Thermal barrier coatings (TBCs) offer the potential to significantly improve efficiencies of aero engines as well as stationary gas turbines for power generation. On internally cooled turbine parts, temperature gradie...Thermal barrier coatings (TBCs) offer the potential to significantly improve efficiencies of aero engines as well as stationary gas turbines for power generation. On internally cooled turbine parts, temperature gradients of the order of 100-150℃ can be achieved. TBCs, typically consisting of an yttrium stabilized zirconia top coat and a metallic bond coat deposited onto a superalloy substrate, are mainly used to extend lifetime. Further efficiency improvements require TBCs being an integral part of the component which requires reliable and predictable TBC performance. TBCs produced by electron beam physical vapor deposition (EB-PVD) or plasma spray (PS) deposition are favored for high performance applications. The paper highlights critical R&D needs for advanced TBC systems with a special focus on reduced thermal conductivity and life prediction needs. To further enhance the efficiency of gas turbines, higher temperature and a longer lifetime of the coating are needed for the next generation of TBCs. This paper presents the development of new materials, new deposition technologies, and new concept for application as novel TBCs. This paper summarizes the basic properties of conventional thermal barrier coatings. Based on our own investigation, we reviewed the progress on materials and technologies of novel thermal barrier coatings. Except yttria stabilized zirconia, other materials such as lanthanum zirconate and rare earth oxides are also promising materials for thermal barrier coatings. Nanostructure thermal barrier coating is presented as a new concept. This paper also summarizes the technologies for depositing the thermal barrier coatings.展开更多
Porous α-Al2O3 thermal barrier coatings （TBCs） containing dispersed Pt particles were prepared by cathode plasma electrolytic deposition （CPED）. The influence of the Pt particles on the microstructure of the coat...Porous α-Al2O3 thermal barrier coatings （TBCs） containing dispersed Pt particles were prepared by cathode plasma electrolytic deposition （CPED）. The influence of the Pt particles on the microstructure of the coatings and the CPED process were studied. The prepared coatings were mainly composed of α-Al2O3. The average thickness of the coatings was approximately 100 μm. Such single-layer TBCs ex- hibited not only excellent high-temperature cyclic oxidation and spallation resistance, but also good thermal insulation properties. Porous α-Al2O3 TBCs inhibit further oxidation of alloy substrates because of their extremely low oxygen diffusion rate, provide good thermal insu- lation because of their porous structure, and exhibit excellent mechanical properties because of the toughening effect of the Pt particles and because of stress relaxation induced by deformation of the porous structure.展开更多
This paper studied the thermal stresses of ceramicl metal gradient thermal barrier coating which combines the conceptions of ceramic thermal barrier coating （TBC） and functionally gradient material （FGM）. Thermal ...This paper studied the thermal stresses of ceramicl metal gradient thermal barrier coating which combines the conceptions of ceramic thermal barrier coating （TBC） and functionally gradient material （FGM）. Thermal stresses and residual thermal stresses were calculated by an ANSYS finite element analysis software. Negative thermal expansion coefficient method was proposed and element birth and death method was applied to analyze the residual thermal stresses which have non-uniform initial temperature field. The numerical results show a good agreement with the analytical results and the experimental results.展开更多
Nanostructured zirconia top coat was deposited by air plasma spray and NiCoCrAlTaY bond coat was deposited on Ni substrate by low pressure plasma spray.Nanostructured and conventional thermal barrier coatings were hea...Nanostructured zirconia top coat was deposited by air plasma spray and NiCoCrAlTaY bond coat was deposited on Ni substrate by low pressure plasma spray.Nanostructured and conventional thermal barrier coatings were heat-treated at temperature varying from 1050 to 1 250oC for 2-20 h.The results show that obvious grain growth was found in both nanostructured and conventional thermal barrier coatings(TBCs)after high temperature heat treatment.Monoclinic/tetragonal phases were transformed into cubic phase in the agglomerated nano-powder after calcination.The cubic phase content increased with increasing calcination temperature.Calcination of the powder made the yttria distributed on the surface of the nanocrystalline particles dissolve in zirconia when grains grew.Different from the phase constituent of the as-sprayed conventional TBC which consisted of diffusionlesstransformed tetragonal,the as-sprayed nanostructured TBC consisted of cubic phase.展开更多
Thermal barrier coatings(TBCs)can effectively protect the alloy substrate of hot components in aeroengines or land-based gas turbines by the thermal insulation and corrosion/erosion resistance of the ceramic top coat....Thermal barrier coatings(TBCs)can effectively protect the alloy substrate of hot components in aeroengines or land-based gas turbines by the thermal insulation and corrosion/erosion resistance of the ceramic top coat.However,the continuous pursuit of a higher operating temperature leads to degradation,delamination,and premature failure of the top coat.Both new ceramic materials and new coating structures must be developed to meet the demand for future advanced TBC systems.In this paper,the latest progress of some new ceramic materials is first reviewed.Then,a comprehensive spalling mechanism of the ceramic top coat is summarized to understand the dependence of lifetime on various factors such as oxidation scale growth,ceramic sintering,erosion,and calcium–magnesium–aluminium–silicate(CMAS)molten salt corrosion.Finally,new structural design methods for high-performance TBCs are discussed from the perspectives of lamellar,columnar,and nanostructure inclusions.The latest developments of ceramic top coat will be presented in terms of material selection,structural design,and failure mechanism,and the comprehensive guidance will be provided for the development of next-generation advanced TBCs with higher temperature resistance,better thermal insulation,and longer lifetime.展开更多
In gas turbine engine, the study of ceramic thermal resistance coating has always been paid more attention because it can effectively reduce metal interface temperatures, improve corrosion and/or oxidation resistance ...In gas turbine engine, the study of ceramic thermal resistance coating has always been paid more attention because it can effectively reduce metal interface temperatures, improve corrosion and/or oxidation resistance and extend life. The microstructures, SEM microfractographs and adhesive strength of three kinds of zirconia plasma-sprayed ceramic coating were investigated. The results indicated that nanostructured zirconia coating have higher adhesive strength and better micro-cracking resistance properties compared with magnesia or yttria stabilized zirconia coating because its less quantities laminar internal structures and closed packed structures with less quantities and uniform distribution cavities. The sprayed power is also an important factor affecting adhesive strength of nanostructured zirconia coating.展开更多
Thermal barrier coating(TBC)materials perform an increasingly important role in the thermal or chemical protection of hot components in a gas turbine.In this study,a novel high entropy hafnate(Y_(0.2)Gd_(0.2)Dy_(0.2)E...Thermal barrier coating(TBC)materials perform an increasingly important role in the thermal or chemical protection of hot components in a gas turbine.In this study,a novel high entropy hafnate(Y_(0.2)Gd_(0.2)Dy_(0.2)Er_(0.2)Yb_(0.2))_(2)Hf_(2)O_(7) was synthesized by solution combustion method and investigated as a potential TBC layer.The as-synthesized(Y_(0.2)Gd_(0.2)Dy_(0.2)Er_(0.2)Yb_(0.2))_(2)Hf_(2)O_(7) possesses a pure single disordered fluorite phase with a highly homogeneous distribution of rare earth(RE)cations,exhibiting prominent phase stability and excellent chemical compatibility with Al_(2)O_(3) even at 1300°C.Moreover,(Y_(0.2)Gd_(0.2)Dy_(0.2)Er_(0.2)Yb_(0.2))_(2)Hf_(2)O_(7) demonstrates a more sluggish grain growth rate than Y_(2)Hf_(2)O_(7).The thermal conductivity of(Y_(0.2)Gd_(0.2)Dy_(0.2)Er_(0.2)Yb_(0.2))_(2)Hf_(2)O_(7)(0.73-0.93 W m^(-1)K^(-1))is smaller than those of components RE_(2)Hf_(2)O_(7) and many high entropy TBC materials.Beside,the calculated thermal expansion coefficient(TEC)of(Y_(0.2)Gd_(0.2)Dy_(0.2)Er_(0.2)Yb_(0.2))_(2)Hf_(2)O_(7)(10.68×10^(-6)/K,1100°C)is smaller than that of yttriastabilized zirconia(YSZ).Based on the results of this work,(Y_(0.2)Gd_(0.2)Dy_(0.2)Er_(0.2)Yb_(0.2))_(2)Hf_(2)O_(7) is suitable for the next generation TBC materials with outstanding properties.展开更多
A novel high-entropy material,(Y_(0.2)Gd_(0.2)Er_(0.2)Yb_(0.2)Lu_(0.2))_(2)Zr_(2)O_(7)was successfully synthesized by the solid state reaction method and spark plasma sintering,and investigated as a promising thermal ...A novel high-entropy material,(Y_(0.2)Gd_(0.2)Er_(0.2)Yb_(0.2)Lu_(0.2))_(2)Zr_(2)O_(7)was successfully synthesized by the solid state reaction method and spark plasma sintering,and investigated as a promising thermal barrier coating material.Rare-earth elements were distributed homogeneously in the pyrochlore structure.It was found that the prepared high-entropy ceramic maintains pyrochlore structure at the temperature up to 1600℃,and it possesses a similar thermal expansion coefficient(10.2×10^(−6)K^(−1) at 25-900℃)to that of YSZ,low thermal conductivity(<0.9 W m^(-1)K^(−1) at 100-1000℃)and good CMAS resistance(infiltration depth is 22μm after annealed at 1300℃for 24 h).The corrosion process was investigated,and RE elements distributing homogeneously in(Y_(0.2)Gd_(0.2)Er_(0.2)Yb_(0.2)Lu_(0.2))_(2)Zr_(2)O_(7)show different diffusion rates in CMAS.RE^(3+) with a larger radius(closer to Ca^(2+))is easier to react with CMAS to form an apatite phase.展开更多
基金Fundamental project of the Beijing general researchinstitute of mining and metallurgy (YG-2004 -27)
文摘Thermal barrier coatings (TBCs) offer the potential to significantly improve efficiencies of aero engines as well as stationary gas turbines for power generation. On internally cooled turbine parts, temperature gradients of the order of 100-150℃ can be achieved. TBCs, typically consisting of an yttrium stabilized zirconia top coat and a metallic bond coat deposited onto a superalloy substrate, are mainly used to extend lifetime. Further efficiency improvements require TBCs being an integral part of the component which requires reliable and predictable TBC performance. TBCs produced by electron beam physical vapor deposition (EB-PVD) or plasma spray (PS) deposition are favored for high performance applications. The paper highlights critical R&D needs for advanced TBC systems with a special focus on reduced thermal conductivity and life prediction needs. To further enhance the efficiency of gas turbines, higher temperature and a longer lifetime of the coating are needed for the next generation of TBCs. This paper presents the development of new materials, new deposition technologies, and new concept for application as novel TBCs. This paper summarizes the basic properties of conventional thermal barrier coatings. Based on our own investigation, we reviewed the progress on materials and technologies of novel thermal barrier coatings. Except yttria stabilized zirconia, other materials such as lanthanum zirconate and rare earth oxides are also promising materials for thermal barrier coatings. Nanostructure thermal barrier coating is presented as a new concept. This paper also summarizes the technologies for depositing the thermal barrier coatings.
基金supported by the Chinese National Natural Science Foundation (Grant No. 51271030)
文摘Porous α-Al2O3 thermal barrier coatings （TBCs） containing dispersed Pt particles were prepared by cathode plasma electrolytic deposition （CPED）. The influence of the Pt particles on the microstructure of the coatings and the CPED process were studied. The prepared coatings were mainly composed of α-Al2O3. The average thickness of the coatings was approximately 100 μm. Such single-layer TBCs ex- hibited not only excellent high-temperature cyclic oxidation and spallation resistance, but also good thermal insulation properties. Porous α-Al2O3 TBCs inhibit further oxidation of alloy substrates because of their extremely low oxygen diffusion rate, provide good thermal insu- lation because of their porous structure, and exhibit excellent mechanical properties because of the toughening effect of the Pt particles and because of stress relaxation induced by deformation of the porous structure.
文摘This paper studied the thermal stresses of ceramicl metal gradient thermal barrier coating which combines the conceptions of ceramic thermal barrier coating （TBC） and functionally gradient material （FGM）. Thermal stresses and residual thermal stresses were calculated by an ANSYS finite element analysis software. Negative thermal expansion coefficient method was proposed and element birth and death method was applied to analyze the residual thermal stresses which have non-uniform initial temperature field. The numerical results show a good agreement with the analytical results and the experimental results.
基金Project(1343-77212)supported by the Innovation Program for Graduate Students of Central South University,China
文摘Nanostructured zirconia top coat was deposited by air plasma spray and NiCoCrAlTaY bond coat was deposited on Ni substrate by low pressure plasma spray.Nanostructured and conventional thermal barrier coatings were heat-treated at temperature varying from 1050 to 1 250oC for 2-20 h.The results show that obvious grain growth was found in both nanostructured and conventional thermal barrier coatings(TBCs)after high temperature heat treatment.Monoclinic/tetragonal phases were transformed into cubic phase in the agglomerated nano-powder after calcination.The cubic phase content increased with increasing calcination temperature.Calcination of the powder made the yttria distributed on the surface of the nanocrystalline particles dissolve in zirconia when grains grew.Different from the phase constituent of the as-sprayed conventional TBC which consisted of diffusionlesstransformed tetragonal,the as-sprayed nanostructured TBC consisted of cubic phase.
文摘Thermal barrier coatings(TBCs)can effectively protect the alloy substrate of hot components in aeroengines or land-based gas turbines by the thermal insulation and corrosion/erosion resistance of the ceramic top coat.However,the continuous pursuit of a higher operating temperature leads to degradation,delamination,and premature failure of the top coat.Both new ceramic materials and new coating structures must be developed to meet the demand for future advanced TBC systems.In this paper,the latest progress of some new ceramic materials is first reviewed.Then,a comprehensive spalling mechanism of the ceramic top coat is summarized to understand the dependence of lifetime on various factors such as oxidation scale growth,ceramic sintering,erosion,and calcium–magnesium–aluminium–silicate(CMAS)molten salt corrosion.Finally,new structural design methods for high-performance TBCs are discussed from the perspectives of lamellar,columnar,and nanostructure inclusions.The latest developments of ceramic top coat will be presented in terms of material selection,structural design,and failure mechanism,and the comprehensive guidance will be provided for the development of next-generation advanced TBCs with higher temperature resistance,better thermal insulation,and longer lifetime.
基金research foundation for Doctors ,Liaoning Province (20051010)
文摘In gas turbine engine, the study of ceramic thermal resistance coating has always been paid more attention because it can effectively reduce metal interface temperatures, improve corrosion and/or oxidation resistance and extend life. The microstructures, SEM microfractographs and adhesive strength of three kinds of zirconia plasma-sprayed ceramic coating were investigated. The results indicated that nanostructured zirconia coating have higher adhesive strength and better micro-cracking resistance properties compared with magnesia or yttria stabilized zirconia coating because its less quantities laminar internal structures and closed packed structures with less quantities and uniform distribution cavities. The sprayed power is also an important factor affecting adhesive strength of nanostructured zirconia coating.
基金financially supported by the National Natural Science Foundation of China (Nos. 51872234, 51502242, 51432008, 51802244, and 51821091)the Key R&D Program of Shaanxi Provence (No. 2019ZDLGY04-02)。
文摘Thermal barrier coating(TBC)materials perform an increasingly important role in the thermal or chemical protection of hot components in a gas turbine.In this study,a novel high entropy hafnate(Y_(0.2)Gd_(0.2)Dy_(0.2)Er_(0.2)Yb_(0.2))_(2)Hf_(2)O_(7) was synthesized by solution combustion method and investigated as a potential TBC layer.The as-synthesized(Y_(0.2)Gd_(0.2)Dy_(0.2)Er_(0.2)Yb_(0.2))_(2)Hf_(2)O_(7) possesses a pure single disordered fluorite phase with a highly homogeneous distribution of rare earth(RE)cations,exhibiting prominent phase stability and excellent chemical compatibility with Al_(2)O_(3) even at 1300°C.Moreover,(Y_(0.2)Gd_(0.2)Dy_(0.2)Er_(0.2)Yb_(0.2))_(2)Hf_(2)O_(7) demonstrates a more sluggish grain growth rate than Y_(2)Hf_(2)O_(7).The thermal conductivity of(Y_(0.2)Gd_(0.2)Dy_(0.2)Er_(0.2)Yb_(0.2))_(2)Hf_(2)O_(7)(0.73-0.93 W m^(-1)K^(-1))is smaller than those of components RE_(2)Hf_(2)O_(7) and many high entropy TBC materials.Beside,the calculated thermal expansion coefficient(TEC)of(Y_(0.2)Gd_(0.2)Dy_(0.2)Er_(0.2)Yb_(0.2))_(2)Hf_(2)O_(7)(10.68×10^(-6)/K,1100°C)is smaller than that of yttriastabilized zirconia(YSZ).Based on the results of this work,(Y_(0.2)Gd_(0.2)Dy_(0.2)Er_(0.2)Yb_(0.2))_(2)Hf_(2)O_(7) is suitable for the next generation TBC materials with outstanding properties.
基金supported by the National Key Research and Development Program of China(No.2016YFB070204)the National Natural Science Foundation of China(Nos.52072381 and U1904217)。
文摘A novel high-entropy material,(Y_(0.2)Gd_(0.2)Er_(0.2)Yb_(0.2)Lu_(0.2))_(2)Zr_(2)O_(7)was successfully synthesized by the solid state reaction method and spark plasma sintering,and investigated as a promising thermal barrier coating material.Rare-earth elements were distributed homogeneously in the pyrochlore structure.It was found that the prepared high-entropy ceramic maintains pyrochlore structure at the temperature up to 1600℃,and it possesses a similar thermal expansion coefficient(10.2×10^(−6)K^(−1) at 25-900℃)to that of YSZ,low thermal conductivity(<0.9 W m^(-1)K^(−1) at 100-1000℃)and good CMAS resistance(infiltration depth is 22μm after annealed at 1300℃for 24 h).The corrosion process was investigated,and RE elements distributing homogeneously in(Y_(0.2)Gd_(0.2)Er_(0.2)Yb_(0.2)Lu_(0.2))_(2)Zr_(2)O_(7)show different diffusion rates in CMAS.RE^(3+) with a larger radius(closer to Ca^(2+))is easier to react with CMAS to form an apatite phase.
