(Mg,Fe)SiO_(3) is primarily located in the mantle and has a substantial impact on geophysical and geochemical processes.Here,we employ molecular dynamics simulations to investigate the structural and transport propert...(Mg,Fe)SiO_(3) is primarily located in the mantle and has a substantial impact on geophysical and geochemical processes.Here,we employ molecular dynamics simulations to investigate the structural and transport properties of(Mg,Fe)SiO_(3) with varying iron contents at temperatures up to 5000 K and pressures up to 135 GPa.We thoroughly examine the effects of pressure,temperature,and iron content on the bond lengths,coordination numbers,viscosities,and electrical conductivities of(Mg,Fe)SiO_(3).Our calculations indicate that the increase of pressure leads to the shortening of the O-O and Mg-O bond lengths,while the Si-O bond lengths exhibit the initial increase with pressure up to 40 GPa,after which they are almost unchanged.The coordination numbers of Si transition from four-fold to six-fold and eventually reach eight-fold coordination at 135 GPa.The enhanced pressure causes the decrease of the diffusion coefficients and the increase of the viscosities of(Mg,Fe)SiO_(3).The increased temperatures slightly decrease the coordination numbers and viscosities,as well as obviously increase the diffusion coefficients and electrical conductivities of(Mg,Fe)SiO_(3).Additionally,iron doping facilitates the diffusion of Si and O,reduces the viscosities,and enhances the electrical conductivities of(Mg,Fe)SiO_(3).These findings advance fundamental understanding of the structural and transport properties of(Mg,Fe)SiO_(3) under high temperature and high pressure,which provide novel insights for unraveling the complexities of geological processes within the Earth's mantle.展开更多
Cubic boron nitride and hexagonal boron nitride are the two predominant crystalline structures of boron nitride.They can interconvert under varying pressure and temperature conditions.However,this transformation requi...Cubic boron nitride and hexagonal boron nitride are the two predominant crystalline structures of boron nitride.They can interconvert under varying pressure and temperature conditions.However,this transformation requires overcoming significant potential barriers in dynamics,which poses great difficulty in determining the c-BN/h-BN phase boundary.This study used high-pressure in situ differential thermal measurements to ascertain the temperature of h-BN/c-BN conversion within the commonly used pressure range(3-6 GPa)for the industrial synthesis of c-BN to constrain the P-T phase boundary of h-BN/c-BN in the pressure-temperature range as much as possible.Based on the analysis of the experimental data,it is determined that the relationship between pressure and temperature conforms to the following equation:P=a+1/bT.Here,P denotes the pressure(GPa)and T is the temperature(K).The coefficients are a=-3.8±0.8 GPa and b=229.8±17.1 GPa/K.These findings call into question existing high-pressure and high-temperature phase diagrams of boron nitride,which seem to overstate the phase boundary temperature between c-BN and h-BN.The BN phase diagram obtained from this study can provide critical temperature and pressure condition guidance for the industrial synthesis of c-BN,thus optimizing synthesis efficiency and product performance.展开更多
During CO_(2)transportation and storage,metal equipment such as oilfield pipelines suffers from severe CO_(2)corrosion,especially in harsh downhole injection equipment.In this study,we investigated the corrosion behav...During CO_(2)transportation and storage,metal equipment such as oilfield pipelines suffers from severe CO_(2)corrosion,especially in harsh downhole injection equipment.In this study,we investigated the corrosion behavior of oil well tubing in a high-temperature,high-pressure(HTHP)CO_(2)-containing environment.The evolution of the corrosion scale was also examined under different flow regimes.The results reveal a lower corrosion rate at 150℃compared to 80℃under different flow regimes,with localized corrosion intensifying as temperature and rotational speeds(vrs)increase.The temperature also induces the corrosion scale conversion of aragonite-type CaCO_(3)(80℃)to calcite-type CaCO_(3)(150℃).Specifically,the variation of the corrosion rate and the corrosion scale evolution can be attributed to the vortices within the reactor.The intact vortex cells enhance mass transfer while also promoting nucleation and growth of CaCO3.However,when vrsexceeds the critical Reynolds number,the vortex cells are disrupted,resulting in viscous dissipation and a reduced corrosion rate.展开更多
To maintain tight control over rheological properties of high-density water-based drilling fluids, it is essential to understand the factors influencing the theology of water-based drilling fluids. This paper examines...To maintain tight control over rheological properties of high-density water-based drilling fluids, it is essential to understand the factors influencing the theology of water-based drilling fluids. This paper examines temperature effects on the rheological properties of two types of high-density water-based drilling fluids （fresh water-based and brine-based） under high temperature and high pressure （HTHP） with a Fann 50SL rheometer. On the basis of the water-based drilling fluid systems formulated in laboratory, this paper mainly describes the influences of different types and concentration of clay, the content of a colloid stabilizer named GHJ-1 and fluid density on the rheological parameters such as viscosity and shear stress. In addition, the effects of aging temperature and aging time of the drilling fluid on these parameters were also examined. Clay content and proportions for different densities of brine-based fluids were recommended to effectively regulate the rheological properties. Four theological models, the Bingham, power law, Casson and H-B models, were employed to fit the rheological parameters. It turns out that the H-B model was the best one to describe the rheological properties of the high-density drilling fluid under HTHP conditions and power law model produced the worst fit. In addition, a new mathematical model that describes the apparent viscosity as a function of temperature and pressure was established and has been applied on site.展开更多
In recent years, there has been an increase of interest in the flow of gases at relatively high pressures and high temperatures. Hydrodynamic calculation of the energy losses in the flow of gases in conduits, as well ...In recent years, there has been an increase of interest in the flow of gases at relatively high pressures and high temperatures. Hydrodynamic calculation of the energy losses in the flow of gases in conduits, as well as through the porous media constituting natural petroleum reservoirs, requires knowledge of the viscosity of the fluid at the pressure and temperature involved. Although there are numerous publications concerning the viscosity of methane at atmospheric pressure, there appears to be little information available relating to the effect of pressure and temperature upon the viscosity. A survey of the literature reveals that the disagreements between published data on the viscosity of methane are common and that most investigations have been conducted over restricted temperature and pressure ranges. Experimental viscosity data for methane are presented for temperatures from 320 to 400 K and pressures from 3000 to 140000 kPa by using falling body viscometer. A summary is given to evaluate the available data for methane, and a comparison is presented for that data common to the experimental range reported in this paper. A new and reliable correlation for methane gas viscosity is presented. Predicted values are given for temperatures up to 400 K and pressures up to 140000 kPa with Average Absolute Percent Relative Error （EABS） of 0.794.展开更多
A series of diamond crystals doped with hydrogen is successfully synthesized using LiH as the hydrogen source in a catalyst-carbon system at a pressure of 6.0 GPa and temperature ranging from 1255 C to 1350 C.It is sh...A series of diamond crystals doped with hydrogen is successfully synthesized using LiH as the hydrogen source in a catalyst-carbon system at a pressure of 6.0 GPa and temperature ranging from 1255 C to 1350 C.It is shown that the high temperature plays a key role in the incorporation of hydrogen atoms during diamond crystallization.Fourier transform infrared micro-spectroscopy reveals that most of the hydrogen atoms in the synthesized diamond are incorporated into the crystal structure as sp 3-CH 2-symmetric（2850 cm-1） and sp 3 CH 2-antisymmetric vibrations（2920 cm-1）.The intensities of these peaks increase gradually with an increase in the content of the hydrogen source in the catalyst.The incorporation of hydrogen impurity leads to a significant shift towards higher frequencies of the Raman peak from 1332.06 cm-1 to 1333.05 cm-1 and gives rise to some compressive stress in the diamond crystal lattice.Furthermore,hydrogen to carbon bonds are evident in the annealed diamond,indicating that the bonds that remain throughout the annealing process and the vibration frequencies centred at 2850 and 2920 cm-1 have no observable shift.Therefore,we suggest that the sp 3 C-H bond is rather stable in diamond crystals.展开更多
Polycrystalline cubic boron nitride(Pc BN)compacts,using the mixture of submicron cubic boron nitride(c BN)powder and hexagonal BN(h BN)powder as starting materials,were sintered at pressures of 6.5–10.0 GPa and temp...Polycrystalline cubic boron nitride(Pc BN)compacts,using the mixture of submicron cubic boron nitride(c BN)powder and hexagonal BN(h BN)powder as starting materials,were sintered at pressures of 6.5–10.0 GPa and temperature of1750℃without additives.In this paper,the sintering behavior and mechanical properties of samples were investigated.The XRD patterns of samples reveal that single cubic phase was observed when the sintering pressure exceeded 7.5 GPa and h BN contents ranged from 20 vol.%to 24 vol.%,which is ascribed to like-internal pressure generated at grain-to-grain contact under high pressure.Transmission electron microscopy(TEM)analysis shows that after high pressure and high temperature(HPHT)treatments,the submicron c BN grains abounded with high-density nanotwins and stacking faults,and this contributed to the outstanding mechanical properties of Pc BN.The pure bulk Pc BN that was obtained at 7.7 GPa/1750℃possessed the outstanding properties,including a high Vickers hardness(~61.5 GPa),thermal stability(~1290℃in air),and high density(~3.46 g/cm^(3)).展开更多
This paper reprots that with Ni-based catalyst/solvent and with a dopant of NAN3, large green single crystal diamonds with perfect shape are successfully synthesized by temperature gradient method under high pressure ...This paper reprots that with Ni-based catalyst/solvent and with a dopant of NAN3, large green single crystal diamonds with perfect shape are successfully synthesized by temperature gradient method under high pressure and high temperature in a China-type cubic anvil high-pressure apparatus （SPD-6 × 1200）, and the highest nitrogen concentration reaches approximately 121-1257 ppm calculated by infrared absorption spectra. The synthesis conditions are about 5.5 CPa and 1240-1300 ℃. The growth behaviour of diamond with high-nitrogen concentration is investigated in detail. The results show that, with increasing the content of NaN3 added in synthesis system, the width of synthesis temperature region for growth high-quality diamonds becomes narrower, and the morphology of diamond crystal is changed from cube-octahedral to octahedral at same temperature and pressure, the crystal growth rate is slowed down, nevertheless, the nitrogen concentration doped in synthetic diamond increases.展开更多
This paper reports the crystal growth of diamond from the Fe Ni–Carbon system with additive phosphorus at high pressures and high temperatures of 5.4–5.8 GPa and 1280–1360°C. Attributed to the presence of addi...This paper reports the crystal growth of diamond from the Fe Ni–Carbon system with additive phosphorus at high pressures and high temperatures of 5.4–5.8 GPa and 1280–1360°C. Attributed to the presence of additive phosphorus,the pressure and temperature condition, morphology, and color of diamond crystals change obviously. The pressure and temperature condition of diamond growth increases evidently with the increase of additive phosphorus content and results in the moving up of the V-shape region. The surfaces of the diamonds also become coarse as the additive phosphorus added in the growth system. Raman spectra indicate that diamonds grown from the Fe Ni-phosphorus-carbon system have more crystal defects and impurities. This work provides a new way to enrich the doping of diamond and improve the experimental exploration for future material applications.展开更多
This study investigated the possibility of using high-temperature and high-pressure schedules to treat Pinus massoniana wood in order to reduce its oil content. We discuss the effect of drying temperature, absolute pr...This study investigated the possibility of using high-temperature and high-pressure schedules to treat Pinus massoniana wood in order to reduce its oil content. We discuss the effect of drying temperature, absolute pressure and the holding time on the deresination ratio in R massoniana wood and establish a model for the deresination ratio as a function of drying temperature, absolute pressure and holding time. The results show that the deresination ratio in- creased from 7.14% to 87.04% when the temperature increased from 150 to 200℃, the absolute pressure from 0.1 to 0.6 MPa and the holding time from 1 to 3 h. The optimal model for the deresination ratio （Y） with drying temperature （t）, absolute pressure （p） and holding time （r） is： Y = 0.284t ＋ 113.424p ＋ 3.518r - 42.486, with a coefficient of determina- tion （R2） of 0.930. Compared with drying temperature and holding time, absolute pressure plays the more significant role in the deresination process. This study could provide a theoretical basis to the practical production of R massoniana wood.展开更多
The synthesis of diamond single crystal in the Fe64Ni36-C system with h-BN additive is investigated at pressure 6.5 GPa and temperature range of 1300-1400℃. The color of the obtained diamond crystals translates from ...The synthesis of diamond single crystal in the Fe64Ni36-C system with h-BN additive is investigated at pressure 6.5 GPa and temperature range of 1300-1400℃. The color of the obtained diamond crystals translates from yellow to dark green with increasing the h-BN addition. Fourier-transform infrared （FTIR） results indicate that sp2 hybridization B-N-B and B-N structures generate when the additive content reaches a certain value in the system. The two peaks are located at 745 and 1425cm-1, respectively. Fhrthermore, the FTIR characteristic peak resulting from nitrogen pairs is noticed and it tends to vanish when the h-BN addition reaches 1.1 wt%. Furthermore, Raman peak of the synthesized diamond shifts down to a lower wavenumber with increasing the h-BN ~ddition content in the synthesis system.展开更多
We synthesized and investigated the boron-doped and boron/nitrogen co-doped large single-crystal diamonds grown under high pressure and high temperature(HPHT) conditions(5.9 GPa and 1290℃). The optical and electrical...We synthesized and investigated the boron-doped and boron/nitrogen co-doped large single-crystal diamonds grown under high pressure and high temperature(HPHT) conditions(5.9 GPa and 1290℃). The optical and electrical properties and surface characterization of the synthetic diamonds were observed and studied. Incorporation of nitrogen significantly changed the growth trace on surface of boron-containing diamonds. X-ray photoelectron spectroscopy(XPS) measurements showed good evident that nitrogen atoms successfully incorporate into the boron-rich diamond lattice and bond with carbon atoms. Raman spectra showed differences on the as-grown surfaces and interior between boron-doped and boron/nitrogen co-doped diamonds. Fourier transform infrared spectroscopy(FTIR) measurements indicated that the nitrogen incorporation significantly decreases the boron acceptor concentration in diamonds. Hall measurements at room temperature showed that the carriers concentration of the co-doped diamonds decreases, and the mobility increases obviously. The highest hole mobility of sample BNDD-1 reached 980 cm^(2)·V^(-1)·s^(-1), possible reasons were discussed in the paper.展开更多
The synergistic influences of boron,oxygen,and titanium on growing large single-crystal diamonds are studied using different concentrations of B_(2)O_(3) in a solvent-carbon system under 5.5 GPa-5.7 GPa and 1300℃-150...The synergistic influences of boron,oxygen,and titanium on growing large single-crystal diamonds are studied using different concentrations of B_(2)O_(3) in a solvent-carbon system under 5.5 GPa-5.7 GPa and 1300℃-1500℃.It is found that the boron atoms are difficult to enter into the crystal when boron and oxygen impurities are doped using B_(2)O_(3) without the addition of Ti atoms.However,high boron content is achieved in the doped diamonds that were synthesized with the addition of Ti.Additionally,boron-oxygen complexes are found on the surface of the crystal,and oxygen-related impurities appear in the crystal interior when Ti atoms are added into the FeNi-C system.The results show that the introduction of Ti atoms into the synthesis cavity can effectively control the number of boron atoms and the number of oxygen atoms in the crystal.This has important scientific significance not only for understanding the synergistic influence of boron,oxygen,and titanium atoms on the growth of diamond in the earth,but also for preparing the high-concentration boron or oxygen containing semiconductor diamond technologies.展开更多
We will build a cubic anvil cell （CAC） apparatus for high-pressure and low-temperature physical property measurements in the synergic extreme condition user facility （SECUF）. In this article, we first introduce th...We will build a cubic anvil cell （CAC） apparatus for high-pressure and low-temperature physical property measurements in the synergic extreme condition user facility （SECUF）. In this article, we first introduce the operating principle, the development history, and the current status of the CAC apparatus, and subsequently describe the design plan and technical targets for the CAC in SECUF. We will demonstrate the unique advantages of CAC, i.e., excellent pressure homogeneity and large hydrostatic pressure capacity, by summarizing our recent research progresses using CAC. Finally, we conclude by providing some perspectives on the applications of CAC in the related research fields.展开更多
The properties of urea under high pressure and high temperature(HPHT) are studied using a China-type large volume cubic high-presentation apparatus(CHPA)(SPD-6 × 600).The samples are characterized by scanning ele...The properties of urea under high pressure and high temperature(HPHT) are studied using a China-type large volume cubic high-presentation apparatus(CHPA)(SPD-6 × 600).The samples are characterized by scanning electron microscopy(SEM), x-ray diffraction(XRD), and Raman spectroscopy.By directly observing the macroscopic morphology of urea with SEM, it is confirmed that the melting point of urea rises with the increase of pressure.The XRD patterns of urea residues derived under different pressures show that the thermal stability of urea also increases with the increase of pressure.The XRD pattern of the urea residue confirms the presence of C3H5N5O(ammeline) in the residue.A new peak emerges at 21.80°, which is different from any peak of all urea pyrolysis products under normal pressure.A more pronounced peak appears at 708 cm^-1 in the Raman spectrum, which is produced by C-H off-plane bending.It is determined that the urea will produce a new substance with a C-H bond under HPHT, and the assessment of this substance requires further experiments.展开更多
We synthesized C60 quantum dots(QDs) with a uniform size by a modified ultrasonic process and studied its polymerization under high pressure and high temperature(HPHT).Raman spectra showed that a phase assemblage of a...We synthesized C60 quantum dots(QDs) with a uniform size by a modified ultrasonic process and studied its polymerization under high pressure and high temperature(HPHT).Raman spectra showed that a phase assemblage of a dimer(D) phase(62 vol%) and a one-dimensional chain orthorhombic(O) phase(38 vol%) was obtained at 1.5 GPa and 300℃.At 2.0 GPa and 430℃,the proportion of the O phase increased to 46 vol%,while the corresponding D phase decreased to 54 vol%.Compared with bulk and nanosized C60,C60 QDs cannot easily form a high-dimensional polymeric structure.This fact is probably caused by the small particle size,orientation of the disordered structure of C60 QDs,and the barrier of oxide function groups between C60 molecules.Our studies enhance the understanding of the polymerization behavior of low-dimension C60 nanomaterials under HPHT conditions.展开更多
The isothermal bulk modulus and its first pressure derivative of NaCl are investigated using the classical molecular dynamics method and the quasi-harmonic Debye model. To ensure faithful molecular dynamics simulation...The isothermal bulk modulus and its first pressure derivative of NaCl are investigated using the classical molecular dynamics method and the quasi-harmonic Debye model. To ensure faithful molecular dynamics simulations, two types of potentials, the shell-model （SM） potential and the two-body rigid-ion Born-Mayer-Huggins-FumiqTosi （BMHFT） potential, are fully tested. Compared with the SM potential based simulation, the molecular dynamics simulation with the BMHFT potential is very successful in reproducing accurately the measured bulk modulus of NaCl. Particular attention is paid to the prediction of the isothermal bulk modulus and its first pressure derivative using the reliable potential and to the comparison of the SM and the BMHFT potentials based molecular dynamics simulations with the quasi-harmonic Debye model. The properties of NaCl in the pressure range of 0-30 GPa at temperatures up to the melting temperature of 1050 K are investigated.展开更多
In this paper,we report on the influence of annealing treatment on as-grown Ib-type diamond crystal under high pressure and high temperature in a china-type cubic anvil high-pressure apparatus.Experiments are carried ...In this paper,we report on the influence of annealing treatment on as-grown Ib-type diamond crystal under high pressure and high temperature in a china-type cubic anvil high-pressure apparatus.Experiments are carried out at a pressure of 7.0 GPa and temperatures ranging from 1700 C to 1900 C for 1 h.Annealing treatment of the diamond crystal shows that the aggregation rate constant of nitrogen atoms in the as-grown Ib-type diamond crystal strongly depends on diamond morphology and annealing temperature.The aggregation rate constant of nitrogen remarkably increases with the increase of annealing temperature and its value in octahedral diamond is much higher than that in cubic diamond annealed at the same temperature.The colour of octahedral diamond crystal is obviously reduced from yellow to nearly colorless after annealing treatment for 1 h at 1900 C,which is induced by nitrogen aggregation in a diamond lattice.The extent of nitrogen aggregation in an annealed diamond could approach approximately 98% indicated from the infrared absorption spectra.The micro-Raman spectrum reveals that the annealing treatment can improve the crystalline quality of Ib-type diamond characterized by a half width at full maximum at first order Raman peak,and therefore the annealed diamond crystals exhibit nearly the same properties as the natural IaA-type diamond stones of high quality in the Raman measurements.展开更多
Diamond crystal crystallized in Fe–Mg–C system with Archimedes buoyancy as a driving force is established under high pressure and high temperature conditions. The experimental results indicate that the addition of t...Diamond crystal crystallized in Fe–Mg–C system with Archimedes buoyancy as a driving force is established under high pressure and high temperature conditions. The experimental results indicate that the addition of the Mg element results in the nitrogen concentration increasing from 87 ppm to 271 ppm in the diamond structure. The occurrence of the {100}plane reveals that the surface character is remarkably changed due to the addition of Mg. Micro-Raman spectra indicate that the half width of full maximum is in a range of 3.01 cm^-1–3.26 cm^-1, implying an extremely good quality of diamond specimens in crystallization.展开更多
We briefly introduce a new high-pressure transport measurement system integrated with low temperature and magnetic field that is being established as one of the user experimental stations of the Synergetic Extreme Con...We briefly introduce a new high-pressure transport measurement system integrated with low temperature and magnetic field that is being established as one of the user experimental stations of the Synergetic Extreme Condition User Facilities in the Huairou District of Beijing, China. To demonstrate the capabilities of the system for condensed matter research, the emergence of some pressure-induced phenomena and physics related to superconductivity found previously is also introduced, and then a perspective for such an advanced high-pressure system is presented.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12174352 and 12111530103)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(Grant No.G1323523065)。
文摘(Mg,Fe)SiO_(3) is primarily located in the mantle and has a substantial impact on geophysical and geochemical processes.Here,we employ molecular dynamics simulations to investigate the structural and transport properties of(Mg,Fe)SiO_(3) with varying iron contents at temperatures up to 5000 K and pressures up to 135 GPa.We thoroughly examine the effects of pressure,temperature,and iron content on the bond lengths,coordination numbers,viscosities,and electrical conductivities of(Mg,Fe)SiO_(3).Our calculations indicate that the increase of pressure leads to the shortening of the O-O and Mg-O bond lengths,while the Si-O bond lengths exhibit the initial increase with pressure up to 40 GPa,after which they are almost unchanged.The coordination numbers of Si transition from four-fold to six-fold and eventually reach eight-fold coordination at 135 GPa.The enhanced pressure causes the decrease of the diffusion coefficients and the increase of the viscosities of(Mg,Fe)SiO_(3).The increased temperatures slightly decrease the coordination numbers and viscosities,as well as obviously increase the diffusion coefficients and electrical conductivities of(Mg,Fe)SiO_(3).Additionally,iron doping facilitates the diffusion of Si and O,reduces the viscosities,and enhances the electrical conductivities of(Mg,Fe)SiO_(3).These findings advance fundamental understanding of the structural and transport properties of(Mg,Fe)SiO_(3) under high temperature and high pressure,which provide novel insights for unraveling the complexities of geological processes within the Earth's mantle.
基金supported by the National Key R&D Program of China(Grant No.2023YFA1406200).
文摘Cubic boron nitride and hexagonal boron nitride are the two predominant crystalline structures of boron nitride.They can interconvert under varying pressure and temperature conditions.However,this transformation requires overcoming significant potential barriers in dynamics,which poses great difficulty in determining the c-BN/h-BN phase boundary.This study used high-pressure in situ differential thermal measurements to ascertain the temperature of h-BN/c-BN conversion within the commonly used pressure range(3-6 GPa)for the industrial synthesis of c-BN to constrain the P-T phase boundary of h-BN/c-BN in the pressure-temperature range as much as possible.Based on the analysis of the experimental data,it is determined that the relationship between pressure and temperature conforms to the following equation:P=a+1/bT.Here,P denotes the pressure(GPa)and T is the temperature(K).The coefficients are a=-3.8±0.8 GPa and b=229.8±17.1 GPa/K.These findings call into question existing high-pressure and high-temperature phase diagrams of boron nitride,which seem to overstate the phase boundary temperature between c-BN and h-BN.The BN phase diagram obtained from this study can provide critical temperature and pressure condition guidance for the industrial synthesis of c-BN,thus optimizing synthesis efficiency and product performance.
基金supported by the National Natural Science Foundation in China(52434002,42176209,52074339)the Natural Science Foundation of Shandong Province(ZR2021ME007)+1 种基金the Opening Fund of Shandong Key Laboratory of Oilfield Chemistrythe Fundamental Research Funds for the Central Universities(19CX05006A)。
文摘During CO_(2)transportation and storage,metal equipment such as oilfield pipelines suffers from severe CO_(2)corrosion,especially in harsh downhole injection equipment.In this study,we investigated the corrosion behavior of oil well tubing in a high-temperature,high-pressure(HTHP)CO_(2)-containing environment.The evolution of the corrosion scale was also examined under different flow regimes.The results reveal a lower corrosion rate at 150℃compared to 80℃under different flow regimes,with localized corrosion intensifying as temperature and rotational speeds(vrs)increase.The temperature also induces the corrosion scale conversion of aragonite-type CaCO_(3)(80℃)to calcite-type CaCO_(3)(150℃).Specifically,the variation of the corrosion rate and the corrosion scale evolution can be attributed to the vortices within the reactor.The intact vortex cells enhance mass transfer while also promoting nucleation and growth of CaCO3.However,when vrsexceeds the critical Reynolds number,the vortex cells are disrupted,resulting in viscous dissipation and a reduced corrosion rate.
文摘To maintain tight control over rheological properties of high-density water-based drilling fluids, it is essential to understand the factors influencing the theology of water-based drilling fluids. This paper examines temperature effects on the rheological properties of two types of high-density water-based drilling fluids （fresh water-based and brine-based） under high temperature and high pressure （HTHP） with a Fann 50SL rheometer. On the basis of the water-based drilling fluid systems formulated in laboratory, this paper mainly describes the influences of different types and concentration of clay, the content of a colloid stabilizer named GHJ-1 and fluid density on the rheological parameters such as viscosity and shear stress. In addition, the effects of aging temperature and aging time of the drilling fluid on these parameters were also examined. Clay content and proportions for different densities of brine-based fluids were recommended to effectively regulate the rheological properties. Four theological models, the Bingham, power law, Casson and H-B models, were employed to fit the rheological parameters. It turns out that the H-B model was the best one to describe the rheological properties of the high-density drilling fluid under HTHP conditions and power law model produced the worst fit. In addition, a new mathematical model that describes the apparent viscosity as a function of temperature and pressure was established and has been applied on site.
基金supported by the Research Institute of Petroleum Industry-Kermanshah Campus.
文摘In recent years, there has been an increase of interest in the flow of gases at relatively high pressures and high temperatures. Hydrodynamic calculation of the energy losses in the flow of gases in conduits, as well as through the porous media constituting natural petroleum reservoirs, requires knowledge of the viscosity of the fluid at the pressure and temperature involved. Although there are numerous publications concerning the viscosity of methane at atmospheric pressure, there appears to be little information available relating to the effect of pressure and temperature upon the viscosity. A survey of the literature reveals that the disagreements between published data on the viscosity of methane are common and that most investigations have been conducted over restricted temperature and pressure ranges. Experimental viscosity data for methane are presented for temperatures from 320 to 400 K and pressures from 3000 to 140000 kPa by using falling body viscometer. A summary is given to evaluate the available data for methane, and a comparison is presented for that data common to the experimental range reported in this paper. A new and reliable correlation for methane gas viscosity is presented. Predicted values are given for temperatures up to 400 K and pressures up to 140000 kPa with Average Absolute Percent Relative Error （EABS） of 0.794.
基金Project supported by the National Natural Science Foundation of China (Grant No. 51172089)the Program for New Century Excellent Talents in University of China
文摘A series of diamond crystals doped with hydrogen is successfully synthesized using LiH as the hydrogen source in a catalyst-carbon system at a pressure of 6.0 GPa and temperature ranging from 1255 C to 1350 C.It is shown that the high temperature plays a key role in the incorporation of hydrogen atoms during diamond crystallization.Fourier transform infrared micro-spectroscopy reveals that most of the hydrogen atoms in the synthesized diamond are incorporated into the crystal structure as sp 3-CH 2-symmetric（2850 cm-1） and sp 3 CH 2-antisymmetric vibrations（2920 cm-1）.The intensities of these peaks increase gradually with an increase in the content of the hydrogen source in the catalyst.The incorporation of hydrogen impurity leads to a significant shift towards higher frequencies of the Raman peak from 1332.06 cm-1 to 1333.05 cm-1 and gives rise to some compressive stress in the diamond crystal lattice.Furthermore,hydrogen to carbon bonds are evident in the annealed diamond,indicating that the bonds that remain throughout the annealing process and the vibration frequencies centred at 2850 and 2920 cm-1 have no observable shift.Therefore,we suggest that the sp 3 C-H bond is rather stable in diamond crystals.
文摘Polycrystalline cubic boron nitride(Pc BN)compacts,using the mixture of submicron cubic boron nitride(c BN)powder and hexagonal BN(h BN)powder as starting materials,were sintered at pressures of 6.5–10.0 GPa and temperature of1750℃without additives.In this paper,the sintering behavior and mechanical properties of samples were investigated.The XRD patterns of samples reveal that single cubic phase was observed when the sintering pressure exceeded 7.5 GPa and h BN contents ranged from 20 vol.%to 24 vol.%,which is ascribed to like-internal pressure generated at grain-to-grain contact under high pressure.Transmission electron microscopy(TEM)analysis shows that after high pressure and high temperature(HPHT)treatments,the submicron c BN grains abounded with high-density nanotwins and stacking faults,and this contributed to the outstanding mechanical properties of Pc BN.The pure bulk Pc BN that was obtained at 7.7 GPa/1750℃possessed the outstanding properties,including a high Vickers hardness(~61.5 GPa),thermal stability(~1290℃in air),and high density(~3.46 g/cm^(3)).
基金Project supported by the National Natural Science Foundation of China (Grant No. 50572032)
文摘This paper reprots that with Ni-based catalyst/solvent and with a dopant of NAN3, large green single crystal diamonds with perfect shape are successfully synthesized by temperature gradient method under high pressure and high temperature in a China-type cubic anvil high-pressure apparatus （SPD-6 × 1200）, and the highest nitrogen concentration reaches approximately 121-1257 ppm calculated by infrared absorption spectra. The synthesis conditions are about 5.5 CPa and 1240-1300 ℃. The growth behaviour of diamond with high-nitrogen concentration is investigated in detail. The results show that, with increasing the content of NaN3 added in synthesis system, the width of synthesis temperature region for growth high-quality diamonds becomes narrower, and the morphology of diamond crystal is changed from cube-octahedral to octahedral at same temperature and pressure, the crystal growth rate is slowed down, nevertheless, the nitrogen concentration doped in synthetic diamond increases.
基金supported by the Doctoral Fund of Henan Polytechnic University,China(Grant Nos.B2013-013 and B2013-044)the Research Projects of Science and Technology of the Education Department of Henan Province,China(Grant Nos.14B430026 and 12A430010)
文摘This paper reports the crystal growth of diamond from the Fe Ni–Carbon system with additive phosphorus at high pressures and high temperatures of 5.4–5.8 GPa and 1280–1360°C. Attributed to the presence of additive phosphorus,the pressure and temperature condition, morphology, and color of diamond crystals change obviously. The pressure and temperature condition of diamond growth increases evidently with the increase of additive phosphorus content and results in the moving up of the V-shape region. The surfaces of the diamonds also become coarse as the additive phosphorus added in the growth system. Raman spectra indicate that diamonds grown from the Fe Ni-phosphorus-carbon system have more crystal defects and impurities. This work provides a new way to enrich the doping of diamond and improve the experimental exploration for future material applications.
基金supported by the Beijing Jointly Building Project of Key Discipline-the High Efficiency Utilization of Fast Growing Wood
文摘This study investigated the possibility of using high-temperature and high-pressure schedules to treat Pinus massoniana wood in order to reduce its oil content. We discuss the effect of drying temperature, absolute pressure and the holding time on the deresination ratio in R massoniana wood and establish a model for the deresination ratio as a function of drying temperature, absolute pressure and holding time. The results show that the deresination ratio in- creased from 7.14% to 87.04% when the temperature increased from 150 to 200℃, the absolute pressure from 0.1 to 0.6 MPa and the holding time from 1 to 3 h. The optimal model for the deresination ratio （Y） with drying temperature （t）, absolute pressure （p） and holding time （r） is： Y = 0.284t ＋ 113.424p ＋ 3.518r - 42.486, with a coefficient of determina- tion （R2） of 0.930. Compared with drying temperature and holding time, absolute pressure plays the more significant role in the deresination process. This study could provide a theoretical basis to the practical production of R massoniana wood.
基金Supported by the National Natural Science Foundation of China under Grant No 51172089the Natural Science Foundation of Guizhou Province Education Department under Grant No KY[2013]183the Natural Science Foundation of Guizhou Province Science and Technology Agency under Grant Nos LH[2015]7232 and LH[2015]7228
文摘The synthesis of diamond single crystal in the Fe64Ni36-C system with h-BN additive is investigated at pressure 6.5 GPa and temperature range of 1300-1400℃. The color of the obtained diamond crystals translates from yellow to dark green with increasing the h-BN addition. Fourier-transform infrared （FTIR） results indicate that sp2 hybridization B-N-B and B-N structures generate when the additive content reaches a certain value in the system. The two peaks are located at 745 and 1425cm-1, respectively. Fhrthermore, the FTIR characteristic peak resulting from nitrogen pairs is noticed and it tends to vanish when the h-BN addition reaches 1.1 wt%. Furthermore, Raman peak of the synthesized diamond shifts down to a lower wavenumber with increasing the h-BN ~ddition content in the synthesis system.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51772120, 11704340, 11604246, and 11865005)the Scientific and Technological Project in Henan Province+2 种基金China (Grant No. 202102210198)the Natural Science Foundation of Guangxi (China)(Grant No. 2018GXNSFAA281024)Doctor Start-up Foundation of Guangxi University of Science and Technology (Grant No. 20Z38)。
文摘We synthesized and investigated the boron-doped and boron/nitrogen co-doped large single-crystal diamonds grown under high pressure and high temperature(HPHT) conditions(5.9 GPa and 1290℃). The optical and electrical properties and surface characterization of the synthetic diamonds were observed and studied. Incorporation of nitrogen significantly changed the growth trace on surface of boron-containing diamonds. X-ray photoelectron spectroscopy(XPS) measurements showed good evident that nitrogen atoms successfully incorporate into the boron-rich diamond lattice and bond with carbon atoms. Raman spectra showed differences on the as-grown surfaces and interior between boron-doped and boron/nitrogen co-doped diamonds. Fourier transform infrared spectroscopy(FTIR) measurements indicated that the nitrogen incorporation significantly decreases the boron acceptor concentration in diamonds. Hall measurements at room temperature showed that the carriers concentration of the co-doped diamonds decreases, and the mobility increases obviously. The highest hole mobility of sample BNDD-1 reached 980 cm^(2)·V^(-1)·s^(-1), possible reasons were discussed in the paper.
基金supported by the National Natural Science Foundation of China(Grant Nos.11804305,12004341,11704340,and 12004342)the Key Research Project of Higher Education Institution of Henan Province,China(Grant No.19A140006)+2 种基金the Scientific and Technological Project in Henan Province,China(Grant No.202102210198)the Natural Science Foundation of Chongqing,China(Grant No.cstc2019jcyjmsxmX0391)the Science and Technology Research Program of Chongqing Municipal Education Commission,China(Grant No.KJQN201901405)。
文摘The synergistic influences of boron,oxygen,and titanium on growing large single-crystal diamonds are studied using different concentrations of B_(2)O_(3) in a solvent-carbon system under 5.5 GPa-5.7 GPa and 1300℃-1500℃.It is found that the boron atoms are difficult to enter into the crystal when boron and oxygen impurities are doped using B_(2)O_(3) without the addition of Ti atoms.However,high boron content is achieved in the doped diamonds that were synthesized with the addition of Ti.Additionally,boron-oxygen complexes are found on the surface of the crystal,and oxygen-related impurities appear in the crystal interior when Ti atoms are added into the FeNi-C system.The results show that the introduction of Ti atoms into the synthesis cavity can effectively control the number of boron atoms and the number of oxygen atoms in the crystal.This has important scientific significance not only for understanding the synergistic influence of boron,oxygen,and titanium atoms on the growth of diamond in the earth,but also for preparing the high-concentration boron or oxygen containing semiconductor diamond technologies.
基金Project supported by the National Natural Science Foundation of China(Grant No.11574377)the State Key Development Program for Basic Research of China(Grant Nos.2018YFA0305700 and 2014CB921500)+1 种基金the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(Grant No.QYZDB-SSW-SLH013)the JSPS KAKENHI(Grant No.15H03681)
文摘We will build a cubic anvil cell （CAC） apparatus for high-pressure and low-temperature physical property measurements in the synergic extreme condition user facility （SECUF）. In this article, we first introduce the operating principle, the development history, and the current status of the CAC apparatus, and subsequently describe the design plan and technical targets for the CAC in SECUF. We will demonstrate the unique advantages of CAC, i.e., excellent pressure homogeneity and large hydrostatic pressure capacity, by summarizing our recent research progresses using CAC. Finally, we conclude by providing some perspectives on the applications of CAC in the related research fields.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51772120,11604246,51872112,and 11804305)the Project of Jilin Science and Technology Development Plan,China(Grant No.20180201079GX)
文摘The properties of urea under high pressure and high temperature(HPHT) are studied using a China-type large volume cubic high-presentation apparatus(CHPA)(SPD-6 × 600).The samples are characterized by scanning electron microscopy(SEM), x-ray diffraction(XRD), and Raman spectroscopy.By directly observing the macroscopic morphology of urea with SEM, it is confirmed that the melting point of urea rises with the increase of pressure.The XRD patterns of urea residues derived under different pressures show that the thermal stability of urea also increases with the increase of pressure.The XRD pattern of the urea residue confirms the presence of C3H5N5O(ammeline) in the residue.A new peak emerges at 21.80°, which is different from any peak of all urea pyrolysis products under normal pressure.A more pronounced peak appears at 708 cm^-1 in the Raman spectrum, which is produced by C-H off-plane bending.It is determined that the urea will produce a new substance with a C-H bond under HPHT, and the assessment of this substance requires further experiments.
基金Project supported by the National Key R&D Program of China(Grant No.2018YFA0305900)the National Natural Science Foundation of China(Grant Nos.11634004 and 11404036)+2 种基金“the 13th Five-year”Planning Project of Jilin Provincial Education Department Foundation,China(Grant No.20190504)JLU Science and Technology Innovative Research Team,China(Grant No.2017TD-01)Natural Science Foundation of Chang-chun Normal University,China(Grant No.2014-001).
文摘We synthesized C60 quantum dots(QDs) with a uniform size by a modified ultrasonic process and studied its polymerization under high pressure and high temperature(HPHT).Raman spectra showed that a phase assemblage of a dimer(D) phase(62 vol%) and a one-dimensional chain orthorhombic(O) phase(38 vol%) was obtained at 1.5 GPa and 300℃.At 2.0 GPa and 430℃,the proportion of the O phase increased to 46 vol%,while the corresponding D phase decreased to 54 vol%.Compared with bulk and nanosized C60,C60 QDs cannot easily form a high-dimensional polymeric structure.This fact is probably caused by the small particle size,orientation of the disordered structure of C60 QDs,and the barrier of oxide function groups between C60 molecules.Our studies enhance the understanding of the polymerization behavior of low-dimension C60 nanomaterials under HPHT conditions.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11164013 and 11064007)the Natural Science Foundation of Gansu Province,China (Grant Nos. 014RJZA046 and 0803RJZA106)the Program for Longyuan Youth Innovation Talents of the Gansu Province,China
文摘The isothermal bulk modulus and its first pressure derivative of NaCl are investigated using the classical molecular dynamics method and the quasi-harmonic Debye model. To ensure faithful molecular dynamics simulations, two types of potentials, the shell-model （SM） potential and the two-body rigid-ion Born-Mayer-Huggins-FumiqTosi （BMHFT） potential, are fully tested. Compared with the SM potential based simulation, the molecular dynamics simulation with the BMHFT potential is very successful in reproducing accurately the measured bulk modulus of NaCl. Particular attention is paid to the prediction of the isothermal bulk modulus and its first pressure derivative using the reliable potential and to the comparison of the SM and the BMHFT potentials based molecular dynamics simulations with the quasi-harmonic Debye model. The properties of NaCl in the pressure range of 0-30 GPa at temperatures up to the melting temperature of 1050 K are investigated.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 50572032 and 50731006)
文摘In this paper,we report on the influence of annealing treatment on as-grown Ib-type diamond crystal under high pressure and high temperature in a china-type cubic anvil high-pressure apparatus.Experiments are carried out at a pressure of 7.0 GPa and temperatures ranging from 1700 C to 1900 C for 1 h.Annealing treatment of the diamond crystal shows that the aggregation rate constant of nitrogen atoms in the as-grown Ib-type diamond crystal strongly depends on diamond morphology and annealing temperature.The aggregation rate constant of nitrogen remarkably increases with the increase of annealing temperature and its value in octahedral diamond is much higher than that in cubic diamond annealed at the same temperature.The colour of octahedral diamond crystal is obviously reduced from yellow to nearly colorless after annealing treatment for 1 h at 1900 C,which is induced by nitrogen aggregation in a diamond lattice.The extent of nitrogen aggregation in an annealed diamond could approach approximately 98% indicated from the infrared absorption spectra.The micro-Raman spectrum reveals that the annealing treatment can improve the crystalline quality of Ib-type diamond characterized by a half width at full maximum at first order Raman peak,and therefore the annealed diamond crystals exhibit nearly the same properties as the natural IaA-type diamond stones of high quality in the Raman measurements.
基金supported by the Natural Science Foundation of Inner Mongolia Autonomous Region,China(Grant No.2013MS0809)the Open Project of Key Laboratory of Functional Materials Physics and Chemistry(Jilin Normal University)of the Ministry of Education of China(Grant No.201608)
文摘Diamond crystal crystallized in Fe–Mg–C system with Archimedes buoyancy as a driving force is established under high pressure and high temperature conditions. The experimental results indicate that the addition of the Mg element results in the nitrogen concentration increasing from 87 ppm to 271 ppm in the diamond structure. The occurrence of the {100}plane reveals that the surface character is remarkably changed due to the addition of Mg. Micro-Raman spectra indicate that the half width of full maximum is in a range of 3.01 cm^-1–3.26 cm^-1, implying an extremely good quality of diamond specimens in crystallization.
文摘We briefly introduce a new high-pressure transport measurement system integrated with low temperature and magnetic field that is being established as one of the user experimental stations of the Synergetic Extreme Condition User Facilities in the Huairou District of Beijing, China. To demonstrate the capabilities of the system for condensed matter research, the emergence of some pressure-induced phenomena and physics related to superconductivity found previously is also introduced, and then a perspective for such an advanced high-pressure system is presented.
