This work studied the thickening progression mechanism of the silica fume-oil well cement composite system at high temperatures(110-180.C)in order to provide a theoretical guidance for the rational application of sili...This work studied the thickening progression mechanism of the silica fume-oil well cement composite system at high temperatures(110-180.C)in order to provide a theoretical guidance for the rational application of silica fume in the cementing engineering.Results showed that silica fume seldom affected the thickening progression of oil well cement slurry at 110-120.C,but when temperature reached above130.C,it would aggravate the bulging degree of thickening curves and significantly extend the thickening time,meanwhile causing the abnormal“temperature-based thickening time reversal”and“dosage-based thickening time reversal”phenomena in the range of 130-160.C and 170-180.C respectively.At 130-160.C,the thickening time of oil well cement slurry was mainly associated with the generation rate of calcium hydroxide(CH)crystal.The introduced silica fume would be attracted to the cement minerals'surface that were hydrating to produce CH and agglomerate together to form an“adsorptive barrier”to hinder further hydration of the inner cement minerals.This“adsorptive barrier”effect strengthened with the rising temperature which extended the thickening time and caused the occurrence of the“temperature-based thickening time reversal”phenomenon.At 170-180.C,the pozzolanic activity of silica fume significantly enhanced and considerable amount of C-S-H was generated,thus the“temperature-based thickening time reversal”vanished and the“dosage-based thickening time reversal”was presented.展开更多
The phase evolution of Bi-2223 precursor powder prepared by spray pyrolysis method is studied with different heat treatment parameters. The results show that the reaction temperature and phase composition of precursor...The phase evolution of Bi-2223 precursor powder prepared by spray pyrolysis method is studied with different heat treatment parameters. The results show that the reaction temperature and phase composition of precursor powder depend on heat treatment atmosphere. Phase assemblage of(Bi,Pb)-2212, AEC, CuO, and small Bi-2201 can be obtained by heat-treated in N2-0.1%O_2 atmosphere. For precursor powder, there is sufficient reaction process at 770℃, and the dimension of Bi-2212 phase increases rapidly with the increase of heat treatment temperature and time. The dimension of AEC phase also increases by extending heat treatment time. As a balance among phase assemblage, dimension of particle and adequate reaction, a reasonable precursor powder can be obtained by heat-treated at 770℃ for 12 h–16 h in N2-0.1%O_2 atmosphere. Critical current of 37-filament Bi-2223 tape is about 120 A, which confirms that these heat treatment parameters are reasonable.展开更多
Employing the advanced relativistic configuration interaction(RCI)combined with the many-body perturbation theory(RMBPT)method,we report energies and lifetime values for the lowest 35 energy levels from the(1s^(2))nl ...Employing the advanced relativistic configuration interaction(RCI)combined with the many-body perturbation theory(RMBPT)method,we report energies and lifetime values for the lowest 35 energy levels from the(1s^(2))nl configurations(where the principal quantum number n=2–6 and the angular quantum number l=0,...,n-1)of lithium-like iron Fe XXIV,as well as complete data on the transition wavelengths,radiative rates,absorption oscillator strengths,and line strengths between the levels.Both the allowed(E1)and forbidden(magnetic dipole M1,magnetic quadrupole M2,and electric quadrupole E2)ones are reported.Through detailed comparisons with previous results,we assess the overall accuracies of present RMBPT results to be likely the most precise ones to date.Configuration interaction effects are found to be very important for the energies and radiative properties for the ion.The present RMBPT results are valuable for spectral line identification,plasma modeling,and diagnosing.展开更多
基金supported by the Basic Research and Strategic Reserve Technology Research Fund Project of China National Petroleum Corporation (Grant No.2021DQ03-14)the National Natu ral Science Foundation of China (Grant No.52204010)Haihe Laboratory of Sustainable Chemical Transformations for financial support。
文摘This work studied the thickening progression mechanism of the silica fume-oil well cement composite system at high temperatures(110-180.C)in order to provide a theoretical guidance for the rational application of silica fume in the cementing engineering.Results showed that silica fume seldom affected the thickening progression of oil well cement slurry at 110-120.C,but when temperature reached above130.C,it would aggravate the bulging degree of thickening curves and significantly extend the thickening time,meanwhile causing the abnormal“temperature-based thickening time reversal”and“dosage-based thickening time reversal”phenomena in the range of 130-160.C and 170-180.C respectively.At 130-160.C,the thickening time of oil well cement slurry was mainly associated with the generation rate of calcium hydroxide(CH)crystal.The introduced silica fume would be attracted to the cement minerals'surface that were hydrating to produce CH and agglomerate together to form an“adsorptive barrier”to hinder further hydration of the inner cement minerals.This“adsorptive barrier”effect strengthened with the rising temperature which extended the thickening time and caused the occurrence of the“temperature-based thickening time reversal”phenomenon.At 170-180.C,the pozzolanic activity of silica fume significantly enhanced and considerable amount of C-S-H was generated,thus the“temperature-based thickening time reversal”vanished and the“dosage-based thickening time reversal”was presented.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFB0902303)the Key Research and Development Program of Shaanxi Province,China(Grant No.2018GY-121N)the National Key Project of Magneto Constrained Fusion Energy Development Program,China(Grant No.2015GB115001)
文摘The phase evolution of Bi-2223 precursor powder prepared by spray pyrolysis method is studied with different heat treatment parameters. The results show that the reaction temperature and phase composition of precursor powder depend on heat treatment atmosphere. Phase assemblage of(Bi,Pb)-2212, AEC, CuO, and small Bi-2201 can be obtained by heat-treated in N2-0.1%O_2 atmosphere. For precursor powder, there is sufficient reaction process at 770℃, and the dimension of Bi-2212 phase increases rapidly with the increase of heat treatment temperature and time. The dimension of AEC phase also increases by extending heat treatment time. As a balance among phase assemblage, dimension of particle and adequate reaction, a reasonable precursor powder can be obtained by heat-treated at 770℃ for 12 h–16 h in N2-0.1%O_2 atmosphere. Critical current of 37-filament Bi-2223 tape is about 120 A, which confirms that these heat treatment parameters are reasonable.
基金Project supported by the Research Foundation for Higher Level Talents of West Anhui University(Grant No.WGKQ2021005)。
文摘Employing the advanced relativistic configuration interaction(RCI)combined with the many-body perturbation theory(RMBPT)method,we report energies and lifetime values for the lowest 35 energy levels from the(1s^(2))nl configurations(where the principal quantum number n=2–6 and the angular quantum number l=0,...,n-1)of lithium-like iron Fe XXIV,as well as complete data on the transition wavelengths,radiative rates,absorption oscillator strengths,and line strengths between the levels.Both the allowed(E1)and forbidden(magnetic dipole M1,magnetic quadrupole M2,and electric quadrupole E2)ones are reported.Through detailed comparisons with previous results,we assess the overall accuracies of present RMBPT results to be likely the most precise ones to date.Configuration interaction effects are found to be very important for the energies and radiative properties for the ion.The present RMBPT results are valuable for spectral line identification,plasma modeling,and diagnosing.
