Tungsten(W)particle-reinforced nickel(Ni)-based composites were fabricated via laser-direct energy de-position(L-DED).The influence of the W particle size on the microstructure and mechanical properties of the deposit...Tungsten(W)particle-reinforced nickel(Ni)-based composites were fabricated via laser-direct energy de-position(L-DED).The influence of the W particle size on the microstructure and mechanical properties of the deposited samples was systematically studied.The results indicate that refining the W particle size could refine theγ-Ni grains and subgrains,thin the(Ni,Cr)_(4)W interface layer,and increase the disloca-tion density of the intergranular matrix,thus improving the tensile strength and elongation of the L-DED samples.As W particle size decreased from 75 to 150μm to 6.5-12μm,the tensile strength and elonga-tion of the deposited samples increased by 150 MPa and 2.9 times to 1347.6±15.7 MPa and 17.5±0.4%,respectively.Based on the properties of the interface(Ni,Cr)_(4)W,a load-transfer efficiency factor suitable for this composite was proposed and the load-transfer strengthening formula was optimized.A quanti-tative analysis of the strengthening mechanisms was established considering load-transfer strengthening,Hall-Petch strengthening,thermal-mismatch strengthening,and solid-solution strengthening.The calcu-lated contribution of each strengthening mechanism to the yield strength and theoretical calculations were in good agreement with the experimental data.The article breaks the bottleneck of poor plasticity of W particle-reinforced Ni-based composites prepared by L-DED and provides a theoretical basis for the construction design of W particle-reinforced Ni-based composites with excellent mechanical properties.展开更多
As one of the critical issues in operations management, spare parts planning classification systems based only on cost may not withstand the test of time because of continuing technological advancement or environmenta...As one of the critical issues in operations management, spare parts planning classification systems based only on cost may not withstand the test of time because of continuing technological advancement or environmental degradation. This study, however, emphasizes using failure mode effect and criticality analysis(FMECA) as a basis for designing an ABC classification system that is capable of more accurately determining critical equipment and making maintenance more efficient. In the proposed methodology, risk priority numbers(RPN) and criticality as an index of safety and reliability can be obtained using a structured failure analysis technique. These indexes can be added to the economic indicator of maintenance cost, and then a classification model of spare parts can be established according to a comprehensive scoring method. The model is calibrated by using case data from a bus braking system, and the components of the braking system are compared and analyzed. The results show that the improved ABC classification method reduces the proportion of key and main components. This method can make maintenance work more efficient, targeting the most critical components, and can reduce administrative costs for enterprises.展开更多
Shale oil and gas plays in continental rift basins are complicated and have not been reported elsewhere.In the Luojia area of the Jiyang Depression,an evaluation workflow for shale oil and gas in this continental rift...Shale oil and gas plays in continental rift basins are complicated and have not been reported elsewhere.In the Luojia area of the Jiyang Depression,an evaluation workflow for shale oil and gas in this continental rift basin is proposed.Based on analysis of oil-and gas-related geological conditions,a favorable area of shale oil and gas can be identified,and a high-frequency sequence stratigraphic framework of the target area can be established,therefore,the spatiotemporal distribution of shale has been elucidated in the Luojia area.According to the rock texture,structure,composition and color,petrographic classification criteria for shale are determined,and well log data are used to demarcate,track and predict high-quality lithofacies.Based on geochemical analyses and physical simulations of hydrocarbon generation,abundance,types and maturity of organic matter are analyzed,furthermore,geochemical parameters criteria of hydrocarbon generation and the characteristics of oil and gas occurrence in shales can be determined.Storage space types,assemblages and evolution characteristics of shale reservoirs are studied through core observation,thin-section analysis,electron microscopy examination and fluorescence spectrometry.Combined with analysis of reservoir physical properties,the reservoir performance is evaluated.A saturation model is established based on core analysis,well-log interpretation and well-test production data.The model is further used for evaluation of the movable hydrocarbon contents and integrated assessment of the oil potential.Finally,the shale oil and gas production capacity and exploration prospects in the Luojia area are forecasted based on the analyses of factors controlling production capacity and the rock fracability.Through an integrated analysis of multi-factors(including the lithofacies,source rocks,reservoir properties,oil saturation,and production capacity),the shales in the Luojia area can be divided into three categories,i.e.,Class I(high porosity-high resistivity),Class II(medium porosity-medium resistivity),and Class III(low porosity-medium resistivity).展开更多
基金supported by the Key Projects of the National Natural Science Foundation of China(Nos.92066201 and 92266101)the Jiangxi Provincial Key R&D Programme Projects(No.20212BBE51011).
文摘Tungsten(W)particle-reinforced nickel(Ni)-based composites were fabricated via laser-direct energy de-position(L-DED).The influence of the W particle size on the microstructure and mechanical properties of the deposited samples was systematically studied.The results indicate that refining the W particle size could refine theγ-Ni grains and subgrains,thin the(Ni,Cr)_(4)W interface layer,and increase the disloca-tion density of the intergranular matrix,thus improving the tensile strength and elongation of the L-DED samples.As W particle size decreased from 75 to 150μm to 6.5-12μm,the tensile strength and elonga-tion of the deposited samples increased by 150 MPa and 2.9 times to 1347.6±15.7 MPa and 17.5±0.4%,respectively.Based on the properties of the interface(Ni,Cr)_(4)W,a load-transfer efficiency factor suitable for this composite was proposed and the load-transfer strengthening formula was optimized.A quanti-tative analysis of the strengthening mechanisms was established considering load-transfer strengthening,Hall-Petch strengthening,thermal-mismatch strengthening,and solid-solution strengthening.The calcu-lated contribution of each strengthening mechanism to the yield strength and theoretical calculations were in good agreement with the experimental data.The article breaks the bottleneck of poor plasticity of W particle-reinforced Ni-based composites prepared by L-DED and provides a theoretical basis for the construction design of W particle-reinforced Ni-based composites with excellent mechanical properties.
基金supported by the Opening Project of the Key Laboratory of Operation Safety Technology on Transportation Vehicles,Ministry of Transport,PRC (No.KFKT2016-03)the Basic Science Research Plan of Shaanxi Province (No.2020JM225)the Fundamental Research Funds for the Central Universities (No.310822173702)。
文摘As one of the critical issues in operations management, spare parts planning classification systems based only on cost may not withstand the test of time because of continuing technological advancement or environmental degradation. This study, however, emphasizes using failure mode effect and criticality analysis(FMECA) as a basis for designing an ABC classification system that is capable of more accurately determining critical equipment and making maintenance more efficient. In the proposed methodology, risk priority numbers(RPN) and criticality as an index of safety and reliability can be obtained using a structured failure analysis technique. These indexes can be added to the economic indicator of maintenance cost, and then a classification model of spare parts can be established according to a comprehensive scoring method. The model is calibrated by using case data from a bus braking system, and the components of the braking system are compared and analyzed. The results show that the improved ABC classification method reduces the proportion of key and main components. This method can make maintenance work more efficient, targeting the most critical components, and can reduce administrative costs for enterprises.
基金This work was funded by National Science and Technology Major Project of China(Grant No.2011ZX05006-003).
文摘Shale oil and gas plays in continental rift basins are complicated and have not been reported elsewhere.In the Luojia area of the Jiyang Depression,an evaluation workflow for shale oil and gas in this continental rift basin is proposed.Based on analysis of oil-and gas-related geological conditions,a favorable area of shale oil and gas can be identified,and a high-frequency sequence stratigraphic framework of the target area can be established,therefore,the spatiotemporal distribution of shale has been elucidated in the Luojia area.According to the rock texture,structure,composition and color,petrographic classification criteria for shale are determined,and well log data are used to demarcate,track and predict high-quality lithofacies.Based on geochemical analyses and physical simulations of hydrocarbon generation,abundance,types and maturity of organic matter are analyzed,furthermore,geochemical parameters criteria of hydrocarbon generation and the characteristics of oil and gas occurrence in shales can be determined.Storage space types,assemblages and evolution characteristics of shale reservoirs are studied through core observation,thin-section analysis,electron microscopy examination and fluorescence spectrometry.Combined with analysis of reservoir physical properties,the reservoir performance is evaluated.A saturation model is established based on core analysis,well-log interpretation and well-test production data.The model is further used for evaluation of the movable hydrocarbon contents and integrated assessment of the oil potential.Finally,the shale oil and gas production capacity and exploration prospects in the Luojia area are forecasted based on the analyses of factors controlling production capacity and the rock fracability.Through an integrated analysis of multi-factors(including the lithofacies,source rocks,reservoir properties,oil saturation,and production capacity),the shales in the Luojia area can be divided into three categories,i.e.,Class I(high porosity-high resistivity),Class II(medium porosity-medium resistivity),and Class III(low porosity-medium resistivity).
