Mg alloy matrix composites reinforced with short carbon fibers(C_(sf)/Mg)are considered as potential candidates for integrated structural-functional electronic parts that satisfy the requirements of lightweight,excell...Mg alloy matrix composites reinforced with short carbon fibers(C_(sf)/Mg)are considered as potential candidates for integrated structural-functional electronic parts that satisfy the requirements of lightweight,excellent mechanical properties,and heat dissipation.However,the different characteristics of C_(sf)and Mg alloy make the interface a critical issue affecting the synergistic improvement of thermal and mechanical properties of the composites.Here,Cu coating with different thicknesses is introduced to modify the C_(sf)/Mg interface,so as to simultaneously enhance the thermal and mechanical performances,which can combine the advantages of coating modification and matrix alloying.Results reveal that thermal diffusivity(TD)of 3-C_(sf)-Cu/Mg composites is as high as 22.12 mm^(2)/s and an enhancement of 52.97%is achieved compared with C_(sf)/Mg composites,as well as 16.3%enhancement of ultimate compressive strength(UCS)in the longitudinal direction,8.84%improvement of UCS in the transverse direction,and 53.08%increasement of ultimate tensile strength(UTS).Such improvement can be ascribed to the formation of intermetallic compounds.The formation of intermetallic compounds can not only effectively alleviate the lattice distortion of the matrix and decrease interfacial thermal resistance,but also bear the loads.Our work is of great significance for designing C_(sf)/Mg composites with integrated structure and function.展开更多
This study focuses on the geology,geochemistry,Sr-Nd isotopes and their tectonic settings of three types of basalts in Diyanmiao ophiolite in the Xar Moron area located on the eastern margin of the Central Asian Oroge...This study focuses on the geology,geochemistry,Sr-Nd isotopes and their tectonic settings of three types of basalts in Diyanmiao ophiolite in the Xar Moron area located on the eastern margin of the Central Asian Orogenic Belt.Type I basalts are oceanic tholeiites with a depleted light rare earth element(LREE)pattern,which are similar to the typical N-mid-oceanic ridge basalt(MORB)and suggests that they were formed at a mid-oceanic ridge.The initial 87Sr/86Sr ratios of Type I basalts range from 0.703966 to 0.705276 and theεNd(t)values are from 16.49 to 17.15,indicating that they were derived from a depleted mantle source.Type II basalts belong to the medium-potassium calc-akaline series and have the geochem-ical characteristics of Nb-enriched basalt(NEB)with high Nb content(14.5 ppm)and strong enrichment in LREEs,implying that they were created by the partial melting of mantle wedge peridotite that previously metasomatized by slab melts.Type III basalts are high-Al basalt(HAB)with high-Al contents(Al_(2)0_(3)=16.75 wt.%-18.00 wt.%),distinct Nb depletion and high Th/Yb ratios.Thus they were likely gen-erated in a normal island-arc setting.Therefore,the association of MORB,NEB,and HAB in the study area may be due to the subduction of a mid-oceanic ridge,and the Diyanmiao ophiolite is proposed to be formed in the forearc setting of a mid-oceanic ridge subduction system.展开更多
The hot wall reactor was used to deposit isotropic pyrocarbon.The density of the product was measured by Archimedes method.The fracture morphology and texture of the product were investigated by scanning electron micr...The hot wall reactor was used to deposit isotropic pyrocarbon.The density of the product was measured by Archimedes method.The fracture morphology and texture of the product were investigated by scanning electron microscopy(SEM)and transmission electron microscopy(TEM).Raman spectroscopy was also applied to characterizing the structure of the product.The results show that the density of the product is about 1.31 g/cm^3.The pyrocarbon consists of granular particles with the size of about 1.5μm under SEM images.Under TEM images,the pyrocarbon is composed of irregular grains and onion-like particles are also detected.The orientation angle(180 deg.)of pyrocarbon reveals its isotropic character.The ID/IG ratio in Raman spectrum is about 1.2,indicating the isotropic feature of the product qualitatively.展开更多
基金supported by the National Natural Science Foundation of China(grant no.52231004 and 52072305).
文摘Mg alloy matrix composites reinforced with short carbon fibers(C_(sf)/Mg)are considered as potential candidates for integrated structural-functional electronic parts that satisfy the requirements of lightweight,excellent mechanical properties,and heat dissipation.However,the different characteristics of C_(sf)and Mg alloy make the interface a critical issue affecting the synergistic improvement of thermal and mechanical properties of the composites.Here,Cu coating with different thicknesses is introduced to modify the C_(sf)/Mg interface,so as to simultaneously enhance the thermal and mechanical performances,which can combine the advantages of coating modification and matrix alloying.Results reveal that thermal diffusivity(TD)of 3-C_(sf)-Cu/Mg composites is as high as 22.12 mm^(2)/s and an enhancement of 52.97%is achieved compared with C_(sf)/Mg composites,as well as 16.3%enhancement of ultimate compressive strength(UCS)in the longitudinal direction,8.84%improvement of UCS in the transverse direction,and 53.08%increasement of ultimate tensile strength(UTS).Such improvement can be ascribed to the formation of intermetallic compounds.The formation of intermetallic compounds can not only effectively alleviate the lattice distortion of the matrix and decrease interfacial thermal resistance,but also bear the loads.Our work is of great significance for designing C_(sf)/Mg composites with integrated structure and function.
基金This study was financially supported by Inner Mongolia Autonomous Region Geological and Mineral Exploration Fund(Nos.2017-YS01 and 2020-YS01)the Project of the Institute of Mineral Resources,China Metallurgical Geology Bureau(No.CMGB202002).
文摘This study focuses on the geology,geochemistry,Sr-Nd isotopes and their tectonic settings of three types of basalts in Diyanmiao ophiolite in the Xar Moron area located on the eastern margin of the Central Asian Orogenic Belt.Type I basalts are oceanic tholeiites with a depleted light rare earth element(LREE)pattern,which are similar to the typical N-mid-oceanic ridge basalt(MORB)and suggests that they were formed at a mid-oceanic ridge.The initial 87Sr/86Sr ratios of Type I basalts range from 0.703966 to 0.705276 and theεNd(t)values are from 16.49 to 17.15,indicating that they were derived from a depleted mantle source.Type II basalts belong to the medium-potassium calc-akaline series and have the geochem-ical characteristics of Nb-enriched basalt(NEB)with high Nb content(14.5 ppm)and strong enrichment in LREEs,implying that they were created by the partial melting of mantle wedge peridotite that previously metasomatized by slab melts.Type III basalts are high-Al basalt(HAB)with high-Al contents(Al_(2)0_(3)=16.75 wt.%-18.00 wt.%),distinct Nb depletion and high Th/Yb ratios.Thus they were likely gen-erated in a normal island-arc setting.Therefore,the association of MORB,NEB,and HAB in the study area may be due to the subduction of a mid-oceanic ridge,and the Diyanmiao ophiolite is proposed to be formed in the forearc setting of a mid-oceanic ridge subduction system.
基金supported by the National Natural Science Foundation of China under Grant Nos.50832004 and 50972120the Program of Introducing Talents of Discipline to University under Grant No.D08040
文摘The hot wall reactor was used to deposit isotropic pyrocarbon.The density of the product was measured by Archimedes method.The fracture morphology and texture of the product were investigated by scanning electron microscopy(SEM)and transmission electron microscopy(TEM).Raman spectroscopy was also applied to characterizing the structure of the product.The results show that the density of the product is about 1.31 g/cm^3.The pyrocarbon consists of granular particles with the size of about 1.5μm under SEM images.Under TEM images,the pyrocarbon is composed of irregular grains and onion-like particles are also detected.The orientation angle(180 deg.)of pyrocarbon reveals its isotropic character.The ID/IG ratio in Raman spectrum is about 1.2,indicating the isotropic feature of the product qualitatively.
