Silicate glass-ceramics were prepared by adding 40 wt%granite wastes.The effects of CaO/MgO(C/M)molar ratio on microstructure and mechanical properties of glass-ceramics were investigated.With C/M ratio increasing,the...Silicate glass-ceramics were prepared by adding 40 wt%granite wastes.The effects of CaO/MgO(C/M)molar ratio on microstructure and mechanical properties of glass-ceramics were investigated.With C/M ratio increasing,the crystallization behavior changed from bulk crystallization to surface crystallization with heat treatment at 800℃.However,bulk crystallization occurred in all samples when crystallized at both 850 and 900℃.The content of forsterite and tainiolite initially increased and then decreased,while diopside and kalsilite increased when heated at 850℃.For 900℃,the increase of C/M ratio promoted the precipitation of diopside rather than forsterite and tainiolite,and interlocked plate crystals abundantly appeared with C/M ratio≥0.14.The values of Vickers hardness for samples crystallized at 850 and 900℃increased initially followed by a decrease,while the values of fracture toughness showed the opposite trend.The glass-ceramic with C/M ratio 0.065 heated at 900℃showed relatively high Vickers hardness((5.7±0.14)GPa)and excellent fracture toughness((3.55±0.14)MPa·m^(1/2)).展开更多
Iron phosphate based glass-ceramics with deliberately added Ce as an active nuclide simulant were prepared by microwave sintering.The sintering characteristics,including phases and structural evolution,and chemical du...Iron phosphate based glass-ceramics with deliberately added Ce as an active nuclide simulant were prepared by microwave sintering.The sintering characteristics,including phases and structural evolution,and chemical durability were investigated.XRD showed that NaZr_(2)(PO_(4))_(3) and FePO_(4) became the main crystalline phases of glass-ceramics with increasing sintering temperature.SEM revealed the glass-ceramics compactness increased first and then decreased as sintering temperature increased.Raman spectrum showed that,as sintering temperature increased,the network structure of glass-ceramics changed from mainly containing orthophosphate and pyrophosphate to a single orthophosphate.After immersion for 28 days,LR_(Na),LR_(Zr) and LR_(Ce) of the glass-ceramics prepared at 1000℃ were as low as 3.64×10^(-5),0.25×10^(-9) and 5.70×10^(-9)g/m^(2)/d respectively.The results indicate that iron phosphate based glass-ceramics can be prepared by rapid microwave sintering of glass powders and there is a potential of employing such microwave sintering technique in processing of glass-ceramics nuclear waste form.展开更多
There is a perpetual pursuit for free-form glasses and ceramics featuring outstanding mechanical properties as well as chemical and thermal resistance.It is a promising idea to shape inorganic materials in three-dimen...There is a perpetual pursuit for free-form glasses and ceramics featuring outstanding mechanical properties as well as chemical and thermal resistance.It is a promising idea to shape inorganic materials in three-dimensional(3D)forms to reduce their weight while maintaining high mechanical properties.A popular strategy for the preparation of 3D inorganic materials is to mold the organic–inorganic hybrid photoresists into 3D micro-and nano-structures and remove the organic components by subsequent sintering.However,due to the discrete arrangement of inorganic components in the organic-inorganic hybrid photoresists,it remains a huge challenge to attain isotropic shrinkage during sintering.Herein,we demonstrate the isotropic sintering shrinkage by forming the consecutive–Si–O–Si–O–Zr–O–inorganic backbone in photoresists and fabricating 3D glass–ceramic nanolattices with enhanced mechanical properties.The femtosecond(fs)laser is used in two-photon polymerization(TPP)to fabricate 3D green body structures.After subsequent sintering at 1000℃,high-quality 3D glass–ceramic microstructures can be obtained with perfectly intact and smooth morphology.In-suit compression experiments and finite-element simulations reveal that octahedral-truss(oct-truss)lattices possess remarkable adeptness in bearing stress concentration and maintain the structural integrity to resist rod bending,indicating that this structure is a candidate for preparing lightweight and high stiffness glass–ceramic nanolattices.3D printing of such glasses and ceramics has significant implications in a number of industrial applications,including metamaterials,microelectromechanical systems,photonic crystals,and damage-tolerant lightweight materials.展开更多
In this study,transparent K_(2)O-Al_(2)O_(3)-SiO_(2)(KAS)glass-ceramics with leucite as the main crystalline phase were prepared by melting-quench method and two-step heat treatment.The effects of SiO_(2)/Al_(2)O_(3) ...In this study,transparent K_(2)O-Al_(2)O_(3)-SiO_(2)(KAS)glass-ceramics with leucite as the main crystalline phase were prepared by melting-quench method and two-step heat treatment.The effects of SiO_(2)/Al_(2)O_(3) ratio and heat treatment on crystallization and mechanical properties were studied.The crystallization kinetics and X-Ray Diffraction(XRD)results showed that SiO_(2)/Al_(2)O_(3) ratio and heat treatment system had a direct impact on the crystallization behavior of potassium aluminosilicate glass-ceramics.When heat-treated at 680℃/2 h and 780℃/1 h,cracks generated on the surface of the sample with the addition of SiO_(2)/Al_(2)O_(3)=4.8(in mol)due to the huge difference in the coefficient of thermal expansion between glass matrix and surface.When the addition of SiO_(2)/Al_(2)O_(3)(in mol)was 4,the sample with leucite as the main crystalline phase showed an excellent fracture toughness(1.46 MPa·m^(0.5))after the heat treatment of 680℃/2 h and 780℃/5 h.And there was a phase transformation from kaliophilite to leucite.The crystalline phases of the sample heat-treated at 680℃/8 h and 780℃/1 h were leucite and kaliophilite,which resulted in the visible light transmittance of 63%and the fracture toughness of 0.91 MPa·m^(0.5).Furthermore,after the heat treatment of 680℃/2 h and 780℃/5 h,the main crystalline phase of the sample with SiO_(2)/Al_(2)O_(3)=3.2(in mol)was still kaliophilite.Because leucite only grows on the surface of the sample and is hard to grow inward,it is hard to achieve the bulk crystallization of leucite in the sample with SiO_(2)/Al_(2)O_(3)=3.2(in mol).展开更多
The presence of Li_(2)Si_(2)O_(5) and LiAlSi_(4)O_(10) could effectively improve the elastic modulus and transmittance of lithium disilicate(LD)glass-ceramics.Through synergistically modulation of the crystal content ...The presence of Li_(2)Si_(2)O_(5) and LiAlSi_(4)O_(10) could effectively improve the elastic modulus and transmittance of lithium disilicate(LD)glass-ceramics.Through synergistically modulation of the crystal content and grain size,we obtained high strength and high transmittance of LD glass-ceramics.The optimal sample had a high transmittance of 90.3%,the hardness was 7.72 GPa,the fracture toughness was 1.07 MPa·m^(1/2),and the elastic modulus was 103.1 GPa.展开更多
The glass-ceramics were prepared with the spodumene mineral as the main raw material,and the effects of ZrO_(2)replacing TiO_(2)on the samples were systematically investigated.The results show that the substitution of...The glass-ceramics were prepared with the spodumene mineral as the main raw material,and the effects of ZrO_(2)replacing TiO_(2)on the samples were systematically investigated.The results show that the substitution of ZrO_(2)for TiO_(2)is not conductive to precipitate𝛽β-quartz solid solution phase,but can improve the transparency and flexural strength of glass-ceramics.And the glass-ceramic with the highest visible light transmittance(87%)and flexural strength(231.80 MPa)exhibits an ultra-low thermal expansion of-0.028×10^(-7)K^(-1)in the region of 30-700℃.展开更多
Glass-ceramic materials of strontium barium niobate system were prepared through a melt-quenching method. The effects of crystallization temperature on the mierostructure, dielectric property, breakdown strength and e...Glass-ceramic materials of strontium barium niobate system were prepared through a melt-quenching method. The effects of crystallization temperature on the mierostructure, dielectric property, breakdown strength and energy storage density of barium strontium niobate glass-ceramics were studied. The crystallization mechanism of the glass-ceramics was discussed and should be one-dimensional interfacial growth. The results indicate that the breakdown strength remarkably increases with the increase of crystallization temperature. The glass-ceramic heat treated at 900 ℃ was found to possess optimal properties with breakdown strength of 1300 kV/cm and energy storage density of 2.8 J/cm3, which is promising dielectric materials for high energy storage density dielectrics.展开更多
Municipal solid waste incineration(MSWI) fly ash is a by-product from municipal waste incineration.According to incomplete statistics, each year more than one million tons MSWI fly ash was produced in China. Owing to ...Municipal solid waste incineration(MSWI) fly ash is a by-product from municipal waste incineration.According to incomplete statistics, each year more than one million tons MSWI fly ash was produced in China. Owing to high heavy elements content, widely used disposal methods of landfill are not suitable for MSWI fly ash treatment. In this study, by using MSWI fly ash as raw materials, glassceramics was synthesized for the solidification of heavy metals and waste recycle. Process parameters, including composition, heat treatment temperature and time, were studied and optimized. Under optimizing conditions, the product has good properties of density of 3.42 g·cm^(-3) and Vickers hardness of 6.91 GPa. Moreover, the leaching concentration of heavy metal elements meets allowable values of toxicity characteristic leaching procedure(TCLP).This study offers an alternative for MSWI fly ash recycle.展开更多
To effectively reuse high-titanium blast furnace slag （TS）, foam glass-ceramics were successfully prepared by powder sintering at 1000℃. TS and waste glass were used as the main raw materials, aluminium nitride （...To effectively reuse high-titanium blast furnace slag （TS）, foam glass-ceramics were successfully prepared by powder sintering at 1000℃. TS and waste glass were used as the main raw materials, aluminium nitride （AIN） as the foaming agent, and borax as the fluxing agent. The influence of the amount of A1N added （lwt%-5wt%） on the crystalline phases, microstructure, and properties of the produced foam glass-ceramics was studied. The results showed that the main crystal phases were perovskite, diopside, and augite. With increasing A1N content, a transformation from diopside to augite occurred and the crystallinity of the pyroxene phases slightly decreased. Initially, the aver- age pore size and porosity of the foam glass-ceramics increased and subsequently decreased; similarly, their bulk density and compressive strength decreased and subsequently increased. The optimal properties were obtained when the foam glass-ceramics were prepared by adding 4wt% AIN.展开更多
The crystallization behavior of wollastonite glass-ceramics was investigated by means of X-ray diffraction （XRD） analysis and surface morphological observations, and the chemical compositions were evaluated by field...The crystallization behavior of wollastonite glass-ceramics was investigated by means of X-ray diffraction （XRD） analysis and surface morphological observations, and the chemical compositions were evaluated by field emission-scanning electron microscopy （FE-SEM） and energy dispersive X-ray spectroscopy （EDS）. Various heat treatment temperatures （850, 900, 950, 1000 and 1050 ℃） were used to obtain glass-ceramics of the ideal wollastonite crystal phase as well as optimum mechanical properties and chemical durability. From XRD, FE-SEM and EDS, the crystallization of acicular crystal phase in the matrix was achieved at heat treatment temperature of 1000 and 1050 ℃, and wollastonite （CaSiO3） was found in the acicular type main crystal phase in the glass-ceramics. Various properties, such as density, compressive strength, bending strength and chemical durability were also examined. The mechanical properties of glass-ceramics obtained at the heat treatment temperature of 1000 and 1050 ℃ were superior to those obtained at the heat treatment temperature of 850 ℃.展开更多
Boron for aluminum substitution in the cordierite structure has been examined by sol-gel preparation of different samples along the compositional junction Mg2Al4-xBxSi5O18 with x=0,0.5,1,1.5.By increasing the x value ...Boron for aluminum substitution in the cordierite structure has been examined by sol-gel preparation of different samples along the compositional junction Mg2Al4-xBxSi5O18 with x=0,0.5,1,1.5.By increasing the x value from 0 to 1.5 the crystallization behavior changed accordingly.Proper amount B2O3 doping can promote the sintering of amorphous cordierite gel,effectively restrain the precipitation of μ-cordierite and enhance the crystallization of α-cordierite.The substitution of B3＋ for Al3＋ in cordierite crystal structure can effectively improve the near-infrared spectral emissivity of this cordierite based glass-ceramics.展开更多
One-step crystallization is one of the most energy conserving methods for glass-ceramics preparation.However,only a few kinetics studies focused on the glass-ceramics prepared by the one-step crystallization.The onest...One-step crystallization is one of the most energy conserving methods for glass-ceramics preparation.However,only a few kinetics studies focused on the glass-ceramics prepared by the one-step crystallization.The onestep crystallization kinetic parameters were studied using differential scanning calorimetry.The activation energy（Ea）and the Avrami parameter（n）were calculated as 152.79kJ·mol-1 and 4.39,respectively.These parameters indicate that continuous nucleation and three-dimensional crystal growth are the dominating mechanisms in the one-step crystallization process of the parent glass.The properties of the obtained glass-ceramics can be compared to the glass-ceramics prepared by the two-stage heat treatment and sintering method.This crystallization kinetics research can be used to evaluate the one-step crystallization potential of a parent glass.展开更多
Foamed glass-ceramics were prepared via a single-step sintering method using high-titanium blast furnace slag and waste glass as the main raw materials The influence of sintering temperature(900–1060℃) on the micros...Foamed glass-ceramics were prepared via a single-step sintering method using high-titanium blast furnace slag and waste glass as the main raw materials The influence of sintering temperature(900–1060℃) on the microstructure and properties of foamed glass-ceramics was studied. The results show that the crystal shape changed from grainy to rod-shaped and finally turned to multiple shapes as the sintering temperature was increased from 900 to 1060℃. With increasing sintering temperature, the average pore size of the foamed glass-ceramics increased and subsequently decreased. By contrast, the compressive strength and the bulk density decreased and subsequently increased. An excessively high temperature, however, induced the coalescence of pores and decreased the compressive strength. The optimal properties, including the highest compressive strength(16.64 MPa) among the investigated samples and a relatively low bulk density(0.83 g/cm^3), were attained in the case of the foamed glass-ceramics sintered at 1000℃.展开更多
Lead-free glass-ceramic composites in barium sodium niobate silica system with Gd2O3 addition were synthesized through melt-casting fol-lowed by controlled crystallization technique. Crystallization and dielectric pro...Lead-free glass-ceramic composites in barium sodium niobate silica system with Gd2O3 addition were synthesized through melt-casting fol-lowed by controlled crystallization technique. Crystallization and dielectric properties of the Gd2O3 adding glass-ceramic composites were investigated. With the increase in the concentration of Gd2O3, the glass transition temperature and the crystallization temperature of the pre-cursor glass shift towards the higher temperature. The crystallization behavior that occurred during the heat treatment procedure leads to the enhancement of dielectric constant. All the three compositions of glass-ceramic composites exhibit ferroelectricity when tested at room tem-perature. Both the values of the remanent polarization and coercive field are enhanced regularly with the gradual increase in the concentration of Gd2O3 additive under the same testing field.展开更多
The effect of microwave radiation on the nucleation and crystallization of tailing-based glass-ceramics was investigated using a 2.45 GHz multimode microwave cavity. Tailing-based glass samples were prepared fi＇om Sh...The effect of microwave radiation on the nucleation and crystallization of tailing-based glass-ceramics was investigated using a 2.45 GHz multimode microwave cavity. Tailing-based glass samples were prepared fi＇om Shandong gold tailings and Guyang iron tailings utilizing a conventional glass melting technique. For comparison, the tailing-based glass samples were crystallized using two different heat-treatment methods： conventional heating and hybrid microwave heating. The nucleation and crystallization temperatures were determined by performing a differential thermal analysis of the quenched tailing-based glass. The prepared glass-ceramic samples were further characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, thermal expansion coefficient measurements, and scanning electron microscopy. The results demonstrated that hybrid microwave heating could be successfully used to crystallize the tailing-based glass, reduce the processing time, and decrease the crystallization temperature. Furthermore, the results indicated that the nucleation and crystallization mechanism of the hybrid microwave heating process slightly differs fi＇om that of the conventional heating process.展开更多
In this pater,effect of alkali,zinc oxide and colorants such as cadmiun sulfide and selenium powder on the colouration of the red glass-ceramic materials in the CaO-Al2O3-SiO2 system has been studied.The relevant laws...In this pater,effect of alkali,zinc oxide and colorants such as cadmiun sulfide and selenium powder on the colouration of the red glass-ceramic materials in the CaO-Al2O3-SiO2 system has been studied.The relevant laws have been presented and analyzed.展开更多
Erbium doped silicate, germanate, and tellurium-germanate oxyfluoride glasses were prepared in a bulk form. Through appropriate heat treatment of the as-prepared glasses, transparent glass-ceramics （TGCs） were obtai...Erbium doped silicate, germanate, and tellurium-germanate oxyfluoride glasses were prepared in a bulk form. Through appropriate heat treatment of the as-prepared glasses, transparent glass-ceramics （TGCs） were obtained with the formation of β-PbF2：Er^3＋ nanocrystals in the glass matrix were confirmed by X-ray diffraction.Well-defined diffraction peaks were observed in the samples after heat-treatment. The average crystal diameter of these precipitated crystals from full-width at half-maximum （FWHM） of the diffraction peak was estimated to be between 8 and 13 nm. Optical absorption, photoluminescence, and upconversion luminescence were measured on as-prepared glass and glass-ceramics. Luminescence spectra in the TGC samples revealed well-resolved, sharp stark-splitting peaks, which indicates that a majority of Er^3＋ ions has been incorporated into the crystalline phase of the nanocrystals. The intensity of the visible and near infrared luminescence mostly increases in TSG compared to that in the as-prepared glass. In 1.53 μm absorption and emission bands, the maximum absorption peak is blue-shifted from 1531 to 1507 nm, whereas the maximum emission peak is redshifted from 1535 to 1543 nm in TGC, as compared with that in glass. The bandwidth at half-maximum （BWHM） of the emission band is significantly broader in TGC than in glass, which is beneficial to the erbium-doped fiber amplifier （EDFA）. Upconversion luminescence was measured using 800 nm near-infrared light excitation. Drastically increased upconversion 1 was observed from the TGC as compared to that from their corresponding as-prepared glasses. In addition to a strong green emission centered at 545 nm because of ^4S3/2→^4I15/2 transition and a weaker red emission centered at 662 nm because of ^4F9/2→^4I15/2 transition, generally seen from the Er^3＋ doped glasses, two violet emissions centered at 410 nm because of ^2H9/2→^4I15/2 transition and centered at 379 nm because of ^4G11/2→^4I15/2 transition were also observed from the was attributed to the decreased effective phonon energy and the increased energy transfer between the excited ions when Er^3＋ ions were incorporated into the precipitated β-PbF2 nanocrystals. The results indicated two attractive spectroscopic properties of the Er^3＋ doped TGC samples, compared to glass samples, namely a reduced multiphonon decay rate and a reduced inhomogeneous broadening. In addition, these oxyfluoride TGC materials were robust,easy and flexibile to process, and possible to be fabricated in the fiber form for device applications.展开更多
Grate fly ash and fluidized bed fly ash mixed with glass cullet additive respectively were melted in the electronic arc-furnace. The product, arc-melting slag, was further treated by crushing, pressing and heat treatm...Grate fly ash and fluidized bed fly ash mixed with glass cullet additive respectively were melted in the electronic arc-furnace. The product, arc-melting slag, was further treated by crushing, pressing and heat treatment in order to make the glass-ceramics. The crystallization behaviors of the produced glass-ceramics were examined by differential thermal analysis （DTA）, X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. Results show that main crystalline phase of the glass-ceramics fi＇om grate fly ash is wollastonite （CaSiO3） with small amount of diopside （Ca（Mg,Al）（Si,Al）206）, and that from fluidized bed fly ash is diopside （Ca（Mg,Al）（Si,Al）206）. It is found that the glass-ceramics sintered at 850 ℃and 1 000℃ from grate fly ash and fluidized bed fly ash respectively have the optimal physical, mechanical and chemical characteristics. Glass-ceramics samples, produced from incinerator fly ash with desirable properties and the low leaching concentration of heavy metals, can be the substitute of nature materials such as marble, granite and porcelain tiles.展开更多
A novel type of ZnO-Al2O3-B2O3-SiO2 glass-ceramics sealing to Kovar in electronic packaging was developed, whose thermal expansion coefficient and electrical resistance are 5.2× 10^-6/℃ and over 1×10^13 Ω&...A novel type of ZnO-Al2O3-B2O3-SiO2 glass-ceramics sealing to Kovar in electronic packaging was developed, whose thermal expansion coefficient and electrical resistance are 5.2× 10^-6/℃ and over 1×10^13 Ω·cm, respectively. The major crystalline phases in the glass-ceramic seals were ZnAl2O4, ZnB2O4, and NaSiAl2O4. The dielectric resistance of the glass-ceramic could be remarkably enhanced through the control of alkali metal ions into crystal lattices. It was found that crystallization happened first on the surface of the sample, leaving the amorphous phase in the inner, which made the glass suitable for sealing. The glass-ceramic showed better wetting on the Kovar surface, and sealing atmosphere and temperature had great effect on the wetting angle. Strong interracial bonding was obtained, which was mainly attributed to the interracial reaction between SiO2 and FeO or Fe3O4.展开更多
Coal fly ash is an industrial by-product generated during the combustion of coal for energy production. Due to the increasing annual consumption of coal power and the serious potential environmental threats of coal fl...Coal fly ash is an industrial by-product generated during the combustion of coal for energy production. Due to the increasing annual consumption of coal power and the serious potential environmental threats of coal fly ash, a considerable amount of research on the utilization of coal fly ash has been undertaken worldwide. Vitrification seems to be one of the most promising options for reusing this industrial waste. This paper presents a short overview of the production of unique high performance glass-ceramics using coal fly ash as a raw material. A detailed description of the methodologies for the synthesis of glass-ceramics from coal fly ash and the principal crystal phases, corresponding property and possible usage of those materials are introduced. Investigations revealed that converting coal fly ash into high performance glass-ceramic materials is a promising new approach to improve the utilization of this industrial by-product. This conversion not only alleviates the problems with disposal but also converts a waste material into a high value-added marketable commodity.展开更多
基金National Natural Science Foundation of China(Nos.52172019,51804131)Shandong Provincial Youth Innovation Team Development Plan of Colleges and Universities(No.2022KJ100)。
文摘Silicate glass-ceramics were prepared by adding 40 wt%granite wastes.The effects of CaO/MgO(C/M)molar ratio on microstructure and mechanical properties of glass-ceramics were investigated.With C/M ratio increasing,the crystallization behavior changed from bulk crystallization to surface crystallization with heat treatment at 800℃.However,bulk crystallization occurred in all samples when crystallized at both 850 and 900℃.The content of forsterite and tainiolite initially increased and then decreased,while diopside and kalsilite increased when heated at 850℃.For 900℃,the increase of C/M ratio promoted the precipitation of diopside rather than forsterite and tainiolite,and interlocked plate crystals abundantly appeared with C/M ratio≥0.14.The values of Vickers hardness for samples crystallized at 850 and 900℃increased initially followed by a decrease,while the values of fracture toughness showed the opposite trend.The glass-ceramic with C/M ratio 0.065 heated at 900℃showed relatively high Vickers hardness((5.7±0.14)GPa)and excellent fracture toughness((3.55±0.14)MPa·m^(1/2)).
基金Funded by the Key Research and Development Projects of Anhui Province(No.2022a05020026)the Key Technologies R&D Program of CNBM(Nos.2021HX0809,2021HX1011)the Anhui Science and Technology Major Project(No.2021e03020009)。
文摘Iron phosphate based glass-ceramics with deliberately added Ce as an active nuclide simulant were prepared by microwave sintering.The sintering characteristics,including phases and structural evolution,and chemical durability were investigated.XRD showed that NaZr_(2)(PO_(4))_(3) and FePO_(4) became the main crystalline phases of glass-ceramics with increasing sintering temperature.SEM revealed the glass-ceramics compactness increased first and then decreased as sintering temperature increased.Raman spectrum showed that,as sintering temperature increased,the network structure of glass-ceramics changed from mainly containing orthophosphate and pyrophosphate to a single orthophosphate.After immersion for 28 days,LR_(Na),LR_(Zr) and LR_(Ce) of the glass-ceramics prepared at 1000℃ were as low as 3.64×10^(-5),0.25×10^(-9) and 5.70×10^(-9)g/m^(2)/d respectively.The results indicate that iron phosphate based glass-ceramics can be prepared by rapid microwave sintering of glass powders and there is a potential of employing such microwave sintering technique in processing of glass-ceramics nuclear waste form.
基金supported by the National Key Research and Development Program of China(2020YFA0715000)the Hainan Provincial Joint Project of Sanya Yazhou Bay Science and Technology City(2021JJLH0058)the Guangdong Basic and Applied Basic Research Foundation(2021B1515120041)。
文摘There is a perpetual pursuit for free-form glasses and ceramics featuring outstanding mechanical properties as well as chemical and thermal resistance.It is a promising idea to shape inorganic materials in three-dimensional(3D)forms to reduce their weight while maintaining high mechanical properties.A popular strategy for the preparation of 3D inorganic materials is to mold the organic–inorganic hybrid photoresists into 3D micro-and nano-structures and remove the organic components by subsequent sintering.However,due to the discrete arrangement of inorganic components in the organic-inorganic hybrid photoresists,it remains a huge challenge to attain isotropic shrinkage during sintering.Herein,we demonstrate the isotropic sintering shrinkage by forming the consecutive–Si–O–Si–O–Zr–O–inorganic backbone in photoresists and fabricating 3D glass–ceramic nanolattices with enhanced mechanical properties.The femtosecond(fs)laser is used in two-photon polymerization(TPP)to fabricate 3D green body structures.After subsequent sintering at 1000℃,high-quality 3D glass–ceramic microstructures can be obtained with perfectly intact and smooth morphology.In-suit compression experiments and finite-element simulations reveal that octahedral-truss(oct-truss)lattices possess remarkable adeptness in bearing stress concentration and maintain the structural integrity to resist rod bending,indicating that this structure is a candidate for preparing lightweight and high stiffness glass–ceramic nanolattices.3D printing of such glasses and ceramics has significant implications in a number of industrial applications,including metamaterials,microelectromechanical systems,photonic crystals,and damage-tolerant lightweight materials.
基金Funded by State Key Laboratory of Silicate Materials for Ar-chitectures(Wuhan University of Technology)(No.2011DA105356)。
文摘In this study,transparent K_(2)O-Al_(2)O_(3)-SiO_(2)(KAS)glass-ceramics with leucite as the main crystalline phase were prepared by melting-quench method and two-step heat treatment.The effects of SiO_(2)/Al_(2)O_(3) ratio and heat treatment on crystallization and mechanical properties were studied.The crystallization kinetics and X-Ray Diffraction(XRD)results showed that SiO_(2)/Al_(2)O_(3) ratio and heat treatment system had a direct impact on the crystallization behavior of potassium aluminosilicate glass-ceramics.When heat-treated at 680℃/2 h and 780℃/1 h,cracks generated on the surface of the sample with the addition of SiO_(2)/Al_(2)O_(3)=4.8(in mol)due to the huge difference in the coefficient of thermal expansion between glass matrix and surface.When the addition of SiO_(2)/Al_(2)O_(3)(in mol)was 4,the sample with leucite as the main crystalline phase showed an excellent fracture toughness(1.46 MPa·m^(0.5))after the heat treatment of 680℃/2 h and 780℃/5 h.And there was a phase transformation from kaliophilite to leucite.The crystalline phases of the sample heat-treated at 680℃/8 h and 780℃/1 h were leucite and kaliophilite,which resulted in the visible light transmittance of 63%and the fracture toughness of 0.91 MPa·m^(0.5).Furthermore,after the heat treatment of 680℃/2 h and 780℃/5 h,the main crystalline phase of the sample with SiO_(2)/Al_(2)O_(3)=3.2(in mol)was still kaliophilite.Because leucite only grows on the surface of the sample and is hard to grow inward,it is hard to achieve the bulk crystallization of leucite in the sample with SiO_(2)/Al_(2)O_(3)=3.2(in mol).
基金Funded by the National Natural Science Foundation of China(No.52372014)the Key R&D Project of Hubei Province(No.2022BAA025)the Key R&D Project of Jincheng City(No.20220120)。
文摘The presence of Li_(2)Si_(2)O_(5) and LiAlSi_(4)O_(10) could effectively improve the elastic modulus and transmittance of lithium disilicate(LD)glass-ceramics.Through synergistically modulation of the crystal content and grain size,we obtained high strength and high transmittance of LD glass-ceramics.The optimal sample had a high transmittance of 90.3%,the hardness was 7.72 GPa,the fracture toughness was 1.07 MPa·m^(1/2),and the elastic modulus was 103.1 GPa.
文摘The glass-ceramics were prepared with the spodumene mineral as the main raw material,and the effects of ZrO_(2)replacing TiO_(2)on the samples were systematically investigated.The results show that the substitution of ZrO_(2)for TiO_(2)is not conductive to precipitate𝛽β-quartz solid solution phase,but can improve the transparency and flexural strength of glass-ceramics.And the glass-ceramic with the highest visible light transmittance(87%)and flexural strength(231.80 MPa)exhibits an ultra-low thermal expansion of-0.028×10^(-7)K^(-1)in the region of 30-700℃.
基金Project(51162002)supported by the National Natural Science Foundation of ChinaProject(2012-250)supported by the Science and Technology Project of Guangxi Returned Personnel,China
文摘Glass-ceramic materials of strontium barium niobate system were prepared through a melt-quenching method. The effects of crystallization temperature on the mierostructure, dielectric property, breakdown strength and energy storage density of barium strontium niobate glass-ceramics were studied. The crystallization mechanism of the glass-ceramics was discussed and should be one-dimensional interfacial growth. The results indicate that the breakdown strength remarkably increases with the increase of crystallization temperature. The glass-ceramic heat treated at 900 ℃ was found to possess optimal properties with breakdown strength of 1300 kV/cm and energy storage density of 2.8 J/cm3, which is promising dielectric materials for high energy storage density dielectrics.
基金financially supported by the National Natural Science Foundation of China (Nos. U1360202, 51472030, 51672024 and 51502014)the Fundamental Research Funds for the Central Universities (No. FRF-TP-16-027A3)the Innovation Project of Yunnan Province New Material Preparation and Processing Key Laboratory (No. 2016cx05)
文摘Municipal solid waste incineration(MSWI) fly ash is a by-product from municipal waste incineration.According to incomplete statistics, each year more than one million tons MSWI fly ash was produced in China. Owing to high heavy elements content, widely used disposal methods of landfill are not suitable for MSWI fly ash treatment. In this study, by using MSWI fly ash as raw materials, glassceramics was synthesized for the solidification of heavy metals and waste recycle. Process parameters, including composition, heat treatment temperature and time, were studied and optimized. Under optimizing conditions, the product has good properties of density of 3.42 g·cm^(-3) and Vickers hardness of 6.91 GPa. Moreover, the leaching concentration of heavy metal elements meets allowable values of toxicity characteristic leaching procedure(TCLP).This study offers an alternative for MSWI fly ash recycle.
基金the Science and Technology Support Projects of Sichuan Province (No. 2014GZ0011)the Industry Promotion Projects of Panzhihua in China (No.2013CY-C-2) for their financial support
文摘To effectively reuse high-titanium blast furnace slag （TS）, foam glass-ceramics were successfully prepared by powder sintering at 1000℃. TS and waste glass were used as the main raw materials, aluminium nitride （AIN） as the foaming agent, and borax as the fluxing agent. The influence of the amount of A1N added （lwt%-5wt%） on the crystalline phases, microstructure, and properties of the produced foam glass-ceramics was studied. The results showed that the main crystal phases were perovskite, diopside, and augite. With increasing A1N content, a transformation from diopside to augite occurred and the crystallinity of the pyroxene phases slightly decreased. Initially, the aver- age pore size and porosity of the foam glass-ceramics increased and subsequently decreased; similarly, their bulk density and compressive strength decreased and subsequently increased. The optimal properties were obtained when the foam glass-ceramics were prepared by adding 4wt% AIN.
文摘The crystallization behavior of wollastonite glass-ceramics was investigated by means of X-ray diffraction （XRD） analysis and surface morphological observations, and the chemical compositions were evaluated by field emission-scanning electron microscopy （FE-SEM） and energy dispersive X-ray spectroscopy （EDS）. Various heat treatment temperatures （850, 900, 950, 1000 and 1050 ℃） were used to obtain glass-ceramics of the ideal wollastonite crystal phase as well as optimum mechanical properties and chemical durability. From XRD, FE-SEM and EDS, the crystallization of acicular crystal phase in the matrix was achieved at heat treatment temperature of 1000 and 1050 ℃, and wollastonite （CaSiO3） was found in the acicular type main crystal phase in the glass-ceramics. Various properties, such as density, compressive strength, bending strength and chemical durability were also examined. The mechanical properties of glass-ceramics obtained at the heat treatment temperature of 1000 and 1050 ℃ were superior to those obtained at the heat treatment temperature of 850 ℃.
基金supported by the National Nature Science Foundation of China (No. 50771014)
文摘Boron for aluminum substitution in the cordierite structure has been examined by sol-gel preparation of different samples along the compositional junction Mg2Al4-xBxSi5O18 with x=0,0.5,1,1.5.By increasing the x value from 0 to 1.5 the crystallization behavior changed accordingly.Proper amount B2O3 doping can promote the sintering of amorphous cordierite gel,effectively restrain the precipitation of μ-cordierite and enhance the crystallization of α-cordierite.The substitution of B3＋ for Al3＋ in cordierite crystal structure can effectively improve the near-infrared spectral emissivity of this cordierite based glass-ceramics.
基金Item Sponsored by National Natural Science Foundation of China(U1360202,51472030,51502014)National Key Project of the Scientific and Technical Support Program of China(2011BAE13B07,2012BAC02B01,2011BAC10B02)+2 种基金National Hi-tech Research and Development Program of China(2012AA063202)Fundamental Research Funds for the Central Universities of China(FRF-TP-15-050A2)China Postdoctoral Science Foundation Funded Project(2014M560885)
文摘One-step crystallization is one of the most energy conserving methods for glass-ceramics preparation.However,only a few kinetics studies focused on the glass-ceramics prepared by the one-step crystallization.The onestep crystallization kinetic parameters were studied using differential scanning calorimetry.The activation energy（Ea）and the Avrami parameter（n）were calculated as 152.79kJ·mol-1 and 4.39,respectively.These parameters indicate that continuous nucleation and three-dimensional crystal growth are the dominating mechanisms in the one-step crystallization process of the parent glass.The properties of the obtained glass-ceramics can be compared to the glass-ceramics prepared by the two-stage heat treatment and sintering method.This crystallization kinetics research can be used to evaluate the one-step crystallization potential of a parent glass.
基金financially supported by the Science and Technology Support Program of Sichuan Province (No.2014GZ0011)the Industry Promotion Project of Panzhihua City, China (No.2012CY-C-2)
文摘Foamed glass-ceramics were prepared via a single-step sintering method using high-titanium blast furnace slag and waste glass as the main raw materials The influence of sintering temperature(900–1060℃) on the microstructure and properties of foamed glass-ceramics was studied. The results show that the crystal shape changed from grainy to rod-shaped and finally turned to multiple shapes as the sintering temperature was increased from 900 to 1060℃. With increasing sintering temperature, the average pore size of the foamed glass-ceramics increased and subsequently decreased. By contrast, the compressive strength and the bulk density decreased and subsequently increased. An excessively high temperature, however, induced the coalescence of pores and decreased the compressive strength. The optimal properties, including the highest compressive strength(16.64 MPa) among the investigated samples and a relatively low bulk density(0.83 g/cm^3), were attained in the case of the foamed glass-ceramics sintered at 1000℃.
基金supported by the National Natural Science Foundation of China (No. 51107005)
文摘Lead-free glass-ceramic composites in barium sodium niobate silica system with Gd2O3 addition were synthesized through melt-casting fol-lowed by controlled crystallization technique. Crystallization and dielectric properties of the Gd2O3 adding glass-ceramic composites were investigated. With the increase in the concentration of Gd2O3, the glass transition temperature and the crystallization temperature of the pre-cursor glass shift towards the higher temperature. The crystallization behavior that occurred during the heat treatment procedure leads to the enhancement of dielectric constant. All the three compositions of glass-ceramic composites exhibit ferroelectricity when tested at room tem-perature. Both the values of the remanent polarization and coercive field are enhanced regularly with the gradual increase in the concentration of Gd2O3 additive under the same testing field.
基金financially supported by the Fundamental Research and Key Technologies Fund for the Integrated Utilization of Bayan Obo Mine Resources with High Added Value (No. 41402060901)the National Natural Science Foundation of China (No. 11564013)the Inner Mongolia University of Science and Technology Innovation Fund (Nos. 2014QNGG09 and 2014QDL042).
文摘The effect of microwave radiation on the nucleation and crystallization of tailing-based glass-ceramics was investigated using a 2.45 GHz multimode microwave cavity. Tailing-based glass samples were prepared fi＇om Shandong gold tailings and Guyang iron tailings utilizing a conventional glass melting technique. For comparison, the tailing-based glass samples were crystallized using two different heat-treatment methods： conventional heating and hybrid microwave heating. The nucleation and crystallization temperatures were determined by performing a differential thermal analysis of the quenched tailing-based glass. The prepared glass-ceramic samples were further characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, thermal expansion coefficient measurements, and scanning electron microscopy. The results demonstrated that hybrid microwave heating could be successfully used to crystallize the tailing-based glass, reduce the processing time, and decrease the crystallization temperature. Furthermore, the results indicated that the nucleation and crystallization mechanism of the hybrid microwave heating process slightly differs fi＇om that of the conventional heating process.
文摘In this pater,effect of alkali,zinc oxide and colorants such as cadmiun sulfide and selenium powder on the colouration of the red glass-ceramic materials in the CaO-Al2O3-SiO2 system has been studied.The relevant laws have been presented and analyzed.
基金Project supported by NSF/CREST HRD-0420516 , NSF-STC CLiPS Grant 0423914 ,and DOD/ARO Contracts : W911NF-05-1-0453 ,04-1-0040
文摘Erbium doped silicate, germanate, and tellurium-germanate oxyfluoride glasses were prepared in a bulk form. Through appropriate heat treatment of the as-prepared glasses, transparent glass-ceramics （TGCs） were obtained with the formation of β-PbF2：Er^3＋ nanocrystals in the glass matrix were confirmed by X-ray diffraction.Well-defined diffraction peaks were observed in the samples after heat-treatment. The average crystal diameter of these precipitated crystals from full-width at half-maximum （FWHM） of the diffraction peak was estimated to be between 8 and 13 nm. Optical absorption, photoluminescence, and upconversion luminescence were measured on as-prepared glass and glass-ceramics. Luminescence spectra in the TGC samples revealed well-resolved, sharp stark-splitting peaks, which indicates that a majority of Er^3＋ ions has been incorporated into the crystalline phase of the nanocrystals. The intensity of the visible and near infrared luminescence mostly increases in TSG compared to that in the as-prepared glass. In 1.53 μm absorption and emission bands, the maximum absorption peak is blue-shifted from 1531 to 1507 nm, whereas the maximum emission peak is redshifted from 1535 to 1543 nm in TGC, as compared with that in glass. The bandwidth at half-maximum （BWHM） of the emission band is significantly broader in TGC than in glass, which is beneficial to the erbium-doped fiber amplifier （EDFA）. Upconversion luminescence was measured using 800 nm near-infrared light excitation. Drastically increased upconversion 1 was observed from the TGC as compared to that from their corresponding as-prepared glasses. In addition to a strong green emission centered at 545 nm because of ^4S3/2→^4I15/2 transition and a weaker red emission centered at 662 nm because of ^4F9/2→^4I15/2 transition, generally seen from the Er^3＋ doped glasses, two violet emissions centered at 410 nm because of ^2H9/2→^4I15/2 transition and centered at 379 nm because of ^4G11/2→^4I15/2 transition were also observed from the was attributed to the decreased effective phonon energy and the increased energy transfer between the excited ions when Er^3＋ ions were incorporated into the precipitated β-PbF2 nanocrystals. The results indicated two attractive spectroscopic properties of the Er^3＋ doped TGC samples, compared to glass samples, namely a reduced multiphonon decay rate and a reduced inhomogeneous broadening. In addition, these oxyfluoride TGC materials were robust,easy and flexibile to process, and possible to be fabricated in the fiber form for device applications.
基金Project(20806051) supported by the National Natural Science Foundation of ChinaProject(20080440680) supported by China Postdoctoral Science Foundation
文摘Grate fly ash and fluidized bed fly ash mixed with glass cullet additive respectively were melted in the electronic arc-furnace. The product, arc-melting slag, was further treated by crushing, pressing and heat treatment in order to make the glass-ceramics. The crystallization behaviors of the produced glass-ceramics were examined by differential thermal analysis （DTA）, X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. Results show that main crystalline phase of the glass-ceramics fi＇om grate fly ash is wollastonite （CaSiO3） with small amount of diopside （Ca（Mg,Al）（Si,Al）206）, and that from fluidized bed fly ash is diopside （Ca（Mg,Al）（Si,Al）206）. It is found that the glass-ceramics sintered at 850 ℃and 1 000℃ from grate fly ash and fluidized bed fly ash respectively have the optimal physical, mechanical and chemical characteristics. Glass-ceramics samples, produced from incinerator fly ash with desirable properties and the low leaching concentration of heavy metals, can be the substitute of nature materials such as marble, granite and porcelain tiles.
基金supported by the National Natural Science Foundation of China (No.50274014, 50774005)the Major State Basic Research Development Program of China (No.2006CB605207)the National High-Tech Research and Development Program of China (No.2006AA03Z557)
文摘A novel type of ZnO-Al2O3-B2O3-SiO2 glass-ceramics sealing to Kovar in electronic packaging was developed, whose thermal expansion coefficient and electrical resistance are 5.2× 10^-6/℃ and over 1×10^13 Ω·cm, respectively. The major crystalline phases in the glass-ceramic seals were ZnAl2O4, ZnB2O4, and NaSiAl2O4. The dielectric resistance of the glass-ceramic could be remarkably enhanced through the control of alkali metal ions into crystal lattices. It was found that crystallization happened first on the surface of the sample, leaving the amorphous phase in the inner, which made the glass suitable for sealing. The glass-ceramic showed better wetting on the Kovar surface, and sealing atmosphere and temperature had great effect on the wetting angle. Strong interracial bonding was obtained, which was mainly attributed to the interracial reaction between SiO2 and FeO or Fe3O4.
基金financial support of the project from the National Natural Science Foundation of China, China (No. 51172016)
文摘Coal fly ash is an industrial by-product generated during the combustion of coal for energy production. Due to the increasing annual consumption of coal power and the serious potential environmental threats of coal fly ash, a considerable amount of research on the utilization of coal fly ash has been undertaken worldwide. Vitrification seems to be one of the most promising options for reusing this industrial waste. This paper presents a short overview of the production of unique high performance glass-ceramics using coal fly ash as a raw material. A detailed description of the methodologies for the synthesis of glass-ceramics from coal fly ash and the principal crystal phases, corresponding property and possible usage of those materials are introduced. Investigations revealed that converting coal fly ash into high performance glass-ceramic materials is a promising new approach to improve the utilization of this industrial by-product. This conversion not only alleviates the problems with disposal but also converts a waste material into a high value-added marketable commodity.
