The impact-abrasive wear behavior of high-C martensitic steel was investigated,taking into account varying carbon(C)contents and different tempering temperatures.The evaluation was done through comprehensive microstru...The impact-abrasive wear behavior of high-C martensitic steel was investigated,taking into account varying carbon(C)contents and different tempering temperatures.The evaluation was done through comprehensive microstructural characterization,analysis of worn surface morphology,and measurement of key performance like impact toughness and surface hardening.The findings demonstrate that increasing C content and tempering temperature both has a positive effect on wear resistance,with C content exhibiting a more pronounced influence compared to the tempering temperature.The improved wear resistance of the steel with higher C content and tempering at a higher temperature can be attributed to its enhanced impact toughness.This increase in impact toughness is primarily a result of microstructural refinement and alterations in carbide morphology.Moreover,cyclic impact loading induces surface hardening due to dislocation strengthening within the martensite and the retained austenite,leading to an increase in surface hardness.The combination of surface hardening and excellent impact toughness synergistically contributes to the overall improved wear resistance observed in the experimental steel with higher C content after tempering at a higher temperature.Additionally,the dominant features observed on the worn surface are scratches and substrate delamination,indicative of a wear mechanism of the experimental steels characterized by micro-cutting/ploughing and fatigue wear.展开更多
Elemental analyzer/isotope ratio mass spectrometry(EA/TRMS) has been widely applied to analyze the^(15)N/^(14)N isotope composition(δ^(15)N) of plants and soils,but the δ^(15)N results may be inaccurate due to incom...Elemental analyzer/isotope ratio mass spectrometry(EA/TRMS) has been widely applied to analyze the^(15)N/^(14)N isotope composition(δ^(15)N) of plants and soils,but the δ^(15)N results may be inaccurate due to incomplete combustion of the high-C/N-ratio plant samples by EA.Therefore,it is necessary to develop a method to solve the problem of imperfect combustion.In this study,we used two methods:1) adding copper oxide powder to the samples,and 2) increasing the O_2 flow(from 100 mL min^(-1) to 200 mL min^(-1)) for the auto sampler inlet purge line of the EA.The δ^(15)N values of the plant samples became more positive and tended to be stable after complete combustion.Also,the required blank samples for each plant sample decreased with increasing amount of the added CuO powder.However,at 200 mL min^(-1) of the oxygen flow in the EA,complete combustion could not be achieved without adding copper oxide,but this was done with decreased amount of CuO powder.Therefore,mixing cupric oxide into the high-C/N-ratio samples was an efficient,simple and convenient way to solve the problem of imperfect combustion in the EA.展开更多
基金supported by Science and Technology Project of Guangzhou(2023A04J0297)Guangdong Basic and Applied Basic Research Foundation(2024A1515011622)+3 种基金National Natural Science Foundation of China(52301040)GDAS’Project of Science and Technology Development(2023GDASQNRC-0205 and 2022GDASZH-2022010107)Evaluation Project of Guangdong Provincial Key Laboratory(2023B1212060043)Young Elite Scientists Sponsorship Program by CAST(2022QNRC001).
文摘The impact-abrasive wear behavior of high-C martensitic steel was investigated,taking into account varying carbon(C)contents and different tempering temperatures.The evaluation was done through comprehensive microstructural characterization,analysis of worn surface morphology,and measurement of key performance like impact toughness and surface hardening.The findings demonstrate that increasing C content and tempering temperature both has a positive effect on wear resistance,with C content exhibiting a more pronounced influence compared to the tempering temperature.The improved wear resistance of the steel with higher C content and tempering at a higher temperature can be attributed to its enhanced impact toughness.This increase in impact toughness is primarily a result of microstructural refinement and alterations in carbide morphology.Moreover,cyclic impact loading induces surface hardening due to dislocation strengthening within the martensite and the retained austenite,leading to an increase in surface hardness.The combination of surface hardening and excellent impact toughness synergistically contributes to the overall improved wear resistance observed in the experimental steel with higher C content after tempering at a higher temperature.Additionally,the dominant features observed on the worn surface are scratches and substrate delamination,indicative of a wear mechanism of the experimental steels characterized by micro-cutting/ploughing and fatigue wear.
文摘Elemental analyzer/isotope ratio mass spectrometry(EA/TRMS) has been widely applied to analyze the^(15)N/^(14)N isotope composition(δ^(15)N) of plants and soils,but the δ^(15)N results may be inaccurate due to incomplete combustion of the high-C/N-ratio plant samples by EA.Therefore,it is necessary to develop a method to solve the problem of imperfect combustion.In this study,we used two methods:1) adding copper oxide powder to the samples,and 2) increasing the O_2 flow(from 100 mL min^(-1) to 200 mL min^(-1)) for the auto sampler inlet purge line of the EA.The δ^(15)N values of the plant samples became more positive and tended to be stable after complete combustion.Also,the required blank samples for each plant sample decreased with increasing amount of the added CuO powder.However,at 200 mL min^(-1) of the oxygen flow in the EA,complete combustion could not be achieved without adding copper oxide,but this was done with decreased amount of CuO powder.Therefore,mixing cupric oxide into the high-C/N-ratio samples was an efficient,simple and convenient way to solve the problem of imperfect combustion in the EA.
