Cu/Ti3AlC2 composite and functional-gradient materials with excellent electrical conductivity and thermal conductivity as well as good flexural properties were prepared by low-temperature spark plasma sintering of Cu ...Cu/Ti3AlC2 composite and functional-gradient materials with excellent electrical conductivity and thermal conductivity as well as good flexural properties were prepared by low-temperature spark plasma sintering of Cu and Ti3AlC2 powder mixtures. The phase compositions of the materials were analyzed by X-ray diffraction, and their microstructure was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. Further, the electrical conductivity, thermal conductivity, and flexural properties of the materials were tested. Results show that, for the composite materials, the resistivity rises from 0.75 × 10^-7 Ω·m only to 1.32 × 10^-7 Ω·m and the thermal diffusivity reduces from 82.5 mm^2/s simply to 39.8 mm^2/s, while the flexural strength improves from 412.9 MPa to 471.3 MPa, as the content of Ti3AlC2 is increased from 5 wt%to 25 wt%. Additionally, the functional-gradient materials sintered without interface between the layers exhibit good designability, and their overall electrical conductivity, thermal conductivity, and flexural strength are all higher than those of the corresponding uniform composite material.展开更多
Nanostructured （NS） W-Cu composite powder was prepared by mechanical alloying （MA）, and nanostructured bulk of W-Cu contact material was fabricated by hot pressed sintering in an electrical vacuum furnace. The mic...Nanostructured （NS） W-Cu composite powder was prepared by mechanical alloying （MA）, and nanostructured bulk of W-Cu contact material was fabricated by hot pressed sintering in an electrical vacuum furnace. The microstructure, electric conductivity, hardness, breakdown voltage and arcing time of NS W-Cu alloys were measured and compared to conventional W-Cu alloys prepared by powder metallurgy. The results show that microstructural refinement and uniformity can improve the breakdown behavior, the electric arc stability and the arc extinction ability of nanostructured W-Cu contacts materials. Also, the nanostructured W-Cu contact material shows the characteristic of spreading electric arcs, which is of benefit to electric arc erosion.展开更多
W/Cu Functionally Graded Materials (FGM) was designed not only for reducing the thermal stress caused by the mismatch of thermal expansion coefficients, but also for combining the features of W, Mo - high plasma-erosi...W/Cu Functionally Graded Materials (FGM) was designed not only for reducing the thermal stress caused by the mismatch of thermal expansion coefficients, but also for combining the features of W, Mo - high plasma-erosion resistance and the advantages of Cu - high heat conductivity and ductility. Four different fabrication processes for W/Cu or Mo/Cu, including hot-pressing, Cu infiltration of sintered porosity-graded W skeleton, spark plasma sintering and plasma spraying, were investigated and compared. It was foundthat the hot-pressing process is difficult to keep the designed composition gradient, while the other three processes are successful in making W/Cu or Mo/Cu FGM. Meanwhile, microstructures and composition gradients are analyzed with SEM and EDAX.展开更多
Nanostructured （ NS ）W-Cu composite powder was prepared by mechanical alloying （ MA ）, and nanostructared bulk of W-Cu contact material was fabricated by hot press sintering in an electrical vacuum furnace. The rn...Nanostructured （ NS ）W-Cu composite powder was prepared by mechanical alloying （ MA ）, and nanostructared bulk of W-Cu contact material was fabricated by hot press sintering in an electrical vacuum furnace. The rnicrostructure, electric conductivity, hardness and break down voltage of NS W- Cu alloys were measured and compared to those of conventional W-Cu alloys prepared by powder metallurg＇y. The experimental results show that microstructural refinement and uniformity can improve the breakdown behavior and the electric arc stability of nanostructared W- Cu contacts materials. Also, the wanostructured W- Cu contact material shows the characteristic of spreading electric arcs, which is of benefit to electric arc erosion.展开更多
The erosion behavior of a nanocomposite W-Cu material under arc breakdown was investigated. The arc erosion rates of the material were determined, and the eroded surfaces and arc erosion mechanisms were studied by sca...The erosion behavior of a nanocomposite W-Cu material under arc breakdown was investigated. The arc erosion rates of the material were determined, and the eroded surfaces and arc erosion mechanisms were studied by scanning eleclion microscopy. It is concluded that the nanocomposite W-Cu electrical contact material shows a characteristic of spreading arcs. The arc breakdown of a commercially used W-Cu alloy was limited in a few areas, and its average arc erosion rate is twice as large as that of the former. Furthermore, it is also proved that the arc extinction ability and arc stability of the nanocomposite W-Cu material are excellent, and melting is the major failure modality in the make-and-break operation of arcs.展开更多
基金Funded by he National Natural Science Foundation of China(51402097)the Open Foundation of Hubei Provincial Key Laboratory of Green Materials for Light Industry(201806A04)the College Students Innovation and Entrepreneurship Training Program of Hubei University of Technology(201810500151)
文摘Cu/Ti3AlC2 composite and functional-gradient materials with excellent electrical conductivity and thermal conductivity as well as good flexural properties were prepared by low-temperature spark plasma sintering of Cu and Ti3AlC2 powder mixtures. The phase compositions of the materials were analyzed by X-ray diffraction, and their microstructure was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. Further, the electrical conductivity, thermal conductivity, and flexural properties of the materials were tested. Results show that, for the composite materials, the resistivity rises from 0.75 × 10^-7 Ω·m only to 1.32 × 10^-7 Ω·m and the thermal diffusivity reduces from 82.5 mm^2/s simply to 39.8 mm^2/s, while the flexural strength improves from 412.9 MPa to 471.3 MPa, as the content of Ti3AlC2 is increased from 5 wt%to 25 wt%. Additionally, the functional-gradient materials sintered without interface between the layers exhibit good designability, and their overall electrical conductivity, thermal conductivity, and flexural strength are all higher than those of the corresponding uniform composite material.
基金supported by the National Natural Science Fundation of China under grant No.50071043the Natural Science Fundation of Shaanxi province under grant No.2004E105.
文摘Nanostructured （NS） W-Cu composite powder was prepared by mechanical alloying （MA）, and nanostructured bulk of W-Cu contact material was fabricated by hot pressed sintering in an electrical vacuum furnace. The microstructure, electric conductivity, hardness, breakdown voltage and arcing time of NS W-Cu alloys were measured and compared to conventional W-Cu alloys prepared by powder metallurgy. The results show that microstructural refinement and uniformity can improve the breakdown behavior, the electric arc stability and the arc extinction ability of nanostructured W-Cu contacts materials. Also, the nanostructured W-Cu contact material shows the characteristic of spreading electric arcs, which is of benefit to electric arc erosion.
文摘W/Cu Functionally Graded Materials (FGM) was designed not only for reducing the thermal stress caused by the mismatch of thermal expansion coefficients, but also for combining the features of W, Mo - high plasma-erosion resistance and the advantages of Cu - high heat conductivity and ductility. Four different fabrication processes for W/Cu or Mo/Cu, including hot-pressing, Cu infiltration of sintered porosity-graded W skeleton, spark plasma sintering and plasma spraying, were investigated and compared. It was foundthat the hot-pressing process is difficult to keep the designed composition gradient, while the other three processes are successful in making W/Cu or Mo/Cu FGM. Meanwhile, microstructures and composition gradients are analyzed with SEM and EDAX.
基金Funded by the National Natural Science Foundation of China(No.50071043)
文摘Nanostructured （ NS ）W-Cu composite powder was prepared by mechanical alloying （ MA ）, and nanostructared bulk of W-Cu contact material was fabricated by hot press sintering in an electrical vacuum furnace. The rnicrostructure, electric conductivity, hardness and break down voltage of NS W- Cu alloys were measured and compared to those of conventional W-Cu alloys prepared by powder metallurg＇y. The experimental results show that microstructural refinement and uniformity can improve the breakdown behavior and the electric arc stability of nanostructared W- Cu contacts materials. Also, the wanostructured W- Cu contact material shows the characteristic of spreading electric arcs, which is of benefit to electric arc erosion.
基金This work was financially supported by the National Natural Science Foundation of China (No. 50071043) the Natural Science Foundation ofShaanxi Province, China (No. 2004E105).
文摘The erosion behavior of a nanocomposite W-Cu material under arc breakdown was investigated. The arc erosion rates of the material were determined, and the eroded surfaces and arc erosion mechanisms were studied by scanning eleclion microscopy. It is concluded that the nanocomposite W-Cu electrical contact material shows a characteristic of spreading arcs. The arc breakdown of a commercially used W-Cu alloy was limited in a few areas, and its average arc erosion rate is twice as large as that of the former. Furthermore, it is also proved that the arc extinction ability and arc stability of the nanocomposite W-Cu material are excellent, and melting is the major failure modality in the make-and-break operation of arcs.
