Ni60-WC particles are used to improve the wear resistance of hard-facing steel due to their high hardness. An emerging technology that combines laser with cold spraying to deposit the hard-facing coatings is known as ...Ni60-WC particles are used to improve the wear resistance of hard-facing steel due to their high hardness. An emerging technology that combines laser with cold spraying to deposit the hard-facing coatings is known as supersonic laser deposition. In this study, Ni60-WC is deposited on low-carbon steel using SLD. The microstructure and performance of the coatings are investigated through SEM, optical microscopy, EDS, XRD, microhardness and pin-on-disc wear tests. The experimental results of the coating processed with the optimal parameters are compared to those of the coating deposited using laser cladding.展开更多
Stellite 6 powders were deposited on low carbon steel using SLD （supersonic laser deposition） under optimized parameters. The structure, line scan of elements and porosity of coating were examined and analyzed using...Stellite 6 powders were deposited on low carbon steel using SLD （supersonic laser deposition） under optimized parameters. The structure, line scan of elements and porosity of coating were examined and analyzed using SEM （scanning electron microscope）, OM （optical microscope） and XRD （X-ray diffraction）. The adhesion strength between coating and substrate was tested by PAT-ADHESION/TENSILE and E900STM adhesive. The results showed the deposition characteristics of optimized coating with N2 at a pressure of 3.0 MPa, a temperature of 450 ℃ and a laser power of 1.5 kW were compared with those of Stellite 6 coating deposited by the HVOF （high velocity oxygen fuel）.展开更多
The supersonic laser deposition （SLD） is a new fabrication process which combines the supersonic powder stream found in cold spray with laser heating of the deposition zone. Because of the instantaneity of particles...The supersonic laser deposition （SLD） is a new fabrication process which combines the supersonic powder stream found in cold spray with laser heating of the deposition zone. Because of the instantaneity of particles impact, the deformation behaviors and the adhesion behaviors of particles impacted on the substrate by SI.D cannot be well investigated through experiments. Therefore, a finite elemen! model was developed to solve the problems above. Meanwhile, the heat effect of the substrate heated by laser was discussed. The effective plastic strain and the effec- tive stress between the particle and substrate at different laser preheal temperatures were studied. The results show that laser depositing temperatures of 1 000 and 1 100 ℃ on substrate would be the optimized for the bonding of parti- cles and substrate. In addition, the simulation results conformed to experimental results.展开更多
The ability to manufacture coatings is critical to engineering design. Many components require the application of additional layers toenhance mechanical properties and protect against hostile environments. Supersonic ...The ability to manufacture coatings is critical to engineering design. Many components require the application of additional layers toenhance mechanical properties and protect against hostile environments. Supersonic laser deposition (SLD) is a novel coating methodbased on cold spray (CS) principles. In this technique, the deposition velocities can be significantly lower than those required foreffective bonding in CS applications. The addition of laser heat energy permits a change in the thermodynamic experience of impactingparticles, thereby offering a greater opportunity for efficient bonding at lower velocities as compared with the CS process. The workreported in this paper demonstrates the ability of the SLD process to deliver hardfacing materials to engineering surfaces. Stellite-6 hasbeen deposited on low-carbon steel tubes over a range of process parameters to establish the appropriate target power and traversespeeds for the coating formation. The coating properties and parameters were examined to determine the primary characteristics andgrain structure size. Their morphology and performance were studied through optical microscopy, scanning electron microscope(SEM), X-ray diffraction, hardness measurements and wear testing. The results have shown that SLD is capable of depositing layers ofStellite-6, with properties that are superior to those of their conventionally manufactured counterparts.展开更多
为了探究高速空气燃料热喷涂(activated combustion-high velocity air fuel,AC-HVAF)过程中喷涂粒子撞击基材后的沉积特性。采用AC-HVAF热喷涂技术在AZ80镁合金基体上沉积WC-10Co-4Cr硬质涂层。通过离散沉积实验获得薄层沉积粒子,探讨...为了探究高速空气燃料热喷涂(activated combustion-high velocity air fuel,AC-HVAF)过程中喷涂粒子撞击基材后的沉积特性。采用AC-HVAF热喷涂技术在AZ80镁合金基体上沉积WC-10Co-4Cr硬质涂层。通过离散沉积实验获得薄层沉积粒子,探讨各种沉积形貌的种类、形成原因、结合机制及射流中粒子的径向和轴向分布。结果表明:在AC-HVAF粒子沉积过程中,嵌入型沉积为主要的沉积形貌,同时包含少量的破碎型与空腔型沉积粒子。在涂层的形成过程中,嵌入型沉积对涂层/基体结合性能起重要作用;空腔型沉积的小颗粒及破碎型沉积的大颗粒是造成沉积效率下降的主要原因。喷涂粒子主要集中在射流中心,越靠近射流边缘,空腔型沉积粒子越多,最终导致AC-HVAF粒子射流呈现出空间分布特征。展开更多
An more reliable human upper respiratory tract model that consisted of an oropharynx and four generations of asymmetric tracheo-bronchial （TB） airways has been constructed to investigate the micro-particle depositio...An more reliable human upper respiratory tract model that consisted of an oropharynx and four generations of asymmetric tracheo-bronchial （TB） airways has been constructed to investigate the micro-particle deposition pattern and mass distribution in five lobes under steady inspiratory condition in former work by Huang and Zhang （2011 ）. In the present work, transient airflow patterns and particle deposition during both inspiratory and expiratory processes were numerically simulated in the realistic human upper respiratory tract model with 14 cartilaginous rings （CRs） in the tracheal tube. The present model was validated under steady inspiratory flow rates by comparing current results with the theoretical models and pub- lished experimental data. The transient deposition fraction was found to strongly depend on breathing flow rate and particle diameter but slightly on turbulence intensity. Particles were mainly distributed in the high axial speed zones and traveled basically following the secondary flow. ＂Hot spots＂ of deposition were found in the lower portion of mouth cavity and posterior wall of pharynx/larynx during inspiration, but transferred to upper portion of mouth and interior wall of pharynx/larynx during expiration. The deposition fraction in the trachea during expiration was found to be much higher than that during inspiration because of the stronger secondary flow.展开更多
基金sponsored by the Centre for Industrial Photonics, Institute for Manufacture, Department of Engineering, University of Cambridgethe Natural Science Foundation of China (51271170)+1 种基金China International Science and Technology Cooperation Project (2011DFR50540)Major Scientific and Technological Special Key Industrial Project of Zhejiang Province (2012C11001)
文摘Ni60-WC particles are used to improve the wear resistance of hard-facing steel due to their high hardness. An emerging technology that combines laser with cold spraying to deposit the hard-facing coatings is known as supersonic laser deposition. In this study, Ni60-WC is deposited on low-carbon steel using SLD. The microstructure and performance of the coatings are investigated through SEM, optical microscopy, EDS, XRD, microhardness and pin-on-disc wear tests. The experimental results of the coating processed with the optimal parameters are compared to those of the coating deposited using laser cladding.
基金Item Sponsored by National Natural Science Foundation of China(51271170)National International Technology Cooperation Project of China(KM JD2011010 )+1 种基金Natural Science Foundation of Zhejiang Province of China(Y4110594)Open Fund of Zhejiang Provincial Key Laboratory of Special Purpose Equipment and Advanced Manufacturing Technology of China(2011EM009 )
文摘Stellite 6 powders were deposited on low carbon steel using SLD （supersonic laser deposition） under optimized parameters. The structure, line scan of elements and porosity of coating were examined and analyzed using SEM （scanning electron microscope）, OM （optical microscope） and XRD （X-ray diffraction）. The adhesion strength between coating and substrate was tested by PAT-ADHESION/TENSILE and E900STM adhesive. The results showed the deposition characteristics of optimized coating with N2 at a pressure of 3.0 MPa, a temperature of 450 ℃ and a laser power of 1.5 kW were compared with those of Stellite 6 coating deposited by the HVOF （high velocity oxygen fuel）.
基金Item Sponsored by National Natural Science Foundation of China(51271170)Ministry of Science and Technology InternationalCooperation Projects of China(KM-JD-2011010)
文摘The supersonic laser deposition （SLD） is a new fabrication process which combines the supersonic powder stream found in cold spray with laser heating of the deposition zone. Because of the instantaneity of particles impact, the deformation behaviors and the adhesion behaviors of particles impacted on the substrate by SI.D cannot be well investigated through experiments. Therefore, a finite elemen! model was developed to solve the problems above. Meanwhile, the heat effect of the substrate heated by laser was discussed. The effective plastic strain and the effec- tive stress between the particle and substrate at different laser preheal temperatures were studied. The results show that laser depositing temperatures of 1 000 and 1 100 ℃ on substrate would be the optimized for the bonding of parti- cles and substrate. In addition, the simulation results conformed to experimental results.
文摘The ability to manufacture coatings is critical to engineering design. Many components require the application of additional layers toenhance mechanical properties and protect against hostile environments. Supersonic laser deposition (SLD) is a novel coating methodbased on cold spray (CS) principles. In this technique, the deposition velocities can be significantly lower than those required foreffective bonding in CS applications. The addition of laser heat energy permits a change in the thermodynamic experience of impactingparticles, thereby offering a greater opportunity for efficient bonding at lower velocities as compared with the CS process. The workreported in this paper demonstrates the ability of the SLD process to deliver hardfacing materials to engineering surfaces. Stellite-6 hasbeen deposited on low-carbon steel tubes over a range of process parameters to establish the appropriate target power and traversespeeds for the coating formation. The coating properties and parameters were examined to determine the primary characteristics andgrain structure size. Their morphology and performance were studied through optical microscopy, scanning electron microscope(SEM), X-ray diffraction, hardness measurements and wear testing. The results have shown that SLD is capable of depositing layers ofStellite-6, with properties that are superior to those of their conventionally manufactured counterparts.
文摘为了探究高速空气燃料热喷涂(activated combustion-high velocity air fuel,AC-HVAF)过程中喷涂粒子撞击基材后的沉积特性。采用AC-HVAF热喷涂技术在AZ80镁合金基体上沉积WC-10Co-4Cr硬质涂层。通过离散沉积实验获得薄层沉积粒子,探讨各种沉积形貌的种类、形成原因、结合机制及射流中粒子的径向和轴向分布。结果表明:在AC-HVAF粒子沉积过程中,嵌入型沉积为主要的沉积形貌,同时包含少量的破碎型与空腔型沉积粒子。在涂层的形成过程中,嵌入型沉积对涂层/基体结合性能起重要作用;空腔型沉积的小颗粒及破碎型沉积的大颗粒是造成沉积效率下降的主要原因。喷涂粒子主要集中在射流中心,越靠近射流边缘,空腔型沉积粒子越多,最终导致AC-HVAF粒子射流呈现出空间分布特征。
基金supported by the National NaturalScience Foundation of China, Project Number 10672081the Foundation of Chinese State Key Laboratory of Loess and Quater-nary Geology
文摘An more reliable human upper respiratory tract model that consisted of an oropharynx and four generations of asymmetric tracheo-bronchial （TB） airways has been constructed to investigate the micro-particle deposition pattern and mass distribution in five lobes under steady inspiratory condition in former work by Huang and Zhang （2011 ）. In the present work, transient airflow patterns and particle deposition during both inspiratory and expiratory processes were numerically simulated in the realistic human upper respiratory tract model with 14 cartilaginous rings （CRs） in the tracheal tube. The present model was validated under steady inspiratory flow rates by comparing current results with the theoretical models and pub- lished experimental data. The transient deposition fraction was found to strongly depend on breathing flow rate and particle diameter but slightly on turbulence intensity. Particles were mainly distributed in the high axial speed zones and traveled basically following the secondary flow. ＂Hot spots＂ of deposition were found in the lower portion of mouth cavity and posterior wall of pharynx/larynx during inspiration, but transferred to upper portion of mouth and interior wall of pharynx/larynx during expiration. The deposition fraction in the trachea during expiration was found to be much higher than that during inspiration because of the stronger secondary flow.
