Structured Thermal Barrier Coatings Research Articles

Data-driven AI for the automated classification of the isothermal heat-treated thermal barrier coatings using pulsed infrared thermography

Abstract Thermal barrier coating (TBC) is a multilayer coating applied to metallic structures exposed to high temperatures, such as aero-engine parts and gas turbine blades. These thermally insulating materials are used to extend the component life by minimizing the high-temperature exposure of structural components. As a result of the high-temperature oxidation tests, a thermally grown oxide (TGO) layer formed at the interface between the ceramic topcoat layer and the bond coat layer. The primary cause of TBC performance decline and structure failure is the growth of the oxide layer. Hence, it is crucial to regularly monitor the formation of the oxide layer and the degradation of coatings. This can be achieved by developing coating-life prediction models, which are vital for quality control, health monitoring of TBCs, maintenance decision-making, and the prevention of catastrophic failures. Existing methods for life estimation, which are dependent on empirical methods and microstructural analysis, often fail due to various material compositions and service conditions. This study proposes an automated classification of iso-thermal heat-treated TBC samples using temperature data, which helps in predicting the TBC life and monitoring the TBC degradation. TBC-coated samples are isothermal heat-treated at 1000 °C, and the initial growth of TGO is monitored using a non-destructive thermal imaging technique. Identifying distinctive features in each class corresponding to layer thickness measurement and service hours is challenging and time-consuming. So, we integrate data-driven AI models and feature extraction techniques to interpret complex thermal patterns. The performance of deep learning models and classical machine learning models demonstrates that our method can achieve maximum classification accuracy and F1-score of 89.2% and 89.0%, respectively. This automated classification framework promises a powerful tool for predictive maintenance and remaining useful lifetime estimation of hot section components reliant on TBCs.

The Effect of Shot Blasting Abrasive Particles on the Microstructure of Thermal Barrier Coatings Containing Ni-Based Superalloy

Grit particles remaining on the substrate surface after grit blasting are generally considered to impair the thermal performance of thermal barrier coatings (TBCs). However, the specific mechanisms by which these particles degrade the multilayer structure of TBCs during thermal cycling have not yet been fully elucidated. In this study, the superalloy substrate was grit-blasted using various processing parameters, followed by the deposition of thermal barrier coatings (TBCs) consisting of a metallic bond coat (BC) and a ceramic top coat (TC). After thermal shock tests, local thinning or discontinuities in the thermally grown oxide (TGO) layer were observed in TBCs where large grit particles were embedded at the BC/substrate interface. Moreover, cracks originated at the concave positions of the TGO layer and propagated vertically towards BC; these cracks may be associated with additional stress imposed by the foreign grit particles during thermal cycling. At the BC/substrate interface, crack origins were observed in the vicinity of large grit particles (~50 μm).

The Effects of Induction Plasma Spheroidization on the Properties of Yttrium-Stabilized Zirconia Powders and the Performance of Corresponding Thermal Barrier Coatings for Gas Turbine Engine Applications

To modify the structure of thermal barrier coatings and improve their high-temperature resistance, induction plasma spheroidization (IPS) technology was applied to regulate the structure of YSZ powders in this study. The surface morphology, particle size distribution, phase composition, and internal microstructure of the conventional agglomerated and spheroidized powders were characterized using scanning electron microscopy and focused ion beam analysis methods. The results showed that the microstructure of the powders presented uneven evolution in the induction plasma stream. Due to the existence of the temperature gradient along the radial direction of the powders, the IPS powders consisted of outer dense shells and internal porous cores. The mechanical property of such shell–core structure was analyzed by using the finite elemental simulation method. In addition, coatings were prepared using the IPS powders and the agglomerated powders. The IPS coating showed improved water-cooling thermal cycling resistance compared to the conventional coating.

A Comprehensive Understanding of Thermal Barrier Coatings (TBCs): Applications, Materials, Coating Design and Failure Mechanisms

This review offers a comprehensive analysis of thermal barrier coatings (TBCs) applied to metallic materials. By reviewing the recent literature, this paper reports on a collection of technical information, involving the structure and role of TBCs, various materials and coating processes, as well as the mechanisms involved in the durability and failure of TBCs. Although TBCs have been successfully utilized in advanced applications for nearly five decades, they continue to be a subject of keen interest and ongoing study in the world of materials science, with overviews of the field’s evolution remaining ever relevant. Thus, this paper outlines the current requirements of the main application areas of TBCs (aerospace, power generation and the automotive and naval industries) and the properties and resistance to thermal, mechanical and chemical stress of the different types of materials used, such as zirconates, niobates, tantalates or mullite. Additionally, recent approaches in the literature, such as high-entropy coatings and multilayer coatings, are presented and discussed. By analyzing the failure processes of TBCs, issues related to delamination, spallation, erosion and oxidation are revealed. Integrating TBCs with the latest generations of superalloys, as well as examining heat transfer mechanisms, could represent key areas for in-depth study.

Collapse characteristics and deposition behaviour of PS–PVD powders with different crushing strengths

Plasma spray–physical vapour deposition uses finely agglomerated spherical powders as raw materials; these powders undergo a complex process of dispersing–melting–evaporation–condensation in high-temperature and high-speed plasma jets to attain the desired physical phase and high-performance columnar-like structure thermal barrier coatings. Currently, the interactions between the powders and the jets have not been fully disclosed. The article examines the crushing strength of powders with various particle sizes and properties. To further elaborate the crushing process, discrete element simulation was used. Additionally, powder spray deposition experiments were conducted to disclose the association between powder properties and the efficiency of coating deposition. The findings indicate that the stiffness of the powder and the size of the internal particles have an impact on the crushing strength of the powder. The stronger the bond strength caused by greater powder stiffness, the more effective the dispersion effect becomes. Furthermore, the smaller the particle size, the higher the compressive and collapse strength. Therefore, the greater the crushing strength of the powder, the higher the rate of powder deposition.

Automatic high depth-resolvability inspection of TBC debonding defects using nonlinear frequency modulation photothermal radar

In this article, a novel nonlinear frequency modulation (NLFM) photothermal radar whose instantaneous frequency curve is a concave quadratic function is proposed and further combines K-means clustering image segmentation algorithm to achieve automatic high depth-resolvability inspection of debonding defects in thermal barrier coating (TBC) structure. Firstly, a 3-dimensional (3D) photothermal finite element (FE) model of TBC structure is established, where the extrapolated Beer-Lambert model is introduced to describe the spatially volumetric heat source within the ceramic coating. Afterwards, the superior depth resolvability of the proposed NLFM photothermal radar is demonstrated compared to conventional waveforms using the established FE model. Meanwhile, its depth resolvability dependence on the thickness and thermal diffusivity of the ceramic coating is also investigated. Finally, the photothermal experiments of the TBC structure containing artificial debonding defects are conducted, and the influence of the coating thickness and metal substrate on the non-destructive testing (NDT) detection of TBC structure by NLFM photothermal radar combining K-means clustering is also experimentally studied. The results reveal that NLFM photothermal radar combining K-means clustering can achieve automatic high depth-resolvability inspection of debonding defects in TBC structure and the coating thickness and metal substrate have also a great influence on the photothermal NDT of the debonding defects of TBC structure.

CMAS infiltration behavior of atmospheric plasma-sprayed thermal barrier coating with tailored pore structures

The degradation of atmospheric plasma spraying (APS) thermal barrier coatings (TBCs) due to calcium-magnesium-alumina-silicate (CMAS) corrosion is considered as a critical issue. In present work, mitigation of CMAS infiltration of APS TBCs has been achieved by tailoring pore characteristics based on a novel APS structure regulation method, and its thermal conductivity, thermal shock lifetime and infiltration behavior were evaluated. The results revealed that the laminar pore distributed TBC formed by horizontally aligned porous embedded particle clusters (PEPC) showed longest thermal shock lifetime and lowest thermal conductivity. Characterization of CMAS corrosion suggested that whilst all the TBCs samples with different pore structures suffered corrosion by CMAS melt, the severity fluctuated greatly. Compared with randomly distributed PEPC areas, these horizontally aligned PEPC areas have a noticeable potential for restricting CMAS infiltration. This unique structure consumes a large amount of CMAS melt and creates anti-CMAS filling pores, thus improving the overall CMAS infiltration resistance of the coating. The alternating dense layers outside the porous layers also provide a layer-by-layer barrier to CMAS infiltration. This study emphasizes that the modulation of the pore structure of APS TBCs is a promising strategy to mitigate CMAS infiltration.

Interfacial delamination of porous thermal barrier coatings based on SEM image processing in finite element model

Numerical analysis of interfacial delamination and the effect of microstructural pores and rough interfaces on the field variables in thermal barrier coatings (TBCs) based on a real scanning electron microscope (SEM) image is performed. The interfacial delamination is modelled by the utilization of cohesive zone method (CZM) in finite element (FE) analysis. The empirical TBC sample considered in this study is constructed via air plasma spray (APS) method and comprises ZrO27-8wt.%Y2O3 ceramic top coat (TC), thermally grown oxide (TGO) made of Al2O3 and NiCrAlY metallic bond coat (BC). A compatible geometry is provided by applying image processing technique to SEM image of the sample's cross-section. SEM image-based geometry imported into FE software to scrutinize the interplay effects of porosity and rough interfaces on temperature fields, thermal stresses and interfacial debonding of TC/TGO and TGO/BC interfaces of the TBC structure. FE analysis reveal that porosity distribution has a prominent role on the stress concentration zones at the sharp corners of pores especially adjacent to undulations of the TC/TGO interface, which is responsible for possible internal cracks and interfacial fracture, respectively. The main findings demonstrate that the porosity near the TC/TGO interface has detrimental effect as leads to aggravation in the TC/TGO interface damage, which causes an increment in TC/TGO interfacial crack length. While, the porosity within the BC has the ability to reduce the stress and damage level along the TGO/BC interface. In addition, considering creep for all layers leads to lower stress levels up to 24.82 % and consequently alleviates the TC/TGO interface damage.

Experimental investigation on detection of coating debonds in thermal barrier coatings using vibrothermography with a piezoceramic actuator

Coating debond, caused by thermal stress, is inevitable during the service of thermal barrier coatings (TBCs) in gas turbine engines. This study investigated detection of coating debonds in TBCs structures using a vibrothermography method. First, the mechanism of detecting coating debond with the vibrothermography was theoretically studied. Then, a finite element model of a TBC structure with an interfacial debond was established and accordingly the eigenfrequency of the local defect resonance was estimated. Second, the vibrothermography tests were conducted on a thermally-spraying coating specimen with artificial debonds. The local heat of the debond defect was generated using a low-power piezoceramic actuator with a selected excitation frequency according to the numerical estimation. Finally, thermal images were captured by an infrared camera and analyzed by thermal signal reconstruction (TSR), principle component analysis (PCA), and fast Fourier transform (FFT). The results indicate that the first principle component of PCA provides the highest temperature contrast and signal-to-noise ratio (SNR). The debond with a diameter of 2 mm and coating thickness of 0.5 mm can be detected with excellent image quality. Also, the debonding area and relative error were quantitatively estimated. The experimental results demonstrate that vibrothermography can provide a fast, reliable, and effective evaluation on detection of debonds in TBCs structures.

Effect of thermal ageing on the optical properties and pore structure of thermal barrier coatings

Thermal radiation represents a significant portion of the thermal heat transfer from the hot gases of an engine to its metallic components. Thermal barrier coatings (TBCs) are used to protect those components from heat and must, therefore, be effective blockers of radiative heat. The porous microstructure of TBCs causes them to be highly reflective in the visible and near-infrared wavelength ranges through the scattering of light. This microstructure, however, is susceptible to degradation. In this study, we establish a clear link between the porosity of a TBC and its ability to reflect heat through radiation scattering by extracting the scattering coefficient of two coatings with different microstructures and quantifying their pore space. Using deep learning trained image segmentation models on high resolution SEM cross-sections, we identify the proportion of the pore space comprised of pores 2 μm in diameter or smaller and show that these are responsible for most of the scattering. The pore size distribution is also confirmed with mercury infiltration porosimetry. The coatings are then subjected to cyclic heat treatments at 1450 K for a total of 1111 h to induce sintering of the microstructure. This results in a reduction of the scattering coefficient by around 20 % for both samples, which is attributed to a reduction in the space occupied by pores 2 μm and less in diameter. Finally, a model is built for finite-difference time-domain (FDTD) simulations using high resolution SEM cross-sections to calculate the reflectivity and transmission of the TBCs. The results exhibit good agreement with our experimental data, showing that such models could be used in the future to predict the effect of degradation on a TBC's optical properties.

Detection method and instrument of interfacial debonding inside a thermal barrier coating based on fluorescence imaging.

The interfacial delamination or debonding induced by local stress concentration is one of the kernel factors leading to spalling failure of thermal barrier coatings (TBC). In this work, for the rapid and accurate characterization of the interface delamination and debonding in TBC, the detection method and instrument were investigated based on fluorescence imaging. First, based on the principle of reflection-enhanced fluorescence, an experimental method was presented to detect interfacial debondings in TBC. A coaxial fluorescence-imaging instrument was established to realize the method above. In addition, an alkaline soluble method (ASM) was presented in this work to prepare prefabricated debondings with different transverse sizes, shapes, and thicknesses, which are basically consistent with the interfacial debondings in an actual TBC structure. Through a series of experiments, this paper verified that, using the proposed method and optical instrument, the resolutions to detect internal debonding are as small as 6 µm in the thickness dimension and less than 0.3 mm in the transverse dimension.

Fracture analysis of Pre-cracked 8YSZ TBCs with edge and internal cracks under Thermo-mechanical load: A numerical approach

The thermal barrier coatings (TBCs) are used for hot component sections of gas turbines and aero-engines. The paper presents the effect of thermo-mechanical on the pre-cracked TBCs to analyze fracture parameters using the FEM method. The TBC model is considered with edge and internal cracks with different crack configurations such as crack length and cracks position between ceramic top coat and bond coat to find the strain energy release rate (SERR) and stress intensity factor (SIF). The TBC mixed-mode I/II fracture criterion is established. The numerical results showed that the crack tip field is shear dominant under thermo-mechanical loading irrespective of different crack configurations. The edge crack's SERR and SIF mode I/II are more significant than the internal crack, resulting in delamination. The long edge crack showed crack driving force of 2.13 J/m2 at P1 position, whereas the shift in crack position till P7 reduces the SERR to 1.48 J/m2. The internal crack at P1 showed the SERR of 0.91 J/m2 which reduces to 0.85 J/m2 at position P7. The edge crack resulted in a high amount of shear stress which is caused due to large opening of crack faces. In all crack configurations, the increase in crack length showed an increase in crack driving force and large opening of crack faces due to high shear stress. Also, the crack positioned in the ceramic topcoat showed a high value of crack driving force, resulting in more probability of surface rupture followed by crack positioned at the interface of the topcoat/bond coat and crack positioned in the bond coat. The interface crack showed a high crack driving force compared to crack located near the interface due to bi-material and geometry discontinuity, resulting in stress intensification. The edge crack showed a high value of SIF mode I in the range of 0.1 to 0.35 MPa.m1/2 compared to internal crack which shows in the range of 0.05 to 0.18 MPa.m1/2. The edge crack shows high value of SIF mode II in the range of −0.05 to −0.22 MPa.m1/2 compared to internal cracks showing upto −0.1 MPa.m1/2. The crack length and position play an important role in crack initiation and propagation. The TBC structure with edge crack appears unstable and more likely to damage than internal crack, leading to an early failure mechanism.

Comprehensive understanding of horizontal and vertical crack effects on failure mechanism of lamellar structured thermal barrier coatings

The local spalling induced by the propagation and coalescence of cracks in the ceramic layer is the fundamental reason for the thermal barrier coatings (TBCs) failure. To clarify the effects of horizontal and vertical cracks on the coating failure, an integrated model combining dynamic TGO growth and ceramic sintering is developed. The effects of cracks on the normal and shear stress characteristics are analyzed. The driving force and propagation ability of cracks under different configurations are evaluated. The interaction between horizontal and vertical cracks is explored by analyzing the variation of the crack driving force. The results show that TGO growth causes the ratcheting increase of σ22 tensile stress above the valley, and the σ12 shear stress is on both sides of the peak. Ceramic sintering mainly contributes to the ratcheting increase of σ11 tensile stress. There is minimum strain energy when the horizontal crack extends to the peak. The vertical cracks on the surface of the ceramic layer are easier to propagate through the coating than that of other locations. When the horizontal and vertical cracks simultaneously appear near the valley, they can promote the propagation of each other. The present results can offer theoretical support for the design of an advanced TBC system in the future.

Rheological and chemical interaction between volcanic ash and thermal barrier coatings

Combustion temperatures (>1200 °C) in gas turbines cause softening and eventually melting of ingested volcanic ash particles. In the downstream section, lower temperatures lead to droplet deposition onto the thermal barrier coatings (TBCs) of the turbine blades. The intensity of interaction (wetting and chemical interaction) depends on the ash and TBC chemistry as well as the TBC structure. We have determined the spreading behavior of five different volcanic ash melts on four types of TBCs. The TBCs differed in their composition - yttria-stabilized zirconia (YSZ) and gadolinium zirconate (GZO) – and in their fabrication - air plasma spraying (APS) and electron-beam physical vapor deposition (EB-PVD). The spreading properties have been parameterized on the basis of four parameters, 1) the CaO-SiO 2 -ratio, 2) optical basicity, 3) the R b/a ratio and 4) the viscosity of the volcanic ash melts. Infiltration efficiency of the melts into the TBCs and corrosion characteristics have been determined via electron microprobe analysis of cross sections. In this study, the highest damage potential was found following interaction with basaltic melt, as its low viscosity is favorable to extensive spreading and high chemical reactivity. • Basaltic (SiO 2 -lean) silicate melts show the most extensive spreading on TBC surfaces and the most intense chemical reaction with the TBC materials • Spreading of silicate melts on APS TBCs is enhanced over EB-PVD TBCs and spreading on GZO TBCs is enhanced over YSZ TBCs • Spreading ability of silicate melts can be estimated based on a parametrization deduced from our spreading experiments

Low-thermal-conductivity thermal barrier coatings with a multi-scale pore design and sintering resistance following thermal exposure

High-insulation, long-life thermal barrier coatings (TBCs) decrease the service temperature of superalloys and improve the service life of gas turbines. Improvement in the thermal insulation properties of the coating mainly depends on the optimization of the TBC structure. An important challenge for TBCs is maintaining a high performance during thermal exposure without degradation, as the pore-rich structure of the topcoat would inevitably be transformed by sintering. A low-thermal-conductivity anti-sintering coating can overcome the trade-off between thermal insulation and sinter degradation. In this review, the design, preparation, and serviceability evaluation of a low-thermal-conductivity anti-sintering coating will be discussed. Furthermore, directions for potential development are introduced. This paper provides a comprehensive understanding of the structured tailoring of TBCs for better thermal insulation and anti-sintering performance.

Material Characterization of PMC/TBC Composite Under High Strain Rates and Elevated Temperatures

Polymer matrix composites (PMC), despite their many advantages, have limited use at elevated temperatures. To expand the scope of their uses, it becomes necessary to use thermal barrier coatings (TBC). In addition to elevated temperatures, composite structures, and thus TBC barriers, can be exposed to damage from impacts of foreign objects. Therefore, before using the thermal barrier in practice, knowledge about its behavior under high-speed loads is necessary. The paper presents results for samples with the PMC/TBC system subjected to dynamic compression using a split Hopkinson pressure bar (SHPB). The substrate was made of CFRP (carbon reinforced polymer) with epoxy matrix and twill fabric. TBC was made of ceramic mat saturated by commercial hardener from Vitcas company. The tests were carried out at ambient temperature and elevated temperature—55 °C and 90 °C. Tests at ambient temperature were carried out for three pressure levels: 1, 1.5, and 2 bar. Only the pressure of 1 bar was used for the elevated temperature. Studies have shown that the limit load is 1 bar for ambient temperature. At 1.5 bar, cracks occurred in the TBC structure. Increased temperature also adversely affects the TBC barrier strength and it is damaged at a pressure of 1 bar.

Effect of substrate rotation on the microstructure of 8YSZ thermal barrier coatings by EB-PVD

Thermal Barrier Coatings (TBCs) is an essential requirement to protect aero engines and gas turbines against high inlet gas temperatures. The microstructure plays an important role in governing the performance and thermal life cycle of the TBC structure. The TBC deposition process is carried using a combination of the Electron Beam Physical Vapor Deposition (EB-PVD) and Atmospheric Plasma Spray (APS) process. The microstructure obtained by EB-PVD represents columnar structure whereas APS represents splat layer structure. The combined deposition process is used to study the grain growth behavior which can affect the performance of the TBCs. The 8YSZ TBC was deposited by the in-house EB-PVD system onto the Ti-6Al-4V substrate with the NiCrAlY bond coat by the APS process. In this paper, the effect of substrate rotation on the microstructure of 8YSZ TBCs has been investigated and discussed in detail. The dissimilar grain growth behavior of the TBC was observed with the stationary and rotating substrate at 20 rpm for microstructural analysis. It was found that the stationary substrate with 8YSZ TBC has dense and fine grain growth behavior compared to a rotating substrate. In stationary condition, the substrate is always exposed to uniform deposition, therefore the grains with less shadow region is present which results in low porosity. Whereas, a substrate with rotation consists of distributed grains resulting in more shadow region contributing towards high porosity. Therefore, the substrate rotation affects the grain distribution resulting in the shadow region which leads to the formation of pores affecting the performance of TBCs.

Comprehensive effects of TGO growth on the stress characteristic and delamination mechanism in lamellar structured thermal barrier coatings

To clarify the role of thermally grown oxide (TGO) in the failure of thermal barrier coating system (TBCs) is beneficial to further understand coating spallation mechanism and optimize the spraying process. In this study, the influences of TGO growth on the stress state and crack growth behavior upon temperature cycling are quantitatively examined based on a novel model with lamellar structure. Three kinds of TGO growth modes are employed to explore the TGO growth effect. The non-uniform distribution of lateral growth strain through TGO thickness is included in the model. TGO growth is dynamically modeled using the material property change step by step. The successive propagation and coalescence of multi-crack are materialized by a fracture mechanics analysis. The results suggest that the continuous increase of tensile and shear stress with cycles can occur only when the lateral growth strain is considered into the TGO. Large stress concentration arises at the crack tip and near the pore, which is responsible for the early crack growth. The successive growth and linkage of multi-crack can be expected in the model with TGO lateral growth. The spallation path and the variation trend of total crack length achieved in the current model are in line with the results in experiments. The large gradient of lateral strain distribution in TGO will result in a higher cycle to failure and incubation period. However, the overall crack propagation behavior and linkage mechanism are not affected by the lateral strain distribution. The computational results in the current model can provide a theoretical foundation for developing advanced TBCs with long lifetime.

An innovative model coupling TGO growth and crack propagation for the failure assessment of lamellar structured thermal barrier coatings

The failure of plasma-sprayed thermal barrier coating (TBC) is often caused by the coating spallation due to crack propagation. In this study, a new model with stacking lamellae is developed based on the cross-section micrograph to explore crack propagation behavior within the ceramic top coat (TC) during isothermal cycling. The dynamic growth process of thermally grown oxide (TGO) is simulated via material properties change step by step. The stress profiles in the lamellar model are first evaluated, and the pore and lamellar interface crack effects on the stress state are further explored. Then, the successive crack growth, linkage, and ultimate coating spallation process is simulated. The results show that the stress intensity in TC enhances with thermal cycling. Large stress concentration always occurs near the pore and lamellar interface crack, which can result in the incipient crack growth. Moreover, the lamellar interface crack also changes the stress distribution within the TC and at the TC/bond coat interface. The multiple crack propagation upon temperature cycling is explored, and the possible coalescence mechanism is proposed. The lamellar crack steadily propagates at the early stage. The crack length sharply increases before the occurrence of coating spallation. The simulated coat spalling path is in line with the experimental result. Therefore, the new lamellar model developed in this work is beneficial to further reveal coating failure mechanism and predict coating lifetime.

On the CMAS Problem in Thermal Barrier Coatings: Benchmarking Thermochemical Resistance of Oxides Alternative to YSZ Through a Microscopic Standpoint

This study focuses on experimental modelling of the failure of Thermal Barrier Coatings (TBCs) due to attack of CMAS (Calcia-Magnesia-Alumina-Silicate), which is often found in harsh environments, via glassy phase infiltration. Volcanic ash and dust, sand particles, and fly ash, which contain CMAS, are imminent threats impeding predictable lifetimes of TBCs. Such incurrence directly affects the geometry and clinging to bond coat, and intrinsic material properties such as thermal conductivity and crystal structure of TBC are modified after exposure to CMAS, which ultimately results in delamination, spallation and failure of the coating material. The scope of this work is to survey the reactivity of CMAS with various oxide systems, and evaluate possible oxide systems that can be replaced and/or used with Yttria-stabilized Zirconia (YSZ) by investigating the penetration depth and reactivity after sintering with CMAS. A cost-effective method to observe the reaction of candidate oxides with CMAS is suggested and administired; understanding the main mechanism that causes the failure of top coat in the wake of CMAS infiltration, and seeking solutions for the problem is performed by taking advantage of Scanning Electron Microscopy (SEM). Recently suggested ceramic oxide systems that form in pyrochlore structure, some perovskite structures in various compositions, monazite, mullite and YSZ are studied. The possible outcome consequent upon CMAS infiltration are concluded and course for designing novel material systems that are expected to withstand the CMAS attacks better than the state-of-the-art 4mole% YSZ is defined. 5% mole Yb-doped SrZrO3(5Yb-SZ) and favored pyrochlores such as Gd2r2O7 and GdYbZr2O7 are found to be better mitigating CMAS attacks.