Kaplama Uygulanmış Buhar Türbini Kanadının Ömrünün Korozyon ve Erozyon Açısından İncelenmesi

Öz

Bu çalışmada türbin kanatlarının işletme koşullarında maruz kaldığı fiziksel ve kimyasal değişimler ve bu değişimlerin malzeme üzerindeki etkileri değerlendirilmiştir. Çalışma kapsamında bir Termik Santralde 25 yıl boyunca kullanılan bir türbin kanadı ve kaplaması ile hiç kullanılmamış aynı malzemeden yapılmış orijinal bir türbin kanadının dayanıklılık/çalışma ömrü boyunca oluşan korozyon ve aşınma miktarları karşılaştırmalı olarak incelenmiştir. Bu araştırma, türbin kanatlarının daha uzun ömürlü olması için mevcut malzeme ve kaplamanın uygunluğunun değerlendirilmesinde ve fiziksel ve kimyasal koşullara dayanıklılık açısından kaplamada yapılabilecek değişikliklere yönelik fikirler edinilmesinde önemli bulgular içermektedir. Çalışmada incelenen türbin kanadının termal metal püskürtme kaplama yöntemi kullanılarak Co esaslı malzeme (Cr, Mo, Ni, Mn içeren) ile kaplandığı belirlenmiştir. Kaplamaya ve altlığa AgCuZn esaslı bağ kaplaması uygulanmıştır. Ortalama 69.466.700 MWh enerji üretimi ile 25 yıllık hizmet süresinden sonra türbin kanadı türbinden sökülerek korozyon ve erozyon hasarı analizleri için incelenmiştir. Deneysel çalışmada numunelerin metalografik hazırlanması nedeniyle kimyasal ve boyutsal ölçümler, optik mikroskopi, SEM ve EDS ölçümleri yapılmıştır. XRD ile yapısal analizler yapılmış, sertlik testi ile numunelerin mekanik özellikleri ve ömürleri belirlenmiştir. Yapılan incelemeler sonucunda türbin kanatçığının hem korozyon ve erozyona hem de korozif erozyona maruz kaldığı, yüzeydeki kaplamanın lokal olarak tamamen aşındığı, kanat uçlarında aşınma (korozif ve erozif) nedeniyle kesit daralması olduğu belirlenmiştir. Kaplanan kısımlar erozif ve korozif etkilere karşı daha dirençli olmuştur. Kaplama aşınmasında taban malzemesi ile kaplama başlangıç ​​noktası arasındaki geçiş bölgesi oldukça etkili olmuştur. Korozyon ve erozyonun birlikte aşınmaya neden olduğu görülmüştür.

Anahtar Kelimeler

• Buhar türbini kanadı
• Erozyon
• Korozyon
• Malzeme karakterizasyonu

Investigation of The Lifetime of the Coating Applied on The Steam Turbine Blade in Terms of Corrosion and Erosion

Öz

This study evaluated the physical and chemical changes that turbine blades are exposed to under operating conditions and their effects on the material. Within the scope of the study, the amount of corrosion and wear that occurred during the durability/operational life of a turbine blade and its coating used for 25 years in a Thermal Power Plant and an original turbine blade made of the same material that has never been used were comparatively examined. This research contains important findings in evaluating the suitability of the existing material and coating for longer life of turbine blades and obtaining ideas for changes to be made to the coating in terms of resistance to physical and chemical conditions. The turbine blade examined in the study was determined to be coated with Co-based material (containing Cr, Mo, Ni, Mn) using the thermal metal spray coating method. AgCuZn-based bond coating was applied to the coating and the substrate. After 25 years of service with an average energy production of 69,466,700 MWh, the turbine blade was removed from the turbine and examined for corrosion and erosion damage analyses. In the experimental study, chemical and dimensional measurements, optical microscopy, SEM, and EDS measurements were carried out due to the metallographic preparation of the samples. XRD performed structural analysis, and hardness testing was used to determine the mechanical properties and life of the samples. As a result of the investigations, it was determined that the turbine blade was subjected to both corrosion and erosion and corrosive erosion, the coating on the surface was completely worn locally, and there was a cross-sectional reduction due to wear (corrosive and erosive) at the blade tips. The coated parts were more resistant to erosive and corrosive effects. The transition zone between the base material and the coating starting point was very effective in coating wear. It has been observed that corrosion and erosion cause abrasion together.

Anahtar Kelimeler

• Steam turbine blade
• Erosion
• Corrosion
• Materials Characterization

Kaynakça

1. [1] Bzymek G., Bryk M., Kruk-Gotzman S., Ziółkowski P.J., "Computational Fluid Dynamics Study of Erosion on 900 MW Steam Turbine ND-45 Blades Using 3D Scanning", Materials,17, 4884, (2024).
2. [2] Rodrígez J.A., Clemente C.M., Zalapa M.A., García J.C., Guillén L.G., "Corrosion Fatigue Analysis in Power Steam Turbine Blade", Metals,13, 544, (2023).
3. [3] Damjanovic D., "Corrosion fatigue failure of steam turbine moving blades: A case study", Engineering Failure Analysis, (2019).
4. [4] Ryzhenkov V.A., Lebedeva A.I., Mednikov A.F., "Erosion wear of the blades of wet-steam turbine stages: Present state of the problem and methods for solving it", Thermal Engineering,58, 713-718, (2011).
5. [5] Çengel Y.A., Boles M.A.,Mühendislik Yaklaşımıyla Termodinamik, New York, USA, (1994).
6. [6] Sigloch H., Strömungsmaschinen. Grundlagen und Anwendungen, 3. neu bearbeitete Auflage, Hanser Verlag, München, (2006).
7. [7] Huttunen-Saarivirta E., Kinnunen H., Tuiremo J., Uusitalo M., Antonov M., "Erosive wear of boiler steels by sand and ash", Wear,317, 213-224, (2014).
8. [8] Gujba A., Hackel L., Kevorkov D., Medraj M., "Water Droplet Erosion Behaviour of Ti-6Al-4V and Mechanisms of Material Damage at the Early and Advanced Stages", Wear,358-359:, (2016).

9. [9] Mahdipoor M.S., Water Droplet Erosion Resistant Materials and Surface Treatment, Concordia University, p.70, (2016).
10. [10] Langston L.S., "Turbines, Gas",in *Encyclopedia of Energy*, Elsevier: Amsterdam, The Netherlands, 221-230, ISBN 9780121764807, (2004).
11. [11] Sonntag, R.E.; Borgnakke, C. Introduction to Engineering Thermodynamics, 2nd ed.; John Wiley: Hoboken, NJ, USA, ISBN 9780471737599, (2006).
12. [12] Finnie, I. "Erosion of surfaces by solid particles". Wear, 3, 87-103, (1960).
13. [13] Bitter, J. A ''study of erosion phenomena Part I’’. Wear, 6, 5-21, (1963).
14. [14] Finnie, I. "Some observations on the erosion of ductile metals". Wear, 19, 81-90, (1972).
15. [15] Urban, L.A. "Parameter Selection for Multiple Fault Diagnostics of Gas Turbine Engines". J. Eng. Power, 97, 225-230, (1975).
16. [16] Chena, W.R.; Zhao, L.R. ''Review-canic ash and its influence on aircraft engine components’’. Proc. Eng., 99, 795-803, (2015).
17. [17] Hamed, A.; Tabakoff, W. (Eds.)83rd Symposium of Propulsion and Energetics Panel on Turbines; AGARD: Rotterdam, The Netherlands, p. 11, (1994).
18. [18] Fortini A., Suman A., Zanini N., "An experimental and numerical study of the solid particle erosion damage in an industrial cement large-sized fan", Engineering Failure Analysis,146, 107058, ISSN 1350-6307, (2023).
19. [19] Pepi, M.; Squillacioti, R.; Pfledderer, L.; Phelps, A "Solid Particle Erosion Testing of Helicopter Rotor Blade Materials". J. Fail. Anal. Prev., 12, 96-108. (2011).
20. [20] Hutchings I., Levy A. "Thermal effects in the erosion of ductile metals," Wear 131, 105-121, (1989).
21. [21] Azevedo C., Sinatora A., "Erosion-fatigue of steam turbine blades", Engineering Failure Analysis,16, 2290-2303, (2009).
22. [22] Babu P., Manager S., "Cause and Prevention for Steam Turbine Blade Scaling and Fouling", (2016).
23. [23] Suez,Water Technology Handbook, Chapter 18: Steam Turbine Deposition, Erosion and Corrosion, (Kurumsal Yayın)
24. [24] Hancox N.L., Brunton J.H., "The erosion of solids by the repeated impact of liquid drops", Philosophical Transactions of the Royal Society of London A: Mathematical, Physical and Engineering Sciences,260(1110), 121-139, (1966).
25. [25] Mann, B. "High-energy particle impact wear resistance of hard coatings and their application in hydroturbines". Wear, 237, 140-146. (2000).
26. [26] Liu, J.; Lu, L.; Zhu, L. "Experiment study on sediment erosion of Pelton turbine flow passage component material". IOP Conf. Series Earth Environ. Sci., 15, 032055., (2012).
27. [27] Taherkhani B., Anaraki A., Kadkhodapour J., Farahani N., Tu H.Y., "Erosion Due to Solid Particle Impact on the Turbine Blade: Experiment and Simulation", Journal of Failure Analysis and Prevention,19, 1-6, (2019).
28. [28] Reynolds, O. XLII. "On the action of a blast of sand in cutting hard material". Philos. Mag. (Fourth Ser.), 46, 337-343. (1873).
29. [29] Bahramnia, H.; Semnani, H.M.; Habibolahzadeh, A.; Abdoos, H. "Epoxy/polyurethane nanocomposite coatings for anti-erosion/wear applications: A review." J. Compos. Mater. 2020, 0021998320908299. (2020).
30. [30] Bai, X.; Yao, Y.; Han, Z.; Zhang, J.; Zhang, S. "Study of Solid Particle Erosion on Helicopter Rotor Blades Surfaces". Appl. Sci., 10, 977. (2020).
31. [31] Edwards K., Mislang H., ‘’History of coatings’’, in Encyclopedia of Materials: Science and Technology, Elsevier, (2000).
32. [32] Bousser, E.; Martinu, L.; Klemberg-Sapieha, J. "Solid particle erosion mechanisms of protective coatings for aerospace applications". Surf. Coat. Technol., 257, 165-181. (2014).
33. [33] Mann V.A.B. "An experimental study to correlate water jet impingement erosion resistance and properties of metallic materials and coatings," Wear, 253, 650-661, (2002).
34. [34] Mann V.A.B.S. "HVOF coating and surface treatment for enhancing droplet erosion resistance of steam turbine blades," Wear, 254, 652-667, (2003).
35. [35] Cerný J.S.I. "Fatigue strength of laser hardened 42CrMo4 steel considering effects of compressive residual stresses on short crack growth," Procedia Engineering, 74, 417-420, (2014).
36. [36] Khan M.S., Sasikumar C., "Failure analysis of AISI 420 steel turbine blade operating at low-pressure", Materials Today: Proceedings,66, Part 9, 3804-3808, (2022).
37. [37] Sadki, A., Younes, R., Bradai, M., Mesrati, N. "Effect of NiAl Bond Layer on the Wear Resistance of an Austenitic Stainless Steel Coating Obtained by Arc Spray Process," SAE Int. J. Mater. Manf. 16(4):321-330, 2023, (2022).
38. [38] Mirshekari R., Daee S., Fatoureh Bonabi S., Tavakoli Shoushtari M., Shafyei A., Safaei M., "Effect of Interlayers on the Microstructure and Wear Resistance of Stellite 6 Coatings Deposited on AISI 420 Stainless Steel by GTAW Technique", Surfaces and Interfaces,9, (2017).
39. [39] Purushotham N., Santhy F.T., Babu P., Govindarajan S., Rajasekaran B., "In Situ High-Temperature X-ray Diffraction Study on Atmospheric Plasma and Detonation Sprayed Ni-5 wt.%Al Coatings", Journal of Thermal Spray Technology,32, (2023).
40. [40] Banea, M. & Silva, L.F.M., "Adhesively bonded joints in composite materials: An overview" . Proc. Inst. Mech. Eng. Part L: J. Mater. Des. Appl..223. 1-18., (2009).
41. [41] Chowdhury T.S., Mohsin F.T., Tonni M.M., Mita N.H., Ehsan M.M., "A critical review on gas turbine cooling performance and failure analysis of turbine blades", International Journal of Thermofluids,18, 100329, (2023).
42. [42] Ugla A., Mushtaq H., Zainalabden I., Dhuha K., "Enhancing thermal properties of steam turbine blades by coating with nanomaterials", (2021).
43. [43] Shubenko A.L., Tarelin A.O., "Simulation of the Erosion‑Corrosion Destruction Process of Steam Turbine Low‑Pressure Cylinder Blades", Journal of Mechanical Engineering - Problemy Mashynobuduvannia,26(1): 29-38, (2023).
44. [44] Bağcan Kayıhan A, Kaya C. ‘’Improving Erosion Properties Of Steam Turbine Blades Via Surface Modifications’’. Sigma., 35(2):253-6., (2017).
45. [45] Houdková, Š.; Česánek, Z.; Polach, P. ‘’Performance of Selected Thermally Sprayed Coatings for Power Applications’’. in Thermal Spray Coatings for Power Applications, Springer, (2022).