Investigation of hot corrosion behavior of thermal barier coating (TBC) produced by cold gas dinamic spray (CGDS) technique

Termal bariyer kaplamalar (TBCs) genellikle gaz türbin motorlarında, uzay ve uçak endüstrisinde, yüksek sıcaklığa maruz kalmış kritik bölge parçalarında ısıl izolasyon amaçlı olarak kullanılan koruyucu kaplamalardır. TBC'ler yüksek sıcaklık koşullarında oluşan oksidasyon, korozyon ve termal şok gibi agresif çevre koşullarını yapıda minimize etmek adına koruyucu görev üstlenmektedirler. Bu çalışmada, Inconel 718 süper alaşım altlık malzeme üzerine, soğuk gaz dinamik sprey (CGDS) yöntemi kullanılarak CoNiCrAlY metalik bağ kaplamaların üretimleri gerçekleştirilmiştir.CGDS tekniği kullanılarak üretilen bağ kaplamaların üzerineZrO2+Y2O3 (YSZ) içerikli seramik üst kaplamaların üretimi atmosferik plazma sprey (APS) ve elektron ışını ile fiziksel buhar biriktirme (EB-PVD) yöntemleri kullanılarak gerçekleştirilmiştir.Üretimleri gerçekleştirilen farklı TBC numuneleri1000ᵒC sıcaklıkta 4'er saatlik çevrim süreçlerinde sıcak korozyon testlerine tabi tutulmuştur. TBC'lerin üretimindeki farklı yöntemlerin ve test edildikleri sıcak korozyon etkilerinin ayrıntılı olarak gözlemlenebilmesi için mikroyapısal ve mekanik incelemelerSEM, EDS, elementel haritalama, porozite, XRD analizleri ve sertlik testleri kullanılaraktamamlanmıştır. Elde edilen sonuçlar, literatürde yapılan güncel çalışmalar ile karşılaştırılarakayrıntılı değerlendirmeler yapılmıştır.Thermal barrier coatings (TBCs) are generally used as a protective coating in gas türbine, aerospace and aircraft industry,critical region parts exposed to high temperatures, for the purpose of thermal insulation. TBCs provide protective to minimize aggressive environmental conditions such as oxidation, corrosion and thermal shock occuring at high temperatures within the structure.In this study, CoNiCrAlY metallic bond coat material was deposited with cold gas dynamic spray (CGDS) on Inconel 718 superalloy substrate material. Production of ceramic top coat, which content ZrO2+Y2O3 (YSZ), were perfomed with using atmospheric plazma spray (APS) and electron beam physical vapor deposition on the bond coats, which were produced using CGDS technique.Produced different TBC samples were subjected to hot corrosion tests under 1000 °C for 4 hours periods. Microstructural and mechanical examinations using SEM, EDS, elemental mapping, porosity, XRD analysis and hardness testing were copleted for different methods of the manufacture of TBC and observing in detail the effects of hot corrosion were tested. Obtained results are evaluated making comparisons with current literature studies

Investigation of hot corrosion behavior of thermal barrier coating (TBC) systems with rare earth contents

Thermal barrier coatings (TBCs) are extensively used to protect critical components such as aircraft turbines to provide thermal insulation at elevated temperatures. At high operating temperatures, damage mechanisms such as oxidation and hot corrosion result in spallation of TBC system. The spallation occurs due to the phase transformation during penetration of hot corrosion salts to top coat. YSZ is mainly used as top coat material for TBC systems. However, YSZ cannot be used in temperature higher than 1000 °C. More superior efficiency of gas turbine engines will demand a new generation materials for TBC systems. Nowadays, rare earth zirconates, Gd 2 Zr 2 O 7 ,La 2 Zr 2 O 7 , YSZ/Gd 2 Zr 2 O 7 , and YSZ/La 2 Zr 2 O used as ceramic top coat materials in gas turbine engine components owing to their superior thermal isolation and hot corrosion resistance properties. In this study, hot corrosion mechanism, rare earth zirconates, and their properties as well as their hot corrosion behavior in TBCs were investigated based on literature studies.This investigation was financially supported by Scientific Research Projects (BAP) Coordinatorship of Karabuk University with the project code of KBÜBAP-17-DR-259 and the Scientific and Technological Research Council of Turkey with the project code of TUBITAK, 113R049. This study was carried out as a Ph.D. thesis by Yasin Ozgurluk in the Graduate School of Natural and Applied Science at the University of Karabuk, Turkey