沖蝕

Parallel abstracts

Co-based superalloys in the past have worse oxidation resistance since the addition of Cr has bad influence on γ′ stability. Furthermore, the protective Cr2O3 layer is tends to volatilize at high temperature. Two sets of Co-based alloys were investigated in this study in order to enhance the high temperature corrosion resistance. One is the modification of composition based on the commercial UMCO50; the other set is γ′-bearing Co-Al-W-Ni-Si alloy system. Experimental works include microstructure analysis, thermal property, mechanical properties like hardness and erosion. Moreover, isothermal oxidation at 900°C, 1000°C, 1100°C, and 1150°C and hot corrosion at 900°C were conducted to observe the surface stability by adding the oxide-forming elements like Al and Si. The results indicated that the continuous Al2O3 protective layer formed by addition of Al or Si can have an improvement on the materials’ high temperature surface stability, i.e. lower down the weight gain condition. Moreover, lower W content can enhance material’s ability of forming Al2O3 protective layer at high temperature as well. Pre-oxidation treatment can also make the alloys have outstanding performance. In the aspect of hot corrosion, alloys studied here were many times better than commercial UMCO50. As the result, these type newly developed Co-based alloys may have the potential for high temperature applications.

Parallel keywords

Co-base superalloys ； γ′ phase ； oxidation ； hot corrosion ； hardness ； erosion

References

[1] D.R. Gaskell, Introduction to the Thermodynamics of Materials, CRC Press, 2008.

[3] N. Eliaz, G. Shemesh, R.M. Latanision, Hot corrosion in gas turbine components, Engineering Failure Analysis, 9 (2002) 31-43.

[4] A. Passerone, R. Sangiorgi, E. Ricci, Penetration kinetics of liquid sulphides in nickel and cobalt, Metallurgical Science and Tecnology, 4 (2013).

[5] R.C. Reed, The superalloys: fundamentals and applications, Cambridge university press, 2006.

[6] M.S. Titus, A. Suzuki, T.M. Pollock, High Temperature Creep of New L12 Containing Cobalt‐Base Superalloys, Superalloys 2012, (2012) 823-832.

Read-around

Altmetrics

新型鈷基超合金的腐蝕特性

Read this ↓