The mechanism of SC-CO_(2)-brine-rock interaction(SCBRI) and its effect on the mechanical properties of shale are crucial for shale oil development and CO_(2)sequestration. To clarify the influence of SCBRI on the mic...The mechanism of SC-CO_(2)-brine-rock interaction(SCBRI) and its effect on the mechanical properties of shale are crucial for shale oil development and CO_(2)sequestration. To clarify the influence of SCBRI on the micromechanics of shale, the lamina and matrix of shale were saturated with SC-CO_(2)-brine for 2, 4, 6,and 8 days, respectively. The micro-scratch technique was then used to measure the localized fracture toughness before and after SC-CO_(2)-brine saturation. Combining the micro-scratch results with SEM-QEMSCAN-EDS analysis, the differences in mineral composition and mechanical properties of lamina(primarily composed of carbonate minerals) and matrix(primarily composed of clay minerals) were studied. The QEMSCAN analysis and micro-scratch results indicate distinct mineralogical compositions and mechanical properties between the lamina and the matrix. The results showed that:(1) SCBRI leads to the decrease in carbonate mineral content and the significant increase in matrix porosity and laminar cracks. In addition, the damage degree increased at saturation for 6 days.(2) SCBRI weakens the mechanical properties of shale. The scratch depth of laminar and matrix increased by 34.38% and 1.02%, and the fracture toughness decreased by 34.38% and 13.11%. It showed a trend of first increasing and then decreasing.(3) SCBRI enhances the plastic deformation behavior of shale, and the plastic index of lamina and matrix increases by 18.75% and 21.58%, respectively. These results are of great significance for evaluating the mechanical properties of shale oil and gas extraction by CO_(2).展开更多
The WC particle-reinforced copper matrix composites with WC content in the range of 5 vol%-30 vol%were prepared and investigated by micro-scratch tests under the loads of 1-4 N.The influences of normal load and WC con...The WC particle-reinforced copper matrix composites with WC content in the range of 5 vol%-30 vol%were prepared and investigated by micro-scratch tests under the loads of 1-4 N.The influences of normal load and WC content on friction coefficient and wear volume of the composites were studied.The hardness and scratch resistance of the composites are greatly improved by the addition of WC.The penetrate depth and residual depth increase near-linearly with normal load increasing and decrease with WC content increasing,and the friction coefficient of the composites also shows the same variation trend.The valid material removal mechanism is found to transform from micro-plowing to micro-cutting as the normal load increases.展开更多
The interface adhesion strength(or interface toughness)of a thin film/substrate system is often assessed by the micro-scratch test.For a brittle film material,the interface adhesion strength is easily obtained through...The interface adhesion strength(or interface toughness)of a thin film/substrate system is often assessed by the micro-scratch test.For a brittle film material,the interface adhesion strength is easily obtained through measuring the scratch driving forces.However,to measure the interface adhesion strength(or in- terface toughness)for a metal thin film material(the ductile material)by the micro- scratch test is very difficult,because intense plastic deformation is involved and the problem is a three-dimensional elastic-plastic one.In the present research,using a double-cohesive zone model,the failure characteristics of the thin film/substrate system can be described and further simulated.For a steady-state scratching pro- cess,a three-dimensional elastic-plastic finite element method based on the double cohesive zone model is developed and adopted,and the steady-state fracture work of the total system is calculated.The parameter relations between the horizontal driving forces(or energy release rate of the scratching process)and the separation strength of thin film/substrate interface,and the material shear strength,as well as the material parameters are developed.Furthermore,a scratch experiment for the Al/Si film/substrate system is carried out and the failure mechanisms are explored. Finally,the prediction results are applied to a scratch experiment for the Pt/NiO material system given in the literature.展开更多
Dry wear behavior of the rheo-casting Al-16Si-4Cu-0.5Mg alloy was investigated by micro-scratch and dry sliding weartests. Analyses of the microstructure, scratch grooves, wear tracks, worn surfaces and wear debris of...Dry wear behavior of the rheo-casting Al-16Si-4Cu-0.5Mg alloy was investigated by micro-scratch and dry sliding weartests. Analyses of the microstructure, scratch grooves, wear tracks, worn surfaces and wear debris of the alloy were carried out byoptical microscope and scanning electron microscope. The microstructural analysis showed that via rheo-processing, the primary Siwas refined and rounded, eutectics dispersed more homogenously, and even the skeleton AlFeMnSi phase was fragmented into facetshape. Micro-scratch test showed that the microstructural refinement resulted in better wear resistance. Dry sliding wear test revealedthat the rheo-processed sample exhibit obviously superior wear resistance because of the microstructure improvement. The dominantmechanism in mild wear condition is abrasion, but it turned to adhesion and oxidation in high applied load and fast sliding velocityconditions.展开更多
基金supported by the National Natural Science Foundation of China (52374014)the Fundamental Research Funds for the Central Universities (2024ZKPYSB03)。
文摘The mechanism of SC-CO_(2)-brine-rock interaction(SCBRI) and its effect on the mechanical properties of shale are crucial for shale oil development and CO_(2)sequestration. To clarify the influence of SCBRI on the micromechanics of shale, the lamina and matrix of shale were saturated with SC-CO_(2)-brine for 2, 4, 6,and 8 days, respectively. The micro-scratch technique was then used to measure the localized fracture toughness before and after SC-CO_(2)-brine saturation. Combining the micro-scratch results with SEM-QEMSCAN-EDS analysis, the differences in mineral composition and mechanical properties of lamina(primarily composed of carbonate minerals) and matrix(primarily composed of clay minerals) were studied. The QEMSCAN analysis and micro-scratch results indicate distinct mineralogical compositions and mechanical properties between the lamina and the matrix. The results showed that:(1) SCBRI leads to the decrease in carbonate mineral content and the significant increase in matrix porosity and laminar cracks. In addition, the damage degree increased at saturation for 6 days.(2) SCBRI weakens the mechanical properties of shale. The scratch depth of laminar and matrix increased by 34.38% and 1.02%, and the fracture toughness decreased by 34.38% and 13.11%. It showed a trend of first increasing and then decreasing.(3) SCBRI enhances the plastic deformation behavior of shale, and the plastic index of lamina and matrix increases by 18.75% and 21.58%, respectively. These results are of great significance for evaluating the mechanical properties of shale oil and gas extraction by CO_(2).
基金financially supported by the National Natural Science Foundation of China (Nos. 21175157 and 21375151)
文摘The WC particle-reinforced copper matrix composites with WC content in the range of 5 vol%-30 vol%were prepared and investigated by micro-scratch tests under the loads of 1-4 N.The influences of normal load and WC content on friction coefficient and wear volume of the composites were studied.The hardness and scratch resistance of the composites are greatly improved by the addition of WC.The penetrate depth and residual depth increase near-linearly with normal load increasing and decrease with WC content increasing,and the friction coefficient of the composites also shows the same variation trend.The valid material removal mechanism is found to transform from micro-plowing to micro-cutting as the normal load increases.
基金The project supported by the National Natural Science Foundation of China (19891180 and 19925211)Bai Ren Plan of CAS
文摘The interface adhesion strength(or interface toughness)of a thin film/substrate system is often assessed by the micro-scratch test.For a brittle film material,the interface adhesion strength is easily obtained through measuring the scratch driving forces.However,to measure the interface adhesion strength(or in- terface toughness)for a metal thin film material(the ductile material)by the micro- scratch test is very difficult,because intense plastic deformation is involved and the problem is a three-dimensional elastic-plastic one.In the present research,using a double-cohesive zone model,the failure characteristics of the thin film/substrate system can be described and further simulated.For a steady-state scratching pro- cess,a three-dimensional elastic-plastic finite element method based on the double cohesive zone model is developed and adopted,and the steady-state fracture work of the total system is calculated.The parameter relations between the horizontal driving forces(or energy release rate of the scratching process)and the separation strength of thin film/substrate interface,and the material shear strength,as well as the material parameters are developed.Furthermore,a scratch experiment for the Al/Si film/substrate system is carried out and the failure mechanisms are explored. Finally,the prediction results are applied to a scratch experiment for the Pt/NiO material system given in the literature.
基金Project(2021JJ30577) supported by Hunan Provincial Natural Science Foundation of ChinaProject(X202110555425) supported by College Students Innovation and Entrepreneurship Training Program of University of South China。
基金Project(51404153)supported by the National Natural Science Foundation of ChinaProject supported by the Joint Ph D Program of the China Scholarship Council(CSC)
文摘Dry wear behavior of the rheo-casting Al-16Si-4Cu-0.5Mg alloy was investigated by micro-scratch and dry sliding weartests. Analyses of the microstructure, scratch grooves, wear tracks, worn surfaces and wear debris of the alloy were carried out byoptical microscope and scanning electron microscope. The microstructural analysis showed that via rheo-processing, the primary Siwas refined and rounded, eutectics dispersed more homogenously, and even the skeleton AlFeMnSi phase was fragmented into facetshape. Micro-scratch test showed that the microstructural refinement resulted in better wear resistance. Dry sliding wear test revealedthat the rheo-processed sample exhibit obviously superior wear resistance because of the microstructure improvement. The dominantmechanism in mild wear condition is abrasion, but it turned to adhesion and oxidation in high applied load and fast sliding velocityconditions.
