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
Diamond has poor interface tolerance with Al.To enhance interface bonding,in this study,tungsten carbide(WC)nanocoatings on the surface of diamond particles were prepared using sol–gel and in-situ reaction methods.WO...Diamond has poor interface tolerance with Al.To enhance interface bonding,in this study,tungsten carbide(WC)nanocoatings on the surface of diamond particles were prepared using sol–gel and in-situ reaction methods.WO_(3) sol–gel with two concentrations,0.2 mol/L,and 0.5 mol/L,was,respectively,coated on diamond particles,then sintered at 1250℃for 2 h to produce WC nanocoatings.The concentration of 0.2 mol/L WO_(3) sol–gel was not enough to cover the surface of the diamond completely,while 0.5 mol/L WO_(3) sol–gel could fully cover it.Moreover,WO_(3) was preferentially deposited on{100}planes of the diamond.WO_(3) converted to WC in-situ nanocoatings after sintering due to the in-situ reaction of WO_(3) and diamond.The diamond-reinforced Al composites with and without WC coating were fabricated by powder metallurgy.The diamond/Al composite without coating has a thermal conductivity of 584.7 W/mK,while the composite with a coating formed by 0.2 mol/L and 0.5 mol/L WO_(3) sol–gel showed thermal conductivities of 626.1 W/mK and 584.2 W/mK,respectively.The moderate thickness of nanocoatings formed by 0.2 mol/L WO_(3) sol–gel could enhance interface bonding,therefore improving thermal conductivity.The nanocoating produced by 0.5 mol/L WO_(3) sol–gel cracked during the fabrication of the composite,leading to Al12W formation and a decrease in thermal conductivity.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supported by the National Natural Science Foundation of China(No.51931009)the Liaoning Revitalization Talents Program(No.XLYC2007009).
文摘Diamond has poor interface tolerance with Al.To enhance interface bonding,in this study,tungsten carbide(WC)nanocoatings on the surface of diamond particles were prepared using sol–gel and in-situ reaction methods.WO_(3) sol–gel with two concentrations,0.2 mol/L,and 0.5 mol/L,was,respectively,coated on diamond particles,then sintered at 1250℃for 2 h to produce WC nanocoatings.The concentration of 0.2 mol/L WO_(3) sol–gel was not enough to cover the surface of the diamond completely,while 0.5 mol/L WO_(3) sol–gel could fully cover it.Moreover,WO_(3) was preferentially deposited on{100}planes of the diamond.WO_(3) converted to WC in-situ nanocoatings after sintering due to the in-situ reaction of WO_(3) and diamond.The diamond-reinforced Al composites with and without WC coating were fabricated by powder metallurgy.The diamond/Al composite without coating has a thermal conductivity of 584.7 W/mK,while the composite with a coating formed by 0.2 mol/L and 0.5 mol/L WO_(3) sol–gel showed thermal conductivities of 626.1 W/mK and 584.2 W/mK,respectively.The moderate thickness of nanocoatings formed by 0.2 mol/L WO_(3) sol–gel could enhance interface bonding,therefore improving thermal conductivity.The nanocoating produced by 0.5 mol/L WO_(3) sol–gel cracked during the fabrication of the composite,leading to Al12W formation and a decrease in thermal conductivity.
