Effects of rare earth oxides(Y_2O_3,La_2O_3,and Er_2O_3) on the viscosity,thermal expansion,and structure of alkali-free boro-aluminosilicate glasses were investigated by the rotating crucible viscometer,dilatometry a...Effects of rare earth oxides(Y_2O_3,La_2O_3,and Er_2O_3) on the viscosity,thermal expansion,and structure of alkali-free boro-aluminosilicate glasses were investigated by the rotating crucible viscometer,dilatometry and FT-IR absorption spectra.The results showed that the melting temperature of alkali-free boroaluminosilicate glasses decreased from 1 697.55 to 1 662.59,1 674.37 and 1 640.87 ℃ with the introduction of 1 mol%La_2O_3,Y_2O_3 and Er_2O_3,respectively.However,the glass transition temperature T_g,dilatometric softening temperature T_d and coefficient of thermal expansion of alkali-free boro-aluminosilicate glasses increased when adding the rare-earth oxides.At high temperatures,incorporating rare earth oxides into glass resulted in the peak at about 1 085 cm^(-1) towards lower wavenumber and the absorption band in the region of850-1 260 cm^(-1) broader,which indicated that rare earths acted as network modifiers and increased the numbers of non-bridging oxygen in the glass melts.However,the rare earths had an opposite effect and accumulated the glass structure at low temperatures near T_g.展开更多
By introducing other oxide materials(SiO_2, Al_2O_3, CaO) into the red mud, all materials were melted into aluminosilicate glasses. On the basis of 17.2Fe_2O_3-5.7CaO-18.2Al_2O_3-50SiO_2-5.9Na_2O-3TiO_2 system glasses...By introducing other oxide materials(SiO_2, Al_2O_3, CaO) into the red mud, all materials were melted into aluminosilicate glasses. On the basis of 17.2Fe_2O_3-5.7CaO-18.2Al_2O_3-50SiO_2-5.9Na_2O-3TiO_2 system glasses, [Al_2O_3]/[CaO] mass ratio changed further. For each sample, the assignment of IR absorption bands for aluminosilicate glasses was investigated by Fourier transform infrared spectroscopy and the glasstransition temperature and high temperature molten state were studied by differential scanning calorimetry. According to X-Ray diffraction and differential scanning calorimetry, the behavior of crystallization was analyzed. The results show that the glass structures of three-dimensional network are depolymerized and the amount of non-bridging oxygens increases gradually with network modifier CaO replacing network intermediate Al_2O_3 when [Al_2O_3]/[CaO] ratio of aluminosilicate glass decreases from 4.05 to 0.66, resulting in decreasing density, melting temperature, crystallization peak temperature and glass-transition temperature. As [Al_2O_3]/[CaO] mass ratio decreases, the concentration of crystallized phase maghemite(γ-Fe_2O_3) will increase which provides the possibility for production of black glass-ceramic further.展开更多
The structure and properties of lithium aluminosilicate glasses containing Y 2 O 3 were investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM),differential thermal analysis (DTA)and Raman spectroscop...The structure and properties of lithium aluminosilicate glasses containing Y 2 O 3 were investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM),differential thermal analysis (DTA)and Raman spectroscopy.Effects of yttria on the viscosity of LAS glasses were investigated,and found that the introduction of yttria effectively decreased the viscosity of LAS glasses.In Raman spectra of initial glasses it is shown the starting glasses are in almost complete disorder,since all bands are weak and broad.In the spectra of heat-treated specimens some new narrow bands appear and increase in intensity,and the frequency changes with varied yttria addition.The DTA and XRD results show that yttria controlled the crystallization of LAS glasses by increasing the crystallization peak temperature(T p ),however,the main crystalline phase of glass-ceramics wasβ-spodumene.展开更多
The crystallinity of lithium aluminosilicate(LAS) glass after crystallization were studied at different temperatures by X-ray diffractometry and the crystallinity of the standard glass ceramic with known crystal and g...The crystallinity of lithium aluminosilicate(LAS) glass after crystallization were studied at different temperatures by X-ray diffractometry and the crystallinity of the standard glass ceramic with known crystal and glass phases was examined. The crystallization mechanism of LAS glass was analyzed by the crystallinity, with a formula relating the crystallinity (X) and temperature (T). The results show that the calculated crystallinity of LAS glass by XRD increases with the crystallization temperature, in the range of 40%?50%, which is close to the calculated ones of standard samples with spodumene quartz ratio of 40%?70%. The activation energy of LAS glass is different within different temperature ranges; nEc is 125.44 kJ/mol at 710?810 ℃ and nEc is 17.42 kJ/mol at 810?980 ℃, which indicates different crystallization mechanisms. It has been proved that the required energy for crystallization of glass in the lower temperature range includes the interfacial energy between glass and crystalline phase and the free energy difference of atoms in structures of glass and crystal, and in the higher temperature ranges only the interfacial energy between glass and crystalline phase is considered.展开更多
The effects of Co2O3 on the crystallization and colorization of lithium aluminosilicate glass ceramic were investigated by using differential thermal analysis (DTA), X-ray diffractometry (XRD) and scanning electron mi...The effects of Co2O3 on the crystallization and colorization of lithium aluminosilicate glass ceramic were investigated by using differential thermal analysis (DTA), X-ray diffractometry (XRD) and scanning electron microscope (SEM). The results showed that the introduction of Co2O3 not only changed the color of lithium aluminosilicate glass but also affected its crystallization by increasing the crystallizing maximum peak temperature (Tp) and weakening the crystallization ability. In addition, the color of LAS glass ceramics could be achieved by controlling the suitable Co2O3 and appropriate crystallization temperature.展开更多
A novel method based on polyacrylamide gel process was used to prepare Li2O-Al2O3-SiO2 （LAS） glass-ceramic powders. The effects of ZrO2 addition on the crystallization and phase transformation process in LAS system ...A novel method based on polyacrylamide gel process was used to prepare Li2O-Al2O3-SiO2 （LAS） glass-ceramic powders. The effects of ZrO2 addition on the crystallization and phase transformation process in LAS system were investigated by using differential thermal analysis （DTA）, X-ray powder diffractometry （XRD） and Fourier transform infrared spectroscopy （FTIR）. The activation energy decreases from 304.6 to 248.9kJ/mol and the frequency factor decreases from 2.49×10 11 to 5.56×108 min -1 as ZrO2 content changes from 0 to 4.0%（mass fraction）. During calcination from 800 to 1200℃, hexagonal β-quartz solid-solution first crystallizes and then gradually transforms into tetragonal β-spodumene solid-solution with increasing temperature. The stability of β-quartz solid-solution increases with more ZrO2 additions and a minor crystalline phase, tetragonal zirconia, also appears.展开更多
Melt treatment is well known to have an important influence on the properties of metallic glasses(MGs).However,for the MGs quenched from different melt temperatures with a quartz tube,the underlying physical origin re...Melt treatment is well known to have an important influence on the properties of metallic glasses(MGs).However,for the MGs quenched from different melt temperatures with a quartz tube,the underlying physical origin responsible for the variation of properties remains poorly understood.In the present work,we systematically studied the influence of melt treatment on the thermal properties of a Zr50Cu36Al14 glass-forming alloy and unveiled the microscopic origins.Specifically,we quenched the melt at different temperatures ranging from 1.1Tl to 1.5Tl(Tl is the liquidus temperature)to obtain melt-spun MG ribbons and investigated the variation of thermal properties of the MGs upon heating.We found that glass transition temperature,Tg,increases by as much as 36 K,and the supercooled liquid region disappears in the curve of differential scanning calorimetry when the melt is quenched at a high temperature up to 1.5Tl.The careful chemical analyses indicate that the change in glass transition behavior originates from the incorporation of oxygen and silicon in the molten alloys.The incorporated oxygen and silicon can both enhance the interactions between atoms,which renders the cooperative rearrangements of atoms difficult,and thus enhances the kinetic stability of the MGs.展开更多
The early stage evolution of local atomic structures in a multicomponent metallic glass during its crystallization process has been investigated via molecular dynamics simulation.It is found that the initial thermal s...The early stage evolution of local atomic structures in a multicomponent metallic glass during its crystallization process has been investigated via molecular dynamics simulation.It is found that the initial thermal stability and earliest stage evolution of the local atomic clusters show no strong correlation with their initial short-range orders,and this leads to an observation of a novel symmetry convergence phenomenon,which can be understood as an atomic structure manifestation of the ergodicity.Furthermore,in our system we have quantitatively proved that the crucial factor for the thermal stability against crystallization exhibited by the metallic glass is not the total amount of icosahedral clusters,but the degree of global connectivity among them.展开更多
In view of the composition analysis and identification of ancient glass products, L1 regularization, K-Means cluster analysis, elbow rule and other methods were comprehensively used to build logical regression, cluste...In view of the composition analysis and identification of ancient glass products, L1 regularization, K-Means cluster analysis, elbow rule and other methods were comprehensively used to build logical regression, cluster analysis, hyper-parameter test and other models, and SPSS, Python and other tools were used to obtain the classification rules of glass products under different fluxes, sub classification under different chemical compositions, hyper-parameter K value test and rationality analysis. Research can provide theoretical support for the protection and restoration of ancient glass relics.展开更多
潜热通量产品的验证与分析对于研究气候变化及能量循环具有重要意义。全球陆表高分辨率蒸散产品(high resolution global lAnd surface evapotranspiration product,Hi-GLASS ET)融合了5种传统蒸散算法,能够生产出较高精度的陆表潜热通...潜热通量产品的验证与分析对于研究气候变化及能量循环具有重要意义。全球陆表高分辨率蒸散产品(high resolution global lAnd surface evapotranspiration product,Hi-GLASS ET)融合了5种传统蒸散算法,能够生产出较高精度的陆表潜热通量产品,但目前没有针对此产品的验证研究。利用Ameriflux通量观测站点的潜热通量观测值与相应的Hi-GLASS陆表潜热通量产品估算值进行对比,获取多组有效验证数据。验证结果显示,所选站点实际观测值与产品估算值的决定系数(R 2)为0.6,均方根误差(RMSE)为34.4 W/m^(2),平均偏差(Bias)为-13.4 W/m^(2),克林-古普塔效率(Kling-Gupta efficiency,KGE)为0.49,Hi-GLASS潜热通量产品具有较高的精度,算法的拟合结果较好;此外,空间分布也表明Hi-GLASS陆表潜热通量产品符合正常的自然规律。由于数据获取的局限性,仅采用了美国地区18个站点数据对产品进行验证,在其他地区仍需进一步验证。展开更多
Solid-state impedance spectroscopy(SS-IS)was used to investigate the influence of structural modifications resulting from the addition of Nb2O5 on the dielectric properties and relaxation processes in the quaternary m...Solid-state impedance spectroscopy(SS-IS)was used to investigate the influence of structural modifications resulting from the addition of Nb2O5 on the dielectric properties and relaxation processes in the quaternary mixed glass former(MGF)system 35Na_(2)O–10V_(2)O_(5)–(55-x)P_(2)O_(5)–xNb_(2)O_(5)(x=0–40,mol%).The dielectric parameters,including the dielectric strength and dielectric loss,are determined from the frequency and temperature-dependent complex permittivity data,revealing a significant dependence on the Nb2O5 content.The transition from a predominantly phosphate glass network(x<10,region I)to a mixed niobate–phosphate glass net-work(10≤x≤20,region II)leads to an increase in the dielectric parameters,which correlates with the observed trend in the direct-cur-rent(DC)conductivity.In the predominantly niobate network(x≥25,region III),the highly polarizable nature of Nb5+ions leads to a fur-ther increase in the dielectric permittivity and dielectric strength.This is particularly evident in Nb-40 glass-ceramic,which contains Na_(13)Nb_(35)O_(94) crystalline phase with a tungsten bronze structure and exhibits the highest dielectric permittivity of 61.81 and the lowest loss factor of 0.032 at 303 K and 10 kHz.The relaxation studies,analyzed through modulus formalism and complex impedance data,show that DC conductivity and relaxation processes are governed by the same mechanism,attributed to ionic conductivity.In contrast to glasses with a single peak in frequency dependence of imaginary part of electrical modulus,M″(ω),Nb-40 glass-ceramic exhibits two distinct contributions with similar relaxation times.The high-frequency peak indicates bulk ionic conductivity,while the additional low-fre-quency peak is associated with the grain boundary effect,confirmed by the electrical equivalent circuit(EEC)modelling.The scaling characteristics of permittivity and conductivity spectra,along with the electrical modulus,validate time-temperature superposition and demonstrate a strong correlation with composition and modification of the glass structure upon Nb_(2)O_(5) incorporation.展开更多
In our modern world, where conserving energy is highly valued, thermal insulation panels play a crucial role in reducing heat transfer between two spaces, surfaces, or materials. They are used to enhance the energy ef...In our modern world, where conserving energy is highly valued, thermal insulation panels play a crucial role in reducing heat transfer between two spaces, surfaces, or materials. They are used to enhance the energy efficiency of various industrial applications by minimizing heat loss and temperature control. These panels function as silent protectors, aiding in reducing energy consumption and making things more sustainable and better for the environment. This is where composite materials come in;they are known for their lightweight nature, high strength-to-weight ratio, and excellent thermal insulation properties and have gained significant attention. Researchers are actively engaged in various studies aimed at enhancing these materials further. This research project focuses on the development of kaolin and glass fiber-reinforced composites for thermally insulating panels, to which natural strengthening materials like corn husk and bamboo fibers are added. The aim is to create cost-effective and efficient composite materials for thermal insulation applications by incorporating these components with a binder consisting of potassium silicate, hydroxide, and distilled water. This project involves conducting compression tests, bending tests, impact tests, thermal conductivity measurements, and microscopic analysis to evaluate the mechanical and thermal properties of the developed composites. The profound impact of these engineered composites on thermal insulation panels stands to revolutionize energy conservation efforts, offering a potent avenue to minimize heat loss and enhance overall energy efficiency across an array of industrial sectors.展开更多
This paper concentrates on the development of glasses with self-cleaning surfaces exhibiting high water contact angles. In this study, we prepared super-hydrophobic nano-ceramic coated glass based on titania & sil...This paper concentrates on the development of glasses with self-cleaning surfaces exhibiting high water contact angles. In this study, we prepared super-hydrophobic nano-ceramic coated glass based on titania & silica using simple sol-gel & dip coating methods and studied the best composition of the coatings by altering ratios of titanium tetraisopropoxide (TTIP)/tetraethyl orthosilicate (TEOS) with different homogenizing agents. We characterized the coatings by surface roughness measurement, percentage of optical transmission, static contact angle, near-infrared (NIR) transmission, and diffuse reflectance. The fabrication of coatings on glass substrates played an important role in increasing the water contact angle of about 95° and visible & NIR transmission of about 90%. We compared our modified glass substrate with commercial low emissivity (Low E) glass using X-ray diffraction (XRD) analysis, which showed pure amorphous surface claiming excellent wettability and thus the prepared glass substrate could have a variety of applications in different fields.展开更多
The dynamic responses and generated voltage in a curved sandwich beam with glass reinforced laminate(GRL)layers and a pliable core in the presence of a piezoelectric layer under low-velocity impact(LVI)are investigate...The dynamic responses and generated voltage in a curved sandwich beam with glass reinforced laminate(GRL)layers and a pliable core in the presence of a piezoelectric layer under low-velocity impact(LVI)are investigated.The current study aims to carry out a dynamic analysis on the sandwich beam when the impactor hits the top face sheet with an initial velocity.For the layer analysis,the high-order shear deformation theory(HSDT)and Frostig's second model for the displacement fields of the core layer are used.The classical non-adhesive elastic contact theory and Hunter's principle are used to calculate the dynamic responses in terms of time.In order to validate the analytical method,the outcomes of the current investigation are compared with those gained by the experimental tests carried out by other researchers for a rectangular composite plate subject to the LVI.Finite element(FE)simulations are conducted by means of the ABAQUS software.The effects of the parameters such as foam modulus,layer material,fiber angle,impactor mass,and its velocity on the generated voltage are reviewed.展开更多
The microstructure and phase composition of high-alumina,chromic oxide,and AZS/Cr refractories containing 30%and 60%(by mass)Cr2O3 after exposure to aluminaboronsilicate glasses and basalt melts depending on the type ...The microstructure and phase composition of high-alumina,chromic oxide,and AZS/Cr refractories containing 30%and 60%(by mass)Cr2O3 after exposure to aluminaboronsilicate glasses and basalt melts depending on the type of melts and temperature have been studied.The mechanisms of refractory corrosion by the used melts and the factors contributing to the inhibition of corrosion development have been investigated by the method of petrographic analysis.On the basis of obtained results,the use of high-alumina,chromic oxide,and AZS/Cr refractories in the sections of glass furnace linings,experiencing the intensive impact of aluminaboronsilicate glasses and basalt melts,has been confirmed and scientifically substantiated.展开更多
The aim of this study was to optimize the geometry and the design of metallic/composite single bolted joints subjected to tension-compression loading. For this purpose, it was necessary to evaluate the stress state in...The aim of this study was to optimize the geometry and the design of metallic/composite single bolted joints subjected to tension-compression loading. For this purpose, it was necessary to evaluate the stress state in each component of the bolted join. The multi-material assembly was based on the principle of double lap bolted joint. It was composed of a symmetrical balanced woven glass-epoxy composite material plate fastened to two stainless sheets using a stainless pre-stressed bolt. In order to optimize the design and the geometry of the assembly, ten configurations were proposed and studied: a classical simple bolted joint, two joints with an insert (a BigHead<sup>R</sup> insert and a stair one) embedded in the composite, two “waved” solutions, three symmetrical configurations composed of a succession of metallic and composites layers, without a sleeve, with one and with two sleeves, and two non-symmetrical constituted of metallic and composites layers associated with a stair-insert (one with a sleeve and one without). A tridimensional Finite Element Method (FEM) was used to model each configuration mentioned above. The FE models taked into account the different materials, the effects of contact between the different sheets of the assembly and the pre-stress in the bolt. The stress state was analyzed in the composite part. The concept of stress concentration factor was used in order to evaluate the stress increase in the highly stressed regions and to compare the ten configurations studied. For this purpose, three stress concentration factors were defined: one for a monotonic loading in tension, another for a monotonic loading in compression, and the third for a tension-compression cyclic loading. The results of the FEM computations showed that the use of alternative metallic and composite layers associated with two sleeves gived low values of stress concentration factors, smaller than 1.4. In this case, there was no contact between the bolt and the composite part and the most stressed region was not the vicinity of the hole but the end of the longest layers of the metallic inserts.展开更多
The effect of substitution La_(2)O_(3)and YF_(3)as network modifiers respectively for Y_(2)O_(3),and ZnO as intermediate oxide for Al_(2)O_(3)on crystallization and viscous behavior of Y_(2)O_(3)-Al_(2)O_(3)-SiO_(2)gl...The effect of substitution La_(2)O_(3)and YF_(3)as network modifiers respectively for Y_(2)O_(3),and ZnO as intermediate oxide for Al_(2)O_(3)on crystallization and viscous behavior of Y_(2)O_(3)-Al_(2)O_(3)-SiO_(2)glass was studied.La_(2)O_(3)and YF_(3)substitution for Y_(2)O_(3)decreases the melting temperature of studied glass from 1402 to 1346 and 1379℃,and the activation energy of viscous flow decreases from 340 to 250 and 265 kJ/mol.Meanwhile,ZnO substitution for Al_(2)O_(3)decreases the melting temperature to 1379℃while increases the activation energy of viscous flow to 542 kJ/mol,due to their different role in glass structure.Substitution ZnO for Al_(2)O_(3)refines and homogenizes the crystals size and lowers crystallinity because the nucleation and crystal growth are depressed by higher activation energy of crystallization and change of crystallization mechanism from bulk crystallization to surface crystallization.Replacement of Y_(2)O_(3)by La_(2)O_(3)and YF_(3)respectively also decreases the crystallinity of Y_(2)O_(3)-Al_(2)O_(3)-SiO_(2)glass ceramic due to competitive and hindering effect on the rearranged atoms,structural units and groups required by precipitated two crystals.Besides,y-Y2Si2O7,precipitation of Y4.67(SiO4)3O,ZnAl_(2)O_(4),and Y3Si3O10F were observed respectively due to incorporation of La_(2)O_(3),ZnO,and YF_(3).展开更多
The structural and spectroscopic properties of Na2O-Al2O3-SiO2-xP2O5 glasses（x = 0 to 7 mol%） are investigated.Both Raman and IR spectra reveal that discrete phosphate species([PO4]-3,[PO3O1/2]-2) with low polymeriz...The structural and spectroscopic properties of Na2O-Al2O3-SiO2-xP2O5 glasses（x = 0 to 7 mol%） are investigated.Both Raman and IR spectra reveal that discrete phosphate species([PO4]-3,[PO3O1/2]-2) with low polymerization degree can be formed in the silicate glass.These phosphate structures scavenge non-bridging oxygen ions and cations from the silicate network,resulting in an increase of the glass transition temperature.According to the Judd-Ofelt intensity parameters（Ω2,Ω4,Ω6） of Er3+.the asymmetry of local environment around Er3+ becomes higher,and the bond covalency between Er3+ and O2-decreases after P2O5 is introduced.In the emission spectra,photo-luminescence intensity increases with increasing P2O5 concentration and the spectra are inhornogeneously broadened,revealing that the ligand electric field around Er3+ is dramatically changed,and the glass matrix becomes disordered.展开更多
The effects of bismuth doping content and temperature on the absorption property and near-infrared(NIR) luminescence of Bi-doped La2O3-Al2O3-SiO2(LAS) glasses are presented.The emission intensity reaches the maximum w...The effects of bismuth doping content and temperature on the absorption property and near-infrared(NIR) luminescence of Bi-doped La2O3-Al2O3-SiO2(LAS) glasses are presented.The emission intensity reaches the maximum when the Bi2O3 content in 3.0Bi-LAS is 1.83%.The emission spectra reach their peaks at 1 190 and 1 117 nm,with full-width at half-maximum(FWHM) values of 330 and 228 nm under 500 and 700-nm excitations,respectively.As the Bi2O3 content increases,the peak wavelengths and FWHMs of emission bands increase,but their lifetimes decrease.The lifetime of 2.0Bi-LAS is 460 μs at 9 K,and is almost temperature independent until 350 K.The NIR emission of Bi in the system has strong resistance to thermal quenching from 9 to 350 K.展开更多
基金Funded by the National Key Research and Development Program of China(No.2016YFB0303702)
文摘Effects of rare earth oxides(Y_2O_3,La_2O_3,and Er_2O_3) on the viscosity,thermal expansion,and structure of alkali-free boro-aluminosilicate glasses were investigated by the rotating crucible viscometer,dilatometry and FT-IR absorption spectra.The results showed that the melting temperature of alkali-free boroaluminosilicate glasses decreased from 1 697.55 to 1 662.59,1 674.37 and 1 640.87 ℃ with the introduction of 1 mol%La_2O_3,Y_2O_3 and Er_2O_3,respectively.However,the glass transition temperature T_g,dilatometric softening temperature T_d and coefficient of thermal expansion of alkali-free boro-aluminosilicate glasses increased when adding the rare-earth oxides.At high temperatures,incorporating rare earth oxides into glass resulted in the peak at about 1 085 cm^(-1) towards lower wavenumber and the absorption band in the region of850-1 260 cm^(-1) broader,which indicated that rare earths acted as network modifiers and increased the numbers of non-bridging oxygen in the glass melts.However,the rare earths had an opposite effect and accumulated the glass structure at low temperatures near T_g.
基金Funded by the Natural Science Foundation of Shandong Province(Nos.51172093,and 51042009)the Natural Science Youth Foundation of Shandong Province and National Natural Science Foundation(No.ZR2011EMQ005)
文摘By introducing other oxide materials(SiO_2, Al_2O_3, CaO) into the red mud, all materials were melted into aluminosilicate glasses. On the basis of 17.2Fe_2O_3-5.7CaO-18.2Al_2O_3-50SiO_2-5.9Na_2O-3TiO_2 system glasses, [Al_2O_3]/[CaO] mass ratio changed further. For each sample, the assignment of IR absorption bands for aluminosilicate glasses was investigated by Fourier transform infrared spectroscopy and the glasstransition temperature and high temperature molten state were studied by differential scanning calorimetry. According to X-Ray diffraction and differential scanning calorimetry, the behavior of crystallization was analyzed. The results show that the glass structures of three-dimensional network are depolymerized and the amount of non-bridging oxygens increases gradually with network modifier CaO replacing network intermediate Al_2O_3 when [Al_2O_3]/[CaO] ratio of aluminosilicate glass decreases from 4.05 to 0.66, resulting in decreasing density, melting temperature, crystallization peak temperature and glass-transition temperature. As [Al_2O_3]/[CaO] mass ratio decreases, the concentration of crystallized phase maghemite(γ-Fe_2O_3) will increase which provides the possibility for production of black glass-ceramic further.
基金the National Natural Science Foundation of China(No.50472039)
文摘The structure and properties of lithium aluminosilicate glasses containing Y 2 O 3 were investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM),differential thermal analysis (DTA)and Raman spectroscopy.Effects of yttria on the viscosity of LAS glasses were investigated,and found that the introduction of yttria effectively decreased the viscosity of LAS glasses.In Raman spectra of initial glasses it is shown the starting glasses are in almost complete disorder,since all bands are weak and broad.In the spectra of heat-treated specimens some new narrow bands appear and increase in intensity,and the frequency changes with varied yttria addition.The DTA and XRD results show that yttria controlled the crystallization of LAS glasses by increasing the crystallization peak temperature(T p ),however,the main crystalline phase of glass-ceramics wasβ-spodumene.
基金Project(2003C11030) supported by the High Science & Technique Brainstorm of Zhejiang Province, China
文摘The crystallinity of lithium aluminosilicate(LAS) glass after crystallization were studied at different temperatures by X-ray diffractometry and the crystallinity of the standard glass ceramic with known crystal and glass phases was examined. The crystallization mechanism of LAS glass was analyzed by the crystallinity, with a formula relating the crystallinity (X) and temperature (T). The results show that the calculated crystallinity of LAS glass by XRD increases with the crystallization temperature, in the range of 40%?50%, which is close to the calculated ones of standard samples with spodumene quartz ratio of 40%?70%. The activation energy of LAS glass is different within different temperature ranges; nEc is 125.44 kJ/mol at 710?810 ℃ and nEc is 17.42 kJ/mol at 810?980 ℃, which indicates different crystallization mechanisms. It has been proved that the required energy for crystallization of glass in the lower temperature range includes the interfacial energy between glass and crystalline phase and the free energy difference of atoms in structures of glass and crystal, and in the higher temperature ranges only the interfacial energy between glass and crystalline phase is considered.
文摘The effects of Co2O3 on the crystallization and colorization of lithium aluminosilicate glass ceramic were investigated by using differential thermal analysis (DTA), X-ray diffractometry (XRD) and scanning electron microscope (SEM). The results showed that the introduction of Co2O3 not only changed the color of lithium aluminosilicate glass but also affected its crystallization by increasing the crystallizing maximum peak temperature (Tp) and weakening the crystallization ability. In addition, the color of LAS glass ceramics could be achieved by controlling the suitable Co2O3 and appropriate crystallization temperature.
文摘A novel method based on polyacrylamide gel process was used to prepare Li2O-Al2O3-SiO2 （LAS） glass-ceramic powders. The effects of ZrO2 addition on the crystallization and phase transformation process in LAS system were investigated by using differential thermal analysis （DTA）, X-ray powder diffractometry （XRD） and Fourier transform infrared spectroscopy （FTIR）. The activation energy decreases from 304.6 to 248.9kJ/mol and the frequency factor decreases from 2.49×10 11 to 5.56×108 min -1 as ZrO2 content changes from 0 to 4.0%（mass fraction）. During calcination from 800 to 1200℃, hexagonal β-quartz solid-solution first crystallizes and then gradually transforms into tetragonal β-spodumene solid-solution with increasing temperature. The stability of β-quartz solid-solution increases with more ZrO2 additions and a minor crystalline phase, tetragonal zirconia, also appears.
基金The work was financially supported by the National Key Research and Development Program of China(Grant Nos.2018YFA0703600,2021YFA0716302,and 2021YFA0718703)the National Natural Science Foundation of China(Grant Nos.51825104 and 52192602)China Postdoctoral Science Foundation(Grant No.2022T150691).
文摘Melt treatment is well known to have an important influence on the properties of metallic glasses(MGs).However,for the MGs quenched from different melt temperatures with a quartz tube,the underlying physical origin responsible for the variation of properties remains poorly understood.In the present work,we systematically studied the influence of melt treatment on the thermal properties of a Zr50Cu36Al14 glass-forming alloy and unveiled the microscopic origins.Specifically,we quenched the melt at different temperatures ranging from 1.1Tl to 1.5Tl(Tl is the liquidus temperature)to obtain melt-spun MG ribbons and investigated the variation of thermal properties of the MGs upon heating.We found that glass transition temperature,Tg,increases by as much as 36 K,and the supercooled liquid region disappears in the curve of differential scanning calorimetry when the melt is quenched at a high temperature up to 1.5Tl.The careful chemical analyses indicate that the change in glass transition behavior originates from the incorporation of oxygen and silicon in the molten alloys.The incorporated oxygen and silicon can both enhance the interactions between atoms,which renders the cooperative rearrangements of atoms difficult,and thus enhances the kinetic stability of the MGs.
基金supported by the National Natural Science Foundation of China (Grant Nos. 52031016 and 11804027)the China Scholarship Council for financial support during part of this work
文摘The early stage evolution of local atomic structures in a multicomponent metallic glass during its crystallization process has been investigated via molecular dynamics simulation.It is found that the initial thermal stability and earliest stage evolution of the local atomic clusters show no strong correlation with their initial short-range orders,and this leads to an observation of a novel symmetry convergence phenomenon,which can be understood as an atomic structure manifestation of the ergodicity.Furthermore,in our system we have quantitatively proved that the crucial factor for the thermal stability against crystallization exhibited by the metallic glass is not the total amount of icosahedral clusters,but the degree of global connectivity among them.
文摘In view of the composition analysis and identification of ancient glass products, L1 regularization, K-Means cluster analysis, elbow rule and other methods were comprehensively used to build logical regression, cluster analysis, hyper-parameter test and other models, and SPSS, Python and other tools were used to obtain the classification rules of glass products under different fluxes, sub classification under different chemical compositions, hyper-parameter K value test and rationality analysis. Research can provide theoretical support for the protection and restoration of ancient glass relics.
文摘Solid-state impedance spectroscopy(SS-IS)was used to investigate the influence of structural modifications resulting from the addition of Nb2O5 on the dielectric properties and relaxation processes in the quaternary mixed glass former(MGF)system 35Na_(2)O–10V_(2)O_(5)–(55-x)P_(2)O_(5)–xNb_(2)O_(5)(x=0–40,mol%).The dielectric parameters,including the dielectric strength and dielectric loss,are determined from the frequency and temperature-dependent complex permittivity data,revealing a significant dependence on the Nb2O5 content.The transition from a predominantly phosphate glass network(x<10,region I)to a mixed niobate–phosphate glass net-work(10≤x≤20,region II)leads to an increase in the dielectric parameters,which correlates with the observed trend in the direct-cur-rent(DC)conductivity.In the predominantly niobate network(x≥25,region III),the highly polarizable nature of Nb5+ions leads to a fur-ther increase in the dielectric permittivity and dielectric strength.This is particularly evident in Nb-40 glass-ceramic,which contains Na_(13)Nb_(35)O_(94) crystalline phase with a tungsten bronze structure and exhibits the highest dielectric permittivity of 61.81 and the lowest loss factor of 0.032 at 303 K and 10 kHz.The relaxation studies,analyzed through modulus formalism and complex impedance data,show that DC conductivity and relaxation processes are governed by the same mechanism,attributed to ionic conductivity.In contrast to glasses with a single peak in frequency dependence of imaginary part of electrical modulus,M″(ω),Nb-40 glass-ceramic exhibits two distinct contributions with similar relaxation times.The high-frequency peak indicates bulk ionic conductivity,while the additional low-fre-quency peak is associated with the grain boundary effect,confirmed by the electrical equivalent circuit(EEC)modelling.The scaling characteristics of permittivity and conductivity spectra,along with the electrical modulus,validate time-temperature superposition and demonstrate a strong correlation with composition and modification of the glass structure upon Nb_(2)O_(5) incorporation.
文摘In our modern world, where conserving energy is highly valued, thermal insulation panels play a crucial role in reducing heat transfer between two spaces, surfaces, or materials. They are used to enhance the energy efficiency of various industrial applications by minimizing heat loss and temperature control. These panels function as silent protectors, aiding in reducing energy consumption and making things more sustainable and better for the environment. This is where composite materials come in;they are known for their lightweight nature, high strength-to-weight ratio, and excellent thermal insulation properties and have gained significant attention. Researchers are actively engaged in various studies aimed at enhancing these materials further. This research project focuses on the development of kaolin and glass fiber-reinforced composites for thermally insulating panels, to which natural strengthening materials like corn husk and bamboo fibers are added. The aim is to create cost-effective and efficient composite materials for thermal insulation applications by incorporating these components with a binder consisting of potassium silicate, hydroxide, and distilled water. This project involves conducting compression tests, bending tests, impact tests, thermal conductivity measurements, and microscopic analysis to evaluate the mechanical and thermal properties of the developed composites. The profound impact of these engineered composites on thermal insulation panels stands to revolutionize energy conservation efforts, offering a potent avenue to minimize heat loss and enhance overall energy efficiency across an array of industrial sectors.
文摘This paper concentrates on the development of glasses with self-cleaning surfaces exhibiting high water contact angles. In this study, we prepared super-hydrophobic nano-ceramic coated glass based on titania & silica using simple sol-gel & dip coating methods and studied the best composition of the coatings by altering ratios of titanium tetraisopropoxide (TTIP)/tetraethyl orthosilicate (TEOS) with different homogenizing agents. We characterized the coatings by surface roughness measurement, percentage of optical transmission, static contact angle, near-infrared (NIR) transmission, and diffuse reflectance. The fabrication of coatings on glass substrates played an important role in increasing the water contact angle of about 95° and visible & NIR transmission of about 90%. We compared our modified glass substrate with commercial low emissivity (Low E) glass using X-ray diffraction (XRD) analysis, which showed pure amorphous surface claiming excellent wettability and thus the prepared glass substrate could have a variety of applications in different fields.
文摘The dynamic responses and generated voltage in a curved sandwich beam with glass reinforced laminate(GRL)layers and a pliable core in the presence of a piezoelectric layer under low-velocity impact(LVI)are investigated.The current study aims to carry out a dynamic analysis on the sandwich beam when the impactor hits the top face sheet with an initial velocity.For the layer analysis,the high-order shear deformation theory(HSDT)and Frostig's second model for the displacement fields of the core layer are used.The classical non-adhesive elastic contact theory and Hunter's principle are used to calculate the dynamic responses in terms of time.In order to validate the analytical method,the outcomes of the current investigation are compared with those gained by the experimental tests carried out by other researchers for a rectangular composite plate subject to the LVI.Finite element(FE)simulations are conducted by means of the ABAQUS software.The effects of the parameters such as foam modulus,layer material,fiber angle,impactor mass,and its velocity on the generated voltage are reviewed.
文摘The microstructure and phase composition of high-alumina,chromic oxide,and AZS/Cr refractories containing 30%and 60%(by mass)Cr2O3 after exposure to aluminaboronsilicate glasses and basalt melts depending on the type of melts and temperature have been studied.The mechanisms of refractory corrosion by the used melts and the factors contributing to the inhibition of corrosion development have been investigated by the method of petrographic analysis.On the basis of obtained results,the use of high-alumina,chromic oxide,and AZS/Cr refractories in the sections of glass furnace linings,experiencing the intensive impact of aluminaboronsilicate glasses and basalt melts,has been confirmed and scientifically substantiated.
文摘The aim of this study was to optimize the geometry and the design of metallic/composite single bolted joints subjected to tension-compression loading. For this purpose, it was necessary to evaluate the stress state in each component of the bolted join. The multi-material assembly was based on the principle of double lap bolted joint. It was composed of a symmetrical balanced woven glass-epoxy composite material plate fastened to two stainless sheets using a stainless pre-stressed bolt. In order to optimize the design and the geometry of the assembly, ten configurations were proposed and studied: a classical simple bolted joint, two joints with an insert (a BigHead<sup>R</sup> insert and a stair one) embedded in the composite, two “waved” solutions, three symmetrical configurations composed of a succession of metallic and composites layers, without a sleeve, with one and with two sleeves, and two non-symmetrical constituted of metallic and composites layers associated with a stair-insert (one with a sleeve and one without). A tridimensional Finite Element Method (FEM) was used to model each configuration mentioned above. The FE models taked into account the different materials, the effects of contact between the different sheets of the assembly and the pre-stress in the bolt. The stress state was analyzed in the composite part. The concept of stress concentration factor was used in order to evaluate the stress increase in the highly stressed regions and to compare the ten configurations studied. For this purpose, three stress concentration factors were defined: one for a monotonic loading in tension, another for a monotonic loading in compression, and the third for a tension-compression cyclic loading. The results of the FEM computations showed that the use of alternative metallic and composite layers associated with two sleeves gived low values of stress concentration factors, smaller than 1.4. In this case, there was no contact between the bolt and the composite part and the most stressed region was not the vicinity of the hole but the end of the longest layers of the metallic inserts.
基金the National Natural Science Foundation of China(No.51974168)the Science and Technology Major Project of Inner Mongolia Autonomous Region in China(Nos.2019ZD023 and 2021ZD0028)the State Key Laboratory of Silicate Materials for Architectures(Wuhan University of Technology)(No.SYSJJ2020-08)。
文摘The effect of substitution La_(2)O_(3)and YF_(3)as network modifiers respectively for Y_(2)O_(3),and ZnO as intermediate oxide for Al_(2)O_(3)on crystallization and viscous behavior of Y_(2)O_(3)-Al_(2)O_(3)-SiO_(2)glass was studied.La_(2)O_(3)and YF_(3)substitution for Y_(2)O_(3)decreases the melting temperature of studied glass from 1402 to 1346 and 1379℃,and the activation energy of viscous flow decreases from 340 to 250 and 265 kJ/mol.Meanwhile,ZnO substitution for Al_(2)O_(3)decreases the melting temperature to 1379℃while increases the activation energy of viscous flow to 542 kJ/mol,due to their different role in glass structure.Substitution ZnO for Al_(2)O_(3)refines and homogenizes the crystals size and lowers crystallinity because the nucleation and crystal growth are depressed by higher activation energy of crystallization and change of crystallization mechanism from bulk crystallization to surface crystallization.Replacement of Y_(2)O_(3)by La_(2)O_(3)and YF_(3)respectively also decreases the crystallinity of Y_(2)O_(3)-Al_(2)O_(3)-SiO_(2)glass ceramic due to competitive and hindering effect on the rearranged atoms,structural units and groups required by precipitated two crystals.Besides,y-Y2Si2O7,precipitation of Y4.67(SiO4)3O,ZnAl_(2)O_(4),and Y3Si3O10F were observed respectively due to incorporation of La_(2)O_(3),ZnO,and YF_(3).
文摘The structural and spectroscopic properties of Na2O-Al2O3-SiO2-xP2O5 glasses（x = 0 to 7 mol%） are investigated.Both Raman and IR spectra reveal that discrete phosphate species([PO4]-3,[PO3O1/2]-2) with low polymerization degree can be formed in the silicate glass.These phosphate structures scavenge non-bridging oxygen ions and cations from the silicate network,resulting in an increase of the glass transition temperature.According to the Judd-Ofelt intensity parameters（Ω2,Ω4,Ω6） of Er3+.the asymmetry of local environment around Er3+ becomes higher,and the bond covalency between Er3+ and O2-decreases after P2O5 is introduced.In the emission spectra,photo-luminescence intensity increases with increasing P2O5 concentration and the spectra are inhornogeneously broadened,revealing that the ligand electric field around Er3+ is dramatically changed,and the glass matrix becomes disordered.
基金supported by the National Natural Science Foundation of China(Nos.60937003 and 61111120100)
文摘The effects of bismuth doping content and temperature on the absorption property and near-infrared(NIR) luminescence of Bi-doped La2O3-Al2O3-SiO2(LAS) glasses are presented.The emission intensity reaches the maximum when the Bi2O3 content in 3.0Bi-LAS is 1.83%.The emission spectra reach their peaks at 1 190 and 1 117 nm,with full-width at half-maximum(FWHM) values of 330 and 228 nm under 500 and 700-nm excitations,respectively.As the Bi2O3 content increases,the peak wavelengths and FWHMs of emission bands increase,but their lifetimes decrease.The lifetime of 2.0Bi-LAS is 460 μs at 9 K,and is almost temperature independent until 350 K.The NIR emission of Bi in the system has strong resistance to thermal quenching from 9 to 350 K.
