In this research, precise motion control and synchronized high-speed microscopic dual-wavelength interferometry were employed to investigate the impact of surface-active components on the rupture behavior of wetting f...In this research, precise motion control and synchronized high-speed microscopic dual-wavelength interferometry were employed to investigate the impact of surface-active components on the rupture behavior of wetting films. The findings unveiled a novel mechanism for wetting film rupture at hydrophobic interfaces, propelled by gas migration towards the solid-liquid interface, resulting in the nucleation and growth of surface nanobubble. Salt ions accelerate film rupture by reducing electrostatic interactions and enhancing gas transfer, whereas surfactant adsorption immobilizes the gas-liquid interface through the Marangoni effect, thereby postponing rupture by impeding gas migration and surface nanobubble formation. Furthermore, surfactants influence the kinetics of three-phase contact line formation, where variations in molecular structure, solubility, and ionic properties contributing to differing levels of friction, and thereby affecting the overall dynamics of wetting films.展开更多
Stress Corrosion Cracking(SCC)process through which cracks occur in a variety of susceptible materials is a result of a combination of residual or applied stresses and corrosion.In oil and gas field,buried pipeline st...Stress Corrosion Cracking(SCC)process through which cracks occur in a variety of susceptible materials is a result of a combination of residual or applied stresses and corrosion.In oil and gas field,buried pipeline steels are made of low-alloy steels with a ferritic-pearlitic structure,such as X70.In dilute solutions,these materials are prone to SCC failure.The Near-neutral simulated soil solution(NS4)solution is established to imitate SCC conditions and subsequently became the industry requirement for crack growth experiments in the majority of laboratories.The strainassisted active crack pathways are considered while modelling SCC growth as an oxide film rupture and anodic dissolution process.It’s been hypothesized that increasing the strain concentration can help with dissolution at the filmfree crack tip.This research focuses on estimating the SCC crack growth rate under various environmental conditions in oil and gas pipelines using finite element modelling.The simulation is carried out using the J-integral theory in the COMSOL Multiphysics program.Simulations are performed to model the crack growth rate(CGR)using slip anodic dissolution(film rupture)mechanism.The plastic strain gradient is required to compute the SCC CGR(da/dt).Because the plastic strain located at crack tip increases proportionally to the crack length as it propagates,the CGR increases as the stress intensity factor(SIF)increases.The crack growth rates increase when constant loads are applied and as the temperature rises,and elevating the cathodic potential has a minimal influence on the propagation rate of cracks but raises the material yield strength and imparts brittle behavior to it.展开更多
基金funding from the Shenzhen Fundamental Research Program(grant No.20231114170652002)the Key R&D Program of Shandong Province,China(grant No.2022SFGC0304)+2 种基金the Science and Technology Plan Project of Guizhou Province,China(grant No.2023190001)The authors also acknowledge the financial supports from the Geely-SUSTech Joint Advanced Biomass Gasification Technology Development Project(grant No.K2342Z221)the Shenzhen R&D Fund(grant No.KQTD20180411143418361).
文摘In this research, precise motion control and synchronized high-speed microscopic dual-wavelength interferometry were employed to investigate the impact of surface-active components on the rupture behavior of wetting films. The findings unveiled a novel mechanism for wetting film rupture at hydrophobic interfaces, propelled by gas migration towards the solid-liquid interface, resulting in the nucleation and growth of surface nanobubble. Salt ions accelerate film rupture by reducing electrostatic interactions and enhancing gas transfer, whereas surfactant adsorption immobilizes the gas-liquid interface through the Marangoni effect, thereby postponing rupture by impeding gas migration and surface nanobubble formation. Furthermore, surfactants influence the kinetics of three-phase contact line formation, where variations in molecular structure, solubility, and ionic properties contributing to differing levels of friction, and thereby affecting the overall dynamics of wetting films.
基金This work is supported by ASPIRE Award for Research Excellence(AARE 2019)under the Advanced Technology Research Council-ASPIRE through Project Number AARE19-098.
文摘Stress Corrosion Cracking(SCC)process through which cracks occur in a variety of susceptible materials is a result of a combination of residual or applied stresses and corrosion.In oil and gas field,buried pipeline steels are made of low-alloy steels with a ferritic-pearlitic structure,such as X70.In dilute solutions,these materials are prone to SCC failure.The Near-neutral simulated soil solution(NS4)solution is established to imitate SCC conditions and subsequently became the industry requirement for crack growth experiments in the majority of laboratories.The strainassisted active crack pathways are considered while modelling SCC growth as an oxide film rupture and anodic dissolution process.It’s been hypothesized that increasing the strain concentration can help with dissolution at the filmfree crack tip.This research focuses on estimating the SCC crack growth rate under various environmental conditions in oil and gas pipelines using finite element modelling.The simulation is carried out using the J-integral theory in the COMSOL Multiphysics program.Simulations are performed to model the crack growth rate(CGR)using slip anodic dissolution(film rupture)mechanism.The plastic strain gradient is required to compute the SCC CGR(da/dt).Because the plastic strain located at crack tip increases proportionally to the crack length as it propagates,the CGR increases as the stress intensity factor(SIF)increases.The crack growth rates increase when constant loads are applied and as the temperature rises,and elevating the cathodic potential has a minimal influence on the propagation rate of cracks but raises the material yield strength and imparts brittle behavior to it.
