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coupled Effects of Temperature Gradient and Oxidation on the Thermal Barrier coating Failure

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材料科学与工程学报 2000年第Z1期20卷 412-425页

作者： y.c.zhou Fracture Research Institute Tohoku University Sendai Japan Institute of Fundamental Mechanics and Material Engineering Xiangtan UniversityXiangtan Hunan 411105 P. R. China Fracture Research Institute Tohoku University Sendai Japan

The present article reviews the investigation about the coupled effects of temperature gradient and oxidation on the failure of thermal barrier ceramic coatings in the past ten years in our laboratory. The investigations include the experimental and theoretical study. On the experimental investigation, the heating method, non-destructive evaluation and interface properties are mainly reviewed. An attempt is done for developing four different heating methods, which are furnace heating, burner heating, plasma heating and laser beam heating. The non-destructive evaluation such as temperature test, acoustic emission (AE) signals detected and impedance spectroscopy (IS) method are successfully used in the study of TBcs system degradation. The interface properties such as oxidation and fracture toughness are studied by test and observation. On the theoretical investigation, the temperature fields and the related thermal stresses fields are analytical solved where the coupling effect of temperature gradient, oxidation, thermal fatigue, creep, morphology of the TBc system as well as the cooling rate are considered. The delamination cracking in thermal barrier coating system with ceramic coating deposited on a substrate is analytical studied. Due to the complication of TBcs degradation, a real physical map of TBcs system failure is not obtained up to now. The investigation on the further is proposed.

关键词： Thermal Barrier coating temperature gradient experimental investigation impedance spectroscopy temperature fields fracture toughness theoretical study temperature test ceramic coatings coupling effect coating system physical map cooling rate laser beam used in

Finite Element Simulation on Thermal Fatigue of a Turbine Blade with Thermal Barrier coatings

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Journal of Materials Science & Technology 2014年第4期30卷 371-380页

作者： L.yang Q.X.Liu y.c.zhou W.G.Mao c.Lu Key Laboratory of Low Dimensional Materials & Application Technology(Ministry of Education) Xiangtan University Faculty of Materials Optoelectronic & PhysicsXiangtan University Department of Mechanical Engineering Curtin University

In this paper, a finite element model was developed for a turbine blade with thermal barrier coatings to investigate its failure behavior under cyclic thermal loading. Based on temperature and stress fields obtained from finite element simulations, dangerous regions in ceramic coating were determined in terms of the maximum principal stress criterion. The results show that damage preferentially occurs in the chamfer and rabbet of a turbine blade with thermal barrier coatings and its thermal fatigue life decreases with the increase of thermal stress induced by high service temperature.

关键词： Turbine blade Thermal barrier coatings Finite element model Thermal fatigue Life prediction

Electrically conductive Honeycomb Monolith of Nanolaminated Ti_3Alc_2:Preparation and characterization

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Journal of Materials Science & Technology 2015年第1期31卷 125-128页

作者： X.M.Fang X.H.Wang H.Zhang y.c.zhou Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences University of chinese Academy of Sciences Science and Technology of Advanced Functional composite Laboratory ARIMPT

Nanolaminated Ti3Alc2honeycomb monolith with parallel and uniform holes has been prepared through a facile extrusion route by using Ti3Alc2powder as the main raw *** fabricated honeycomb monolith has high compressive strength of 133 ± 11 and 59 ± 9 MPa,along and perpendicular to the extrusion direction,*** also has good electrical conductivity,and excellent match of thermal expansion coefficient with the washcoat material of γ-*** combined properties endow the honeycomb monolith a promising candidate as catalysis substrate for cleaning vehicle exhaust.

关键词： Honeycomb ceramic Ti3Alc2 Extrusion catalysis

Adaptive Finite Element Modeling Techniques for the Poisson-Boltzmann Equation

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communications in computational Physics 2012年第1期11卷 179-214页

作者： M.Holst J.A.Mccammon Z.yu y.c.zhou y.Zhu Department of Mathematics University of California at San DiegoLa JollaCA 92093USA Department of Physics University of California at San DiegoLa JollaCA 92093USA Department of chemistry&Biochemistry University of California at San DiegoLa JollaCA 92093USA center for Theoretical Biological Physics(cTBP) University of California at San DiegoLa JollaCA 92093USA National Biomedical computation Resource(NBcR) University of California at San DiegoLa JollaCA 92093USA Howard Hughes Medical Institute University of California at San DiegoLa JollaCA 92093USA

We consider the design of an effective and reliable adaptive finite element method(AFEM)for the nonlinear Poisson-Boltzmann equation(PBE).We first examine the two-term regularization technique for the continuous problem recently proposed by chen,Holst and Xu based on the removal of the singular electrostatic potential inside biomolecules;this technique made possible the development of the first complete solution and approximation theory for the Poisson-Boltzmann equation,the first provably convergent discretization and also allowed for the development of a provably convergent ***,in practical implementation,this two-term regularization exhibits numerical ***,we examine a variation of this regularization technique which can be shown to be less susceptible to such *** establish a priori estimates and other basic results for the continuous regularized problem,as well as for Galerkin finite element *** show that the new approach produces regularized continuous and discrete problemswith the samemathematical advantages of the original *** then design an AFEM scheme for the new regularized problem and show that the resulting AFEM scheme is accurate and reliable,by proving a contraction result for the *** result,which is one of the first results of this type for nonlinear elliptic problems,is based on using continuous and discrete a priori L¥*** provide a high-quality geometric model as input to the AFEM algorithm,we also describe a class of feature-preserving adaptive mesh generation algorithms designed specifically for constructing meshes of biomolecular structures,based on the intrinsic local structure tensor of the molecular *** of the algorithms described in the article are implemented in the Finite Element Toolkit(FETK),developed and maintained at *** stability advantages of the new regularization scheme are demonstrated with FETK through comparisons with the original regula

关键词： Poisson-Boltzmann equation semi-linear partial differential equations supercritical nonlinearity singularity a priori L¥estimates existence uniqueness well-posedness Galerkin methods discrete a priori L¥estimates quasi-optimal a priori error estimates adaptive finite methods contraction convergence optimality surface and volume mesh generation mesh improvement and decimation.

Numerical Simulation of Temperature Distribution and ThermalStress Field in a Turbine Blade with Multilayer-Structure TBcs by a Fluid–Solid coupling Method

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Journal of Materials Science & Technology 2016年第5期32卷 452-458页

作者： W.Z.Tang L.yang W.Zhu y.c.zhou J.W.Guo c.LU Key Laboratory of Key Film Materials and Application for Equipment(Hunan Province) School of Materials Science and EngineeringXiangtan UniversityXiangtan 411105China Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education School of Materials Science and EngineeringXiangtan UniversityXiangtan 411105China Hunan Provincial Key laboratory of Thin Film Materials and Devices School of Materials Science and EngineeringXiangtan UniversityXiangtan 411105China School of Mechanical Engineering Xiangtan University Xiangtan 411105China Department of Mechanical Engineering Curtin UniversityPerthWA 6845Australia

To study the temperature distribution and thermal-stress field in different service stages, a two-dimensional model of a turbine blade with thermal barrier coatings is developed, in which the conjugate heat transfer analysis and the decoupled thermal-stress calculation method are adopted. Based on the simulation results, it is found that a non-uniform distribution of temperature appears in different positions of the blade surface, which has directly impacted on stress field. The maximum temperature with a value of 1030 ℃ occurs at the leading edge. During the steady stage, the maximum stress of thermally grown oxide （TGO） appears in the middle of the suction side, reaching 3.75 GPa. At the end stage of cooling, the maximum compressive stress of TGO with a value of-3.5 GPa occurs at the leading edge. Thus, it can be predicted that during the steady stage the dangerous regions may locate at the suction side, while the leadine edge mav be more Drone to failure on cooling.

关键词： Thermal barrier coatings Temperature distribution Thermal-stress field conjugate heat transfer Decoupled thermal-stress calculation Fluid–solid coupling

Recent Progress in Numerical Methods for the Poisson-Boltzmann Equation in Biophysical Applications

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communications in computational Physics 2008年第5期3卷 973-1009页

作者： B.Z.Lu y.c.zhou M.J.Holst J.A.Mccammon Howard Hughes Medical Institute University of CaliforniaSan Diego 9500 Gilman DriveDept.0112La JollaCA 92093-0112USA. Department of Mathematics University of CaliforniaSan Diego 9500 Gilman DriveDept.0112La JollaCA 92093-0112USA. center for Theoretical Biological Physics University of CaliforniaSan Diego 9500 Gilman DriveDept.0112La JollaCA 92093-0112USA. Department of chemistry and Biochemistry University of CaliforniaSan Diego 9500 Gilman DriveDept.0112La JollaCA 92093-0112USA. Department of Pharmacology University of CaliforniaSan Diego 9500 Gilman DriveDept.0112La JollaCA 92093-0112USA.

Efficiency and accuracy are two major concerns in numerical solutions of the Poisson-Boltzmann equation for applications in chemistry and *** developments in boundary element methods,interface methods,adaptive methods,finite element methods,and other approaches for the Poisson-Boltzmann equation as well as related mesh generation techniques are *** also discussed the challenging problems and possible future work,in particular,for the aim of biophysical applications.

关键词： Biomolecular electrostatics Poisson-Boltzmann equation numerical methods finite difference methods finite element methods boundary element methods adaptive methods hybrid methods mesh generation electrostatic forces

First-principles Study of Point Defects in Stoichiometric and Non-stoichiometric y_4Al_2O_9

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Journal of Materials Science & Technology 2013年第12期29卷 1161-1165页

作者： Z.Li B.Liu J.M.Wang L.c.Sun J.y.Wang y.c.zhou Z.J.Hu High-performance ceramics Division Shenyang National Laboratory for Materials ScienceInstitute of Metal ResearchChinese Academy of Sciences Aerospace Research Institute of Materials and Processing Technology

By using the first-principles calculation, we studied the mechanisms of point defects in y4AI209 （yAM）, a promising ternary oxide with excellent optical and thermal properties. It is found that the predominant native defect species is closely dependent on the chemical potentials of each constituent. In the case of O-rich condition, the oxygen interstitial has the very low defect formation energy, followed by the anti-site defects and AI vacancy; in the case of AI-rich condition, the oxygen vacancy yields the lowest defect formation energy, followed by the anti-site defects and AI interstitial. The present result shows that in all the possible chemical potential ranges, anti-site defects have relatively low defect formation energy and might exist in high concentration in yAM. Furthermore, AIy anti-site has relatively lower defect formation energy than the yAt anti- site throughout. The behaviors of defect complexes under non-stoichiometric condition, such as the AI203 or y203 excess, are also investigated. The results provide helpful guide to optimize the experimental synthesizing of yAM.

关键词： Ternary y-AI-O oxide Defect formation energy chemical potential

Oxygen vacancies in ferroelectric perovskites and their regulation from first-principles study

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Oxygen vacancies in ferroelectric perovskites and their regu...

Pb-DOPING EFFEcTS ON THE DIELEcTRIc AND PyROELEcTRIc PROPERTIES OF(Sr,Pb)TiO_(3)SySTEM

第十三届全国物理力学学术会议

作者： Q.yang J.X.cao y.c.zhou Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education Xiangtan University

Oxygen vacancy(VO)is one of the common and mobile defects,which is believed to play an important role in the electrical properties of ferroelectric *** present work,the physical properties of VO were studied with a prototypical ferroelectric perovskite oxide Pt Ti O3(PTO)using density functional theory(DFT)***,we studied the effects of potential regulation means,such as epitaxial strain,on the structural and electronic properties of *** was found to result in a tail-to-tail domain configuration and pinning the domain wall *** results show that VO in ferroelectric epitaxial thin films can be systematically tuned from a strong domain-pinning centre to a non-pinning centre by applying a compressive misfit *** formation and migration energies of VO can be enhanced by compressive *** suggests that proper strain may solve the VO-induced ferroelectric failure.

关键词： Ferroelectric perovskites Oxygen vacancies Domain-pinning centre Leakage current First-principles study

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Journal of Advanced Dielectrics 2012年第1期2卷 78-85页

作者： y.P.JIANG X.G.TANG y.c.zhou Q.X.LIU Key Laboratory of Low Dimensional Materials and Application Technology Xiangtan University Xiangtan 411105P.R.China School of Physics&Optoelectric Engineering Guangdong University of Technology Guangzhou Higher Education Mega center Guangzhou 510006 P.R.China

Lead strontium titanate(Sr_(1-x)Pbx)TiO_(3)(0.20≤x≤0.45,step=0.05)ceramics were prepared by conventional mixed oxide *** X-ray diffraction patterns indicate that the prepared samples have perovskite-type *** the increase of Pb content,there is a tendency from the cubic to tetragonal *** scanning electron microscopy micrographs reveal that the addition of Pb can affect *** dependent temperature dielectric permittivity and dielectric loss were investigated in the frequency range from 100 Hz to *** maximum peak of the dielectric permittivity versus temperature curve was broadened and a frequency dispersion of the dielectric permittivity was observed for the(Sr_(0.8)Pb_(0.2))TiO_(3)*** results obtained at the frequency of 10 kHz reveal the curie temperature linearly increased with the lead *** curves of temperature versus inverse dielectric permittivity at 10 kHz for(Sr_(1-x)Pbx)TiO_(3)ceramics are consistent with curie-Weiss *** Pyroelectric properties were also *** high pyroelectric coe±cients andfigure of merits indicate that the SPT ceramics are potential materials for pyroelectric sensors.

关键词： (Sr_(1-x)Pbx)TiO_(3)(SPT)ceramics dielectric properties curie temperature curieWeiss law pyroelectric properties