Structural evolution of alloys by ball milling during solid state amorphization were studied by means of XAFS technique. The first one is amorphization process of Fe and B powder mixtures by mechanical alloying (MA), ...Structural evolution of alloys by ball milling during solid state amorphization were studied by means of XAFS technique. The first one is amorphization process of Fe and B powder mixtures by mechanical alloying (MA), and the second one is amorphization process of ordered B2 CoZr intermetallic compound by mechanical milling (MM). The mixing process of Fe and B and disintegration process of ordered B2 CoZr intermetallic compound crystal were observed clearly in atomic level by XAFS method. The micro mechanism of amorphization process of alloy by ball milling was discussed.展开更多
MoSx coatings were prepared by bipolar-pulse DC unbalanced magnetron-sputtering system with the variation of coating thickness at different Ar pressures. The composition and surface morphology were determined by using...MoSx coatings were prepared by bipolar-pulse DC unbalanced magnetron-sputtering system with the variation of coating thickness at different Ar pressures. The composition and surface morphology were determined by using energy dispersive X-ray and scanning electron microscopy; the structural characterisation was analyzed by X-ray diffraction. The friction and wear properties were investigated by fretting tests in air with less than 10% and 50% relative humidity. At 0.40 Pa pressure, (002) basal plane orientation was formed throughout the coatings. At 0.88 Pa and 1.60 Pa pressures, (002) basal plane orientation was only noticed in the first stage of coating growth (around 0.20祄 in thickness), and then edge orientations with their basal planes perpendicular to the surface would be evolved in the coatings. Humidity has a minor influence on the coatings that have (002) basal plane orientation, whereas the tribological properties of MoSx coatings with edge orientations are greatly affected by humidity. The mechanisms of coating growth and friction and wear processes are discussed.展开更多
MoS coatings were prepared by means of bipolar-pulsed DC magnetron sputtering on different substrate type at various temperature. The structure and fretting behavior of MoS, coatings have been determined respectively ...MoS coatings were prepared by means of bipolar-pulsed DC magnetron sputtering on different substrate type at various temperature. The structure and fretting behavior of MoS, coatings have been determined respectively by XRD and fretting tester in air of 10% to 90% RH and under the load of 1 to 10 N. With increasing substrate temperature, the edge orientation evolves in the MoSx coating, and the relative content of edge-to-basal orientation becomes large. The tribological performance of coatings gets deteriorated. Compared with MoS, coatings on TiN/H13, CrN/H13 and MoS /Ti multilayer, MoS coating on H13 substrate has a lower load bearing capacity, and worn away easily under higher normal load 5N or ION and in air of 90% RH during the fretting process. The friction and wear properties of MoS, coatings on TiN/H13 and CrN/H13 (dual-layer) are slight better than that of MoS, /Ti multilayer under the normal load tested and in air of<10%to90%RH.展开更多
In contrary to the commonly used arc melting method, samples in the present paper were prepared by the solid state reaction from elemental powders at 1173 K under a flowing Ar atmosphere for 96-168 h. The constituent ...In contrary to the commonly used arc melting method, samples in the present paper were prepared by the solid state reaction from elemental powders at 1173 K under a flowing Ar atmosphere for 96-168 h. The constituent phases and the elemental compositions were determined and shown that the samples were of single phase and stoichiometry. Then the spark plasma sintering technique was used to consolidate them. It is found that, dense ZrNiSn-based compounds with fine grain size and homogeneous microstructure were achieved under the condition of 1123 K/40 MPa/25 min.展开更多
Nano-scale rutile phase was transformed from nano-scale anatase upon heating, which was prepared by a sol-gel technique. The XRD data corresponding to the anatase and rutile phases were analyzed and the grain sizes of...Nano-scale rutile phase was transformed from nano-scale anatase upon heating, which was prepared by a sol-gel technique. The XRD data corresponding to the anatase and rutile phases were analyzed and the grain sizes of as-derived phases were calculated by Sherrer equation. The lattice parameters of the as-derived anatase and rutile unit cells were calculated and compared with those of standard lattice parameters on PDF cards. It was shown that the smaller the grain sizes, the larger the lattice deformation. The lattice parameter a has the negative deviation from the standard and the lattice parameter c has the positive deviation for both phases. The particles sizes had preferential in-fluence on the longer parameter between the lattice parameters of a and c. With increasing temperatures, the lattice parameters of a and c in both phases approached to the equilibrium state. The larger lattice deformation facilitated the nucleation process, which lowered the transformation temperature. During the transformation from nano-scale anatase to rutile, besides the mechanism involving retention of the {112} pseudo-close-packed planes of oxygen in anatase as the {100} pseudo-close-packed planes in rutile, the new phase occurred by relaxation of lattice deformation and adjustment of the atomic sites in parent phase. The orientation relationships were suggested to be anatase {101}//rutile {101} and anatase <201>//rutile<111>, and the habit plane was anatase (101).展开更多
The recent significant advances in the molecular electronics show that the molecular device is a good candidate with great potential as the successor to the sil-icon-based semi-conductors. After the successful ex-peri...The recent significant advances in the molecular electronics show that the molecular device is a good candidate with great potential as the successor to the sil-icon-based semi-conductors. After the successful ex-perimental work made by Reed et al. in which the sin-gle benzene molecule acts as the core of the molecular device, many experimental and theoretical investiga-tions have been done on this subject.展开更多
文摘Structural evolution of alloys by ball milling during solid state amorphization were studied by means of XAFS technique. The first one is amorphization process of Fe and B powder mixtures by mechanical alloying (MA), and the second one is amorphization process of ordered B2 CoZr intermetallic compound by mechanical milling (MM). The mixing process of Fe and B and disintegration process of ordered B2 CoZr intermetallic compound crystal were observed clearly in atomic level by XAFS method. The micro mechanism of amorphization process of alloy by ball milling was discussed.
基金This research is a part of an Eureka project funded by the Flemish government (Lubrimat 960235), a Belgium-China interna-tional scientific and technological co-operation project supported by the Flemish government and the China government (project BIL 96
文摘MoSx coatings were prepared by bipolar-pulse DC unbalanced magnetron-sputtering system with the variation of coating thickness at different Ar pressures. The composition and surface morphology were determined by using energy dispersive X-ray and scanning electron microscopy; the structural characterisation was analyzed by X-ray diffraction. The friction and wear properties were investigated by fretting tests in air with less than 10% and 50% relative humidity. At 0.40 Pa pressure, (002) basal plane orientation was formed throughout the coatings. At 0.88 Pa and 1.60 Pa pressures, (002) basal plane orientation was only noticed in the first stage of coating growth (around 0.20祄 in thickness), and then edge orientations with their basal planes perpendicular to the surface would be evolved in the coatings. Humidity has a minor influence on the coatings that have (002) basal plane orientation, whereas the tribological properties of MoSx coatings with edge orientations are greatly affected by humidity. The mechanisms of coating growth and friction and wear processes are discussed.
文摘MoS coatings were prepared by means of bipolar-pulsed DC magnetron sputtering on different substrate type at various temperature. The structure and fretting behavior of MoS, coatings have been determined respectively by XRD and fretting tester in air of 10% to 90% RH and under the load of 1 to 10 N. With increasing substrate temperature, the edge orientation evolves in the MoSx coating, and the relative content of edge-to-basal orientation becomes large. The tribological performance of coatings gets deteriorated. Compared with MoS, coatings on TiN/H13, CrN/H13 and MoS /Ti multilayer, MoS coating on H13 substrate has a lower load bearing capacity, and worn away easily under higher normal load 5N or ION and in air of 90% RH during the fretting process. The friction and wear properties of MoS, coatings on TiN/H13 and CrN/H13 (dual-layer) are slight better than that of MoS, /Ti multilayer under the normal load tested and in air of<10%to90%RH.
文摘In contrary to the commonly used arc melting method, samples in the present paper were prepared by the solid state reaction from elemental powders at 1173 K under a flowing Ar atmosphere for 96-168 h. The constituent phases and the elemental compositions were determined and shown that the samples were of single phase and stoichiometry. Then the spark plasma sintering technique was used to consolidate them. It is found that, dense ZrNiSn-based compounds with fine grain size and homogeneous microstructure were achieved under the condition of 1123 K/40 MPa/25 min.
文摘Nano-scale rutile phase was transformed from nano-scale anatase upon heating, which was prepared by a sol-gel technique. The XRD data corresponding to the anatase and rutile phases were analyzed and the grain sizes of as-derived phases were calculated by Sherrer equation. The lattice parameters of the as-derived anatase and rutile unit cells were calculated and compared with those of standard lattice parameters on PDF cards. It was shown that the smaller the grain sizes, the larger the lattice deformation. The lattice parameter a has the negative deviation from the standard and the lattice parameter c has the positive deviation for both phases. The particles sizes had preferential in-fluence on the longer parameter between the lattice parameters of a and c. With increasing temperatures, the lattice parameters of a and c in both phases approached to the equilibrium state. The larger lattice deformation facilitated the nucleation process, which lowered the transformation temperature. During the transformation from nano-scale anatase to rutile, besides the mechanism involving retention of the {112} pseudo-close-packed planes of oxygen in anatase as the {100} pseudo-close-packed planes in rutile, the new phase occurred by relaxation of lattice deformation and adjustment of the atomic sites in parent phase. The orientation relationships were suggested to be anatase {101}//rutile {101} and anatase <201>//rutile<111>, and the habit plane was anatase (101).
文摘The recent significant advances in the molecular electronics show that the molecular device is a good candidate with great potential as the successor to the sil-icon-based semi-conductors. After the successful ex-perimental work made by Reed et al. in which the sin-gle benzene molecule acts as the core of the molecular device, many experimental and theoretical investiga-tions have been done on this subject.
