As a reliable additive manufacturing technology,the stereolithography(SLA)ceramic core necessitates a tailored sintering process to achieve optimal performance.This study explored the effects of final sintering temper...As a reliable additive manufacturing technology,the stereolithography(SLA)ceramic core necessitates a tailored sintering process to achieve optimal performance.This study explored the effects of final sintering temperatures(specifically 1,150,1,250,and 1,300°C)on the properties of SLA-fabricated SiO_(2)-based ceramic cores reinforced with nano-ZrO_(2)(at concentrations of 1.0wt.%,1.5wt.%,and 2.0wt.%).The results demonstrate that increasing the final sintering temperature and the incorporation of nano-ZrO_(2)enhance the viscous fiow of quartz glass,resulting in a higher sintering degree.As the final sintering temperature rises,the ceramic samples exhibit increased shrinkage rate,decreased apparent porosity,and increased bulk density.Higher final sintering temperatures also promote greater cristobalite precipitation,promoting an increase in the amount and precipitation rate of quartz during investment casting.The formation of a cristobalite and ZrSiO_4 network at elevated temperatures effectively inhibits the viscous flow of quartz glass,thereby significantly improving high-temperature flexural strength and creep resistance of ceramic cores.When the content of nano-ZrO_(2)is between 1.5wt.%and 2.0wt.%,the final sintering temperature of 1,250°C is the best choice.Under these conditions,the shrinkage rate along the Z direction ranges from 3.35%to 3.68%,the porosity lies between 25.57%and 26.03%,the bulk density varies from 1.612 to 1.645 g·cm^(-3),the room temperature fiexural strength is between 26.79 and 27.85 MPa,and the fiexural strength at high temperatures is within the range of 30.77 to 33.02 MPa.The defiection at high-temperatures is 3.37-5.31 mm,while the surface roughness of the upper surface is 3.26-4.79μm,and the surface roughness of the side surface is 4.97-5.79μm.These findings provide valuable guidance for optimizing the sintering processes of SLA ceramic cores,offering potential for industrial applications.展开更多
Ceramic materials with intricate structures can be efficiently fabricated using stereolithography(SLA)based 3D printing technology,offering advantages over traditional methods.Sintering temperature has primary effect ...Ceramic materials with intricate structures can be efficiently fabricated using stereolithography(SLA)based 3D printing technology,offering advantages over traditional methods.Sintering temperature has primary effect on properties of ceramics.This study investigated the crucial sintering temperature for 3D printed ceramics to ensure the desired properties.The results indicate that all samples exhibit a consistent layered structure across the experimental sintering temperatures.When the sintering temperature is increased from 1,250℃ to 1,350℃,the grain's morphology changes from spherical to plate-like.Surface morphology analysis reveals a decrease in surface roughness at sintering temperatures above 1,350℃.Mechanical tests show improved flexural strength and stiffness as the sintering temperature rises.Friction and wear experiments demonstrate that as the sintering temperature increases from 1,450℃ to 1,550℃,the wear pattern on ceramic surfaces transitions from deep pits to shallow grooves.The increase in sintering temperature effectively enhances the wear resistance of 3D printed alumina ceramics.This improvement plays a significant role in expanding the application field of these ceramics,prolonging the lifespan of parts,reducing production costs,enhancing performance,and promoting environmental protection.In this study,ceramics achieve the highest strength and best wear resistance when sintered at 1,600℃,resulting in the best overall performance.展开更多
In order to develop a marine engineering material with excellent mechanical properties and corrosion resistance,a novel non-equiatomic Co_(1.5)CrFeNi_(1.5)Ti_(0.6)high-entropy alloy(HEA)was fabricated through mechanic...In order to develop a marine engineering material with excellent mechanical properties and corrosion resistance,a novel non-equiatomic Co_(1.5)CrFeNi_(1.5)Ti_(0.6)high-entropy alloy(HEA)was fabricated through mechanical alloying and spark plasma sintering.The results revealed that the sintering temperature significantly affected the microstructure and phase composition of the HEA owing to the diffusion rate,homogenization,and sluggish diffusion effect of metal atoms.At sintering temperatures below 1050℃,HEA mainly consisted of face-centered cubic(FCC),Ni_(3)Ti(ε),Ni_(2.67)Ti_(1.33)(R),and Fe-Cr(σ)phases.The microstructure of alloy comprised coarse dendritic crystals,whose content and size gradually decreased with increasing sintering temperature.However,the HEA sintered above 1100℃contained only fine equiaxed crystals.HEA sintered at 1100℃featured only the FCC solid solution,while theε-phase precipitated at temperatures above 1150℃.At a sintering temperature of 1050℃,the alloy microstructure consisted of short rod-like dendrites and fine equiaxed crystals.This alloy achieved the highest yield strength of 1198.71 MPa owing to the effects of precipitation strengthening and grain boundary strengthening.Meanwhile,HEA sintered above 1050℃exhibited significantly improved corrosion resistance.Considering the microstructure,mechanical,and corrosion properties,1050℃was identified as the optimal sintering temperature for Co_(1.5)CrFeNi_(1.5)Ti_(0.6)HEA.展开更多
LiNi0.8Co0.1Mn0.1O2 powder was prepared by mixing LiOH·H2O and co-precipitated Ni0.8Co0.1Mn0.1（OH）2 at a molar ratio of 1：1.05, followed by sintering at different temperatures. The effects of temperature on th...LiNi0.8Co0.1Mn0.1O2 powder was prepared by mixing LiOH·H2O and co-precipitated Ni0.8Co0.1Mn0.1（OH）2 at a molar ratio of 1：1.05, followed by sintering at different temperatures. The effects of temperature on the morphology, structure and electrochemical performance were extensively studied. SEM and XRD results demonstrate that the sintering temperature has large influence on the morphology and structure and suitable temperature is very important to obtain spherical materials and suppresses the ionic distribution. The charge-discharge tests show that the electrochemical performance of LiNi0.8Co0.1Mn0.1O2 powders becomes better with the increase of temperature from 700 ℃ to 750 ℃ and higher temperature will deteriorate the performance. Although both of materials obtained at 750 ℃ and 780 ℃ demonstrate almost identical cyclic stability at 2C rate, which delivers 71.9%retention after 200 cycles, the rate performance of powder calcined at 780 ℃ is much poorer than that at 750 ℃. The XRD results demonstrate that the poor performance is ascribed to more severe ionic distribution caused by higher temperature.展开更多
A procedure of low temperature solid-phase sintering（LTSS） was carried out to fabricate sintered metal fibrous media（SMFM） with high specific surface area.Stainless steel fibers which were produced by cutting proc...A procedure of low temperature solid-phase sintering（LTSS） was carried out to fabricate sintered metal fibrous media（SMFM） with high specific surface area.Stainless steel fibers which were produced by cutting process were first plated with a coarse copper coating layer by electroless plating process.A low-temperature sintering process was then completed at about 800 °C for 1 h under the protection of hydrogen atmosphere.The results show that a novel SMFM with complex surface morphology and high specific surface area（0.2 m2/g） can be obtained in this way.The effect of sintering temperature on the surface morphology and specific surface area of SMFM was studied by means of scanning electron microscopy and Brunauer-Emmett-Teller.The damage of micro-structure during the sintering process mainly contributed to the loss of specific surface area of SMFM and the optimal sintering temperature was 800 °C.展开更多
A series of (1-x)La0.6Dy0.1Sr0.3MnO3/0.5x(Sb2O3)(x=0.15) samples were prepared by the solid-state reaction method, and the influence of sintering temperature of the matrix on low-field magnetoresistance of (1-x)La0.6D...A series of (1-x)La0.6Dy0.1Sr0.3MnO3/0.5x(Sb2O3)(x=0.15) samples were prepared by the solid-state reaction method, and the influence of sintering temperature of the matrix on low-field magnetoresistance of (1-x)La0.6Dy0.1Sr0.3MnO3/0.5x (Sb2O3) was studied through the measurements of X-ray diffraction (XRD) patterns, scanning electron microscope (SEM) image, resistivity-temperature (ρ-T) curves, and magnetoresistance-temperature (MR-T) curves. The results indicate that for the samples with low sintering temperature of the matrix, lowfield magnetoresistance effect appears on the whole temperature range and can be explained by grain boundary effect; for the sample with high sintering temperature of the matrix, intrinsic magnetoresistance peak appears on the high-temperature range, low-field magnetore-sistance effect appears on low temperature range, and the magnetoresistance in the magnetic field of 0.2 T and on the comparatively large temperature range between 280 K and 225 K hardly changes with temperature and remains at 4.8%, which can be explained by the competition between the intrinsic magnetoresistance induced by double-exchange function inside grains and the tunneling magnetoresis-tance (TMR) induced by grain boundary effect. The temperature stability of magnetoresistance is beneficial to the practical applications of MR.展开更多
Effects of sintering temperature in hot pressing, t yp es, states and amounts of rare earth as well as TiH 2 on the transverse rupture strength (TRS) of Fe-based composites are studied by means of orthogonal test and ...Effects of sintering temperature in hot pressing, t yp es, states and amounts of rare earth as well as TiH 2 on the transverse rupture strength (TRS) of Fe-based composites are studied by means of orthogonal test and variance analysis in this paper. It is found that sintering temperature has a significant effect on the TRS of Fe-based diamond composites. The optimal sin tering temperature is 780～860 ℃. On the contrary, the effects of RE additi v es on values of TRS of the diamond composites have on distinct difference no mat ter the RE is in the state of mixture or compound or oxidization. Experimental r esults demonstrate that Fe-based diamond composites with RE additives exhibit h igher TRS, which results in an increase in diamond retention capacity. The degre e of increment of TRS is different at different sintering temperatures. The opti mal amount of rare earth was found to be about 1% in weight. The effect of RE is more significant at lower sintering temperature. The experimental results also reveal that TiH 2 additive has a negative effect on the TRS of Fe-based compos ites. Microscope observations demonstrate that specimen without TiH 2 additives , shows fewer pores and denser structures in the base metal. It can also be seen from the SEM observation of the resulting fracturing surface of bending test sp ecimens that the bonding of the diamond-matrix interface is better in the speci men without TiH 2 than in the specimen with TiH 2. Also the fracture surface o f the specimen without TiH 2 reveals ductile cup and cone behavior.展开更多
Mg-Al spinel is synthesized by using industrial waste-residue and basic magnesium carbonate in the aluminum factory as the main raw materials. The influence of sintering temperature on crystalline structure and micros...Mg-Al spinel is synthesized by using industrial waste-residue and basic magnesium carbonate in the aluminum factory as the main raw materials. The influence of sintering temperature on crystalline structure and microstructure of Mg-Al spinel has been mainly discussed. The crystalline structure of sample is characterized by using XRD, SEM and relevant analytical software. The experimental results show that compared to the conventional synthetic method, the application of waste aluminum slag as the raw material can greatly decrease the synthetic tem-perature. The content of Mg-Al spinel first increases and then decreases with the rise of sintering temperature, and its purity can reach as high as 96wt% at 1550 ℃, which is therefore determined to be the optimum synthetic temperature. SEM observations demonstrate that as the rise of sintering temperature, the grain of Mg-Al spinel grows up obviously with typical octahedral characteristic appearance.展开更多
The microstructures and magnetic properties of Ce-32.15Co_49.36Cu_9.84Fe_9.65 magnet sintered at the temperatures ranging from 1005 to 1105 °C were investigated. The results on scanning electron microscopy and X-...The microstructures and magnetic properties of Ce-32.15Co_49.36Cu_9.84Fe_9.65 magnet sintered at the temperatures ranging from 1005 to 1105 °C were investigated. The results on scanning electron microscopy and X-ray diffraction analysis indicate that the remanence B r of the magnets is mainly influenced by the degree of the easy-axis orientation when sintering temperature is less than 1085 °C, the rapidly increasing amount of the secondly phase (5:19 phase) gives rise to the deterioration of the magnetic properties of the magnet above 1085 °C. Moreover, it is found that intrinsic coercivity H ci is strongly related to the content of copper in the matrix of the sintered magnets. The optimal sintering temperature is located in 1025~1055 °C, the corresponding magnetic properties of the magnets are B_r =0.685T, H_(ci) =350kA·m^-1 , and maximum energy product (BH)_m =85.6 kJ·m 3 .展开更多
The La-Co substituted Sr1–xLaxFe12–xCoxO19 (x=0–0.5) ferrites with appropriate Bi2O3 additive were prepared by conventional sintering method and microwave sintering method at low sintering temperatures compatible w...The La-Co substituted Sr1–xLaxFe12–xCoxO19 (x=0–0.5) ferrites with appropriate Bi2O3 additive were prepared by conventional sintering method and microwave sintering method at low sintering temperatures compatible with LTCC (low temperature co-fired ceramics) systems, and their sintering behavior was chiefly investigated, including the crystal structure, saturation magnetizationMs, magnetic anisotropy fieldHa, intrinsic coercivityHci, and Curie temperatureTC. Experiment results clearly showed that the pure M-type crystal phase was successfully obtained when the La-Co substitution amountx did not exceed 0.3. However, the single M-type phase structure transformed to multiphase structure with further increased x, where the M-type phase coexisted with the non-magnetic phase such asα-Fe2O3 phase, La2O3 phase, and LaCoO3 phase. Appropriate La-Co substitution improved theMs (>62 emu/g),Ha (>1400 kA/m), andHci (>320 kA/m) for the ferrites withx varying from 0.1 to 0.3, but theTC decreased with increasing substitution amount. More-over, the microwave sintered ferrites could provide largerHci and similarMs compared with the conventional sintered ferrites.展开更多
Excessive sintering of mould fluxes can readily cause defects and sticker breakouts in continuously cast strands.Studying the sintering property is important to minimize problems related to sintering arising from the ...Excessive sintering of mould fluxes can readily cause defects and sticker breakouts in continuously cast strands.Studying the sintering property is important to minimize problems related to sintering arising from the use of mould fluxes in continuous casting.An effective method of measuring the apparent sintering temperature has been developed in this study.The method is based on monitoring the formation of cavities caused by melting of samples.For monitoring,the differential pressure of an inert gas flow was measured through a set volume of sample（mould flux A）held in a furnace tube.The apparent sintering temperature was defined in this test to determine sintering process.The sintering properties of fluxes with various contents of carbon black were examined along with identification of mineralogical phases and the nature of the sinter for samples of mould flux A held for one hour at different temperatures.The experimental results indicated that the apparent sintering temperature（AST）was a useful parameter to assess the threat of problems related to sinter.展开更多
The influence of the composition （Yb2O3, MgO, CeO2, Li2CO3） on the dielectric properties of medium temperature sintering （Ba, Sr）TiO3 （BST） series capacitor ceramics was investigated by means of conventional tec...The influence of the composition （Yb2O3, MgO, CeO2, Li2CO3） on the dielectric properties of medium temperature sintering （Ba, Sr）TiO3 （BST） series capacitor ceramics was investigated by means of conventional technology process and orthogonal design experiments. The major secondary influencing factors and the influencing tendency of various factor＇s levels for the dielectric properties of BST ceramics were obtained. The optimum formula for maximum dielectric constant （ε） and for minimum dielectric loss （tanδ） was obtained under the experimental conditions. The BST ceramics with optimum comprehensive properties was obtained by means of orthogonal design experiments, with the sintering temperature at 1200 ℃, the dielectric constant 5239, the dielectric loss 0.0097, withstand electric voltage over 6 MV·m^-1, capacitance temperature changing ence of various components on the providing the basis for preparation rate （△C/C） - 75.67%, and suited for Y5V character. The mechanism of the infludielectric properties of medium temperature sintering BST ceramics was studied, thus of multilayer capacitor ceramics and single-chip capacitor ceramics.展开更多
Aluminum nitride （AlN）/borosilicate glass composites were prepared by the tape casting process and hot-press sintered at 950 ℃ with AIN and SiO2-B203-ZnO-Al2O3-Li2O glass as starting materials. We characterized and...Aluminum nitride （AlN）/borosilicate glass composites were prepared by the tape casting process and hot-press sintered at 950 ℃ with AIN and SiO2-B203-ZnO-Al2O3-Li2O glass as starting materials. We characterized and analyzed the variation of the microstructure, bulk density, porosity, dielectric constant, thermal conductivity and thermal expansion coefficient （TEC） of the ceramic samples as a function of AIN content. Results show that AIN and SiO2-B2O3-ZnO-Al2O3-Li2O glass can be sintered at 950 ℃, and ZnAI204 and Zn2SiO4 phase precipitated to form glass-ceramic. The performance of the ceramic samples was determined by the composition and bulk density of the composites. Lower AlN content was found redounding to liquid phase sintering, and higher bulk density of composites can be accordingly obtained. With the increase of porosity, corresponding decreases were located in the dielectric constant, thermal conductivity and TEC of the ceramic samples. When the mass fraction of AlN was 40%, the ceramic samples possessed a low dielectric constant （4.5-5.0）, high thermal conductivity （11.6 W/（m.K）） and a proper TEC （3.0× 10^-6 K^-1 which matched that of silicon）. The excellent performance makes this kind of low temperature co-fired ceramic a promising candidate for application in the micro-electronics packaging industry.展开更多
Li-Zn mixed ferrites with composition formula ZnxLi0.5-x/2Fe2.5-x/2O4 (0.2≤x≤0.8) were prepared by the usual ceramic method in 1000~1150℃. The effects of Zn substitution and sintering temperature on the formation, ...Li-Zn mixed ferrites with composition formula ZnxLi0.5-x/2Fe2.5-x/2O4 (0.2≤x≤0.8) were prepared by the usual ceramic method in 1000~1150℃. The effects of Zn substitution and sintering temperature on the formation, densification, microstructure and a.c. electrical conductivity have been studied. Under the effect of changing the firing temperature and Zn content, high sintered Li-Zn ferrite bodies are achieved. More fine structure bodies having high electrical resistance are obtained at high Zn content展开更多
ZnO varistors are prepared using the 0.1-0.3mm ZnO powders. The effects of the sintering temperature, contents of In2O3 doping on the non-linear properties of ZnO varistors have been investigated. Theresults show that...ZnO varistors are prepared using the 0.1-0.3mm ZnO powders. The effects of the sintering temperature, contents of In2O3 doping on the non-linear properties of ZnO varistors have been investigated. Theresults show that this kind of ZnO powder has a high sintering activity. It is suitable for making the low voltage varistors. The Vc decreases with the increase of sintered temperature, when the In2O3 content is fixed(0. 98 %, mass fraction), and increases with the increase of In2O3 contents when the temperature is steady.展开更多
The ultrafine Mo-Y_(2)O_(3)composite powders were successfully synthesized by innovative freeze-drying method.Consequently,the freeze-dried Mo-Y_(2)O_(3)composite powders with high sintering activities possess an aver...The ultrafine Mo-Y_(2)O_(3)composite powders were successfully synthesized by innovative freeze-drying method.Consequently,the freeze-dried Mo-Y_(2)O_(3)composite powders with high sintering activities possess an average grain size of 54 nm.After low temperature sintering at 1600°C,the Mo-Y_(2)O_(3)alloys maintaining a high density(99.6%)have the finest grain size(620 nm)comparing with available literature about oxide dispersion strengthened molybdenum alloy(ODS-Mo).The oxide particles remain their small size(mainly<50 nm)within Mo grains and at Mo grain boundaries.Furthermore,the Y_(5)MO_(2)O_(12)particles were firstly observed within Mo matrix,and its formation can absorb nearby oxygen impurities,which involves the purification of Mo matrix.The mechanical properties show that Mo-Y_(2)O_(3)alloy possess a high hardness of 487±28 HV_(0.2),a high yield strength of 902 MPa,a high compressive strength of1110 MPa,respectively.Our work suggests that freeze-drying and subsequent low temperature sintering can shed light on the preparation of ultrafine ODS-Mo alloys with high performance.展开更多
Li/Sb-doped (Na,K)NbO3 with a nominal composition of [Li0.05(Na0.535K0.48)0.95](Nb0.94Sb0.06)O3 ceramic was synthesized by normal sintering. The phase structure, microstructure, and electrical properties were investig...Li/Sb-doped (Na,K)NbO3 with a nominal composition of [Li0.05(Na0.535K0.48)0.95](Nb0.94Sb0.06)O3 ceramic was synthesized by normal sintering. The phase structure, microstructure, and electrical properties were investigated with a special emphasis on the influence of the sintering temperature. A polymorphic phase transition (PPT) from orthorhombic to tetragonal symmetry was observed when the sintering temperature was raised from 1040 to 1050 ℃, whereby the piezoelectric coefficient d33 and the electromechanical coupling coefficient kp reached the peak values of 245 pC·N-1 and 41.2%, respectively. The PPT induced by varying the sintering temperature is due to the different volatilization extents of alkali metals and appears to a lower sintering temperature with increasing Li content. The trace modifying of alkali metal content is more effective than doping B site element to enhance the d33 value.展开更多
The effect of changes in sintering temperature on electrical properties and microstructure of ZnO?polyaniline?polyethylene composite ceramics,prepared in disk form at the pressure of 60 MPa and at five different tempe...The effect of changes in sintering temperature on electrical properties and microstructure of ZnO?polyaniline?polyethylene composite ceramics,prepared in disk form at the pressure of 60 MPa and at five different temperatures,has been investigated.Increasing sintering temperature from 30 to 120°C noticeably reduces breakdown voltage from 830 to 610 V.Further increase in sintering temperature causes breakdown voltage to increase.Interface voltage barrier height behaves differently when sintering temperature increases,which is in contrast to breakdown voltage behavior.These samples have a very low leakage current,a factor which indicates low degradation.Then again,the higher the sintering temperature gets,the less the nonlinear coefficient becomes.In addition,each sample has hysteresis which decreases through increase of sintering temperature up to 120°C.Further increase in sintering temperature,however,causes the hysteresis loop to spread.Regarding UV spectra of the samples,it is revealed that there are three impurity levels whose behaviors against sintering temperature are subtractive.Analysis of composite samples by scanning electron microscopy indicates that their microstructure consists of grains and grain boundaries.Resistivity of grain boundaries is the main responsible factor for these changes in varistor characteristic as a function of sintering temperature.展开更多
A series of Ba8Ga16Si30 clathrate samples were prepared by arc melting, ball milling, acid washing, and spark plasma sintering （SPS）. X-ray diffraction analysis revealed that the lattice of the Ba8Ga16Si30 samples e...A series of Ba8Ga16Si30 clathrate samples were prepared by arc melting, ball milling, acid washing, and spark plasma sintering （SPS）. X-ray diffraction analysis revealed that the lattice of the Ba8Ga16Si30 samples expanded as the SPS temperature was increased from 400 to 750℃. Lattice contraction recurred when the SPS temperature was further increased in the range of 750-1000℃. This phenomenon can be explained by the variation of Ga content in the lattice. The thermoelectric figure of the merit ZT value of clathrates increased with the increase in SPS temperature and reached a maximum when the sample was subjected to SPS at 800℃. A further increase in SPS temperature did not contribute to the improvement of ZT. The variation of the lattice parameter a vs. SPS temperature T was similar to the variation ob-served in the ZT-T curve.展开更多
This study aims to develop a magnesium-based hybrid composite via a powder metallurgy(PM)technique by simultaneously reinforcing the matrix(Mg-3 Zn-0.7 Zr-1 Cu)alloy with micro-alumina(3.0 wt%)and nano-alumina(0.5 wt%...This study aims to develop a magnesium-based hybrid composite via a powder metallurgy(PM)technique by simultaneously reinforcing the matrix(Mg-3 Zn-0.7 Zr-1 Cu)alloy with micro-alumina(3.0 wt%)and nano-alumina(0.5 wt%and 1.0 wt%)particulates.The extensive processing involved two different sintering temperatures(400 and 450℃)followed by hot extrusion and a heat treatment process.The study aimed to add to our understanding of the effects of sintering temperature and alumina content on the physical characteristics of Mg-based composites.It was revealed that increasing sintering temperature improves the density of composites by increasing their diffusion rates.In addition,significant improvements in the hardness,tensile properties and compressive properties of the composites were observed at higher sintering temperatures.It was also discovered that composites with higher alumina concentrations experienced agglomeration and were more porous than other composites.A micro-structural examination showed that composites with higher concentrations of nano-alumina had a finer grain structure than other composites and underwent a marginal reduction in grain size.However,the tensile and compressive properties of composites decreased when the nano-alumina content was increased to 1.0 wt%.The magnesium hybrid composite containing 3.0 wt%micro-alumina and 0.5 wt%nano-alumina sintered at 450℃displayed the greatest tensile strength properties in all composites studied.A transformation from brittle to mixed-mode failure,with sufficient evidence of increased plastic deformation,was also noted in the hybrid composites.The present study suggests that adding up to 0.5 wt%nano-alumina and employing a higher sintering temperature enhances the overall characteristics of magnesium/alumina microcomposites.展开更多
基金supported by the Natural Science Foundation of Shanghai(No.23ZR1421500)the National Natural Science Foundation of China(Nos.52474412,52127807,52271035)+3 种基金the Shanghai Municipal Commission of Economy and Informatization(No.GYOJ2022-2-02)the United Innovation Program of Shanghai Commercial Aircraft Engine(No.AR966)the SPMI Project from Shanghai Academy of Spaceflight Technology(No.SPMI2022-06)the Ningbo International Science and Technology Cooperation Program(No.2023H004)。
文摘As a reliable additive manufacturing technology,the stereolithography(SLA)ceramic core necessitates a tailored sintering process to achieve optimal performance.This study explored the effects of final sintering temperatures(specifically 1,150,1,250,and 1,300°C)on the properties of SLA-fabricated SiO_(2)-based ceramic cores reinforced with nano-ZrO_(2)(at concentrations of 1.0wt.%,1.5wt.%,and 2.0wt.%).The results demonstrate that increasing the final sintering temperature and the incorporation of nano-ZrO_(2)enhance the viscous fiow of quartz glass,resulting in a higher sintering degree.As the final sintering temperature rises,the ceramic samples exhibit increased shrinkage rate,decreased apparent porosity,and increased bulk density.Higher final sintering temperatures also promote greater cristobalite precipitation,promoting an increase in the amount and precipitation rate of quartz during investment casting.The formation of a cristobalite and ZrSiO_4 network at elevated temperatures effectively inhibits the viscous flow of quartz glass,thereby significantly improving high-temperature flexural strength and creep resistance of ceramic cores.When the content of nano-ZrO_(2)is between 1.5wt.%and 2.0wt.%,the final sintering temperature of 1,250°C is the best choice.Under these conditions,the shrinkage rate along the Z direction ranges from 3.35%to 3.68%,the porosity lies between 25.57%and 26.03%,the bulk density varies from 1.612 to 1.645 g·cm^(-3),the room temperature fiexural strength is between 26.79 and 27.85 MPa,and the fiexural strength at high temperatures is within the range of 30.77 to 33.02 MPa.The defiection at high-temperatures is 3.37-5.31 mm,while the surface roughness of the upper surface is 3.26-4.79μm,and the surface roughness of the side surface is 4.97-5.79μm.These findings provide valuable guidance for optimizing the sintering processes of SLA ceramic cores,offering potential for industrial applications.
基金supported by the Xinjiang Tianchi Talent Introduction Plan (51052300585)the Fundamental Research Funds for Autonomous Region Universities (XJEDU2022P002)+1 种基金the Natural science foundation project of Xinjiang Uygur Autonomous Region (2023D01C192,2023D01C33)the Tianshan Innovation Team Program of Xinjiang Uygur Autonomous Region (2023D14001)。
文摘Ceramic materials with intricate structures can be efficiently fabricated using stereolithography(SLA)based 3D printing technology,offering advantages over traditional methods.Sintering temperature has primary effect on properties of ceramics.This study investigated the crucial sintering temperature for 3D printed ceramics to ensure the desired properties.The results indicate that all samples exhibit a consistent layered structure across the experimental sintering temperatures.When the sintering temperature is increased from 1,250℃ to 1,350℃,the grain's morphology changes from spherical to plate-like.Surface morphology analysis reveals a decrease in surface roughness at sintering temperatures above 1,350℃.Mechanical tests show improved flexural strength and stiffness as the sintering temperature rises.Friction and wear experiments demonstrate that as the sintering temperature increases from 1,450℃ to 1,550℃,the wear pattern on ceramic surfaces transitions from deep pits to shallow grooves.The increase in sintering temperature effectively enhances the wear resistance of 3D printed alumina ceramics.This improvement plays a significant role in expanding the application field of these ceramics,prolonging the lifespan of parts,reducing production costs,enhancing performance,and promoting environmental protection.In this study,ceramics achieve the highest strength and best wear resistance when sintered at 1,600℃,resulting in the best overall performance.
基金supported by Special Fund for the Development of 1500-Meter Subsea Christmas Trees and Control Systems.
文摘In order to develop a marine engineering material with excellent mechanical properties and corrosion resistance,a novel non-equiatomic Co_(1.5)CrFeNi_(1.5)Ti_(0.6)high-entropy alloy(HEA)was fabricated through mechanical alloying and spark plasma sintering.The results revealed that the sintering temperature significantly affected the microstructure and phase composition of the HEA owing to the diffusion rate,homogenization,and sluggish diffusion effect of metal atoms.At sintering temperatures below 1050℃,HEA mainly consisted of face-centered cubic(FCC),Ni_(3)Ti(ε),Ni_(2.67)Ti_(1.33)(R),and Fe-Cr(σ)phases.The microstructure of alloy comprised coarse dendritic crystals,whose content and size gradually decreased with increasing sintering temperature.However,the HEA sintered above 1100℃contained only fine equiaxed crystals.HEA sintered at 1100℃featured only the FCC solid solution,while theε-phase precipitated at temperatures above 1150℃.At a sintering temperature of 1050℃,the alloy microstructure consisted of short rod-like dendrites and fine equiaxed crystals.This alloy achieved the highest yield strength of 1198.71 MPa owing to the effects of precipitation strengthening and grain boundary strengthening.Meanwhile,HEA sintered above 1050℃exhibited significantly improved corrosion resistance.Considering the microstructure,mechanical,and corrosion properties,1050℃was identified as the optimal sintering temperature for Co_(1.5)CrFeNi_(1.5)Ti_(0.6)HEA.
基金Project(2014CB643406)supported by the National Basic Research Program of China
文摘LiNi0.8Co0.1Mn0.1O2 powder was prepared by mixing LiOH·H2O and co-precipitated Ni0.8Co0.1Mn0.1（OH）2 at a molar ratio of 1：1.05, followed by sintering at different temperatures. The effects of temperature on the morphology, structure and electrochemical performance were extensively studied. SEM and XRD results demonstrate that the sintering temperature has large influence on the morphology and structure and suitable temperature is very important to obtain spherical materials and suppresses the ionic distribution. The charge-discharge tests show that the electrochemical performance of LiNi0.8Co0.1Mn0.1O2 powders becomes better with the increase of temperature from 700 ℃ to 750 ℃ and higher temperature will deteriorate the performance. Although both of materials obtained at 750 ℃ and 780 ℃ demonstrate almost identical cyclic stability at 2C rate, which delivers 71.9%retention after 200 cycles, the rate performance of powder calcined at 780 ℃ is much poorer than that at 750 ℃. The XRD results demonstrate that the poor performance is ascribed to more severe ionic distribution caused by higher temperature.
基金Project (50930005) supported by the National Natural Science Foundation of ChinaProject (U0834002) supported by the Key Programof NSFC-Guangdong Joint Funds of China+1 种基金Project (LYM09024) supported by Training Program for Excellent Young Teachers withInnovation of Guangdong University, ChinaProject (2009ZM0121) supported by the Fundamental Research Funds for the CentralUniversities of South China University of Technology,China
文摘A procedure of low temperature solid-phase sintering（LTSS） was carried out to fabricate sintered metal fibrous media（SMFM） with high specific surface area.Stainless steel fibers which were produced by cutting process were first plated with a coarse copper coating layer by electroless plating process.A low-temperature sintering process was then completed at about 800 °C for 1 h under the protection of hydrogen atmosphere.The results show that a novel SMFM with complex surface morphology and high specific surface area（0.2 m2/g） can be obtained in this way.The effect of sintering temperature on the surface morphology and specific surface area of SMFM was studied by means of scanning electron microscopy and Brunauer-Emmett-Teller.The damage of micro-structure during the sintering process mainly contributed to the loss of specific surface area of SMFM and the optimal sintering temperature was 800 °C.
基金supported by the National Natural Foundation of China (No. 19934003) the Natural Science Research Key Program of Anhui Educational Committee (No. KJ2011A259)+3 种基金the Opening Program of Cultivating Base of Anhui Key Laboratory of Spintronics and Nanomaterials (Nos. 2010YKF04 2011YKF05)the Professors’and Doctors’Research Startup Foundation of Suzhou University (Nos. 2011jb01 2011jb02)
文摘A series of (1-x)La0.6Dy0.1Sr0.3MnO3/0.5x(Sb2O3)(x=0.15) samples were prepared by the solid-state reaction method, and the influence of sintering temperature of the matrix on low-field magnetoresistance of (1-x)La0.6Dy0.1Sr0.3MnO3/0.5x (Sb2O3) was studied through the measurements of X-ray diffraction (XRD) patterns, scanning electron microscope (SEM) image, resistivity-temperature (ρ-T) curves, and magnetoresistance-temperature (MR-T) curves. The results indicate that for the samples with low sintering temperature of the matrix, lowfield magnetoresistance effect appears on the whole temperature range and can be explained by grain boundary effect; for the sample with high sintering temperature of the matrix, intrinsic magnetoresistance peak appears on the high-temperature range, low-field magnetore-sistance effect appears on low temperature range, and the magnetoresistance in the magnetic field of 0.2 T and on the comparatively large temperature range between 280 K and 225 K hardly changes with temperature and remains at 4.8%, which can be explained by the competition between the intrinsic magnetoresistance induced by double-exchange function inside grains and the tunneling magnetoresis-tance (TMR) induced by grain boundary effect. The temperature stability of magnetoresistance is beneficial to the practical applications of MR.
文摘Effects of sintering temperature in hot pressing, t yp es, states and amounts of rare earth as well as TiH 2 on the transverse rupture strength (TRS) of Fe-based composites are studied by means of orthogonal test and variance analysis in this paper. It is found that sintering temperature has a significant effect on the TRS of Fe-based diamond composites. The optimal sin tering temperature is 780～860 ℃. On the contrary, the effects of RE additi v es on values of TRS of the diamond composites have on distinct difference no mat ter the RE is in the state of mixture or compound or oxidization. Experimental r esults demonstrate that Fe-based diamond composites with RE additives exhibit h igher TRS, which results in an increase in diamond retention capacity. The degre e of increment of TRS is different at different sintering temperatures. The opti mal amount of rare earth was found to be about 1% in weight. The effect of RE is more significant at lower sintering temperature. The experimental results also reveal that TiH 2 additive has a negative effect on the TRS of Fe-based compos ites. Microscope observations demonstrate that specimen without TiH 2 additives , shows fewer pores and denser structures in the base metal. It can also be seen from the SEM observation of the resulting fracturing surface of bending test sp ecimens that the bonding of the diamond-matrix interface is better in the speci men without TiH 2 than in the specimen with TiH 2. Also the fracture surface o f the specimen without TiH 2 reveals ductile cup and cone behavior.
基金Supported by the Development and Reform Commission of Fujian Province and Talent Foundation of Fuzhou University
文摘Mg-Al spinel is synthesized by using industrial waste-residue and basic magnesium carbonate in the aluminum factory as the main raw materials. The influence of sintering temperature on crystalline structure and microstructure of Mg-Al spinel has been mainly discussed. The crystalline structure of sample is characterized by using XRD, SEM and relevant analytical software. The experimental results show that compared to the conventional synthetic method, the application of waste aluminum slag as the raw material can greatly decrease the synthetic tem-perature. The content of Mg-Al spinel first increases and then decreases with the rise of sintering temperature, and its purity can reach as high as 96wt% at 1550 ℃, which is therefore determined to be the optimum synthetic temperature. SEM observations demonstrate that as the rise of sintering temperature, the grain of Mg-Al spinel grows up obviously with typical octahedral characteristic appearance.
基金supported by the National High-Tech R&D Program of China(No.2010AA03A401)the National Basic Research Program of China(No.2010CB934601)the National Nature Science Foundation of China(Nos.50931001,50901021)
文摘The microstructures and magnetic properties of Ce-32.15Co_49.36Cu_9.84Fe_9.65 magnet sintered at the temperatures ranging from 1005 to 1105 °C were investigated. The results on scanning electron microscopy and X-ray diffraction analysis indicate that the remanence B r of the magnets is mainly influenced by the degree of the easy-axis orientation when sintering temperature is less than 1085 °C, the rapidly increasing amount of the secondly phase (5:19 phase) gives rise to the deterioration of the magnetic properties of the magnet above 1085 °C. Moreover, it is found that intrinsic coercivity H ci is strongly related to the content of copper in the matrix of the sintered magnets. The optimal sintering temperature is located in 1025~1055 °C, the corresponding magnetic properties of the magnets are B_r =0.685T, H_(ci) =350kA·m^-1 , and maximum energy product (BH)_m =85.6 kJ·m 3 .
基金supported by the National Public Welfare Fund Industry Research(201410026)Scientific Research Foundation of Education Office of Sichuan Province(13Z198)the Young and Middle-aged Academic Leaders of Scientific Research Funds of Chengdu University of Information Technology(J201222)
文摘The La-Co substituted Sr1–xLaxFe12–xCoxO19 (x=0–0.5) ferrites with appropriate Bi2O3 additive were prepared by conventional sintering method and microwave sintering method at low sintering temperatures compatible with LTCC (low temperature co-fired ceramics) systems, and their sintering behavior was chiefly investigated, including the crystal structure, saturation magnetizationMs, magnetic anisotropy fieldHa, intrinsic coercivityHci, and Curie temperatureTC. Experiment results clearly showed that the pure M-type crystal phase was successfully obtained when the La-Co substitution amountx did not exceed 0.3. However, the single M-type phase structure transformed to multiphase structure with further increased x, where the M-type phase coexisted with the non-magnetic phase such asα-Fe2O3 phase, La2O3 phase, and LaCoO3 phase. Appropriate La-Co substitution improved theMs (>62 emu/g),Ha (>1400 kA/m), andHci (>320 kA/m) for the ferrites withx varying from 0.1 to 0.3, but theTC decreased with increasing substitution amount. More-over, the microwave sintered ferrites could provide largerHci and similarMs compared with the conventional sintered ferrites.
基金Item Sponsored by National Natural Science Foundation of China(50904083,50474023)
文摘Excessive sintering of mould fluxes can readily cause defects and sticker breakouts in continuously cast strands.Studying the sintering property is important to minimize problems related to sintering arising from the use of mould fluxes in continuous casting.An effective method of measuring the apparent sintering temperature has been developed in this study.The method is based on monitoring the formation of cavities caused by melting of samples.For monitoring,the differential pressure of an inert gas flow was measured through a set volume of sample（mould flux A）held in a furnace tube.The apparent sintering temperature was defined in this test to determine sintering process.The sintering properties of fluxes with various contents of carbon black were examined along with identification of mineralogical phases and the nature of the sinter for samples of mould flux A held for one hour at different temperatures.The experimental results indicated that the apparent sintering temperature（AST）was a useful parameter to assess the threat of problems related to sinter.
文摘The influence of the composition （Yb2O3, MgO, CeO2, Li2CO3） on the dielectric properties of medium temperature sintering （Ba, Sr）TiO3 （BST） series capacitor ceramics was investigated by means of conventional technology process and orthogonal design experiments. The major secondary influencing factors and the influencing tendency of various factor＇s levels for the dielectric properties of BST ceramics were obtained. The optimum formula for maximum dielectric constant （ε） and for minimum dielectric loss （tanδ） was obtained under the experimental conditions. The BST ceramics with optimum comprehensive properties was obtained by means of orthogonal design experiments, with the sintering temperature at 1200 ℃, the dielectric constant 5239, the dielectric loss 0.0097, withstand electric voltage over 6 MV·m^-1, capacitance temperature changing ence of various components on the providing the basis for preparation rate （△C/C） - 75.67%, and suited for Y5V character. The mechanism of the infludielectric properties of medium temperature sintering BST ceramics was studied, thus of multilayer capacitor ceramics and single-chip capacitor ceramics.
文摘Aluminum nitride （AlN）/borosilicate glass composites were prepared by the tape casting process and hot-press sintered at 950 ℃ with AIN and SiO2-B203-ZnO-Al2O3-Li2O glass as starting materials. We characterized and analyzed the variation of the microstructure, bulk density, porosity, dielectric constant, thermal conductivity and thermal expansion coefficient （TEC） of the ceramic samples as a function of AIN content. Results show that AIN and SiO2-B2O3-ZnO-Al2O3-Li2O glass can be sintered at 950 ℃, and ZnAI204 and Zn2SiO4 phase precipitated to form glass-ceramic. The performance of the ceramic samples was determined by the composition and bulk density of the composites. Lower AlN content was found redounding to liquid phase sintering, and higher bulk density of composites can be accordingly obtained. With the increase of porosity, corresponding decreases were located in the dielectric constant, thermal conductivity and TEC of the ceramic samples. When the mass fraction of AlN was 40%, the ceramic samples possessed a low dielectric constant （4.5-5.0）, high thermal conductivity （11.6 W/（m.K）） and a proper TEC （3.0× 10^-6 K^-1 which matched that of silicon）. The excellent performance makes this kind of low temperature co-fired ceramic a promising candidate for application in the micro-electronics packaging industry.
文摘Li-Zn mixed ferrites with composition formula ZnxLi0.5-x/2Fe2.5-x/2O4 (0.2≤x≤0.8) were prepared by the usual ceramic method in 1000~1150℃. The effects of Zn substitution and sintering temperature on the formation, densification, microstructure and a.c. electrical conductivity have been studied. Under the effect of changing the firing temperature and Zn content, high sintered Li-Zn ferrite bodies are achieved. More fine structure bodies having high electrical resistance are obtained at high Zn content
文摘ZnO varistors are prepared using the 0.1-0.3mm ZnO powders. The effects of the sintering temperature, contents of In2O3 doping on the non-linear properties of ZnO varistors have been investigated. Theresults show that this kind of ZnO powder has a high sintering activity. It is suitable for making the low voltage varistors. The Vc decreases with the increase of sintered temperature, when the In2O3 content is fixed(0. 98 %, mass fraction), and increases with the increase of In2O3 contents when the temperature is steady.
基金the National Natural Science Foundation of China(No.51822404)the Natural Science Foundation of Tianjin(No.18JCYBJC17900)+1 种基金supported by the Science and Technology Program of Tianjin(Nos.19YFZCGX00790 and 18YFZCGX00070)Researchers Supporting Project number(No.RSP-2021/6),King Saud University,Riyadh,Saudi Arabia。
文摘The ultrafine Mo-Y_(2)O_(3)composite powders were successfully synthesized by innovative freeze-drying method.Consequently,the freeze-dried Mo-Y_(2)O_(3)composite powders with high sintering activities possess an average grain size of 54 nm.After low temperature sintering at 1600°C,the Mo-Y_(2)O_(3)alloys maintaining a high density(99.6%)have the finest grain size(620 nm)comparing with available literature about oxide dispersion strengthened molybdenum alloy(ODS-Mo).The oxide particles remain their small size(mainly<50 nm)within Mo grains and at Mo grain boundaries.Furthermore,the Y_(5)MO_(2)O_(12)particles were firstly observed within Mo matrix,and its formation can absorb nearby oxygen impurities,which involves the purification of Mo matrix.The mechanical properties show that Mo-Y_(2)O_(3)alloy possess a high hardness of 487±28 HV_(0.2),a high yield strength of 902 MPa,a high compressive strength of1110 MPa,respectively.Our work suggests that freeze-drying and subsequent low temperature sintering can shed light on the preparation of ultrafine ODS-Mo alloys with high performance.
基金financially supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20090006110010)Beijing Natural Science Foundation(No.2112028)
文摘Li/Sb-doped (Na,K)NbO3 with a nominal composition of [Li0.05(Na0.535K0.48)0.95](Nb0.94Sb0.06)O3 ceramic was synthesized by normal sintering. The phase structure, microstructure, and electrical properties were investigated with a special emphasis on the influence of the sintering temperature. A polymorphic phase transition (PPT) from orthorhombic to tetragonal symmetry was observed when the sintering temperature was raised from 1040 to 1050 ℃, whereby the piezoelectric coefficient d33 and the electromechanical coupling coefficient kp reached the peak values of 245 pC·N-1 and 41.2%, respectively. The PPT induced by varying the sintering temperature is due to the different volatilization extents of alkali metals and appears to a lower sintering temperature with increasing Li content. The trace modifying of alkali metal content is more effective than doping B site element to enhance the d33 value.
文摘The effect of changes in sintering temperature on electrical properties and microstructure of ZnO?polyaniline?polyethylene composite ceramics,prepared in disk form at the pressure of 60 MPa and at five different temperatures,has been investigated.Increasing sintering temperature from 30 to 120°C noticeably reduces breakdown voltage from 830 to 610 V.Further increase in sintering temperature causes breakdown voltage to increase.Interface voltage barrier height behaves differently when sintering temperature increases,which is in contrast to breakdown voltage behavior.These samples have a very low leakage current,a factor which indicates low degradation.Then again,the higher the sintering temperature gets,the less the nonlinear coefficient becomes.In addition,each sample has hysteresis which decreases through increase of sintering temperature up to 120°C.Further increase in sintering temperature,however,causes the hysteresis loop to spread.Regarding UV spectra of the samples,it is revealed that there are three impurity levels whose behaviors against sintering temperature are subtractive.Analysis of composite samples by scanning electron microscopy indicates that their microstructure consists of grains and grain boundaries.Resistivity of grain boundaries is the main responsible factor for these changes in varistor characteristic as a function of sintering temperature.
基金supported by the National Natural Science Foundation of China(No.51072023)the National Science Foundation of US(No.DMR-0821284)the National Aeronautics and Space Administration of US(Nos.NNX10AM80H and NNX07AO30A)
文摘A series of Ba8Ga16Si30 clathrate samples were prepared by arc melting, ball milling, acid washing, and spark plasma sintering （SPS）. X-ray diffraction analysis revealed that the lattice of the Ba8Ga16Si30 samples expanded as the SPS temperature was increased from 400 to 750℃. Lattice contraction recurred when the SPS temperature was further increased in the range of 750-1000℃. This phenomenon can be explained by the variation of Ga content in the lattice. The thermoelectric figure of the merit ZT value of clathrates increased with the increase in SPS temperature and reached a maximum when the sample was subjected to SPS at 800℃. A further increase in SPS temperature did not contribute to the improvement of ZT. The variation of the lattice parameter a vs. SPS temperature T was similar to the variation ob-served in the ZT-T curve.
文摘This study aims to develop a magnesium-based hybrid composite via a powder metallurgy(PM)technique by simultaneously reinforcing the matrix(Mg-3 Zn-0.7 Zr-1 Cu)alloy with micro-alumina(3.0 wt%)and nano-alumina(0.5 wt%and 1.0 wt%)particulates.The extensive processing involved two different sintering temperatures(400 and 450℃)followed by hot extrusion and a heat treatment process.The study aimed to add to our understanding of the effects of sintering temperature and alumina content on the physical characteristics of Mg-based composites.It was revealed that increasing sintering temperature improves the density of composites by increasing their diffusion rates.In addition,significant improvements in the hardness,tensile properties and compressive properties of the composites were observed at higher sintering temperatures.It was also discovered that composites with higher alumina concentrations experienced agglomeration and were more porous than other composites.A micro-structural examination showed that composites with higher concentrations of nano-alumina had a finer grain structure than other composites and underwent a marginal reduction in grain size.However,the tensile and compressive properties of composites decreased when the nano-alumina content was increased to 1.0 wt%.The magnesium hybrid composite containing 3.0 wt%micro-alumina and 0.5 wt%nano-alumina sintered at 450℃displayed the greatest tensile strength properties in all composites studied.A transformation from brittle to mixed-mode failure,with sufficient evidence of increased plastic deformation,was also noted in the hybrid composites.The present study suggests that adding up to 0.5 wt%nano-alumina and employing a higher sintering temperature enhances the overall characteristics of magnesium/alumina microcomposites.
