Three types of FeMnCrAl/Cr3C2 coatings with different AI content were deposited on 20# steel substrates by the high velocity arc spraying （HVAS） process. Surface microstructures of the coatings were analyzed by opti...Three types of FeMnCrAl/Cr3C2 coatings with different AI content were deposited on 20# steel substrates by the high velocity arc spraying （HVAS） process. Surface microstructures of the coatings were analyzed by optical microscopy （OM） and X-ray diffractometry （XRD）. High temperature erosion （HTE） tests were performed in an erosion tester at different impact angles. The surface morphologies of the eroded coatings were observed on a field emission scanning electron microscope（FE-SEM）. The laminated structure is found on all the prepared coatings with the porosity and oxide fraction in the coatings decreasing with the Al content from 0 to 15% （mass fraction）. Sample FA3 with 15% Al, possessing the lowest porosity and oxide fraction, has the best HTE resistance, which demonstrates that Al addition can improve the HTE resistance of the coatings. The erosion rate of sample FA1 exhibits a maximum value at 90° impact angle. The maximum erosion rates of both FA2 and FA3 samples appear in the range of 60°-90° impact angles. Erosion loss of the coatings occurs through brittle breaking, cutting and fatigue spalling.展开更多
Model updating for aircraft in a high temperature environment(HTE)is proposed based on the hierarchical method.With this method,the problem can be decomposed into temperature field updating and dynamic structural upda...Model updating for aircraft in a high temperature environment(HTE)is proposed based on the hierarchical method.With this method,the problem can be decomposed into temperature field updating and dynamic structural updating.In order to improve the estimation accuracy,the model updating problem is turned into a multi-objective optimization problem by constructing the objective function which combined with residues of modal frequency and effective modal mass.Then the metamodeling,support vector regression(SVR)is introduced to improve the optimization efficiency,and the solution can be determined by adaptive weighted-sum method(AWS).Finally,the proposed method is tested on a finite element(FE)model of a reentry vehicle model.The results show that the multi-objective model updating method in HTE can identify the input parameters of the temperature field and structure with good accuracy.展开更多
The paper presents a study of model development for predicting the oxide thickness on metals under high temperature solid-particle erosion.The model is created based on the theory of solid-particle erosion that charac...The paper presents a study of model development for predicting the oxide thickness on metals under high temperature solid-particle erosion.The model is created based on the theory of solid-particle erosion that characterizes the erosion damage as deformation wear and cutting wear,incorporating the effect of the oxide scale on the eroded surface under high temperature erosion.Then the instantaneous oxide thickness is the result of the synergetic effect of erosion and oxidation.The developed model is applied on a Ni-based Al-containing(Ni–Al)alloy to investigate the oxide thickness variation with erosion duration of the alloy at high temperatures.The results show that the thickness of the oxide scale on the alloy surface increases with the exposure time and temperature when the surface is not attacked by particles.However,when particles impact on the alloy surface,the oxide thickness is reduced,although oxidation is continuing.This indicates that oxidation does not benefit the erosion resistance of this alloy at high temperatures due to the low growth rate of the oxide.展开更多
基金Project(2009C31129) supported by the Science and Technology Department of Zhejiang Province, China
文摘Three types of FeMnCrAl/Cr3C2 coatings with different AI content were deposited on 20# steel substrates by the high velocity arc spraying （HVAS） process. Surface microstructures of the coatings were analyzed by optical microscopy （OM） and X-ray diffractometry （XRD）. High temperature erosion （HTE） tests were performed in an erosion tester at different impact angles. The surface morphologies of the eroded coatings were observed on a field emission scanning electron microscope（FE-SEM）. The laminated structure is found on all the prepared coatings with the porosity and oxide fraction in the coatings decreasing with the Al content from 0 to 15% （mass fraction）. Sample FA3 with 15% Al, possessing the lowest porosity and oxide fraction, has the best HTE resistance, which demonstrates that Al addition can improve the HTE resistance of the coatings. The erosion rate of sample FA1 exhibits a maximum value at 90° impact angle. The maximum erosion rates of both FA2 and FA3 samples appear in the range of 60°-90° impact angles. Erosion loss of the coatings occurs through brittle breaking, cutting and fatigue spalling.
基金supported by the National Natural Science Foundation of China(No.11472132)the Fundamental Research Funds for Central University (No. NJ20160050)the Fundamental Research Funds for Central University(No.NJ2016098)
文摘Model updating for aircraft in a high temperature environment(HTE)is proposed based on the hierarchical method.With this method,the problem can be decomposed into temperature field updating and dynamic structural updating.In order to improve the estimation accuracy,the model updating problem is turned into a multi-objective optimization problem by constructing the objective function which combined with residues of modal frequency and effective modal mass.Then the metamodeling,support vector regression(SVR)is introduced to improve the optimization efficiency,and the solution can be determined by adaptive weighted-sum method(AWS).Finally,the proposed method is tested on a finite element(FE)model of a reentry vehicle model.The results show that the multi-objective model updating method in HTE can identify the input parameters of the temperature field and structure with good accuracy.
文摘The paper presents a study of model development for predicting the oxide thickness on metals under high temperature solid-particle erosion.The model is created based on the theory of solid-particle erosion that characterizes the erosion damage as deformation wear and cutting wear,incorporating the effect of the oxide scale on the eroded surface under high temperature erosion.Then the instantaneous oxide thickness is the result of the synergetic effect of erosion and oxidation.The developed model is applied on a Ni-based Al-containing(Ni–Al)alloy to investigate the oxide thickness variation with erosion duration of the alloy at high temperatures.The results show that the thickness of the oxide scale on the alloy surface increases with the exposure time and temperature when the surface is not attacked by particles.However,when particles impact on the alloy surface,the oxide thickness is reduced,although oxidation is continuing.This indicates that oxidation does not benefit the erosion resistance of this alloy at high temperatures due to the low growth rate of the oxide.
