The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Jianxin Deng - One of the best experts on this subject based on the ideXlab platform.
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Erosion Wear Resistance of CWS Laminated Ceramic Nozzles
Advanced Materials Research, 2012Co-Authors: Jianxin Deng, Yang Yang Chen, You Qiang XingAbstract:In coal-water-slurry (CWS) boilers, the Nozzle is eroded continuously by the abrasive action of the CWS, and there are high temperature and temperature gradient inside Nozzle, which may cause large tensile stress and lead to an increased erosion wear of the Nozzle. In this paper, Al2O3/(W,Ti)C+Al2O3/TiC laminated ceramics were developed to be used as Nozzles in CWS boilers. The purpose is to reduce the tensile stresses at the Nozzle during the CWS burning process. The value of the residual stresses, which arise from a mismatch between the coefficients of thermal expansion of the constituent phases and neighbouring layers, was calculated by means of the finite element method. The erosion wear behavior of the laminated Nozzles was investigated and compared with an unstressed reference Nozzle. Results showed that the laminated ceramic Nozzles exhibited an apparent increase in erosion wear resistance over the unstressed reference one. It is suggested that laminated structures in ceramic Nozzles is an effective way to improve their erosion wear resistance in industrial CWS boilers.
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Layered structures in ceramic Nozzles for improved erosion wear resistance in industrial coal-water-slurry boilers
Ceramics International, 2010Co-Authors: Jianxin Deng, Dongling Yun, Houmin Zhou, Yuanqiang TanAbstract:The Nozzle is the most critical part in the coal-water-slurry (CWS) boilers. Ceramics being highly wear resistant have great potential as CWS Nozzle materials. In this paper, Al2O3/(W,Ti)C + Al2O3/TiC layered ceramics (LN1, LN2, and LN3) with different thickness ratios among constituent layers were developed to be used as Nozzles in CWS boilers. CWS burning tests in a boiler with these Nozzles were carried out. The erosion wear behavior of the layered Nozzles was investigated and compared with an unstressed reference Nozzle (N5). Results showed that the layered ceramic Nozzles exhibited an apparent increase in erosion wear resistance over the unstressed reference one. The mechanisms responsible were found to be that layered structure in the CWS Nozzles can improve the hardness and fracture toughness of the external layer, and reduce the temperature gradients and the thermal stresses at the exit of the Nozzle during CWS burning processes. It is suggested that layered structures in ceramic Nozzles is an effective way to improve the erosion wear resistance over the stress-free ceramic Nozzles in industrial CWS boilers. © 2009 Elsevier Ltd and Techna Group S.r.l.
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Performance and wear characteristics of ceramic, cemented carbide, and metal Nozzles used in coal-water-slurry boilers
International Journal of Refractory Metals and Hard Materials, 2009Co-Authors: Jianxin Deng, Zeliang Ding, Houming Zhou, Yuanqiang TanAbstract:Ceramics, cemented carbides, and metals were prepared to be used as Nozzles in CWS boilers. CWS burning tests in a boiler with these Nozzles were carried out. The erosion wear resistance of these Nozzles was compared by determining their erosion rates and hole diameter variation. Results showed that the life of the ceramic Nozzles is about 30 times high than that of the metal Nozzles. The wear types at the Nozzle wall surface differed in various positions. The Nozzle center wall section suffers form abrasive impact under low impact angles, and the damage at the center wall mainly occurs by plowing and plastic deformation for metals, and by polishing action for carbides and ceramics. The primary wear mechanisms at the exit of ceramic Nozzle exhibited thermal shock damage with chipping owing to the greater thermal stresses. © 2009 Elsevier Ltd. All rights reserved.
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Effect of experimental parameters on the erosion wear of ceramic Nozzles in coal-water-slurry industrial boilers
Industrial Ceramics, 2007Co-Authors: Zeliang Ding, X Zen, D Luo, Jianxin Deng, Y. ZouAbstract:Al2O3/(W,Ti)C ceramic composites were prepared for use as Nozzles in coal-water-slurry (CWS) industrial boilers. Effects of Nozzle length, Nozzle inlet angle, Nozzle exit structure, atomizing air pressure and experimental temperature on the erosive wear of these ceramic Nozzles have been investigated. Results showed that reasonable Nozzle structure is beneficial to decrease Nozzle wear. Lower atomizing air pressure can help to increase Nozzle life. Thermal shock damage such as cracking and chipping was considered as the dominant reason for the failure of ceramic Nozzles.
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Erosion wear mechanisms of coal-water-slurry (CWS) ceramic Nozzles in industry boilers
Materials Science and Engineering A, 2006Co-Authors: Jianxin Deng, Zeliang Ding, Dongling YuanAbstract:Al2O3/(W, Ti)C ceramic composites were prepared for the use of coal-water-slurry (CWS) Nozzles in industry boilers. The erosion rates of the CWS ceramic Nozzles were measured. Eroded bore surfaces of the Nozzles was examined by scanning electron microscopy. Finite element method (FEM) was used as a means of numerically evaluating temperature, temperature gradient, thermal stress and its distribution inside the ceramic Nozzle. Results showed that the primary wear mechanisms of the CWS ceramic Nozzle exhibited polishing action in the inner center hole and thermal shock damage with chipping at exit. The temperature, temperature gradient and thermal stress at exit surfaces of the CWS ceramic Nozzle were higher than those of other parts of the Nozzle. Greater temperature gradient and higher thermal stress were the main reason that caused the failure of the exit surface of the CWS ceramic Nozzle. © 2005 Elsevier B.V. All rights reserved.
Zeliang Ding - One of the best experts on this subject based on the ideXlab platform.
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Performance and wear characteristics of ceramic, cemented carbide, and metal Nozzles used in coal-water-slurry boilers
International Journal of Refractory Metals and Hard Materials, 2009Co-Authors: Jianxin Deng, Zeliang Ding, Houming Zhou, Yuanqiang TanAbstract:Ceramics, cemented carbides, and metals were prepared to be used as Nozzles in CWS boilers. CWS burning tests in a boiler with these Nozzles were carried out. The erosion wear resistance of these Nozzles was compared by determining their erosion rates and hole diameter variation. Results showed that the life of the ceramic Nozzles is about 30 times high than that of the metal Nozzles. The wear types at the Nozzle wall surface differed in various positions. The Nozzle center wall section suffers form abrasive impact under low impact angles, and the damage at the center wall mainly occurs by plowing and plastic deformation for metals, and by polishing action for carbides and ceramics. The primary wear mechanisms at the exit of ceramic Nozzle exhibited thermal shock damage with chipping owing to the greater thermal stresses. © 2009 Elsevier Ltd. All rights reserved.
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Effect of experimental parameters on the erosion wear of ceramic Nozzles in coal-water-slurry industrial boilers
Industrial Ceramics, 2007Co-Authors: Zeliang Ding, X Zen, D Luo, Jianxin Deng, Y. ZouAbstract:Al2O3/(W,Ti)C ceramic composites were prepared for use as Nozzles in coal-water-slurry (CWS) industrial boilers. Effects of Nozzle length, Nozzle inlet angle, Nozzle exit structure, atomizing air pressure and experimental temperature on the erosive wear of these ceramic Nozzles have been investigated. Results showed that reasonable Nozzle structure is beneficial to decrease Nozzle wear. Lower atomizing air pressure can help to increase Nozzle life. Thermal shock damage such as cracking and chipping was considered as the dominant reason for the failure of ceramic Nozzles.
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Erosion wear mechanisms of coal-water-slurry (CWS) ceramic Nozzles in industry boilers
Materials Science and Engineering A, 2006Co-Authors: Jianxin Deng, Zeliang Ding, Dongling YuanAbstract:Al2O3/(W, Ti)C ceramic composites were prepared for the use of coal-water-slurry (CWS) Nozzles in industry boilers. The erosion rates of the CWS ceramic Nozzles were measured. Eroded bore surfaces of the Nozzles was examined by scanning electron microscopy. Finite element method (FEM) was used as a means of numerically evaluating temperature, temperature gradient, thermal stress and its distribution inside the ceramic Nozzle. Results showed that the primary wear mechanisms of the CWS ceramic Nozzle exhibited polishing action in the inner center hole and thermal shock damage with chipping at exit. The temperature, temperature gradient and thermal stress at exit surfaces of the CWS ceramic Nozzle were higher than those of other parts of the Nozzle. Greater temperature gradient and higher thermal stress were the main reason that caused the failure of the exit surface of the CWS ceramic Nozzle. © 2005 Elsevier B.V. All rights reserved.
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Thermal shock behaviors of ceramic Nozzles in coal water slurry burning
Xiyou Jinshu Cailiao Yu Gongcheng Rare Metal Materials and Engineering, 2005Co-Authors: Zeliang Ding, Jianxin Deng, Jianjian LiAbstract:CNW-1 and CNW-2 ceramic composite materials were prepared for the use of Nozzle materials. The thermal shock behaviors of the Nozzles made from these materials were investigated. Results showed that the flexural strength and fracture toughness of the Nozzle materials plays an important role with respect to its thermal shock resistance in coal water slurry (CWS) burning. The CNW-2 Nozzles being with high flexural strength and toughness exhibited lower wear rates, while the CNW-1 Nozzles with low flexural strength and toughness showed higher wear rates under the same test conditions. Cracks and collapsing caused by thermal shock can be seen in exit zone of the ceramic Nozzles. Taper-shaped structure introduced at the Nozzle exit can improve the thermal shock resistance of ceramic Nozzles. Analysis of eroded bore surface of the Nozzles demonstrated that the failure mechanisms of Nozzles varied from entry to exit zone. The failure mechanisms of entry zone was mainly brittle fracture, the middle zone showed polishing, while the exit zone exhibited thermal cracking and collapsing.
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Wear behavior of ceramic Nozzles in coal water slurry burning
Ceramics International, 2004Co-Authors: Zeliang Ding, Gaozuo Sun, Jianfeng Li, Jianxin Deng, Xing AiAbstract:In this paper, Al2O3/(W,Ti)C ceramic composite and WC/Co cemented carbide were prepared for the use of Nozzle materials in coal water slurry (CWS) burning. The wear behavior of Nozzles made from these materials was compared by determining the cumulative volume loss and the erosion rates. Results showed that the hardness of the Nozzles plays an important role with respect to its erosion wear in CWS burning processing. The Al 2O3/(W,Ti)C Nozzles possessing high hardness exhibited lower erosion rates, while the WC/Co cemented carbide Nozzles with a low hardness showed higher erosion rates under the same test conditions. Examination of eroded bore surface of the Nozzles showed that wear of the WC/Co cemented carbide Nozzle occurred by a preferential removal of the metal binder followed by pluck out of the exposed WC grains, while the primary wear mechanisms of Al2O3/(W,Ti)C ceramic Nozzle exhibited polishing action in the hole and thermal shock damage with chipping at the bore exit. © 2003 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Yuanqiang Tan - One of the best experts on this subject based on the ideXlab platform.
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Layered structures in ceramic Nozzles for improved erosion wear resistance in industrial coal-water-slurry boilers
Ceramics International, 2010Co-Authors: Jianxin Deng, Dongling Yun, Houmin Zhou, Yuanqiang TanAbstract:The Nozzle is the most critical part in the coal-water-slurry (CWS) boilers. Ceramics being highly wear resistant have great potential as CWS Nozzle materials. In this paper, Al2O3/(W,Ti)C + Al2O3/TiC layered ceramics (LN1, LN2, and LN3) with different thickness ratios among constituent layers were developed to be used as Nozzles in CWS boilers. CWS burning tests in a boiler with these Nozzles were carried out. The erosion wear behavior of the layered Nozzles was investigated and compared with an unstressed reference Nozzle (N5). Results showed that the layered ceramic Nozzles exhibited an apparent increase in erosion wear resistance over the unstressed reference one. The mechanisms responsible were found to be that layered structure in the CWS Nozzles can improve the hardness and fracture toughness of the external layer, and reduce the temperature gradients and the thermal stresses at the exit of the Nozzle during CWS burning processes. It is suggested that layered structures in ceramic Nozzles is an effective way to improve the erosion wear resistance over the stress-free ceramic Nozzles in industrial CWS boilers. © 2009 Elsevier Ltd and Techna Group S.r.l.
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Performance and wear characteristics of ceramic, cemented carbide, and metal Nozzles used in coal-water-slurry boilers
International Journal of Refractory Metals and Hard Materials, 2009Co-Authors: Jianxin Deng, Zeliang Ding, Houming Zhou, Yuanqiang TanAbstract:Ceramics, cemented carbides, and metals were prepared to be used as Nozzles in CWS boilers. CWS burning tests in a boiler with these Nozzles were carried out. The erosion wear resistance of these Nozzles was compared by determining their erosion rates and hole diameter variation. Results showed that the life of the ceramic Nozzles is about 30 times high than that of the metal Nozzles. The wear types at the Nozzle wall surface differed in various positions. The Nozzle center wall section suffers form abrasive impact under low impact angles, and the damage at the center wall mainly occurs by plowing and plastic deformation for metals, and by polishing action for carbides and ceramics. The primary wear mechanisms at the exit of ceramic Nozzle exhibited thermal shock damage with chipping owing to the greater thermal stresses. © 2009 Elsevier Ltd. All rights reserved.
Deng Jianxin - One of the best experts on this subject based on the ideXlab platform.
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Gradient structures in ceramic Nozzles for improved erosion wear resistance
Ceramics International, 2007Co-Authors: Deng Jianxin, Liu Lili, Ding MingweiAbstract:In sand blasting processes, the Nozzle entry region suffers form severe abrasive impact, which may cause large tensile stress and lead to an increased erosion wear at the Nozzle entry area. In this paper, a (W,Ti)C/SiC gradient ceramic Nozzle was produced by hot pressing. The purpose is to reduce the tensile stress at the entry region of the Nozzle during sand blasting processes. The erosion wear behavior of the gradient ceramic Nozzle was investigated in comparison with the common ceramic Nozzles. Results showed that the gradient ceramic Nozzles exhibited an apparent increase in erosion wear resistance over the common ceramic Nozzles. The mechanism responsible was explained as the formation of compressive residual stresses in Nozzle entry region in fabricating process of the gradient ceramic Nozzles, which may partially counteract the tensile stresses resulting from external loadings. It is indicated that gradient structures in ceramic Nozzles is an effective way to improve the erosion wear resistance of common ceramic Nozzles.
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Erosion wear of laminated ceramic Nozzles
International Journal of Refractory Metals & Hard Materials, 2007Co-Authors: Deng Jianxin, Liu Lili, Zhao Jinlong, Sun JunlongAbstract:Abstract SiC/(W,Ti)C ceramic Nozzles with laminated structures were produced by hot pressing in order to reduce the tensile stress at the entry and exit region of the Nozzle. Finite element method was used to evaluate the residual stresses due to the different thermal expansion coefficients and shrinkage of the SiC and (W,Ti)C solid–solution during the sintering process of the composite. The erosion wear of the laminated ceramic Nozzle was assessed by sand blasting; the results were compared with those obtained with an unstressed reference Nozzle with the same composition. The experimental results have shown that the laminated ceramic Nozzles have superior erosion wear resistance to that of the homologous stress-free Nozzles.
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erosion wear mechanisms of coal water slurry cws ceramic Nozzles in industry boilers
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: Deng Jianxin, Ding Zeliang, Yuan DonglingAbstract:Abstract Al 2 O 3 /(W, Ti)C ceramic composites were prepared for the use of coal–water–slurry (CWS) Nozzles in industry boilers. The erosion rates of the CWS ceramic Nozzles were measured. Eroded bore surfaces of the Nozzles was examined by scanning electron microscopy. Finite element method (FEM) was used as a means of numerically evaluating temperature, temperature gradient, thermal stress and its distribution inside the ceramic Nozzle. Results showed that the primary wear mechanisms of the CWS ceramic Nozzle exhibited polishing action in the inner center hole and thermal shock damage with chipping at exit. The temperature, temperature gradient and thermal stress at exit surfaces of the CWS ceramic Nozzle were higher than those of other parts of the Nozzle. Greater temperature gradient and higher thermal stress were the main reason that caused the failure of the exit surface of the CWS ceramic Nozzle.
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erosion wear of boron carbide ceramic Nozzles by abrasive air jets
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2005Co-Authors: Deng JianxinAbstract:Boron carbide Nozzles were produced by hot pressing. The erosion wear of this Nozzle caused by abrasive particle impact was investigated by abrasive air-jets. Silica, silicon carbide and alumina powders with different hardness were used as the erodent abrasive particles. Results showed that the hardness of the erodent particles played an important role with respect to the erosion wear of the boron carbide Nozzles. As the hardness of the erodent particles increases, there is a dramatic increase in erosion rate of the Nozzles. The Nozzle entrance area suffered from severe abrasive impact under large impact angles, and generated maximum tensile stresses. The wear mechanisms of boron carbide Nozzle at this area appeared to be entirely brittle in nature with the evidence of large scale-chipping, and exhibited a brittle fracture induced removal process. While at the Nozzle center wall section, most of the particles traveled parallel to the Nozzle wall, and showed minimum tensile stresses. The wear mode in this area of the Nozzle changed from impact to sliding erosion, and the wear mechanisms appeared to be the lateral cracking owing to a surface fatigue fracture mechanism.
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Erosion wear mechanisms of coal–water–slurry (CWS) ceramic Nozzles in industry boilers
Materials Science and Engineering: A, 2005Co-Authors: Deng Jianxin, Ding Zeliang, Yuan DonglingAbstract:Al2O3/(W, Ti)C ceramic composites were prepared for the use of coal–water–slurry (CWS) Nozzles in industry boilers. The erosion rates of the CWS ceramic Nozzles were measured. Eroded bore surfaces of the Nozzles was examined by scanning electron microscopy. Finite element method (FEM) was used as a means of numerically evaluating temperature, temperature gradient, thermal stress and its distribution inside the ceramic Nozzle. Results showed that the primary wear mechanisms of the CWS ceramic Nozzle exhibited polishing action in the inner center hole and thermal shock damage with chipping at exit. The temperature, temperature gradient and thermal stress at exit surfaces of the CWS ceramic Nozzle were higher than those of other parts of the Nozzle. Greater temperature gradient and higher thermal stress were the main reason that caused the failure of the exit surface of the CWS ceramic Nozzle.
Yuan Dongling - One of the best experts on this subject based on the ideXlab platform.
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erosion wear mechanisms of coal water slurry cws ceramic Nozzles in industry boilers
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: Deng Jianxin, Ding Zeliang, Yuan DonglingAbstract:Abstract Al 2 O 3 /(W, Ti)C ceramic composites were prepared for the use of coal–water–slurry (CWS) Nozzles in industry boilers. The erosion rates of the CWS ceramic Nozzles were measured. Eroded bore surfaces of the Nozzles was examined by scanning electron microscopy. Finite element method (FEM) was used as a means of numerically evaluating temperature, temperature gradient, thermal stress and its distribution inside the ceramic Nozzle. Results showed that the primary wear mechanisms of the CWS ceramic Nozzle exhibited polishing action in the inner center hole and thermal shock damage with chipping at exit. The temperature, temperature gradient and thermal stress at exit surfaces of the CWS ceramic Nozzle were higher than those of other parts of the Nozzle. Greater temperature gradient and higher thermal stress were the main reason that caused the failure of the exit surface of the CWS ceramic Nozzle.
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Erosion wear mechanisms of coal–water–slurry (CWS) ceramic Nozzles in industry boilers
Materials Science and Engineering: A, 2005Co-Authors: Deng Jianxin, Ding Zeliang, Yuan DonglingAbstract:Al2O3/(W, Ti)C ceramic composites were prepared for the use of coal–water–slurry (CWS) Nozzles in industry boilers. The erosion rates of the CWS ceramic Nozzles were measured. Eroded bore surfaces of the Nozzles was examined by scanning electron microscopy. Finite element method (FEM) was used as a means of numerically evaluating temperature, temperature gradient, thermal stress and its distribution inside the ceramic Nozzle. Results showed that the primary wear mechanisms of the CWS ceramic Nozzle exhibited polishing action in the inner center hole and thermal shock damage with chipping at exit. The temperature, temperature gradient and thermal stress at exit surfaces of the CWS ceramic Nozzle were higher than those of other parts of the Nozzle. Greater temperature gradient and higher thermal stress were the main reason that caused the failure of the exit surface of the CWS ceramic Nozzle.
