为了进一步提高超细粉末WC喷涂层的性能,以5~15μm的超细WC-10Co-4Cr粉末为材料,分别采用低温超音速火焰喷涂(LT-HVOF)和超音速火焰喷涂(HVOF)技术在316L不锈钢表面制备WC涂层。通过聚焦离子束(Focused ion beam,FIB)对WC-10Co-4Cr粒子...为了进一步提高超细粉末WC喷涂层的性能,以5~15μm的超细WC-10Co-4Cr粉末为材料,分别采用低温超音速火焰喷涂(LT-HVOF)和超音速火焰喷涂(HVOF)技术在316L不锈钢表面制备WC涂层。通过聚焦离子束(Focused ion beam,FIB)对WC-10Co-4Cr粒子剖面形貌进行了原位切割并分析,利用SEM形貌、EDS谱和摩擦磨损试验对涂层的显微结构和干摩擦磨损性能进行了表征。结果表明:HVOF的高焰流温度使超细WC-10Co-4Cr粉末的粘结相充分熔融,WC硬质相溶于粘结相或发生脱碳,形成Cox(WC)y脆性相和W2C相,另外因Cr较低的表面张力使涂层内界面存在富Cr带,而LT-HVOF涂层没有富Cr带;LT-HVOF涂层的摩擦系数和磨损率分别为0.632 2,1.560×10-5mm3/(N·m),均低于HVOF涂层;2种WC涂层的磨损形式均以磨粒磨损为主,HVOF涂层中的富Cr带在载荷作用下形成裂纹并易于沿其扩展,造成涂层较大块剥落,降低了WC涂层的耐磨性能。展开更多
Titanium dioxide(TiO_(2))was elaborated by four different thermal spray techniques-(i)plasma spraying using a water-stabilized torch,(ii)plasma spraying using a gas-stabilized torch,(iii)high velocity oxy-fuel gun,and...Titanium dioxide(TiO_(2))was elaborated by four different thermal spray techniques-(i)plasma spraying using a water-stabilized torch,(ii)plasma spraying using a gas-stabilized torch,(iii)high velocity oxy-fuel gun,and(iv)oxy-acetylene flame.The porosity of the coatings was studied by optical microscopy,nano-structural features by scanning electron microscopy(SEM),phase composition by X-ray diffraction(XRD);the microhardness,surface roughness and wear resistance were evaluated.The diffuse reflectance was measured by ultra-violet/visible/near-infrared(UV/Vis/NIR)scanning spectrophotometer.The kinetics of photocatalytic degradation of gaseous acetone was measured under a UV lamp with 365 nm wavelength.After all the applied spray processes,the transformation of anatase phase from the initial powders to rutile phase in the coatings occurred.In spite of this transformation,all the coatings exhibited certain photocatalytic activity,which correlated well with their band gap energy calculated from reflectivity.All the coatings offer relatively good mechanical properties and can serve as robust photocatalysts.展开更多
文摘为了进一步提高超细粉末WC喷涂层的性能,以5~15μm的超细WC-10Co-4Cr粉末为材料,分别采用低温超音速火焰喷涂(LT-HVOF)和超音速火焰喷涂(HVOF)技术在316L不锈钢表面制备WC涂层。通过聚焦离子束(Focused ion beam,FIB)对WC-10Co-4Cr粒子剖面形貌进行了原位切割并分析,利用SEM形貌、EDS谱和摩擦磨损试验对涂层的显微结构和干摩擦磨损性能进行了表征。结果表明:HVOF的高焰流温度使超细WC-10Co-4Cr粉末的粘结相充分熔融,WC硬质相溶于粘结相或发生脱碳,形成Cox(WC)y脆性相和W2C相,另外因Cr较低的表面张力使涂层内界面存在富Cr带,而LT-HVOF涂层没有富Cr带;LT-HVOF涂层的摩擦系数和磨损率分别为0.632 2,1.560×10-5mm3/(N·m),均低于HVOF涂层;2种WC涂层的磨损形式均以磨粒磨损为主,HVOF涂层中的富Cr带在载荷作用下形成裂纹并易于沿其扩展,造成涂层较大块剥落,降低了WC涂层的耐磨性能。
基金This work was supported by the Czech Science Foundation under Project P108/12/1872.
文摘Titanium dioxide(TiO_(2))was elaborated by four different thermal spray techniques-(i)plasma spraying using a water-stabilized torch,(ii)plasma spraying using a gas-stabilized torch,(iii)high velocity oxy-fuel gun,and(iv)oxy-acetylene flame.The porosity of the coatings was studied by optical microscopy,nano-structural features by scanning electron microscopy(SEM),phase composition by X-ray diffraction(XRD);the microhardness,surface roughness and wear resistance were evaluated.The diffuse reflectance was measured by ultra-violet/visible/near-infrared(UV/Vis/NIR)scanning spectrophotometer.The kinetics of photocatalytic degradation of gaseous acetone was measured under a UV lamp with 365 nm wavelength.After all the applied spray processes,the transformation of anatase phase from the initial powders to rutile phase in the coatings occurred.In spite of this transformation,all the coatings exhibited certain photocatalytic activity,which correlated well with their band gap energy calculated from reflectivity.All the coatings offer relatively good mechanical properties and can serve as robust photocatalysts.
