The product quality of graiworiented silicon steel may be affected by each process because of its complicat- ed production technology. Morphologies, compositions and structures of forsterite film formed in different c...The product quality of graiworiented silicon steel may be affected by each process because of its complicat- ed production technology. Morphologies, compositions and structures of forsterite film formed in different conditions on the samples subjected to high temperature annealing were measured by using a scanning electron microscope, an energy disperse spectroscope, an X ray diffractometer and Fourier transform infrared technique respectively. The morphologies and influential factors of forsterite film were investigated. The results showed that the major compo- nent of forsterite film composed of light-gray spherical particles was Mg2 SiO4, and the minor was MgAl2O4. If the amount of MgO coated on the surface of the steel was less, bare holes or even large-scale bare grains for forsterite film appeared. The higher temperature of water bath during decarburization annealing led to gaps of strips in forster ite film. Moreover, MgO coating method had great influence on forsterite film. Roller coating method was beneficial to increase compactness and smoothness of forsterite film, but was disadvantageous to its thickness.展开更多
In this study, highly porous forsterite scaffolds with interconnected porosities were synthesized using multi-step sintering(MSS) method. The starting powder was nanosized forsterite, which was synthesized from talc a...In this study, highly porous forsterite scaffolds with interconnected porosities were synthesized using multi-step sintering(MSS) method. The starting powder was nanosized forsterite, which was synthesized from talc and magnesium carbonate powders. The phase composition, average particle size and morphology of the produced forsterite powder were characterized by X-ray diffraction technique(XRD) and transition electron microscopy(TEM). Forsterite scaffolds were produced by foamy method using polymeric sponges. MSS process including three steps was used to efficiently sinter the forsterite nanopowders without destroying the initial porous structure of polymeric sponges. The results showed that MSS technique is an efficient and appropriate procedure to produce highly porous forsterite scaffolds with pore size in the range of 100-300 μm. The compressive strength, compressive modulus and porosity of C12 specimen(sintered at 1650℃ for 1 h with subsequent annealing at 1000℃ for 1000 min) was 1.88 MPa, 29.2 MPa, and 72.4%, respectively, which is very close to that of cancellous bone. The approach studied in this research can be developed for other nanostructure ceramics to produce highly porous scaffolds with interconnected porosities for load bearing applications.展开更多
Forsterite, a new biocompatible material was synthesized from Mg（NO3）2.6H20 and TEOS by using the sol-gel method. The material was then heated at 800, 900 and 1000 ℃. The forsterite was noticed as the main crystall...Forsterite, a new biocompatible material was synthesized from Mg（NO3）2.6H20 and TEOS by using the sol-gel method. The material was then heated at 800, 900 and 1000 ℃. The forsterite was noticed as the main crystalline phase in the material fired at 900 and 1000 ℃, while periclase （MgO） was present in all the samples. The tests confirm that in the first two samples forsterite is present as crystallites 〈60 nm, while in the sample synthesized at 1000 ℃ it forms aggregates of micrometre-sized grains. In vitro test was performed by immersing the forsterite powder in the simulating body fluids （SBF） and hydroxyapatite formation on the surface was investigated. We could evidence the formation of hydroxyapatite on the forsterite surface after 7 days of immersion. The MTT test confirmed that forsterite powders dissolution promote osteoblast proliferation of the human-type osteoblasts with no significant cytotoxicity effects.展开更多
Previous theoretical studies have found that the concentration variations within a certain range have a prominent effect on inter-mineral equilibrium isotope fractionation(10^3 lna).Based on the density functional the...Previous theoretical studies have found that the concentration variations within a certain range have a prominent effect on inter-mineral equilibrium isotope fractionation(10^3 lna).Based on the density functional theory,we investigated how the average Ca–O bond length and the reduced partition function ratios(10^3 lnb)and103lna of 44 Ca/40 Ca in forsterite(Fo)are affected by its Ca concentration.Our results show that Ca–O bond length in forsterite ranges from 2.327 to 2.267 A with the Ca/(Ca+Mg)varying between a narrow range limited by an upper limit of 1/8 and a lower limit of 1/64.However,outside this narrow range,i.e.,Ca/(Ca+Mg)is lower than1/64 or higher than 1/8,Ca–O bond length becomes insensitive to Ca concentration and maintains to be a constant.Because the 10^3 lnb is negatively correlated with Ca–O bond length,the 10^3lnb significantly increases with decreasing Ca/(Ca+Mg)when 1/64<Ca/(Ca+Mg)<2/16.As a consequence,the 10^3lna between forsterite and other minerals also strongly depend on the Ca content in forsterite.Combining previous studies with our results,the heavier Ca isotopes enrichment sequence in minerals is:forsterite[orthopyroxene[clinopyroxene[calcite & diopside[dolomite[aragonite.Olivineand pyroxenes are enriched in heavier Ca isotope compared to carbonates.The 10^3lna between forsterite with a Ca/(Ca+Mg)of 1/64 and clinopyroxene(Ca/Mg=1/1,i.e.,diopside)is up to^0.64%at 1200 K.The large 103lnaFodiopsiderelative to the current analytical precision for Ca isotope measurements suggests that the dependence of10^3 lnaFo-diopsideon temperature can be used as a thermometer,similar to the one based on the 103lna of 44 Ca/40 Ca between orthopyroxene and diopside.These two Ca isotope thermometers both have a precision approximate to that of elemental thermometers and provide independent constraints on temperature.展开更多
In order to develop new basic light-weight refractory raw materials,natural forsterite(<0.045 mm)and magnesite(<0.045 mm)were batched according to the chemical composition of forsterite(2MgO·SiO_(2)),wet mi...In order to develop new basic light-weight refractory raw materials,natural forsterite(<0.045 mm)and magnesite(<0.045 mm)were batched according to the chemical composition of forsterite(2MgO·SiO_(2)),wet milled,semi-dry molded and calcined at different temperatures.Then cylinder samples with diameter of 36 mm were prepared.The effects of the wet milling jar rotation speed,the calcination temperature and the anthracite addition on the properties of the samples were researched.The results show that:when the calcination temperature exceeds 1300℃,all the mineral phases have converted to the desired phases;with the increase of the rotation speed and the calcination temperature,the bulk density of the samples increases,the apparent porosity decreases and the compressive strength improves.By comprehensive consideration,400 r·min^(-1) and 1450℃ are taken as the optimal scheme.High addition of anthracite makes the samples light,so series of light-weight raw materials with uniformly distributed micro-pores can be gained.The light-weight raw materials achieved were used for insulation refractory castables,obtaining good application.展开更多
Magnesite fine powder, natural silica powder,light-burned magnesia fine powder, silica fume and middle grade magnesia fine powder were used as the starting materials,and silica sol as binder to get high purity lightwe...Magnesite fine powder, natural silica powder,light-burned magnesia fine powder, silica fume and middle grade magnesia fine powder were used as the starting materials,and silica sol as binder to get high purity lightweight spherical forsterite aggregates. The mixture was granulated on a disc pelletizer and then calcined at 1 400 ℃ for 3h. The synthesized spherical forsterite aggregates were added in Mg O based castables with MgO-SiO2-H2O binding system to replace equaldensity high purity common forsterite aggregates. Effect of spherical forsterite aggregates addition on properties of MgO based castables was investigated. The results show that: compared with common aggregates,lightweight spherical forsterite aggregates can improve castables ’flow ability and decrease water addition; addition of spherical aggregates has little effect on cold strength of castables; with the increase of spherical aggregate addition,shrinkage of specimens after drying and heating at intermediate temperatures decreases,but the expansion of specimens after heating at high temperatures increases,bulk density decreases and apparent porosity increases,and thermal conductivity declines.展开更多
Lizardite rich peridotite has never been used to prepare ceramic specimens,especially in Morocco.For this raison,potential use of naturally abundant lizarditic material from the Rif domain,as a supply for ceramic indu...Lizardite rich peridotite has never been used to prepare ceramic specimens,especially in Morocco.For this raison,potential use of naturally abundant lizarditic material from the Rif domain,as a supply for ceramic industry,has been evaluated.The effects of lizardite addition to magnesite and dolomite mixtures on the thermomechanical properties of the calcined ceramics were also detailed.To achieve this target,natural lizardite,magnesite and dolomite samples were collected in ultrabasic Beni Bousra massif.Those raw samples were used for the synthesis of a forsterite-monticellite rich ceramics.Both raw and sintered samples were characterized by x-ray diffraction,scanning electron microscope and fourier transform infrared.The obtained results showed that both magnesite and dolomite were mainly composed of MgCO_(3) and CaCO_(3).In contrast,lizardite sample showed high amounts of SiO_(2),MgO and Fe2O_(3).An increased amount of lizardite in the initial mixtures enhanced mechanical and dimensional properties of the prepared ceramic specimens,and subsequently,the production of ceramics with the required technological properties.Thus,the preparation of Moroccan lizardite-based ceramics is technically feasible,economically justifiable and socially desirable due to the contribution to the economic growth of the raw materials sector,especially ceramic industry.展开更多
Some volcanic rocks from Nyiragongo volcano in the Democratic Republic of Congo contain highly oxidized olivine crystals.These olivines crystals are made of two phases,dark olivine on backscattered electron images of ...Some volcanic rocks from Nyiragongo volcano in the Democratic Republic of Congo contain highly oxidized olivine crystals.These olivines crystals are made of two phases,dark olivine on backscattered electron images of pure forsterite composition and grey Mg-poor areas made of olivine and iron-rich oxides.Calculation of the initial composition confirms that they are primary olivine with late separation of two different olivine compositions.Pure forsterite is enriched in SiO_(2) but contains lower amounts of CaO than Fe-rich areas,in agreement with expected partitioning of these elements related to the composition of the olivine.Iron-rich oxides formed around or inside the olivine crystals during the separation process and confirm a highly oxidized environment during their evolution.We propose that this separation occurred during subsolidus recrystallization under high fO_(2) conditions of the olivine crystals after cooling of the volcanic rocks.It provides evidences for circulation of iron-rich fluids or gas inducing deuteritic processes occurring in the large volcanic cone of the Nyiragongo,in relation with the presence of a shallow magma chamber connected to a large and permanent lava lake.展开更多
High purity forsterite with a mass ratio 60：40 of MgO over SiO2 was synthesized using magnesite, caustic magnesia and natural silica as starting materials. The synthesized forsterite aggregates were added in magnesia...High purity forsterite with a mass ratio 60：40 of MgO over SiO2 was synthesized using magnesite, caustic magnesia and natural silica as starting materials. The synthesized forsterite aggregates were added in magnesia based custable with MgO -SiO2 -H2 0 binding system to replace dead burned magnesia up to 60 mass% at an in- terval of 15 mass%. Effect of the forsterite addition on properties ~f MgO based castables was investigated. Micro- structure analysis of related specimens was carried out by means of SEM. Special grade bauxite powders were also in- corporated to form spinel by reaction with magnesia, ac- companying volumetric expansion to compensate high tem- perature shrinkage. Bulk density of the castable decreases with increased forsterite addition. Properties in terms of cold crushing strength and cold modulus of rupture, hot modulus of rupture at 1 400 ℃ and thermal shock resist- ance can be improved by adding an appropriate amount of the forsterite aggregate, preferably around 30 mass%.展开更多
High purity forsterite was prepared with magnesite tailings and quartz pounder as starting materials. The influence of the preparution process on the physical properties of the synthetic forsterite was studied. The ph...High purity forsterite was prepared with magnesite tailings and quartz pounder as starting materials. The influence of the preparution process on the physical properties of the synthetic forsterite was studied. The ph,se composition and the microstructure of the synthetic forsterite were analyzed by means of XRD and SEM. The results ,show thal the composites with 63% MgO fired at 1 670℃ exhibit the highest compact structure.展开更多
Low grade magnesite is one of the main research directions in the future as the raw material for the preparation of magnesia based insulating refractories.Periclase-forsterite(MgO-Mg_(2)SiO_(4)) lightweight insulating...Low grade magnesite is one of the main research directions in the future as the raw material for the preparation of magnesia based insulating refractories.Periclase-forsterite(MgO-Mg_(2)SiO_(4)) lightweight insulating refractories were prepared by the molten salt method with high silica magnesite and tertiary talc ore as raw materials by pretreating them to get light burnt magnesia and talc,and NaCl molten salt as the reaction medium.The effects of the NaCl addition,the sintering temperature,the holding time and the raw material ratio on the sample preparation were studied.The results show that when the NaCl addition is 20% of the mass of light burnt magnesia and talc mixture,the sintering temperature is 1 200 ℃,the holding time is 6 h,and m(light burnt magnesia):m(talc)=5:5,the sample has the optimal comprehensive properties:the bulk density of 1.46 g·cm^(-3) and the apparent porosity of 55.0%.In addition,it is found that self-decomposition of talc and the formation of forsterite can form pores inside the sample.展开更多
Which rule of mixture is the best for predicting the overall elastic properties of polyphase rocks based on the elastic properties and volume fractions of their constituents? In order to address this question, we sint...Which rule of mixture is the best for predicting the overall elastic properties of polyphase rocks based on the elastic properties and volume fractions of their constituents? In order to address this question, we sintered forsterite-enstatite polycrystalline aggregates with a varied forsterite volume fraction (0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1.0). Elastic properties (shear, bulk, and Young’s moduli) of these synthesized composites were measured as a function of pressure up to 3.0 GPa in a liquid-medium piston-cylinder apparatus using a high-precision ultrasonic interferometric technique. The experimental data can be much better described by the shear-lag model than by the commonly used simple models such as Voigt, Ruess and Hill averages, Hashin-Shtrikman bounds, Ravichandran bounds, Halpin-Tsai equations, and Paul’s calculations. We attributed this to the fact that the elastic interaction and stress transfer between phases are neglected in all the models except for the shear-lag model. In particular,展开更多
The comprehension of the composition and physical state of the deep interiors of large planets,as well as the impact events pertinent to planetary formation and evolution,necessitates an understanding of the propertie...The comprehension of the composition and physical state of the deep interiors of large planets,as well as the impact events pertinent to planetary formation and evolution,necessitates an understanding of the properties of planetary materials under extreme conditions.Forsterite(Mg2SiO4),a significant geological mineral,has not been fully characterized in terms of its behavior under shock compression due to a lack of consensus among previous experiments and simulations aimed at determining its Hugoniot,as well as the absence of knowledge of sound velocity at high pressures,a critical parameter indicative of phase transformation and melting.In this study,we delineated the Hugoniot curve of the mineral forsterite up to immense pressures of 1200 GPa.For the first time,we successfully constrained its sound velocity along the Hugoniot curve up to 760 GPa by combining laser-driven shock experiments with first-principles molecular dynamics simulations.The measured Hugoniot data for forsterite corroborated previous findings and suggested the occurrence of incongruent melting during shock compression.Remarkably,along their respective Hugoniot curves,the sound velocity of forsterite was observed to fall between that of the minerals bridgmanite and periclase.The remarkable agreement between the experimental results and simulation data provides reliable sound velocity measurements on the forsterite Hugoniot,which is critical for comprehensively understanding the phase transition and melting behavior of forsterite under ultra-high pressures.This knowledge sheds invaluable light on the behavior of this significant geological mineral under extreme conditions akin to those found in the interiors of planets.展开更多
The improvement of composite phase change materials in energy storage density and thermal conductivity is significant for the efficient use of energy.This study proposed novel composite materials based on forsterite w...The improvement of composite phase change materials in energy storage density and thermal conductivity is significant for the efficient use of energy.This study proposed novel composite materials based on forsterite with high specific heat as matrix materials,chloride salts(NaCl-KCl)with high latent heat as phase change materials and SiO_(2)nanoparticles as fillers.The results indicated that forsterite and chloride salts exhibited excellent chemical compatibility,and the composite materials containing 40%(in weight)chloride salts achieved an energy storage density of 882.5 J/g within the range of 100℃to 800℃,a latent heat of 108.1 J/g,and a thermal conductivity of 0.68-0.81 W/(m·K)at 300℃-500℃.Furthermore,the addition of SiO_(2)enhanced the thermal conductivity and energy storage density of composite materials due to the formation of unique nanostructures.More importantly,the removal of structural water during heat-treatment process resulted in the formation of micropores and increased specific surface area of forsterite particles,which facilitated the adsorption and stabilization of molten chloride salts.Combined with the stabilization effect of forsterite and synergistic effect of SiO_(2)nanoparticles,the obtained composite materials with 2.0%(in weight)SiO_(2)nanoparticles exhibited good thermal stability with 1.80%weight loss and 2.34%reduction in latent heat after 150 cycles,indicating a promising application in high-temperature thermal energy storage.展开更多
Forsterite is a highly demanded material in high-temperature industries due to its superior performance in elevated temperatures.This study proposes synthesizing high-quality forsterite via high-temperature thermochem...Forsterite is a highly demanded material in high-temperature industries due to its superior performance in elevated temperatures.This study proposes synthesizing high-quality forsterite via high-temperature thermochemical reactions using abundant boron mud waste.The new synthesis method capitalizes on the high reactivity of fine raw powder materials,enabling the reaction to reach completion at low temperatures rapidly.The chemical characteristics,microscopic morphology,and structure of synthe-sized samples are systematically studied using XRD and SEM.The results confirm that boron mud can be efficiently transformed into forsterite after 10 min of reactions at 1500℃.The synthesized products attain over 98.7%densification and contain more than 85.0%forsterite with well-developed grains.The activation energy of forsterite grain growth in the 1100-1500℃temperature range is 165.5 kJ/mol.This study provides a low-cost method for producing forsterite and an efficient and environmentally friendly solution for treating solid waste.展开更多
Bone engineering scaffolds with antibacterial activity satisfy the repair of bacterial infected bone defects,which is an expected issue in clinical.In this work,3D-printed polymer-derived forsterite scaffolds were pro...Bone engineering scaffolds with antibacterial activity satisfy the repair of bacterial infected bone defects,which is an expected issue in clinical.In this work,3D-printed polymer-derived forsterite scaffolds were proposed to be deposited with hydroxyapatite(HA)coating via a hydrothermal treatment,achieving the functions of photothermal-induced antibacterial ability and bioactivity.The results showed that polymer-derived forsterite scaffolds possessed the photothermal antibacterial ability to inhibit Staphylococcus aureus(S.aureus)and Escherichia coli(E.coli)in vitro,owing to the photothermal effect of free carbon embedded in the scaffolds.The morphology of HA coating on forsterite scaffolds could be controlled through changing the hydrothermal temperature and the pH value of the reaction solution during hydrothermal treatment.Furthermore,HA coating did not influence the mechanical strength and photothermal effect of the scaffolds,but facilitated the proliferation and osteogenic differentiation of rat bone mesenchymal stem cells(rBMSCs)on scaffolds.Hence,the HA-deposited forsterite scaffolds would be greatly promising for repairing bacterial infected bone defects.展开更多
Three Dimensional Finite Element Method(3D-FEM)has been used to model the deviatoric stress field in a forsterite aggregate with a sandwich geometry:two forsterite cubes aligned in the same crystallographic orientatio...Three Dimensional Finite Element Method(3D-FEM)has been used to model the deviatoric stress field in a forsterite aggregate with a sandwich geometry:two forsterite cubes aligned in the same crystallographic orientation(the"breads")sandwich a third forsterite cube(the"filling"),which might have an identical or different crystallographic orientation.The results show that there is no von Mises stress in the forsterite sandwich if the sandwiching and sandwiched forsterite cubes are aligned in the same crystallographic orientation.If the crystallographic orientations are different,however,von Mises stress and heterogeneous stress distribution occur both along the boundary and in the forsterite cubes.For the investigated P-T conditions(up to 6.4GPa and 500°C),the resulted deviatoric stress is much lower than the yield strength of forsterite,so that higher P,higher T,or other means to create higher deviatoric stress is necessary,in order to constrain the yielding behavior of forsterite.展开更多
There are few mineral reaction experiments dealing with the stable isotope fractionation factors between the reaction products. The only known example is to determine oxygen isotope fractionations between quartz and m...There are few mineral reaction experiments dealing with the stable isotope fractionation factors between the reaction products. The only known example is to determine oxygen isotope fractionations between quartz and magnetite at 600 and 800℃ by oxidizing fayalite to form quartz and magnetite. This experimental result has been confirmed by the experiments of isotope exchange reaction. In this note, we report the results of an investigation of oxygen isotope fractionation between calcite展开更多
To maintain the volume stability of lightweight magnesia-silica castables during heating,lightweight spherical forsterite aggregates(8-5,5-3,3-1 and 1-0 mm),pre-synthesized forsterite fine powder(≤0.074 and≤0.044 mm...To maintain the volume stability of lightweight magnesia-silica castables during heating,lightweight spherical forsterite aggregates(8-5,5-3,3-1 and 1-0 mm),pre-synthesized forsterite fine powder(≤0.074 and≤0.044 mm),natural silica powder(≤0.074 mm),middle grade magnesia fine powder(≤0.074 and≤0.044 mm)and silica fume were used as the raw materials to prepare lightweight magnesia-silica castables,and the magnesia fine powder and natural silica powder were gradually replaced by pre-synthesized forsterite fine powder(10%,20%,30%and 40%,by mass).The properties of the castables were tested and the microstructure was analyzed.The influence of the pre-synthesized forsterite fine powder addition on their properties was researched.The results show that:with the increase of the pre-synthesized forsterite fine powder addition in the matrix,the workability of the castables is almost the same.After being heated at 1450℃for 3 h,the bulk density of the castables increases,the apparent porosity decreases,the permanent linear change changes from expansion to shrinkage,the cold strengths increase firstly and then decrease,and the thermal conductivity at different temperatures increases.Generally,the optimal pre-synthesized forsterite fine powder addition is 20%.展开更多
文摘The product quality of graiworiented silicon steel may be affected by each process because of its complicat- ed production technology. Morphologies, compositions and structures of forsterite film formed in different conditions on the samples subjected to high temperature annealing were measured by using a scanning electron microscope, an energy disperse spectroscope, an X ray diffractometer and Fourier transform infrared technique respectively. The morphologies and influential factors of forsterite film were investigated. The results showed that the major compo- nent of forsterite film composed of light-gray spherical particles was Mg2 SiO4, and the minor was MgAl2O4. If the amount of MgO coated on the surface of the steel was less, bare holes or even large-scale bare grains for forsterite film appeared. The higher temperature of water bath during decarburization annealing led to gaps of strips in forster ite film. Moreover, MgO coating method had great influence on forsterite film. Roller coating method was beneficial to increase compactness and smoothness of forsterite film, but was disadvantageous to its thickness.
文摘In this study, highly porous forsterite scaffolds with interconnected porosities were synthesized using multi-step sintering(MSS) method. The starting powder was nanosized forsterite, which was synthesized from talc and magnesium carbonate powders. The phase composition, average particle size and morphology of the produced forsterite powder were characterized by X-ray diffraction technique(XRD) and transition electron microscopy(TEM). Forsterite scaffolds were produced by foamy method using polymeric sponges. MSS process including three steps was used to efficiently sinter the forsterite nanopowders without destroying the initial porous structure of polymeric sponges. The results showed that MSS technique is an efficient and appropriate procedure to produce highly porous forsterite scaffolds with pore size in the range of 100-300 μm. The compressive strength, compressive modulus and porosity of C12 specimen(sintered at 1650℃ for 1 h with subsequent annealing at 1000℃ for 1000 min) was 1.88 MPa, 29.2 MPa, and 72.4%, respectively, which is very close to that of cancellous bone. The approach studied in this research can be developed for other nanostructure ceramics to produce highly porous scaffolds with interconnected porosities for load bearing applications.
基金financially supported by research project 171/ 2012(M.A.Naghiu) thanks the financial support of the Sectoral Operational Programme for Human Resources Development 2007-2013,co-financed by the European Social Fund,under the project No.POSDRU/107/1.5/S/76841, 76841F.Kristaly thanks for support of the European Union and the European Social Fund under the grant agreement No. TAMOP-4.2.1.B-10/2/KONV-2010-0001
文摘Forsterite, a new biocompatible material was synthesized from Mg（NO3）2.6H20 and TEOS by using the sol-gel method. The material was then heated at 800, 900 and 1000 ℃. The forsterite was noticed as the main crystalline phase in the material fired at 900 and 1000 ℃, while periclase （MgO） was present in all the samples. The tests confirm that in the first two samples forsterite is present as crystallites 〈60 nm, while in the sample synthesized at 1000 ℃ it forms aggregates of micrometre-sized grains. In vitro test was performed by immersing the forsterite powder in the simulating body fluids （SBF） and hydroxyapatite formation on the surface was investigated. We could evidence the formation of hydroxyapatite on the forsterite surface after 7 days of immersion. The MTT test confirmed that forsterite powders dissolution promote osteoblast proliferation of the human-type osteoblasts with no significant cytotoxicity effects.
基金financially supported by the Natural Science Foundation of China (Nos. 41721002, 41473011)Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund
文摘Previous theoretical studies have found that the concentration variations within a certain range have a prominent effect on inter-mineral equilibrium isotope fractionation(10^3 lna).Based on the density functional theory,we investigated how the average Ca–O bond length and the reduced partition function ratios(10^3 lnb)and103lna of 44 Ca/40 Ca in forsterite(Fo)are affected by its Ca concentration.Our results show that Ca–O bond length in forsterite ranges from 2.327 to 2.267 A with the Ca/(Ca+Mg)varying between a narrow range limited by an upper limit of 1/8 and a lower limit of 1/64.However,outside this narrow range,i.e.,Ca/(Ca+Mg)is lower than1/64 or higher than 1/8,Ca–O bond length becomes insensitive to Ca concentration and maintains to be a constant.Because the 10^3 lnb is negatively correlated with Ca–O bond length,the 10^3lnb significantly increases with decreasing Ca/(Ca+Mg)when 1/64<Ca/(Ca+Mg)<2/16.As a consequence,the 10^3lna between forsterite and other minerals also strongly depend on the Ca content in forsterite.Combining previous studies with our results,the heavier Ca isotopes enrichment sequence in minerals is:forsterite[orthopyroxene[clinopyroxene[calcite & diopside[dolomite[aragonite.Olivineand pyroxenes are enriched in heavier Ca isotope compared to carbonates.The 10^3lna between forsterite with a Ca/(Ca+Mg)of 1/64 and clinopyroxene(Ca/Mg=1/1,i.e.,diopside)is up to^0.64%at 1200 K.The large 103lnaFodiopsiderelative to the current analytical precision for Ca isotope measurements suggests that the dependence of10^3 lnaFo-diopsideon temperature can be used as a thermometer,similar to the one based on the 103lna of 44 Ca/40 Ca between orthopyroxene and diopside.These two Ca isotope thermometers both have a precision approximate to that of elemental thermometers and provide independent constraints on temperature.
基金The work was supported by Student Research Training Program of Henan University of Science and Technology in 2020(No.2020029).
文摘In order to develop new basic light-weight refractory raw materials,natural forsterite(<0.045 mm)and magnesite(<0.045 mm)were batched according to the chemical composition of forsterite(2MgO·SiO_(2)),wet milled,semi-dry molded and calcined at different temperatures.Then cylinder samples with diameter of 36 mm were prepared.The effects of the wet milling jar rotation speed,the calcination temperature and the anthracite addition on the properties of the samples were researched.The results show that:when the calcination temperature exceeds 1300℃,all the mineral phases have converted to the desired phases;with the increase of the rotation speed and the calcination temperature,the bulk density of the samples increases,the apparent porosity decreases and the compressive strength improves.By comprehensive consideration,400 r·min^(-1) and 1450℃ are taken as the optimal scheme.High addition of anthracite makes the samples light,so series of light-weight raw materials with uniformly distributed micro-pores can be gained.The light-weight raw materials achieved were used for insulation refractory castables,obtaining good application.
文摘Magnesite fine powder, natural silica powder,light-burned magnesia fine powder, silica fume and middle grade magnesia fine powder were used as the starting materials,and silica sol as binder to get high purity lightweight spherical forsterite aggregates. The mixture was granulated on a disc pelletizer and then calcined at 1 400 ℃ for 3h. The synthesized spherical forsterite aggregates were added in Mg O based castables with MgO-SiO2-H2O binding system to replace equaldensity high purity common forsterite aggregates. Effect of spherical forsterite aggregates addition on properties of MgO based castables was investigated. The results show that: compared with common aggregates,lightweight spherical forsterite aggregates can improve castables ’flow ability and decrease water addition; addition of spherical aggregates has little effect on cold strength of castables; with the increase of spherical aggregate addition,shrinkage of specimens after drying and heating at intermediate temperatures decreases,but the expansion of specimens after heating at high temperatures increases,bulk density decreases and apparent porosity increases,and thermal conductivity declines.
文摘Lizardite rich peridotite has never been used to prepare ceramic specimens,especially in Morocco.For this raison,potential use of naturally abundant lizarditic material from the Rif domain,as a supply for ceramic industry,has been evaluated.The effects of lizardite addition to magnesite and dolomite mixtures on the thermomechanical properties of the calcined ceramics were also detailed.To achieve this target,natural lizardite,magnesite and dolomite samples were collected in ultrabasic Beni Bousra massif.Those raw samples were used for the synthesis of a forsterite-monticellite rich ceramics.Both raw and sintered samples were characterized by x-ray diffraction,scanning electron microscope and fourier transform infrared.The obtained results showed that both magnesite and dolomite were mainly composed of MgCO_(3) and CaCO_(3).In contrast,lizardite sample showed high amounts of SiO_(2),MgO and Fe2O_(3).An increased amount of lizardite in the initial mixtures enhanced mechanical and dimensional properties of the prepared ceramic specimens,and subsequently,the production of ceramics with the required technological properties.Thus,the preparation of Moroccan lizardite-based ceramics is technically feasible,economically justifiable and socially desirable due to the contribution to the economic growth of the raw materials sector,especially ceramic industry.
基金World Bank Group,GFDRR TF-OA162,Innocent Badriyo Agama。
文摘Some volcanic rocks from Nyiragongo volcano in the Democratic Republic of Congo contain highly oxidized olivine crystals.These olivines crystals are made of two phases,dark olivine on backscattered electron images of pure forsterite composition and grey Mg-poor areas made of olivine and iron-rich oxides.Calculation of the initial composition confirms that they are primary olivine with late separation of two different olivine compositions.Pure forsterite is enriched in SiO_(2) but contains lower amounts of CaO than Fe-rich areas,in agreement with expected partitioning of these elements related to the composition of the olivine.Iron-rich oxides formed around or inside the olivine crystals during the separation process and confirm a highly oxidized environment during their evolution.We propose that this separation occurred during subsolidus recrystallization under high fO_(2) conditions of the olivine crystals after cooling of the volcanic rocks.It provides evidences for circulation of iron-rich fluids or gas inducing deuteritic processes occurring in the large volcanic cone of the Nyiragongo,in relation with the presence of a shallow magma chamber connected to a large and permanent lava lake.
文摘High purity forsterite with a mass ratio 60：40 of MgO over SiO2 was synthesized using magnesite, caustic magnesia and natural silica as starting materials. The synthesized forsterite aggregates were added in magnesia based custable with MgO -SiO2 -H2 0 binding system to replace dead burned magnesia up to 60 mass% at an in- terval of 15 mass%. Effect of the forsterite addition on properties ~f MgO based castables was investigated. Micro- structure analysis of related specimens was carried out by means of SEM. Special grade bauxite powders were also in- corporated to form spinel by reaction with magnesia, ac- companying volumetric expansion to compensate high tem- perature shrinkage. Bulk density of the castable decreases with increased forsterite addition. Properties in terms of cold crushing strength and cold modulus of rupture, hot modulus of rupture at 1 400 ℃ and thermal shock resist- ance can be improved by adding an appropriate amount of the forsterite aggregate, preferably around 30 mass%.
基金Zhengzhou Municipal Science and Technology Special Fund Project(No.153PZDZX043)
文摘High purity forsterite was prepared with magnesite tailings and quartz pounder as starting materials. The influence of the preparution process on the physical properties of the synthetic forsterite was studied. The ph,se composition and the microstructure of the synthetic forsterite were analyzed by means of XRD and SEM. The results ,show thal the composites with 63% MgO fired at 1 670℃ exhibit the highest compact structure.
文摘Low grade magnesite is one of the main research directions in the future as the raw material for the preparation of magnesia based insulating refractories.Periclase-forsterite(MgO-Mg_(2)SiO_(4)) lightweight insulating refractories were prepared by the molten salt method with high silica magnesite and tertiary talc ore as raw materials by pretreating them to get light burnt magnesia and talc,and NaCl molten salt as the reaction medium.The effects of the NaCl addition,the sintering temperature,the holding time and the raw material ratio on the sample preparation were studied.The results show that when the NaCl addition is 20% of the mass of light burnt magnesia and talc mixture,the sintering temperature is 1 200 ℃,the holding time is 6 h,and m(light burnt magnesia):m(talc)=5:5,the sample has the optimal comprehensive properties:the bulk density of 1.46 g·cm^(-3) and the apparent porosity of 55.0%.In addition,it is found that self-decomposition of talc and the formation of forsterite can form pores inside the sample.
文摘Which rule of mixture is the best for predicting the overall elastic properties of polyphase rocks based on the elastic properties and volume fractions of their constituents? In order to address this question, we sintered forsterite-enstatite polycrystalline aggregates with a varied forsterite volume fraction (0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1.0). Elastic properties (shear, bulk, and Young’s moduli) of these synthesized composites were measured as a function of pressure up to 3.0 GPa in a liquid-medium piston-cylinder apparatus using a high-precision ultrasonic interferometric technique. The experimental data can be much better described by the shear-lag model than by the commonly used simple models such as Voigt, Ruess and Hill averages, Hashin-Shtrikman bounds, Ravichandran bounds, Halpin-Tsai equations, and Paul’s calculations. We attributed this to the fact that the elastic interaction and stress transfer between phases are neglected in all the models except for the shear-lag model. In particular,
基金the financial support from the Natural Science Foundation of China(41925017)Toshimori Sekine acknowledges the financial support from Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments,China(No.22dz2260800)+1 种基金Shanghai Science and Technology Committee,China(No.22JC1410300)the financial support from the Sichuan Science and Technology Program(No.2023NSFSC1910).
文摘The comprehension of the composition and physical state of the deep interiors of large planets,as well as the impact events pertinent to planetary formation and evolution,necessitates an understanding of the properties of planetary materials under extreme conditions.Forsterite(Mg2SiO4),a significant geological mineral,has not been fully characterized in terms of its behavior under shock compression due to a lack of consensus among previous experiments and simulations aimed at determining its Hugoniot,as well as the absence of knowledge of sound velocity at high pressures,a critical parameter indicative of phase transformation and melting.In this study,we delineated the Hugoniot curve of the mineral forsterite up to immense pressures of 1200 GPa.For the first time,we successfully constrained its sound velocity along the Hugoniot curve up to 760 GPa by combining laser-driven shock experiments with first-principles molecular dynamics simulations.The measured Hugoniot data for forsterite corroborated previous findings and suggested the occurrence of incongruent melting during shock compression.Remarkably,along their respective Hugoniot curves,the sound velocity of forsterite was observed to fall between that of the minerals bridgmanite and periclase.The remarkable agreement between the experimental results and simulation data provides reliable sound velocity measurements on the forsterite Hugoniot,which is critical for comprehensively understanding the phase transition and melting behavior of forsterite under ultra-high pressures.This knowledge sheds invaluable light on the behavior of this significant geological mineral under extreme conditions akin to those found in the interiors of planets.
基金the financial support from the National Natural Science Foundation of China(52372031)。
文摘The improvement of composite phase change materials in energy storage density and thermal conductivity is significant for the efficient use of energy.This study proposed novel composite materials based on forsterite with high specific heat as matrix materials,chloride salts(NaCl-KCl)with high latent heat as phase change materials and SiO_(2)nanoparticles as fillers.The results indicated that forsterite and chloride salts exhibited excellent chemical compatibility,and the composite materials containing 40%(in weight)chloride salts achieved an energy storage density of 882.5 J/g within the range of 100℃to 800℃,a latent heat of 108.1 J/g,and a thermal conductivity of 0.68-0.81 W/(m·K)at 300℃-500℃.Furthermore,the addition of SiO_(2)enhanced the thermal conductivity and energy storage density of composite materials due to the formation of unique nanostructures.More importantly,the removal of structural water during heat-treatment process resulted in the formation of micropores and increased specific surface area of forsterite particles,which facilitated the adsorption and stabilization of molten chloride salts.Combined with the stabilization effect of forsterite and synergistic effect of SiO_(2)nanoparticles,the obtained composite materials with 2.0%(in weight)SiO_(2)nanoparticles exhibited good thermal stability with 1.80%weight loss and 2.34%reduction in latent heat after 150 cycles,indicating a promising application in high-temperature thermal energy storage.
基金support provided by the National Natural Science Foundation of China (grant number U22A20410).
文摘Forsterite is a highly demanded material in high-temperature industries due to its superior performance in elevated temperatures.This study proposes synthesizing high-quality forsterite via high-temperature thermochemical reactions using abundant boron mud waste.The new synthesis method capitalizes on the high reactivity of fine raw powder materials,enabling the reaction to reach completion at low temperatures rapidly.The chemical characteristics,microscopic morphology,and structure of synthe-sized samples are systematically studied using XRD and SEM.The results confirm that boron mud can be efficiently transformed into forsterite after 10 min of reactions at 1500℃.The synthesized products attain over 98.7%densification and contain more than 85.0%forsterite with well-developed grains.The activation energy of forsterite grain growth in the 1100-1500℃temperature range is 165.5 kJ/mol.This study provides a low-cost method for producing forsterite and an efficient and environmentally friendly solution for treating solid waste.
基金supported by the National Natural Science Foundation of China(Nos.51872185,51972212,and 52072246)Shanghai Natural Science Foundation(No.19ZR1435100).
文摘Bone engineering scaffolds with antibacterial activity satisfy the repair of bacterial infected bone defects,which is an expected issue in clinical.In this work,3D-printed polymer-derived forsterite scaffolds were proposed to be deposited with hydroxyapatite(HA)coating via a hydrothermal treatment,achieving the functions of photothermal-induced antibacterial ability and bioactivity.The results showed that polymer-derived forsterite scaffolds possessed the photothermal antibacterial ability to inhibit Staphylococcus aureus(S.aureus)and Escherichia coli(E.coli)in vitro,owing to the photothermal effect of free carbon embedded in the scaffolds.The morphology of HA coating on forsterite scaffolds could be controlled through changing the hydrothermal temperature and the pH value of the reaction solution during hydrothermal treatment.Furthermore,HA coating did not influence the mechanical strength and photothermal effect of the scaffolds,but facilitated the proliferation and osteogenic differentiation of rat bone mesenchymal stem cells(rBMSCs)on scaffolds.Hence,the HA-deposited forsterite scaffolds would be greatly promising for repairing bacterial infected bone defects.
基金supported by National Natural Science Foundation of China(Grant No.41090371)
文摘Three Dimensional Finite Element Method(3D-FEM)has been used to model the deviatoric stress field in a forsterite aggregate with a sandwich geometry:two forsterite cubes aligned in the same crystallographic orientation(the"breads")sandwich a third forsterite cube(the"filling"),which might have an identical or different crystallographic orientation.The results show that there is no von Mises stress in the forsterite sandwich if the sandwiching and sandwiched forsterite cubes are aligned in the same crystallographic orientation.If the crystallographic orientations are different,however,von Mises stress and heterogeneous stress distribution occur both along the boundary and in the forsterite cubes.For the investigated P-T conditions(up to 6.4GPa and 500°C),the resulted deviatoric stress is much lower than the yield strength of forsterite,so that higher P,higher T,or other means to create higher deviatoric stress is necessary,in order to constrain the yielding behavior of forsterite.
基金Study supported by funds from the German Science Foundation(DFG)the Universlty of ScienceTechology of China(USTC).
文摘There are few mineral reaction experiments dealing with the stable isotope fractionation factors between the reaction products. The only known example is to determine oxygen isotope fractionations between quartz and magnetite at 600 and 800℃ by oxidizing fayalite to form quartz and magnetite. This experimental result has been confirmed by the experiments of isotope exchange reaction. In this note, we report the results of an investigation of oxygen isotope fractionation between calcite
文摘To maintain the volume stability of lightweight magnesia-silica castables during heating,lightweight spherical forsterite aggregates(8-5,5-3,3-1 and 1-0 mm),pre-synthesized forsterite fine powder(≤0.074 and≤0.044 mm),natural silica powder(≤0.074 mm),middle grade magnesia fine powder(≤0.074 and≤0.044 mm)and silica fume were used as the raw materials to prepare lightweight magnesia-silica castables,and the magnesia fine powder and natural silica powder were gradually replaced by pre-synthesized forsterite fine powder(10%,20%,30%and 40%,by mass).The properties of the castables were tested and the microstructure was analyzed.The influence of the pre-synthesized forsterite fine powder addition on their properties was researched.The results show that:with the increase of the pre-synthesized forsterite fine powder addition in the matrix,the workability of the castables is almost the same.After being heated at 1450℃for 3 h,the bulk density of the castables increases,the apparent porosity decreases,the permanent linear change changes from expansion to shrinkage,the cold strengths increase firstly and then decrease,and the thermal conductivity at different temperatures increases.Generally,the optimal pre-synthesized forsterite fine powder addition is 20%.
