Ultra-fine aluminum nitride has been synthesized by the evaporation of aluminum powder at atmospheric-pressure nitrogen plasma in a hot-wall reactor. The average size of aluminum nitride particle is 0.11 μm measured ...Ultra-fine aluminum nitride has been synthesized by the evaporation of aluminum powder at atmospheric-pressure nitrogen plasma in a hot-wall reactor. The average size of aluminum nitride particle is 0.11 μm measured by scanning electric mirror (SEM), and the purity is at least over 90% evaluated by X-Ray diffraction (XRD). The conversion of Al powder to aluminum nitride is strongly depended on the injection of NH3. Typical experimental parameters such as the feed rate of raw material, the flow rate of ammonia and the position of injecting aluminum powder into the reactor are given.展开更多
Separation of aluminum from fine granules of black dross, which is a waste by-product in secondary aluminum production, was investigated. The separation was performed by a multi-stage electrostatic separation method. ...Separation of aluminum from fine granules of black dross, which is a waste by-product in secondary aluminum production, was investigated. The separation was performed by a multi-stage electrostatic separation method. There are three stages to complete the separation, including preliminary separation, pulse charging enhancement and secondary concentration. Chemical and mineralogical compositions of collection products were analyzed and determined by X-ray diffraction(XRD) and X-ray Fluorescence(XRF). After multistage electrostatic separation, the Al2O3 content of the collection products increases from 50.74% to 69.77%.The mineralogical phase analysis indicates that the final recovery of metallic aluminum phase increases from 8%to 37%, and the aluminum oxide phase increases from 20% to 26%. The research results show the multi-stage electrostatic separation method is effective for recovering of aluminum from fine granules of black dross, and upgrades the black dross to a recoverable material.展开更多
Performance of commercial alloys can be improved greatly by severe plastic deformation, which refines grain of metals to several micrometer or sub micrometer order. During severe plastic deformation, the final size of...Performance of commercial alloys can be improved greatly by severe plastic deformation, which refines grain of metals to several micrometer or sub micrometer order. During severe plastic deformation, the final size of grain structure depends on the following factors: strain rate, total strain, deformation temperature and so on. Under a certain condition, structure cannot be infinitely refined, which means that the size of grain has a limit with the increase of total strain. Under conventional hot deformation temperature, the grain size of 7075 aluminum alloy can be refined to 12 μm, and it will not become smaller with the increase of total strain, that is to say, the limit of grain refinement is about 1 μm.展开更多
Experiments were conducted to evaluate the grain refinement and thermal stability of ultra-fine grained Al-4Mgalloy introduced by equal-channel angular pressing (ECAP) at 473 K. The results show that the intensities o...Experiments were conducted to evaluate the grain refinement and thermal stability of ultra-fine grained Al-4Mgalloy introduced by equal-channel angular pressing (ECAP) at 473 K. The results show that the intensities of X-ray(111/222) and (200/400) peaks for the alloy processed by ECAP decrease significantly and the peak widths of halfheight become broadening compared with the corresponding value in the annealed alloy. The microstructure of 2passes ECAPed alloy consists of both elongated and equiaxed subgrains. The residual strain in the alloy increaseswith increasing passes numbers, that appears as increasing dislocation density and lattice constant of matrix. Anequiaxed ultra-fine grained structure of～0.2μm is obtained in the present alloy after 8 passes. The ultra-fine grainsare stable below 523 K, because the alloy retains extremely fine grain size of～1μm after static annealing at 523 Kfor 1 h.展开更多
The microstructure characteristics with super fine ferrite grain size less than 5mm, appropriate retained austenite fraction around 5.0% and or removable abundant dislocations have been obtained by controlled rolling ...The microstructure characteristics with super fine ferrite grain size less than 5mm, appropriate retained austenite fraction around 5.0% and or removable abundant dislocations have been obtained by controlled rolling and cooling, which leads to well balance com- prehensive properties with high tensile strength of 510 and 615MPa, high elongation of 40% and 27%, low ratio of yield strength to tensile strength 0.83 and 0.80, as well as low ductile- brittle transition temperature less than -80 and -70℃ for advanced aluminum hot-rolled TRIP steel and silicon hot-rolled TRIP steel, respectively.展开更多
An as-cast magnesium alloy with high Al content Mg15Al was subjected to equal-channel angular pressing （ECAP） through a die with an angle of φ= 90？ at 553 K following route Bc. It is found that the network β-Mg17...An as-cast magnesium alloy with high Al content Mg15Al was subjected to equal-channel angular pressing （ECAP） through a die with an angle of φ= 90？ at 553 K following route Bc. It is found that the network β-Mg17Al12 phases in the as-cast Mg15Al alloy are broken into small blocks and dispersed uniformly with increasing numbers of pressing passes. Moreover, many nano-sized Mg17Al12 particles precipitate in the ultra-fine α-Mg matrix. The grains are obviously refined. However, the grain structure is inhomogeneous in different areas of the alloy. The average size of the primary phase α-Mg is reduced to about 1 μm while grains of around 0.1-0.2 μm are obtained in some two-phase areas. With additional ECAP passes （up to 8）, coarsening of the grains occurs by dynamic recovery. Room temperature tensile tests show that the mechanical properties of Mg15Al alloys are markedly improved after 4 ECAP passes. The ultimate tensile strength and elongation to failure increase from 150 MPa to 269.3 MPa and from 0.05% to 7.4%, respectively. Compared with that after 4 passes, the elongation to failure of the alloy increases but the strength of the alloy slightly decreases after 8 ECAP passes. Fracture morphology of the ECAP-processed alloy exhibits dimple-like fracture characteristics while the as-cast alloy shows quasi-cleavage fractures.展开更多
Ultra-fine aluminum silicate is synthesized from aluminum sulfate and sodium silicate generally.It consumes aluminum containing chemicals with a high cost.Therefore, a new method that used aluminum bearing waste liqui...Ultra-fine aluminum silicate is synthesized from aluminum sulfate and sodium silicate generally.It consumes aluminum containing chemicals with a high cost.Therefore, a new method that used aluminum bearing waste liquid as raw material was developed. The new method consisted of reaction, polymerization, surface modification, aging,and washing.Besides, the properties of the product were studied with compositional analysis, infrared spectroscopy, SEM, XRD.The results showed that the diameter of primary particles of the product was about 10～40 nm, and the mean diameter was 100nm for the secondary particles.A kind of 3-D network with Si—O and Al—O bonds built up its amorphous non-crystalline structure.The product was up to the current enterprise standard of China.Its chemical formula was Na2O · Al2O 3 ·mSiO 2 ·nH2O（m=9—11, n=4—6）.展开更多
基金This work was supported by Science and Technology Innovation Fund of Middle-Minor Enterprises from Ministy of Science and Technology.
文摘Ultra-fine aluminum nitride has been synthesized by the evaporation of aluminum powder at atmospheric-pressure nitrogen plasma in a hot-wall reactor. The average size of aluminum nitride particle is 0.11 μm measured by scanning electric mirror (SEM), and the purity is at least over 90% evaluated by X-Ray diffraction (XRD). The conversion of Al powder to aluminum nitride is strongly depended on the injection of NH3. Typical experimental parameters such as the feed rate of raw material, the flow rate of ammonia and the position of injecting aluminum powder into the reactor are given.
基金Funded by the National Natural Science Foundation of China(No.51607023)the Fundamental Research Funds for the Central Universities(No.DUT16QY36)
文摘Separation of aluminum from fine granules of black dross, which is a waste by-product in secondary aluminum production, was investigated. The separation was performed by a multi-stage electrostatic separation method. There are three stages to complete the separation, including preliminary separation, pulse charging enhancement and secondary concentration. Chemical and mineralogical compositions of collection products were analyzed and determined by X-ray diffraction(XRD) and X-ray Fluorescence(XRF). After multistage electrostatic separation, the Al2O3 content of the collection products increases from 50.74% to 69.77%.The mineralogical phase analysis indicates that the final recovery of metallic aluminum phase increases from 8%to 37%, and the aluminum oxide phase increases from 20% to 26%. The research results show the multi-stage electrostatic separation method is effective for recovering of aluminum from fine granules of black dross, and upgrades the black dross to a recoverable material.
文摘Performance of commercial alloys can be improved greatly by severe plastic deformation, which refines grain of metals to several micrometer or sub micrometer order. During severe plastic deformation, the final size of grain structure depends on the following factors: strain rate, total strain, deformation temperature and so on. Under a certain condition, structure cannot be infinitely refined, which means that the size of grain has a limit with the increase of total strain. Under conventional hot deformation temperature, the grain size of 7075 aluminum alloy can be refined to 12 μm, and it will not become smaller with the increase of total strain, that is to say, the limit of grain refinement is about 1 μm.
文摘Experiments were conducted to evaluate the grain refinement and thermal stability of ultra-fine grained Al-4Mgalloy introduced by equal-channel angular pressing (ECAP) at 473 K. The results show that the intensities of X-ray(111/222) and (200/400) peaks for the alloy processed by ECAP decrease significantly and the peak widths of halfheight become broadening compared with the corresponding value in the annealed alloy. The microstructure of 2passes ECAPed alloy consists of both elongated and equiaxed subgrains. The residual strain in the alloy increaseswith increasing passes numbers, that appears as increasing dislocation density and lattice constant of matrix. Anequiaxed ultra-fine grained structure of～0.2μm is obtained in the present alloy after 8 passes. The ultra-fine grainsare stable below 523 K, because the alloy retains extremely fine grain size of～1μm after static annealing at 523 Kfor 1 h.
文摘The microstructure characteristics with super fine ferrite grain size less than 5mm, appropriate retained austenite fraction around 5.0% and or removable abundant dislocations have been obtained by controlled rolling and cooling, which leads to well balance com- prehensive properties with high tensile strength of 510 and 615MPa, high elongation of 40% and 27%, low ratio of yield strength to tensile strength 0.83 and 0.80, as well as low ductile- brittle transition temperature less than -80 and -70℃ for advanced aluminum hot-rolled TRIP steel and silicon hot-rolled TRIP steel, respectively.
基金Funded by the Taiyuan Special Fund for Sci-Tech Star (No. 09121002)the Youth Science Foundation of Shanxi Province (No.2008021033)Shanxi Research Fund for Returned Scholars (No.2007-25)
文摘An as-cast magnesium alloy with high Al content Mg15Al was subjected to equal-channel angular pressing （ECAP） through a die with an angle of φ= 90？ at 553 K following route Bc. It is found that the network β-Mg17Al12 phases in the as-cast Mg15Al alloy are broken into small blocks and dispersed uniformly with increasing numbers of pressing passes. Moreover, many nano-sized Mg17Al12 particles precipitate in the ultra-fine α-Mg matrix. The grains are obviously refined. However, the grain structure is inhomogeneous in different areas of the alloy. The average size of the primary phase α-Mg is reduced to about 1 μm while grains of around 0.1-0.2 μm are obtained in some two-phase areas. With additional ECAP passes （up to 8）, coarsening of the grains occurs by dynamic recovery. Room temperature tensile tests show that the mechanical properties of Mg15Al alloys are markedly improved after 4 ECAP passes. The ultimate tensile strength and elongation to failure increase from 150 MPa to 269.3 MPa and from 0.05% to 7.4%, respectively. Compared with that after 4 passes, the elongation to failure of the alloy increases but the strength of the alloy slightly decreases after 8 ECAP passes. Fracture morphology of the ECAP-processed alloy exhibits dimple-like fracture characteristics while the as-cast alloy shows quasi-cleavage fractures.
文摘Ultra-fine aluminum silicate is synthesized from aluminum sulfate and sodium silicate generally.It consumes aluminum containing chemicals with a high cost.Therefore, a new method that used aluminum bearing waste liquid as raw material was developed. The new method consisted of reaction, polymerization, surface modification, aging,and washing.Besides, the properties of the product were studied with compositional analysis, infrared spectroscopy, SEM, XRD.The results showed that the diameter of primary particles of the product was about 10～40 nm, and the mean diameter was 100nm for the secondary particles.A kind of 3-D network with Si—O and Al—O bonds built up its amorphous non-crystalline structure.The product was up to the current enterprise standard of China.Its chemical formula was Na2O · Al2O 3 ·mSiO 2 ·nH2O（m=9—11, n=4—6）.
