A multilayer tungsten carbide particle（WCp）-reinforced Ni-based alloy coating was fabricated on a steel substrate using vacuum cladding technology.The morphology,microstructure,and formation mechanism of the coating...A multilayer tungsten carbide particle（WCp）-reinforced Ni-based alloy coating was fabricated on a steel substrate using vacuum cladding technology.The morphology,microstructure,and formation mechanism of the coating were studied and discussed in different zones.The microstructure morphology and phase composition were investigated by scanning electron microscopy,optical microscopy,X-ray diffraction,and energy-dispersive X-ray spectroscopy.In the results,the coating presents a dense and homogeneous microstructure with few pores and is free from cracks.The whole coating shows a multilayer structure,including composite,transition,fusion,and diffusion-affected layers.Metallurgical bonding was achieved between the coating and substrate because of the formation of the fusion and diffusion-affected layers.The Ni-based alloy is mainly composed of y-Ni solid solution with finely dispersed Cr7C3/Cr（23）C6,CrB,and Ni＋Ni3Si.WC particles in the composite layer distribute evenly in areas among initial Ni-based alloying particles,forming a special three-dimensional reticular microstructure.The macrohardness of the coating is HRC 55,which is remarkably improved compared to that of the substrate.The microhardness increases gradually from the substrate to the composite zone,whereas the microhardness remains almost unchanged in the transition and composite zones.展开更多
Ni-W-P composite coatings reinforced by Ce O2 and Si O2 nano-particles on the surface of common carbon steels, were prepared by double pulse electrodeposition. The crystallization course was characterized by phase str...Ni-W-P composite coatings reinforced by Ce O2 and Si O2 nano-particles on the surface of common carbon steels, were prepared by double pulse electrodeposition. The crystallization course was characterized by phase structures, crystallinity, grain sizes and microstructures. The results indicate that as-deposited composite coating is amorphous. Whereas it turns into the crystalline structure with 98.25% crystallinity, and Ni3 P, Ni2 P and Ni5P2 alloy phases precipitate from structures at 400 °C. Thereafter, Ni2 P and Ni5P2 metastable alloy phases turn into Ni3 P stable alloy phase at 500 °C. The crystallization course of the composite coating has finished when being heat-treated at 700 °C. The average sizes of Ni grains increase with the rise of heat treatment temperature from400 °C to 700 °C. Ce O2 and Si O2 nano-particles deposited into Ni-W-P alloys can delay the crystallization course and habit the growth of alloy phases.展开更多
[ Objective] This study is to provide basis for the genetic improvement of triploid watermelon cultivars from seed coat characteristiscs by analyzing its genetic properties. [ Method ] Genetic effects of seed coat cha...[ Objective] This study is to provide basis for the genetic improvement of triploid watermelon cultivars from seed coat characteristiscs by analyzing its genetic properties. [ Method ] Genetic effects of seed coat characteristics and their related characteristics in tdploid watermelon were analyzed by additive dominant genetic model based on 36 F1 hybrids which were crossed by six female parents of four ecotypes and six male parents of same ecotype according to North Carolina II crossing design. [ Result] The seed coat number characteristics was controlled by additive effects, dominant effects and error variance of genetic together. The additive effects of the length and width of abortive seed coat were significant, and the error variance was significant or highly significant. It was observed that there was a significant negative correlation of additive effects between the seed coat number and fringe soluble sugar. Also there was a significant negative correlation of dominant effects between lycopenes, dry matter and the seed coat number. However, there was a highly significant positive correlation in additive effects between the length and width of abortive seed coat. [ Conclusion ] The results provide guidance for genetic breeding of triploid watermelon cultivars.展开更多
A particle sub-model describing the bed characteristics of a bubbling fluidised bed is presented. Atomisation air, applied at high pressures via a nozzle positioned above the bed for spray formation, is incorporated i...A particle sub-model describing the bed characteristics of a bubbling fluidised bed is presented. Atomisation air, applied at high pressures via a nozzle positioned above the bed for spray formation, is incorporated in the model since its presence has a profound influence on the bed characteristics, though the spray itself is not yet considered. A particle sub-model is developed using well-known empirical relations for particle drag force, bubble growth and velocity and particle distribution above the fluidised-bed surface. Simple but effective assumptions and abstractions were made concerning bubble distribution, particle ejection at the bed surface and the behaviour of atomisation air flow upon impacting the surface of a bubbling fluidised bed, The model was shown to be capable of predicting the fluidised bed characteristics in terms of bed heights, voidage distributions and solids volume fractions with good accuracy in less than 5 min of calculation time on a regular desktop PC. It is therefore suitable for incorporation into general process control models aimed at dynamic control for process efficiency and product quality in top-spray fluidised bed coating processes.展开更多
The propagation characteristics of laser-generated like-Rayleigh waves in viscoelastic adhesive coating/substrate structures were studied.Considering the viscoelasticity of the coating and substrate,we have establishe...The propagation characteristics of laser-generated like-Rayleigh waves in viscoelastic adhesive coating/substrate structures were studied.Considering the viscoelasticity of the coating and substrate,we have established the finite element models in frequency domain for the laser-generated like-Rayleigh waves in the epoxy coating/aluminum substrate,epoxy coating/brass substrate,and epoxy coating/foam substrate structures,respectively.In addition,we have investigated the waveform and propagation characteristics of the like-Rayleigh waves and studied the influences of the coating transparency,coating thickness,coating viscoelasticity,and substrate viscoelasticity on the propagation characteristics of the like-Rayleigh waves.Moreover,we have verified the results by the theoretical phase velocity and attenuation curves.The results show that the coating viscoelasticity induces the attenuation characteristics of the higher frequencies of the like-Rayleigh waves,but has little effect on the lower frequencies,and the substrate viscoelasticity has the influences on both the higher and lower frequencies of the like-Rayleigh waves,especially the lower frequencies.Furthermore,the mode and dispersive characteristics of the like-Rayleigh waves are closely related to the substrates.This study provides a useful theoretical basis for inverting mechanical parameters and evaluating the adhesive quality of the viscoelastic adhesive coating/substrate structures.展开更多
基金supported by the National Natural Science Foundation of China(No.51205178)the Natural Science Foundation of Gansu Province,China(No.1208RJZA189)the Doctor Fund Project of Lanzhou University of Technology
文摘A multilayer tungsten carbide particle（WCp）-reinforced Ni-based alloy coating was fabricated on a steel substrate using vacuum cladding technology.The morphology,microstructure,and formation mechanism of the coating were studied and discussed in different zones.The microstructure morphology and phase composition were investigated by scanning electron microscopy,optical microscopy,X-ray diffraction,and energy-dispersive X-ray spectroscopy.In the results,the coating presents a dense and homogeneous microstructure with few pores and is free from cracks.The whole coating shows a multilayer structure,including composite,transition,fusion,and diffusion-affected layers.Metallurgical bonding was achieved between the coating and substrate because of the formation of the fusion and diffusion-affected layers.The Ni-based alloy is mainly composed of y-Ni solid solution with finely dispersed Cr7C3/Cr（23）C6,CrB,and Ni＋Ni3Si.WC particles in the composite layer distribute evenly in areas among initial Ni-based alloying particles,forming a special three-dimensional reticular microstructure.The macrohardness of the coating is HRC 55,which is remarkably improved compared to that of the substrate.The microhardness increases gradually from the substrate to the composite zone,whereas the microhardness remains almost unchanged in the transition and composite zones.
基金Project(20806035)supported by the National Natural Science Foundation of ChinaProject(2009CI026)supported by the Back-up Personnel Foundation of Academic and Technology Leaders of Yunnan Province,ChinaProject(KKZ6200927001)supported by the Opening Fund of Key Laboratory of Inorganic Coating Materials,Chinese Academy of Sciences
文摘Ni-W-P composite coatings reinforced by Ce O2 and Si O2 nano-particles on the surface of common carbon steels, were prepared by double pulse electrodeposition. The crystallization course was characterized by phase structures, crystallinity, grain sizes and microstructures. The results indicate that as-deposited composite coating is amorphous. Whereas it turns into the crystalline structure with 98.25% crystallinity, and Ni3 P, Ni2 P and Ni5P2 alloy phases precipitate from structures at 400 °C. Thereafter, Ni2 P and Ni5P2 metastable alloy phases turn into Ni3 P stable alloy phase at 500 °C. The crystallization course of the composite coating has finished when being heat-treated at 700 °C. The average sizes of Ni grains increase with the rise of heat treatment temperature from400 °C to 700 °C. Ce O2 and Si O2 nano-particles deposited into Ni-W-P alloys can delay the crystallization course and habit the growth of alloy phases.
文摘[ Objective] This study is to provide basis for the genetic improvement of triploid watermelon cultivars from seed coat characteristiscs by analyzing its genetic properties. [ Method ] Genetic effects of seed coat characteristics and their related characteristics in tdploid watermelon were analyzed by additive dominant genetic model based on 36 F1 hybrids which were crossed by six female parents of four ecotypes and six male parents of same ecotype according to North Carolina II crossing design. [ Result] The seed coat number characteristics was controlled by additive effects, dominant effects and error variance of genetic together. The additive effects of the length and width of abortive seed coat were significant, and the error variance was significant or highly significant. It was observed that there was a significant negative correlation of additive effects between the seed coat number and fringe soluble sugar. Also there was a significant negative correlation of dominant effects between lycopenes, dry matter and the seed coat number. However, there was a highly significant positive correlation in additive effects between the length and width of abortive seed coat. [ Conclusion ] The results provide guidance for genetic breeding of triploid watermelon cultivars.
基金the financial support of the Special Research Fund (BOF) of the Ghent University
文摘A particle sub-model describing the bed characteristics of a bubbling fluidised bed is presented. Atomisation air, applied at high pressures via a nozzle positioned above the bed for spray formation, is incorporated in the model since its presence has a profound influence on the bed characteristics, though the spray itself is not yet considered. A particle sub-model is developed using well-known empirical relations for particle drag force, bubble growth and velocity and particle distribution above the fluidised-bed surface. Simple but effective assumptions and abstractions were made concerning bubble distribution, particle ejection at the bed surface and the behaviour of atomisation air flow upon impacting the surface of a bubbling fluidised bed, The model was shown to be capable of predicting the fluidised bed characteristics in terms of bed heights, voidage distributions and solids volume fractions with good accuracy in less than 5 min of calculation time on a regular desktop PC. It is therefore suitable for incorporation into general process control models aimed at dynamic control for process efficiency and product quality in top-spray fluidised bed coating processes.
基金supported by National Basic Research Program of China(2012CB921504)Major Program of National Natural Science Foundation of China(51239005)+4 种基金National Natural Science Foundation of China(11404147,11174142)Natural Science Foundation of Jiangsu Province(BK20140519)China Postdoctoral Science Foundation(2015M571672)Research Fund for Advanced Talents of Jiangsu University(11JDG118)Training Project of Young Backbone Teachers of Jiangsu University
文摘The propagation characteristics of laser-generated like-Rayleigh waves in viscoelastic adhesive coating/substrate structures were studied.Considering the viscoelasticity of the coating and substrate,we have established the finite element models in frequency domain for the laser-generated like-Rayleigh waves in the epoxy coating/aluminum substrate,epoxy coating/brass substrate,and epoxy coating/foam substrate structures,respectively.In addition,we have investigated the waveform and propagation characteristics of the like-Rayleigh waves and studied the influences of the coating transparency,coating thickness,coating viscoelasticity,and substrate viscoelasticity on the propagation characteristics of the like-Rayleigh waves.Moreover,we have verified the results by the theoretical phase velocity and attenuation curves.The results show that the coating viscoelasticity induces the attenuation characteristics of the higher frequencies of the like-Rayleigh waves,but has little effect on the lower frequencies,and the substrate viscoelasticity has the influences on both the higher and lower frequencies of the like-Rayleigh waves,especially the lower frequencies.Furthermore,the mode and dispersive characteristics of the like-Rayleigh waves are closely related to the substrates.This study provides a useful theoretical basis for inverting mechanical parameters and evaluating the adhesive quality of the viscoelastic adhesive coating/substrate structures.
