Accurately characterizing the wettability of solid surfaces is essential for various applications.Numerous factors,such as operating conditions and the features of the sample surface,affect wettability.In subsurface a...Accurately characterizing the wettability of solid surfaces is essential for various applications.Numerous factors,such as operating conditions and the features of the sample surface,affect wettability.In subsurface applications,precise wettability characterization of rock/fluid systems is particularly important because it determines fluid distribution and multiphase flow within porous media.Despite operating under similar conditions,significant variations are observed in the reported wettability of specific rock/fluid systems.Factors contributing to these inconsistencies include surface roughness and surface cleavage,which are often overlooked in contact angle measurements.Therefore,this study examines the impact of surface roughness and cleavage planes on freshly cleaved surfaces in comparison to surfaces exposed to the atmosphere.Pure calcite and clean quartz surfaces were selected in this study.For the surface cleavage effect,both macro and micro contact angles have been utilized,coupled with advanced image analysis to visualize the wettability changes as a function of scale.Furthermore,Fourier Transform Infrared(FTIR)spectroscopy is utilized to determine surface functional groups responsible for wettability variation due to atmospheric contaminants.Findings suggest that freshly cleaved surfaces exhibit greater hydrophilicity than their exposed counterparts,underscoring the necessity for caution when dealing with calcite and quartz due to the pivotal role of exposure time in determining wettability.Surface roughness measurements have been conducted to examine the impact of exposure time on surface topography and the results confirm that the change in surface roughness was negligible.The findings from this study enhance comprehension of the mechanisms at thenano-to milli-metre scale responsible for wettability variations.Also,a scientific understanding of the mechanisms responsible for wetting characteristics is established,which can be beneficial in addressing the discrepancies in the observed wetting behaviour.展开更多
铜钨材料(copper tungsten material,CuW)是高压断路器应用最广泛的电触头材料,触头烧蚀性能直接影响高压断路器的使用寿命和电网安全。该文以不同W含量(70%、75%、80%、85%)的Gr(石墨烯)CuW触头为研究对象,安装于40.5 k V断路器,进行20...铜钨材料(copper tungsten material,CuW)是高压断路器应用最广泛的电触头材料,触头烧蚀性能直接影响高压断路器的使用寿命和电网安全。该文以不同W含量(70%、75%、80%、85%)的Gr(石墨烯)CuW触头为研究对象,安装于40.5 k V断路器,进行20次23 k A实验电流的电弧烧蚀实验。研究实验后触头质量、长度、接触电阻、表面宏观及截面微观烧蚀形貌变化,对比分析不同W含量的GrCuW触头耐烧蚀性能。结果表明,GrCuW中W含量为70%~80%时,W含量增加,弧触头烧蚀表面趋于平整,接触电阻下降,耐烧蚀性能提高。GrCuW80中80%的W和20%的GrCu平衡了触头的硬度、韧性及导电性能,使触头耐烧蚀性能最好。当W含量大于80%时,触头表面重熔W层增厚,烧蚀表面呈片状剥落,接触电阻增大,触头耐烧蚀性能下降。因此,GrCuW触头材料Cu与W的比例优化对CuW触头产品研发具有一定指导意义。展开更多
文摘Accurately characterizing the wettability of solid surfaces is essential for various applications.Numerous factors,such as operating conditions and the features of the sample surface,affect wettability.In subsurface applications,precise wettability characterization of rock/fluid systems is particularly important because it determines fluid distribution and multiphase flow within porous media.Despite operating under similar conditions,significant variations are observed in the reported wettability of specific rock/fluid systems.Factors contributing to these inconsistencies include surface roughness and surface cleavage,which are often overlooked in contact angle measurements.Therefore,this study examines the impact of surface roughness and cleavage planes on freshly cleaved surfaces in comparison to surfaces exposed to the atmosphere.Pure calcite and clean quartz surfaces were selected in this study.For the surface cleavage effect,both macro and micro contact angles have been utilized,coupled with advanced image analysis to visualize the wettability changes as a function of scale.Furthermore,Fourier Transform Infrared(FTIR)spectroscopy is utilized to determine surface functional groups responsible for wettability variation due to atmospheric contaminants.Findings suggest that freshly cleaved surfaces exhibit greater hydrophilicity than their exposed counterparts,underscoring the necessity for caution when dealing with calcite and quartz due to the pivotal role of exposure time in determining wettability.Surface roughness measurements have been conducted to examine the impact of exposure time on surface topography and the results confirm that the change in surface roughness was negligible.The findings from this study enhance comprehension of the mechanisms at thenano-to milli-metre scale responsible for wettability variations.Also,a scientific understanding of the mechanisms responsible for wetting characteristics is established,which can be beneficial in addressing the discrepancies in the observed wetting behaviour.
文摘铜钨材料(copper tungsten material,CuW)是高压断路器应用最广泛的电触头材料,触头烧蚀性能直接影响高压断路器的使用寿命和电网安全。该文以不同W含量(70%、75%、80%、85%)的Gr(石墨烯)CuW触头为研究对象,安装于40.5 k V断路器,进行20次23 k A实验电流的电弧烧蚀实验。研究实验后触头质量、长度、接触电阻、表面宏观及截面微观烧蚀形貌变化,对比分析不同W含量的GrCuW触头耐烧蚀性能。结果表明,GrCuW中W含量为70%~80%时,W含量增加,弧触头烧蚀表面趋于平整,接触电阻下降,耐烧蚀性能提高。GrCuW80中80%的W和20%的GrCu平衡了触头的硬度、韧性及导电性能,使触头耐烧蚀性能最好。当W含量大于80%时,触头表面重熔W层增厚,烧蚀表面呈片状剥落,接触电阻增大,触头耐烧蚀性能下降。因此,GrCuW触头材料Cu与W的比例优化对CuW触头产品研发具有一定指导意义。
文摘【目的】以某重卡10挡变速器为研究对象,针对其在6挡、7挡、8挡急加速工况下存在的啸叫问题进行分析解决。【方法】采用阶次跟踪法确定变速器啸叫源,通过计算机辅助工程技术(Computer Aided Engineering,CAE)对齿轮进行优化;通过整车噪声、振动与声振粗糙度(Noise,Vibration and Harshness,NVH)测试性能对优化方案进行验证。【结果】分析发现,通过调整齿轮阶次、提高齿轮重合度、对齿轮进行微观修形等方法,可以有效解决重卡变速器的啸叫问题。
