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Powłokowe bariery cieplne typu DCL

Moskal G.

Inżynieria Materiałowa

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2014

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Vol. 35, nr 4

303--307

PL

W artykule przedstawiono wyniki mikrostrukturalnych badań powłokowych barier cieplnych typu DCL, tzn. otrzymanych w wyniku natrysku plazmowego dwóch różnych materiałów ceramicznych: 8YSZ i RE2Zr2O7 (gdzie RE = Gd, La, Sm, Nd). Wewnętrzną część warstwy izolującej otrzymano w wyniku natrysku proszku konwencjonalnego 8YSZ bezpośrednio na warstwę żaroodporną NiCrAlY. Strefę zewnętrzną stanowiła warstwa uzyskana w wyniku osadzenia cyrkonianów ziem rzadkich. Ocenie poddano mikrostrukturę warstw, ich grubość i budowę. Stwierdzono, że uzyskano warstwy o grubości od 250 do 320 μm, złożone z trzech stref o zbliżonej grubości. Poza strefami zewnętrzną i wewnętrzną wykazano obecność strefy przejściowej złożonej z 8YSZ oraz RE2Zr2O7. Analizowano również budowę morfologiczną warstwy wierzchniej powłok TBC. Scharakteryzowano jakościowo i ilościowo topografię powierzchni wszystkich badanych powłok. Wykonano badania dyfrakcyjne, które pozwoliły na określenie składu zewnętrznej warstwy izolującej, a także na tej podstawie metodą sin2ψ oszacowano stan naprężeń.

EN

The paper presents the results of microstructural investigations of DCL (double ceramic layer) thermal barrier coatings. The term DCL describes insulating the top surface of a TBC system which comprises two different ceramic materials. It consisted of the zirconates of rare earth elements as the outer part and conventional 8YSZ as the inner part. The obtained DCLs were characterized in terms of their topography, morphology, microstructure, thicknesses of the sublayers and phase composition. The thickness of the obtained DCL’s ranged from 250 to 320 μm, and the entire layers consisted of three sublayers: inner (8YSZ), outer (RE2Zr2O7) and transition, the latter being a mixture of 8YSZ and RE2Zr2O7). Stresses were assessed using XRD measurements and a sin2ψ approach.

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Modelowanie fizyczne rozkładu temperatury w powłokowych barierach cieplnych typu Gd2Zr2O7 podczas obróbki laserowej

Grabowski A., Moskal G., Jasik A., Mikuśkiewicz M.

Inżynieria Materiałowa

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2013

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Vol. 34, nr 6

699--702

PL

W artykule przedstawiono wyniki badań modelowych wpływu parametrów pracy lasera ciągłego i impulsowego na rozkład temperatury w warstwie ceramicznej typu Gd2Zr2O7 w powłokowych barierach cieplnych. Model fizyczny zjawiska obejmował charakterystykę wpływu takich parametrów pracy lasera jak prędkość skanowania na profil temperaturowy oceniany na przekroju warstwy izolującej. Analizy wykonano dla laserów typu 100 LM i 3.60 VLS.

EN

Results of investigations included physical analysis of laser heat treatment of Gd2Zr2O7 thermal barrier coatings by pulse and continuous work laser was showed in this article. Physical model of laser treatment which characterized influence of scanning speed on temperature profile on the coatings thickness was developed. Carried accounts gave possibility to elaboration of characteristic described temperature profile in coats in function of depth and speed of scanning for laser 100 LM and laser 3.60 VLS types.

3

The porosity assessment of thermal barrier coatings obtained by APS method

Moskal G.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 20, nr 1-2

483-486

EN

Purpose: The article presents the outline of methods and range of microstructural assessment of ceramic coatings, using the example of thermal barrier coatings. The major structural parameters describing the quality of the barrier layers have been characterised as well as the problems related to the correct metallographic specimen preparation and the methodology of their assessment. Design/methodology/approach: A procedure of porosity assessment, employing quantitative metallographic principles and authomatic image analysis has been propounded, together with types of quantitative parameters and methods of their application. Findings: It was found that the application of the quantitative metallographic methods combined with automatic image analysis can form an effective tool of both quantitative and qualitative assessment such parameters of structural ceramic layers as porosity. Research limitations/implications: This type of assessment enables obtaining more than just the absolute value of the porosity of the given area: it provides the means for determining a number of other qualitative parameters, e.g. the surface area of the pores, their elogation and shape together with the whole statistical analysis. Practical implications: The application of scanning microscopy, especially observation techniques such as BSE, BSETOPO or BSE3D enables a precise differentiation of the areas constituting pores from other artefacts. Originality/value: Description of procedure of porosity assessments in APS TBC system by the use of the quantitative metallographic methods combined with automatic image analysis, and possibility of applications special techniques of scanning microscopy.

4

Effect of TBC on oxidation behaviour of gamma-TiAl based alloy

Moskal G.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 22, nr 2

31-34

EN

Purpose: The purpose of the research was identification of the influence of TBC coating system on oxidation resistance of TiAl based alloy during oxidation at temperature of 900 and 950 degrees centigrade for 500 h and 200 h respectively. Design/methodology/approach: The APS technique was used to modify and improvement of oxidation resistance of TiAl intermetallic alloy. As a bond coat the NiCrAlY overlay coating was applied. The bond-coat provided a good bonding strength between matrix and ceramic top coat. The research allowed the identification of microstructural changes that take place between top coat and bond coat and bond coat and substrate. The examinations were conducted on specimens after 200 h and 500 h of exposition at 950 and 900 degrees centigrade. Findings: It was found that the surface conditions of basic alloy is electively protected by used type of ceramic coating. The basic alloy exhibited poor oxidation resistance at this range of temperature due to formation of mixed Al2O3 + TiO2 scale which is easily spalled off. A ceramic top coat together with bond coat can be effectively coated on the surface of TiAl basic alloy by APS method. Oxidation test both at 900 and 950 degrees centigrade showed that oxidation resistance of APS coated 48-2-2 alloy was improved. Research limitations/implications: Application of TBC remarkably improve the oxidation resistance of TiAl basic alloy due to lowering temperature of the substrate surface and due to formation of dense alumina sublayer (TGO) on the top surface of bond coat which can prevent diffusion processes of titanium and oxygen. Practical implications: The results obtained allow the determination of the degree of life-time lost of the TBC system used as protection for titanium aluminides alloys. Originality/value: The results obtained are valuable contribution to the development of new type of TBC for TiAl alloys. They enable the identification of the degradation mechanisms in YSZ/MCrAlY/substrate system.

5

Advanced materials and protective coatings in aero-engines application

Hetmańczyk M., Swadźba L., Mendala B.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 24, nr 1

372-381

EN

Purpose: The following article demonstrates the characteristics of the materials applied as parts of aircraft engine turbines and the stationary gas turbines. The principal technologies for manufacturing the heat resistant coatings and the erosion and corrosion resistant coatings were characterized. Sample applications for the aforementioned coatings are presented: on turbine blades, compressor blades and on parts of combustion chambers of aircraft engines. Design/methodology/approach: The nickel-based alloys were characterized. The following methods of depositing diffusion aluminide coatings were described: pack cementation, out of pack and CVD (chemical vapour deposition). The properties of thermal barrier coatings obtained by thermal spraying and physical vapour deposition (PVD) were presented. Findings: : The structures of aluminide and platinum modified aluminide coatings, which displayed higher heat resistance during the cyclic oxidation test, were presented. The structure of TBC coatings was described as well. During aircraft engine tests, the compressor blades with multilayer type Cr/CrN coatings exhibited higher wear resistance than the coatings covered with Ti/TiN. Research limitations/implications: The aluminide coatings were deposited on nickel-based superalloys, which are typically used to manufacture turbine blades for aircraft engines. The multilayer nitride coatings were produced by Arc-PVD method. Practical implications: All the described technologies and coatings find applications on parts of aircraft engines. Originality/value: The presented advanced technologies of manufacturing protective coatings on the parts of aircraft engines were developed by the authors of the following study as parts of their planned scientific research, research projects, and purpose projects.