Thermal Barrier Coatings Research Articles

Understanding the CMAS corrosion behavior of high‐entropy (La0.2Sm0.2Er0.2Y0.2Yb0.2)2Ce2O7

AbstractCeramic thermal barrier coating (TBC) materials are used to protect the superalloys from the damage of harmful high‐temperature airflow and improve the efficiency of jet and gas turbine engines. However, the long‐term application of TBC materials and the robustness of these materials can be destroyed by aggressive calcium‐magnesium‐alumina‐silicate (CMAS) melt during high‐temperature service. Increasing the configuration entropy of material by doping multiple principal components has become a research hotspot in the design of corrosion‐resistant thermal barrier coating material and has opened an infinite space of chemical composition, structure, and material properties. In this study, high‐entropy (La0.2Sm0.2Er0.2Y0.2Yb0.2)2Ce2O7 was synthesized and its CMAS corrosion behavior was investigated by experimental investigation and first‐principles calculation. The effects of the increase of configurational entropy and the subsequent potential effects on the CMAS corrosion behavior of Ce‐based fluorite oxides have been sufficiently investigated. By compared with control samples, the high‐entropy (La0.2Sm0.2Er0.2Y0.2Yb0.2)2Ce2O7 possesses the minimum infiltration depth of CMAS melts and the denser corrosion reaction layer, indicating the best corrosion resistance. The corrosion resistance mechanism of high‐entropy (La0.2Sm0.2Er0.2Y0.2Yb0.2)2Ce2O7 was studied by first‐principles calculation. The greater stability and resistance to segregation of CMAS melt in the CMAS/(La0.2Sm0.2Er0.2Y0.2Yb0.2)2Ce2O7 system, the poor adsorption capacity for CMAS melt which leads to a weak infiltration ability of CMAS melt; the weakest interfacial chemical reaction at the interface indicated by the smallest value of Griffith rupture work and the least species migration of high‐entropy fluorite oxide can be responsible to the enhanced corrosion resistance. Our work reveals that increasing the configuration entropy can be an effective strategy for TBC material to enhance corrosion resistance.

Correction to: Numerical and Experimental Studies on the In-Situ Measurement of Thermal Conductivity of the Thermal Barrier Coating

Correction to: Numerical and Experimental Studies on the In-Situ Measurement of Thermal Conductivity of the Thermal Barrier Coating

A density functional theory perspective on the structural, elastic, thermal, and electronic properties of copper nitride doped with transition metal (Fe, Co, and Ni)

Abstract The present study demonstrates structural, elastic, thermal and electronic properties of transition metal M (M: Fe, Co and Ni) doped copper nitride (Cu3N) using pseudopotential based density functional calculations as implemented in Quantum ESPRESSO simulation code. The exchange-correlation is approximated by PBE-GGA functional. The doped matrices represented as Cu3NM are verified to be stable structures, both thermodynamically and mechanically. Tailoring of elastic properties and their anisotropy due to M doping has been successfully demonstrated through comprehensive analysis of the computed elastic stiffness coefficients, elastic moduli, elastic anisotropy factors and spatial variation of the elastic moduli, which were not explored yet. An increase in bulk modulus due to M doping ensures enhanced mechanical stability under isotropic stress. Conversely, while doping of Co and Ni enhances the shear resistance of the host material, Fe doping slightly reduces it. Superior ductile nature of all the studied systems predicts their suitability for application in flexible electronics. It is evident that doping of M substantially reduces the elastic anisotropy of Cu3N. Using the calculated elastic moduli, velocity of acoustic waves and its anisotropy for Cu3N and Cu3NM are also predicted. The anisotropy in the acoustic velocity of the studied materials recommends their potential application in acoustic devices with directional selectivity. It is also noticed that, while average acoustic velocity is reduced due to Fe doping, it increases for Co and Ni doping. Furthermore, analysis of computed Debye temperature and minimum thermal conductivity forecasts their employability as thermal barrier coatings. Finally, the calculations reveal ferromagnetic nature of Cu3NFe and Cu3NCo with respective induced magnetic moments of 2.71 and 1.47 μB/cell, recommending their potential application in spintronics. It is also proved that, the M-d ― Cu-d coupling stabilizes the ferromagnetic ordering in such magnetic systems. On the other hand, Cu3NNi is observed to be non-magnetic.

Key Technologies to 50% Brake Thermal Efficiency for Gasoline Engine of Passenger Car

Review Key Technologies to 50% Brake Thermal Efficiency for Gasoline Engine of Passenger Car Xinke Miao, Bingxin Xu, Jun Deng, and Liguang Li * School of Automotive Studies, Tongji University, Shanghai 201804, China * Correspondence: liguang@tongji.edu.cn Received: 13 August 2024; Revised: 6 December 2024; Accepted: 17 December 2024; Published: 20 January 2025 Abstract: As fuel consumption and emissions regulations become increasingly stringent, various advanced strategies have been proposed to achieve higher efficiency in internal combustion engines. This paper reviews the advancements in thermal efficiency of gasoline engines and analyzes the key technological methods to achieve over 50% brake thermal efficiency (BTE). The technological routes proposed for high-efficiency gasoline engine are primarily focused on high compression ratios and lean combustion combined with novel combustion technologies. Supporting technologies mainly include Atkinson/Miller cycles, intake boosting, exhaust gas re-circulation (EGR), water injection, thermal barrier coatings, friction reduction, structural optimization, and combustion diagnostics and control.

Interaction effects of anisotropic roughness interface and component shape characteristics on fatigue life of thermal barrier coatings

Interaction effects of anisotropic roughness interface and component shape characteristics on fatigue life of thermal barrier coatings

Reinforced High-Entropy Fluorite Oxide Ceramic Composites for Thermal Barrier Coating Application.

High-entropy ceramics hold promise for application as thermal barrier coating materials. However, a key challenge in practical applications lies in the low fracture toughness compared to that of yttria-stabilized zirconia (YSZ). Herein, we designed (Hf,Zr,Ce,M)O2-δ-Al2O3 (M = Y, Ca, and Gd) ceramic composites by following a set of fundamental guidelines. First-principles calculations predicted that the inclusion of Al2O3 in compositions containing the other four binary oxides decreased the propensity for single high-entropy phase formation. Instead, it increased the potential for Al2O3 to form a second phase within the high-entropy ceramic matrix, compared to compositions without Al2O3. Ceramic composites consisting of the Al2O3 second phase in a high-entropy fluorite oxide (Hf,Zr,Ce,M)O2-δ matrix were synthesized in situ via conventional solid-state reactions from the five constituent binary oxides. Both the hardness and fracture toughness of the ceramic composites were enhanced due to toughening mechanisms from the discrete Al2O3 particles, microcracks, and crack deflections. Additionally, the ceramic composites exhibited coefficients of thermal expansion and thermal conductivities comparable with those of YSZ. Our findings demonstrated the potential of the high-entropy (Hf,Zr,Ce,M)O2-δ-Al2O3 ceramic composites for advanced thermal barrier coating materials and offered a possible approach to reinforce other high-entropy oxide-based ceramic systems.

Effect of Centrifugal Load on Residual Stresses in Nickel-Based Single-Crystal Substrate and Thermal Barrier Coating System

Effect of Centrifugal Load on Residual Stresses in Nickel-Based Single-Crystal Substrate and Thermal Barrier Coating System

Modelling on How Topcoat/Bond Coat Micro-Rough Interface and Nearby Voids Affect the Stress Distribution in Thermal Barrier Coating Systems in Quenching Process

The distribution of voids in ceramic topcoats (TC) and the micro-roughness of metallic bond coat (BC) interfaces are important for the structure design and coating life of thermal barrier coating (TBC) systems. In this study, finite elemental (FE) models were built by considering those two structural factors to investigate their influence on the stress distribution in TBCs in quenching processes under thermal shock conditions. According to the simulation analyses, the function of the voids in TCs includes the dilution effect of the stress concentration at the macro-scale, the releasing effect of the tensile stress along the vertical direction above the TC peak, and the “stress trapping” effect bringing higher stress at the horizontal tips of the voids on the micro-scale. The micro-roughness of the TC/BC interface did not have much effect on the stress values in the TC, aside from at the TC peak, but had a significant influence on the stress value along the interface due to the “stress trapping” effect. The TBC samples that were experimentally tested under water-cooling thermal shock conditions were also analyzed in this paper to verify the modelling results.

Optimization of laser process parameters and improved corrosion behaviour of LZ/YSZ thermal barrier coating

Abstract Laser processing the surfaces of plasma-sprayed thermal barrier coatings is one of the methods used to improve the corrosion resistance of the coatings. However, laser glazing alone is not sufficient to fully protect coatings from corrosion. In this study, optimum laser surface modification parameters were determined for plasma-sprayed LZ/YSZ double-layer thermal barrier coatings. The coating surface, whose entire surface was scanned with optimum parameters, was modified with nano YSZ using the electrophoretic deposition technique. Thus, the network cracks formed during laser glazing were filled with nano YSZ. The coating modified by laser and electrophoretic deposition processes was subjected to corrosion tests. As a result of the characterizations, it was determined that the optimum laser surface modification parameters for LZ/YSZ thermal barrier coatings were 200 mm laser distance, 120 scan speed, and 28w laser power. With these parameters, discontinuities on the as-sprayed coating surface were eliminated. A dense layer was successfully created on the LZ layer. As a result of the corrosion tests, it was determined that modifying the laser-glazed surface with nano YSZ reduced the penetration depth of corrosive contaminants. Thus, the glassy melt and hot corrosion resistance of LZ/YSZ thermal barrier coatings was increased.

Failure Mechanism Analysis of Thermal Barrier Coatings Under a Service Simulation Environment

In this paper, the ceramic coating of thermal barrier coatings (TBCs) was prepared on the surface of the tube specimens by Electron Beam Physical Vapor Deposition (EB-PVD) process. Subsequently, a service simulation was conducted using a simulation device to analyze the failure behavior of the TBCs. The effects of high-temperature sintering and CaO-MgO-Al2O3-SiO2 (CMAS) corrosion on the microstructural evolution, phase structural changes, and insulation performance of the thermal barrier coatings were investigated. The results indicated that with increasing high-temperature sintering time, the “feather” structures at the boundaries of the columnar grains evolve into the “tentacle” structure that facilitates the fusion of adjacent columnar grains, resulting in increased grain diameter and wider gaps. No transformation from t’-ZrO2 to the monoclinic phase m-ZrO2 occurred during the high-temperature sintering process. Over time, CMAS wets the coating surface and infiltrates the interior of the coating, causing corrosion to the Yttria-stabilised zirconia (YSZ) and accelerating sintering. A new phase, ZrSiO4, was formed after corrosion without inducing the transition.

Numerical simulation of thermal barrier coating in gas turbine combustion chamber liner: a comparative study of YSZ and PSZ

Abstract This study investigates the potential of Yttria-Stabilized Zirconia (YSZ) and Partially Stabilized Zirconia (PSZ) thermal barrier coatings (TBCs) in improving gas turbine performance through a theoretical simulation. Using the finite element method, we compared temperature and thermal flow distributions within YSZ and PSZ coated combustion chambers against an uncoated Ni substrate liner wall. Our results demonstrate significant reductions in outer wall temperature (2.61%–3.54%) and heat flux (0.44%–0.6%) achieved through TBC application. The findings were validated through similar studies, with results aligning closely with established data. These reductions translate to cooler and more efficient engine operation. This comparative analysis not only sheds light on TBC effectiveness but also provides valuable insights for optimizing combustion chamber design. These findings pave the way for the development of next-generation TBC materials and engineering strategies, ultimately leading to enhanced gas turbine performance.

Evaluation of AlCoCrFeNiTi-high entropy alloy (HEA) as top coat material in thermal barrier coating (TBC) system and investigation of its high temperature oxidation behavior

To obtain compatible properties of high-temperature performance and mechanical strength properties, AlCoCrFeNiTi high-entropy alloy (HEA) was designed as a new candidate material for metal-based thermal barrier coating (TBC) systems. The aim of this study is to investigate potential applications of AlCoCrFeNiTi-HEA as a coating material for TBC systems and to determine its behavior under high temperature conditions. CoNiCrAlY bond coatings were produced on the Inconel-718 substrate surface using high-velocity oxygen fuel (HVOF) technique. AlCoCrFeNiTi-HEAs were produced on CoNiCrAlY bond coatings using atmospheric plasma spray (APS) technique and a typical TBC system structure was obtained. The produced AlCoCrFeNiTi-HEA TBC system was exposed to oxidation at temperatures of 1000 °C and 1100 °C for time periods of 5 h, 25 h, 50 h and 100 h in order to determine the oxidation resistance under isothermal conditions and to investigate formation and growth behavior of oxide structures formed at the coating interface. As a result of oxidation tests, the growth behavior of the thermally grown oxide (TGO) layer formed between the coating interfaces and the microstructural changes occurring in the coating system were investigated depending on temperature and time processes. In the TBC system with Ti-containing HEA content, a transformation from body-centered cubic (BCC) structure to rhombohedral crystal lattice structure occurred as a result of increasing temperature. Many spinel compound forms were formed at the coating interface. It was observed that the coating system with AlCoCrFeNiTi-HEA content maintained its structural integrity without any damage such as microstructural and mechanical spalling and cracking under conditions of high temperature and different time periods.

Thermal barrier coatings in compression ignition engines: Analysis of combustion strategies and insights into convection vive

Thermal barrier coatings in compression ignition engines: Analysis of combustion strategies and insights into convection vive

Thermophysical properties and sintering resistance of novel Al2O3/YTaO4 thermal barrier coatings

Thermophysical properties and sintering resistance of novel Al2O3/YTaO4 thermal barrier coatings

ADVANCED ULTRA-SUPERCRITICAL BOILER TECHNOLOGY IN THERMAL POWER PLANTS: INNOVATIONS IN MATERIALS, DESIGN, AND OPERATIONAL EFFICIENCY

Advanced ultra-supercritical (AUSC) boiler technology represents a major breakthrough in power generation since it offers lower emissions and better thermal efficiency than traditional subcritical and supercritical systems. The most recent advancements in materials, designs, and operating techniques that are propelling the development of AUSC boilers are closely examined in this review article. Because they can tolerate the high temperatures and pressures involved in AUSC operation, advanced materials like thermal barrier coatings and nickel-based superalloys are highlighted as having the potential to increase durability and lower maintenance costs. Studies of global AUSC boiler implementations underscore the practical applications of these advancements and offer insights into best practices and lessons learned. The development of next-generation materials and the use of carbon capture technologies are just two examples of the trends and directions that the article examines for future research. By identifying upcoming challenges and synthesizing current knowledge, this review aims to provide a comprehensive resource to optimize AUSC boiler technology for a more efficient and sustainable energy future.

Effect of bond coating surface roughness on high-temperature performance of EB-PVD thermal barrier coatings

Effect of bond coating surface roughness on high-temperature performance of EB-PVD thermal barrier coatings

A novel single-phase Zr-Hf-Ta-O ceramic with high fracture toughness for thermal barrier coatings

A novel single-phase Zr-Hf-Ta-O ceramic with high fracture toughness for thermal barrier coatings

Study on high-entropy rare-earth zirconate ceramics for thermal barrier coatings: High-temperature phase stability, thermophysical and mechanical properties

Study on high-entropy rare-earth zirconate ceramics for thermal barrier coatings: High-temperature phase stability, thermophysical and mechanical properties

Effective thermal conductivity and thermal insulation performance of plasma-sprayed Mo/YSZ functionally graded thermal barrier coatings

Effective thermal conductivity and thermal insulation performance of plasma-sprayed Mo/YSZ functionally graded thermal barrier coatings

Numerical investigation of thermal barrier coating on performance and emissions of HPDI dual-fuel engine

ABSTRACT Thermal barrier coatings (TBC) represent a promising technology for enhancing the thermal efficiency of internal combustion engines. This study investigates the impact of TBC on in-cylinder combustion processes of a dual-fuel HPDI engine to achieve higher energy conservation with low heat transfer loss. In the present study, a one-dimensional conjugate heat transfer (1D CHT) model is constructed that incorporates TBC material features. By coupling the 1D CHT model with the three-dimensional combustion model of dual-fuel HPDI engines in CONVERGE software, the influences of TBC to the combustion process and temperature distribution within the engine cylinder is illustrated in details. Meanwhile, the adiabatic combustion characteristics of HPDI engines are investigated based on various adiabatic components or porosity. The results demonstrate that the reduction in heat transfer under P_TBC (TBC on top boundary of piston) conditions leads to an increase in the volume proportions of the high-temperature intervals within the cylinder, thus enhancing both mixture activity and heat release rate. The combination of these two factors lead to a 0.4% increase in indicated thermal efficiency under P_TBC conditions compared to the baseline. Under the current injection strategy, P_TBC conditions could effectively eliminate the heat flow area in the piston bowl and step area, thereby significantly reducing heat transfer loss. Since heat transfer loss is basically influenced by both temperature difference between fluid and wall as well as thermal conductivity of TBC, increasing porosity therefore is able to enhance thermal resistance by reducing thermal conductivity of TBC. However, when there is an increased temperature difference between fluid and wall, increasing porosity does not continually lead to a further reduction of heat transfer loss. Finally, it is observed that the utilization of P_TBC with a porosity of 0.1 resulted in an increase of 0.7% in the indicated thermal efficiency compared to the baseline, while marginally reducing CH4 and CO emissions.