CO2 laser is adopted on the surface of austenitic stainless steel (ICrlSNiQ) to clad nickel based nanometer WC/Co composite coating. SEM, EDAX, XRD, AFM and Scratch Testers are adopted to conduct analysis and research...CO2 laser is adopted on the surface of austenitic stainless steel (ICrlSNiQ) to clad nickel based nanometer WC/Co composite coating. SEM, EDAX, XRD, AFM and Scratch Testers are adopted to conduct analysis and research on the microstructure, composition, phase and bonding strength of the coating. Results indicate that the microstructure of coating is metallurgically bonded with stainless steel base, eliminating porosities and cracks. The coating has a considerable quantity of nanometer particles visible with a granularity ^lOOnm under a nanoscope atomic microscope. The bonding strength of the laser cladded coating is remarkably improved respectively compared with conventional hot-sprayed coating and spray welding. The nanometer effect of nanometer WC/Co introduced into the coating plays an important role in the laser cladding processes.展开更多
The microstructure, phase consistence and microhardness of thermal sprayed coatings were investigated. The tungsten and chromium carbide coatings and also composite NiCrSiB coating were analyzed. The microstructure of...The microstructure, phase consistence and microhardness of thermal sprayed coatings were investigated. The tungsten and chromium carbide coatings and also composite NiCrSiB coating were analyzed. The microstructure of coatings were observed by using optical microscopy (MO), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Almost equiaxial carbide particles settled inside the surrounded material of coating were found. The cracks propagating thorough the particles and along boundaries between the particles and surrounded material were observed. This phenomenon was connected with the porosity of coatings. The decarburization process was detected in coatings by phase composition investigation using X-ray method. The decarburization process was the reason due to which beside initial Cr3C2 the Cr7C3 and Cr23C6 particles were found. In the tungsten coatings beside the initial WC carbides the W2Cones were found.展开更多
Regulating chemical bonds to balance the adsorption and disassociation of water molecules on catalyst surfaces is crucial for overall water splitting in alkaline solution.Here we report a facile strategy for designing...Regulating chemical bonds to balance the adsorption and disassociation of water molecules on catalyst surfaces is crucial for overall water splitting in alkaline solution.Here we report a facile strategy for designing Ni2W4C-W3C Janus structures with abundant Ni-W metallic bonds on surfaces through interfacial engineering.Inserting Ni atoms into the W3C crystals in reaction progress generates a new Ni2 W4C phase,making the inert W atoms in W3C be active sites in Ni2W4C for overall water splitting.The Ni2W4CW3C/carbon nanofibers(Ni2 W4-W3C/CNFs)require overpotentials of 63 mV to reach 10 mA cm^-2 for hydrogen evolution reaction(HER)and 270 mV to reach 30 mA cm^-2 for oxygen evolution reaction(OER)in alkaline electrolyte,respectively.When utilized as both cathode and anode in alkaline solution for overall water splitting,cell voltages of 1.55 and 1.87 V are needed to reach 10 and 100 mA cm^-2,respectively.Density functional theory(DFT)results indicate that the strong interactions between Ni and W increase the local electronic states of W atoms.The Ni2W4C provides active sites for cleaving H-OH bonds,and the W3C facilitates the combination of Hads intermediates into H2 molecules.The in situ electrochemical-Raman results demonstrate that the strong absorption ability for hydroxyl and water molecules and further demonstrate that W atoms are the real active sites.展开更多
文摘CO2 laser is adopted on the surface of austenitic stainless steel (ICrlSNiQ) to clad nickel based nanometer WC/Co composite coating. SEM, EDAX, XRD, AFM and Scratch Testers are adopted to conduct analysis and research on the microstructure, composition, phase and bonding strength of the coating. Results indicate that the microstructure of coating is metallurgically bonded with stainless steel base, eliminating porosities and cracks. The coating has a considerable quantity of nanometer particles visible with a granularity ^lOOnm under a nanoscope atomic microscope. The bonding strength of the laser cladded coating is remarkably improved respectively compared with conventional hot-sprayed coating and spray welding. The nanometer effect of nanometer WC/Co introduced into the coating plays an important role in the laser cladding processes.
基金financially supported by polish project NR15 0001 06the Ministry of Higher Education and Science/AGH University of Science and Technology,Krakow,Poland,grant number 11.11.180.255 is greatly acknowledged.
文摘The microstructure, phase consistence and microhardness of thermal sprayed coatings were investigated. The tungsten and chromium carbide coatings and also composite NiCrSiB coating were analyzed. The microstructure of coatings were observed by using optical microscopy (MO), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Almost equiaxial carbide particles settled inside the surrounded material of coating were found. The cracks propagating thorough the particles and along boundaries between the particles and surrounded material were observed. This phenomenon was connected with the porosity of coatings. The decarburization process was detected in coatings by phase composition investigation using X-ray method. The decarburization process was the reason due to which beside initial Cr3C2 the Cr7C3 and Cr23C6 particles were found. In the tungsten coatings beside the initial WC carbides the W2Cones were found.
基金supported by the National Natural Science Foundation of China(51803077,51872204)the National Key Research and Development Program of China(2017YFA0204600)+4 种基金the Natural Science Foundation of Jiangsu Province(BK20180627)Postdoctoral Science Foundation of China(2018M630517,2019T120389)the Ministry of Education(MOE)and the State Administration for Foreign Expert Affairs(SAFEA),111 Project(B13025)the National First-Class Discipline Program of Light Industry Technology and Engineering(LITE2018-19)the Fundamental Research Funds for the Central Universities。
文摘Regulating chemical bonds to balance the adsorption and disassociation of water molecules on catalyst surfaces is crucial for overall water splitting in alkaline solution.Here we report a facile strategy for designing Ni2W4C-W3C Janus structures with abundant Ni-W metallic bonds on surfaces through interfacial engineering.Inserting Ni atoms into the W3C crystals in reaction progress generates a new Ni2 W4C phase,making the inert W atoms in W3C be active sites in Ni2W4C for overall water splitting.The Ni2W4CW3C/carbon nanofibers(Ni2 W4-W3C/CNFs)require overpotentials of 63 mV to reach 10 mA cm^-2 for hydrogen evolution reaction(HER)and 270 mV to reach 30 mA cm^-2 for oxygen evolution reaction(OER)in alkaline electrolyte,respectively.When utilized as both cathode and anode in alkaline solution for overall water splitting,cell voltages of 1.55 and 1.87 V are needed to reach 10 and 100 mA cm^-2,respectively.Density functional theory(DFT)results indicate that the strong interactions between Ni and W increase the local electronic states of W atoms.The Ni2W4C provides active sites for cleaving H-OH bonds,and the W3C facilitates the combination of Hads intermediates into H2 molecules.The in situ electrochemical-Raman results demonstrate that the strong absorption ability for hydroxyl and water molecules and further demonstrate that W atoms are the real active sites.
