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Development of oxide based diffusion barrier coatings for CFC components applied in modern furnaces

Kirsten BOBZIN, Lidong ZHAO, Thomas SCHLAEFER, Thomas WARDA

《机械工程前沿(英文)》 2011年 第6卷 第4期   页码 392-396 doi: 10.1007/s11465-011-0241-z

摘要:

Carbon fibre reinforced carbon (CFC) materials show a high potential for usage in furnaces as sample carriers for example, which is due to their excellent thermal stability compared to steel carriers. Only their tendency to react with different metals at high temperatures by C-diffusion is a disadvantage, which can be solved by application of diffusion barriers. In order to enable the utilization of CFC-carriers for e.g. brazing furnaces, within the frame of this study thermally sprayed diffusion barrier coatings were developed. Coatings of mullite and ZrO2-7%βY2O3 (YSZ) were prepared by air plasma spraying (APS). The coatings were investigated in terms of their microstructure and thermal shock behaviour. In order to prove the suitability of the coatings for the application in brazing furnaces, the wettability of the coating surfaces by a Ni-based brazing alloy was investigated. The results showed that both mullite and YSZ could be deposited on CFC substrates with a bond coat of W or SiC. Both coatings exhibited good thermal shock behaviour and an excellent non-wetting behaviour against the used Ni-based braze alloy.

关键词: diffusion barrier coatings     carbon fibre reinforced carbon (CFC)     plasma spraying     microstructure     furnace    

Feasibility study of plasma sprayed Al2O3 coatings as diffusion barrier on CFC

Kirsten BOBZIN, Lidong ZHAO, Nils KOPP, Thomas WARDA

《机械工程前沿(英文)》 2012年 第7卷 第4期   页码 371-375 doi: 10.1007/s11465-012-0339-y

摘要:

Carbon fibre reinforced carbon (CFC) materials are increasingly applied as sample carriers in modern furnaces. Only their tendency to react with different metals at high temperatures by C-diffusion is a disadvantage, which can be solved by application of diffusion barriers. Within this study the feasibility of plasma sprayed Al2O3 coatings as diffusion barrier was studied. Al2O3 coatings were prepared by air plasma spraying (APS). The coatings were investigated in terms of their microstructure, bonding to CFC substrates and thermal stability. The results showed that Al2O3 could be well deposited onto CFC substrates. The coatings had a good bonding and thermal shock behavior at 1060°C. At higher temperature of 1270°C, crack network formed within the coating, showing that the plasma sprayed Al2O3 coatings are limited regarding to their application temperatures as diffusion barrier on CFC components.

关键词: diffusion barrier coatings     CFC     plasma spraying     microstructure     Al2O3    

Preparation and characterization of nanocrystalline ZrO2-7%Y2O3 powders for thermal barrier coatings

Kirsten BOBZIN, Lidong ZHAO, Thomas SCHLAEFER, Thomas WARDA

《机械工程前沿(英文)》 2011年 第6卷 第2期   页码 176-181 doi: 10.1007/s11465-011-0220-4

摘要:

High-energy ball milling is an effective method to produce nanocrystalline oxides. In this study, a conventional ZrO2-7%Y2O3spray powder was ball-milled to produce nanocrystalline powders with high levels of crystalline disorders for deposition of thermal barrier coatings. The powder was milled both with 100Cr6 steel balls and with ZrO2-3%Y2O3 ceramic balls as grinding media. The milling time was varied in order to investigate the effect of the milling time on the crystallite size. The powders were investigated in terms of their crystallite sizes and morphologies by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that under given milling conditions the powder was already nanostructured after 40 min milling. The crystallite size decreased significantly with increasing milling time within first 120 min. After that, a further increase of milling time did not lead to a significant reduction of the crystallite size. Ball-milling led to lattice microstrains. Milling with the steel balls resulted in finer nano-sized crystal grains, but caused the contamination of the powder. The nano-sized crystal grains coarsened during the heat-treatment at 1250°C.

关键词: nanostrucured powders     yttria stabilized zirconia (YSZ)     high-energy ball milling     thermal barrier coatings    

Effect of TGO on the tensile failure behavior of thermal barrier coatings

Le WANG, Yuelan DI, Ying LIU, Haidou WANG, Haoxing YOU, Tao LIU

《机械工程前沿(英文)》 2019年 第14卷 第4期   页码 452-460 doi: 10.1007/s11465-019-0541-2

摘要: Thermally grown oxide (TGO) may be generated in thermal barrier coatings (TBCs) after high-temperature oxidation. TGO increases the internal stress of the coatings, leading to the spalling of the coatings. Scanning electron microscopy and energy-dispersive spectroscopy were used to investigate the growth characteristics, microstructure, and composition of TGO after high-temperature oxidation for 0, 10, 30, and 50 h, and the results were systematically compared. Acoustic emission (AE) signals and the strain on the coating surface under static load were measured with AE technology and digital image correlation. Results showed that TGO gradually grew and thickened with the increase in oxidation time. The thickened TGO had preferential multi-cracks at the interface of TGO and the bond layer and delayed the strain on the surface of the coating under tensile load. TGO growth resulted in the generation of pores at the interface between the TGO and bond layer. The pores produced by TGO under tensile load delayed the generation of surface cracks and thus prolonged the failure time of TBCs.

关键词: thermally grown oxides     thermal barrier coatings     acoustic emission technology     digital image correlation     pores    

Time of flight improved thermally grown oxide thickness measurement with terahertz spectroscopy

《机械工程前沿(英文)》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0705-3

摘要: As a nondestructive testing technique, terahertz time-domain spectroscopy technology is commonly used to measure the thickness of ceramic coat in thermal barrier coatings (TBCs). However, the invisibility of ceramic/thermally grown oxide (TGO) reflective wave leads to the measurement failure of natural growth TGO whose thickness is below 10 μm in TBCs. To detect and monitor TGO in the emergence stage, a time of flight (TOF) improved TGO thickness measurement method is proposed. A simulative investigation on propagation characteristics of terahertz shows the linear relationship between TGO thickness and phase shift of feature wave. The accurate TOF increment could be acquired from wavelet soft threshold and cross-correlation function with negative effect reduction of environmental noise and system oscillation. Thus, the TGO thickness could be obtained efficiently from the TOF increment of the monitor area with different heating times. The averaged error of 1.61 μm in experimental results demonstrates the highly accurate and robust measurement of the proposed method, making it attractive for condition monitoring and life prediction of TBCs.

关键词: thermal barrier coatings     thermally grown oxide     terahertz spectroscopy     time of flight    

Effect of electrolyte concentration on the tribological performance of MAO coatings on aluminum alloys

Chao Wang, Jun Chen, Jihua He, Jing Jiang, Qinyong Zhang

《化学科学与工程前沿(英文)》 2020年 第14卷 第6期   页码 1065-1071 doi: 10.1007/s11705-019-1909-x

摘要: Micro-arc oxidation (MAO) is an efficient approach to improve the hardness, wear resistance, and other properties of aluminum alloys. In order to investigate the effect of the electrolyte concentration on the properties of MAO coatings for LY12 alloy, the voltage variation during the MAO process was recorded. The surface morphologies and phase compositions of the coatings produced with different electrolytes were investigated using scanning electron microscopy and X-ray diffraction, respectively. The roughness and thickness of the coatings were measured using a pocket roughness meter and an eddy-current thickness meter, respectively. The tribological performances of the coatings were investigated against GCr15 bearing steel on a ball-on-disc wear tester in open air. The results showed that with an increase in the Na SiO content, the working voltage of the MAO process decreased, the roughness and thickness of the coatings increased significantly, and the relative content of the -Al O phase decreased. With an increase in the KOH content, the working voltage decreased slightly, the roughness and thickness of the coatings increased slightly, and the α- and -Al O phase contents remained unchanged. The friction coefficient and wear rate of the coatings increased with an increase in the Na SiO and KOH concentrations. A decrease in the porosity and roughness and an increase in the α-Al O content of the coatings reduced their wear mass loss.

关键词: aluminum alloy     micro-arc oxidation     coating     electrolyte concentration     tribological performance    

Technology for the preparation and application of cermet coatings and claddings in thermal power plants

Zongde LIU, Miao LIU, Liping ZHAO

《能源前沿(英文)》 2011年 第5卷 第3期   页码 257-262 doi: 10.1007/s11708-010-0129-3

摘要: This paper introduces the applied background of wear and corrosion-resistant materials in the electricity industry. Next, the paper summarizes the development of preparation technology for cermets and cermet coatings and claddings, finally explaining the application and development of submicron-grain cermet coatings and claddings through reaction synthesis technology.

关键词: cermets     cermet coatings/claddings     electro-thermal explosion spraying     reaction synthesis    

Research on a quantificational method for chromatic-light emotions of architectural wall coatings in

Ting WANG, Ma JIAN, Gang LIU, Xiaoxi LIU, Mingyu ZHANG

《结构与土木工程前沿(英文)》 2010年 第4卷 第4期   页码 498-502 doi: 10.1007/s11709-010-0096-0

摘要: Research on quantificational methods for chromatic-light emotion is an effective way of finding out the laws of light cognitive impact and the solution to the problem on application of light color in landscape lighting. This paper took chromatic-light-induced-emotion towards architectural wall coatings in landscape as the research object. The methods in use were real-state simulation and laboratory quantitative study. Consequently, the study successfully extracted light emotional factors and the rule of predictability to assist landscape light professionals.

关键词: landscape illumination     architectural wall coatings     chromatic-light emotion     quantitative research    

A comprehensive assessment on the durability of gas diffusion electrode materials in PEM fuel cell stack

Arunkumar JAYAKUMAR

《能源前沿(英文)》 2019年 第13卷 第2期   页码 325-338 doi: 10.1007/s11708-019-0618-y

摘要: Polymer electrolyte membrane (PEM) fuel cell is the most promising among the various types of fuel cells. Though it has found its applications in numerous fields, the cost and durability are key barriers impeding the commercialization of PEM fuel cell stack. The crucial and expensive component involved in it is the gas diffusion electrode (GDE) and its degradation, which limits the performance and life of the fuel cell stack. A critical analysis and comprehensive understanding of the structural and functional properties of various materials involved in the GDE can help us to address the related durability and cost issues. This paper reviews the key GDE components, and in specific, the root causes influencing the durability. It also envisages the role of novel materials and provides a critical recommendation to improve the GDE durability.

关键词: PEM fuel cell     gas diffusion electrode(GDE)     gas diffusion layer(GDL)     membrane electrode assembly     durability     fuel cell catalyst    

通过 B 位Ta置换对 AB O4型EuNbO4的热学和力学性质进行优化 Article

陈琳, 冯晶

《工程(英文)》 2020年 第6卷 第2期   页码 177-184 doi: 10.1016/j.eng.2019.12.006

摘要:

铁弹性的ABO4型RETaO4陶瓷和RENbO4陶瓷(RE表示稀土)是具有潜在应用价值的热障涂层(TBC)材料,研究人员正在对其进行大量研究。结果显示, RETaO4陶瓷的力学性质优于RENbO4陶瓷的力学性质。在本研究中,我们通过B位钽(Ta)置换对利用固相法(SSR)制备的EuNbO4陶瓷的热学和力学性质进行优化。我们使用X射线衍射(XRD)法和拉曼光谱技术对所制备的晶体结构进行确认,并利用扫描电子显微镜(SEM)对结构表面的微观形貌进行观察。结果表明,通过B位Ta置换可以有效提高EuNbO4陶瓷的杨氏模量和热膨胀系数(TEC),且其最大值分别为169 GPa和1.12×10−5 K−1(1200 ℃); EuNbO4陶瓷的热导率被降低至1.52 W·K–1·m–1(700 ℃),且材料的抗热辐射能力得到了改善。我们建立了声子热扩散系数与温度之间的关系,用以通过消除热辐射效应来确定声子本征热导率。研究结果表明,通过B位Ta置换能够有效优化EuNbO4的热学和力学性质,从而使得此种材料在将来可成为一种高温结构陶瓷材料。

关键词: 热障涂层,稀土铌酸盐,置换,热导率,热膨胀系数,杨氏模量    

Passive convergence-permeable reactive barrier (PC-PRB): An effective configuration to enhance hydraulic

《环境科学与工程前沿(英文)》 2022年 第16卷 第12期 doi: 10.1007/s11783-022-1591-y

摘要:

● A novel PRB configuration based on passive convergent flow effect was proposed.

关键词: Passive convergence-permeable reactive barrier (PC-PRB)     Permeable reactive barrier configuration     Numerical simulation     Hydraulic performance evaluation     Sensitivity analysis    

Coupled diffusion of chloride and other ions in saturated concrete

Nattapong DAMRONGWIRIYANUPAP, Linyuan LI, Yunping XI

《结构与土木工程前沿(英文)》 2011年 第5卷 第3期   页码 267-277 doi: 10.1007/s11709-011-0112-z

摘要: Corrosion of reinforcing steel due to chloride ions is one of the severe deterioration problems in long-term performance of reinforced concrete structures. The deterioration process is frequently found in marine concrete structures, highway pavements, and bridges exposed to deicing salts. The diffusion of chloride ions is associated and strongly affected by other ions in the pore solution in concrete. In this paper, chloride penetration into concrete structures was mathematically characterized by the Nernst-Planck equation which considered not only diffusion mechanism of the chloride ions but also ionic interaction among other ions coming from externally applied deicers and within the Portland cement paste. Electroneutrality was used to determine the electrostatic potential induced by the ionic interaction. The material models of chloride binding capacity and chloride diffusion coefficient were incorporated in the governing equations. The governing equations were solved by using finite element method. A numerical example was used to illustrate the coupling effect of multi-ionic interactions and the effect of influential parameters. The numerical results obtained from the present model agreed very well with available test data.

关键词: diffusion     chloride     concrete     Nernst-Planck equation     durability    

Effects of additive NaI on electrodeposition of Al coatings in AlCl

Tianyu Yao, Haiyan Yang, Kui Wang, Haiyan Jiang, Xiao-Bo Chen, Hezhou Liu, Qudong Wang, Wenjiang Ding

《化学科学与工程前沿(英文)》 2021年 第15卷 第1期   页码 138-147 doi: 10.1007/s11705-020-1935-8

摘要: Effects of NaI as an additive on electrodeposition of Al coatings in AlCl -NaCl-KCl (80-10-10 wt-%) molten salts electrolyte at 150°C were investigated by means of cyclic voltammetry, chronopotentiometry, scanning electron microscopy and X-ray diffraction (XRD). Results reveal that addition of NaI in the electrolyte intensifies cathodic polarization, inhibits growth of Al deposits and increases number density of charged particles. The electrodeposition of Al coatings in the AlCl -NaCl-KCl molten salts electrolyte proceeds via three-dimensional instantaneous nucleation which however exhibits irrelevance with NaI. Galvanostatic deposition results indicate that NaI could facilitate the formation of uniform Al deposits. A compact coating consisting of Al deposits with an average particle size of 3 μm was obtained at a current density of 50 mA∙cm in AlCl -NaCl-KCl molten salts electrolyte with 10 wt-% NaI. XRD analysis confirmed that NaI could contribute to the formation of Al coating with a preferred crystallographic orientation along (220) plane.

关键词: NaI     additive     electrodeposition     molten salts     Al coating    

Hydrogen production from methanol through dielectric barrier discharge

Baowei WANG, Xu ZHANG, Haiying BAI, Yijun Lü, Shuanghui HU

《化学科学与工程前沿(英文)》 2011年 第5卷 第2期   页码 209-214 doi: 10.1007/s11705-010-1018-3

摘要: The hydrogen fuel cell is a promising option as a future energy resource and the production of hydrogen is mainly depended on fossil fuels now. In this paper, methanol reforming to produce H through dielectric-barrier discharge (DBD) plasma reaction was studied. Effects of the power supply parameters, reactor parameters and process conditions on conversion of methanol and distribution of products were investigated. The best reaction conditions were following: input power (45 W), material of inner electrode (stainless steel), discharge gap (3.40 mm), length of reaction zone (90.00 mm), dielectric thickness (1.25 mm), and methanol content (37.65%). The highest conversion of methanol and the yield of H were 82.38% and 27.43%, respectively.

关键词: methanol     dielectric-barrier discharge     hydrogen     plasma    

Experimental study of humid air reverse diffusion combustion in a turbulent flow field

GE Bing, ZANG Shusheng, GU Xin

《能源前沿(英文)》 2007年 第1卷 第4期   页码 428-434 doi: 10.1007/s11708-007-0062-6

摘要: Experiments were performed to investigate the differences between the propane/air turbulent diffusion reactive flows past bluff-body and the propane/humid air turbulent diffusion reactive flows in the same conditions. The velocity

关键词: propane/humid     propane/air turbulent     bluff-body     turbulent diffusion    

标题 作者 时间 类型 操作

Development of oxide based diffusion barrier coatings for CFC components applied in modern furnaces

Kirsten BOBZIN, Lidong ZHAO, Thomas SCHLAEFER, Thomas WARDA

期刊论文

Feasibility study of plasma sprayed Al2O3 coatings as diffusion barrier on CFC

Kirsten BOBZIN, Lidong ZHAO, Nils KOPP, Thomas WARDA

期刊论文

Preparation and characterization of nanocrystalline ZrO2-7%Y2O3 powders for thermal barrier coatings

Kirsten BOBZIN, Lidong ZHAO, Thomas SCHLAEFER, Thomas WARDA

期刊论文

Effect of TGO on the tensile failure behavior of thermal barrier coatings

Le WANG, Yuelan DI, Ying LIU, Haidou WANG, Haoxing YOU, Tao LIU

期刊论文

Time of flight improved thermally grown oxide thickness measurement with terahertz spectroscopy

期刊论文

Effect of electrolyte concentration on the tribological performance of MAO coatings on aluminum alloys

Chao Wang, Jun Chen, Jihua He, Jing Jiang, Qinyong Zhang

期刊论文

Technology for the preparation and application of cermet coatings and claddings in thermal power plants

Zongde LIU, Miao LIU, Liping ZHAO

期刊论文

Research on a quantificational method for chromatic-light emotions of architectural wall coatings in

Ting WANG, Ma JIAN, Gang LIU, Xiaoxi LIU, Mingyu ZHANG

期刊论文

A comprehensive assessment on the durability of gas diffusion electrode materials in PEM fuel cell stack

Arunkumar JAYAKUMAR

期刊论文

通过 B 位Ta置换对 AB O4型EuNbO4的热学和力学性质进行优化

陈琳, 冯晶

期刊论文

Passive convergence-permeable reactive barrier (PC-PRB): An effective configuration to enhance hydraulic

期刊论文

Coupled diffusion of chloride and other ions in saturated concrete

Nattapong DAMRONGWIRIYANUPAP, Linyuan LI, Yunping XI

期刊论文

Effects of additive NaI on electrodeposition of Al coatings in AlCl

Tianyu Yao, Haiyan Yang, Kui Wang, Haiyan Jiang, Xiao-Bo Chen, Hezhou Liu, Qudong Wang, Wenjiang Ding

期刊论文

Hydrogen production from methanol through dielectric barrier discharge

Baowei WANG, Xu ZHANG, Haiying BAI, Yijun Lü, Shuanghui HU

期刊论文

Experimental study of humid air reverse diffusion combustion in a turbulent flow field

GE Bing, ZANG Shusheng, GU Xin

期刊论文