Abstract




 
   

IJE TRANSACTIONS A: Basics Vol. 26, No. 1 (January 2013) 13-18   

PDF URL: http://www.ije.ir/Vol26/No1/A/2-1345.pdf  
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  COMPARATIVE STUDY OF PLASMA SPRAYED YITTRIA AND CERIA STABILIZED ZIRCONIA PROPERTIES
 
M. R. Rahimipour and M. S. Mahdipoor
 
( Received: May 11, 2011 – Accepted: November 15, 2012 )
 
 

Abstract    Thermal Barrier Coatings are subjected to spallation and destabilization due to hot corrosion.Recently, Ceria Stabilized Zirconia (CSZ)-based TBCs have been intensively investigated for the YSZreplacement because CSZ has a much lower thermal conductivity and a higher expected thermalexpansion coefficient than those of YSZ. In this research, Yttria stabilized zirconia (YSZ) andceria stabilized zirconia (ZrO2 25CeO2 2.5Y2O3) TBCs were fabricated, followed by hot corrosiontests with a Na2SO4+V2O5 salt at 1050 °C. The treated samples were characterized using XRD andSEM equipped with EDS. From studies on microscopic failure behavior, the formation of YVO4 crystalsand the amount of phase transformations of tetragonal ZrO2 to monoclinic lead to degradation ofcoatings. Results revealed that CSZ TBCs were better resistant to hot corrosion than YSZ TBCs. Theamount of YVO4 crystals and monoclinic ZrO2 in YSZ are much more than CSZ which leads soonerdegradation of YSZ than CSZ. The strength of the Adhesive coatings of the substrate was alsomeasured in this study.

 

Keywords    Thermal Barrier Coatings, Hot Corrosion, Bond Strength

 

چکیده    به دلیل خواص حرارتی مطلوب­تر پوشش­های زیرکونیای پایدار شده با سریا (CSZ) درمقایسه با زیرکونیای پایدار شده با ایتریا (YSZ)، رایج­ترین پوشش سد حرارتی، تحقیقات فراوانی به منظور بررسی امکان استفاده گسترده این ماده به عنوان پوشش سد حرارتی در حال انجام است. یکی از دلایل تخریب پوشش­های سد حرارتی، خوردگی داغ می باشد که در این پژوهش برای پوشش­های YSZ و CSZ بررسی شده است. ابتدا این پوشش­ها با روش پاشش پلاسمایی بر روی زیرلایه­هایی از جنس سوپر آلیاژ پایه نیکل ایجاد شدند. جهت بررسی مقاومت به خوردگي داغ نمونه­ها، آزمون­هاي خوردگي داغ روي سطح این پوشش­ها در نمک مذاب (55% وزني V2O5 و 45% وزني Na2SO4 ) در دماي C °1050 انجام شد. بر اساس مطالعه میکروسکوپی فرآیند خوردگی داغ و بررسی میزان تشکیل YVO4 به عنوان محصول خوردگی داغ در نمونه­ها، پوشش­های سد حرارتی CSZ مقاومت به خوردگی داغ بالاتری از خود نشان دادند. در واقع کریستال های YVO4 کوچک تر و به تبع آن زیرکونیای مونوکلینیکی کمتری در نمونه های با پوشش CSZ دیده شد که نشان دهنده مقاومت بیشتر و عمر طولانی­تر این پوشش­ها می­باشد. استحکام چسبندگی پوشش­ها نیر مورد بررسی قرار گرفته است.

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