Effect of Sintering Temperature on the Microstructure and Mechanical Properties of Nanocrystalline Cemented Carbide

WC-Co nanocrystalline nitrogen-containing cemented carbides were prepared by vacuum sintering and low pressure sintering.The sintering processes of Cr_(2)(C,N)doped nano WC-Co powders were studied by using thermogravimetric analysis(TGA)and differential scanning calorimetry(DSC).The effect of sintering temperature on the microstructure and mechanical properties of nanocrystalline cemented carbide was studied by scanning electron microscope(SEM),high resolution transmission electron microscope(HRTEM)and mechanical property test.The results showed that the nano WC grains began to grow in the solid phase sintering stage.A high-performance nano-nitrogen-containing cemented carbide with uniform microstructure and good interfacial bonding can be obtained by increasing the sintering temperature to 1380℃.It has a transverse rupture strength(TRS)of 5057 MPa and a hardness of 1956 HV30.

Effect of sintering temperature on microstructure and properties of 3D printing polysilazane reinforced Al_(2)O_(3)core

Ceramic cores are the key intermediate components of hollow blades for aero-engine.Conventional processes,such as hot-press molding and gel film casting,face difficulties in fabricating complex-structured ceramic cores due to the complexity of moulds and long process cycles.Stereolithography 3D printing provides a new idea for the fabrication of complex-structured ceramic cores.The effect of sintering temperature on open porosity,bulk density,weight loss rate,shrinkage rate,flexural strength and microstructure of the Al_(2)O_(3)-based ceramic core doped with 10vol.%polysilazane(PSZ)was studied.The sintering mechanism of PSZ-reinforced ceramic cores was analyzed.Results show that the optimum sintering temperature of PSZ-reinforced ceramic cores is 1,450°C.At this temperature,the open porosity of the ceramic core is 36.60%,bulk density is 2.33 g·cm^(-3),weight loss rate is 22.11%,shrinkage rate along the X,Y,Z directions is 5.72%,5.01%,9.61%,respectively;the flexural strength is 28.794 MPa at 25°C and 13.649 MPa at 1,500°C.Properties of 3D printing PSZ-reinforced ceramic cores can meet the casting requirement of superalloy hollow blades,which is expected to promote the industrial application of 3D printing complex structure ceramic cores.

Effects of Rare Earth and Hot Pressing Sintering Temperature on the Transverse Rupture Strength of Fe-based Diamond Composites

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.

Studies on the Influence of Sintering Temperature on Crystalline Structures of Mg-Al Spinel Synthesized by Waste Aluminum Slag

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.

Effect of Sintering Temperature and Zinc Content on Some Properties of Li-Zn Ferrites

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

Influence of sintering temperature on the thermoelectric properties of Ba_8Ga_(16)Si_(30) clathrate treated by spark plasma sintering

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.

Effect of Sintering Temperature on Aging Resistance and Mechanical Properties of 3Y-TZP Dental Ceramic

In order to investigate the effect of sintering temperature on aging properties and mechanical properties of 3Y-TZP dental ceramic in simulated oral environment, 3Y-TZP nanopowder compacts were pressurelessly sintered at 1 350℃, 1 400 ℃, 1 450 ℃,1 500 ℃, respectively, then were treated by soaking in artificial saliva （65 ℃, pH=7） for two months. The treated specimens sintered at 1 350 ℃ showed there was no phase transformation but whose strength and toughnesswere significantly improved （P〈0.05）, while those sintered at 1 400 ℃- 1 500 ℃ revealed a small amount of phase transformation and insignificant mechanical reinforcement （P〉0.05）. No microcracks were detected but increment in lattice volume was found in all specimens. Lowering sintering temperature favors aging resistance and mechanical reinforcement of 3Y-TZP in a simulated oral environment.

Influence of Sintering Temperature on the Structure and High-temperature Discharge Performance of Li Ni_(1/3)Mn_(1/3)Co_(1/3)O_2 Cathode Materials

Layered cathode materials of high-temperature lithium batteries, Li Ni1/3Mn1/3Co1/3O2 are synthesized by a sol-gel method with variation in final sintering temperature for borehole applications. The structure, morphology and high-temperature discharge performance of these resulting products are investigated by X-Ray Diffraction(XRD), scanning electron microscopy(SEM), laser particle size analysis, galvanostatic and pulse discharge. The results of structural analysis indicate that the sample sintered at 800 ℃ has the characteristics of good crystallinity, narrow size distribution and large specific surface area at the same time. The discharge experiments also indicate that this sample has the best electrochemical properties, with the maximum discharge capacities of 314.57 and 434.14 m Ah·g-1 at 200 and 300 ℃ respectively and the minimum cell internal resistances at both temperatures.

The Effect of Sintering Temperature on Microstructure of High Chrome Bricks

The microstructure of high chrome bricks made at different sintering temperature are analyzed by SEM . The results indicate that the sintering temperature of high chromebricks has an optimum range , it is not the higher, the better, The high chrome bricks made at this -sintering temperature have the moderate crystal six in the matrix and of dense structure. The closed bonding structure could be obtained between grains and matrix and no crackle occurred.The high chrome bricks with this microstructure have the best dynamic properties.

Effects of sintering temperature on the microstructural evolution and wear behavior of WCp reinforced Ni-based coatings

This article focuses on the microstructural evolution and wear behavior of 50wt%WC reinforced Ni-based composites prepared onto 304 stainless steel substrates by vacuum sintering at different sintering temperatures. The microstructure and chemical composition of the coatings were investigated by X-ray diffraction （XRD）, differential thermal analysis （DTA）, scanning and transmission electron microscopy （SEM and TEM） equipped with energy-dispersive X-ray spectroscopy （EDS）. The wear resistance of the coatings was tested by thrust washer testing. The mechanisms of the decomposition, dissolution, and precipitation of primary carbides, and their influences on the wear resistance have been discussed. The results indicate that the coating sintered at 1175℃ is composed of fine WC particles, coarse M6C （M=Ni, Fe, Co, etc.） carbides, and discrete borides dispersed in solid solution. Upon increasing the sintering temperature to 1225℃, the microstructure reveals few incompletely dissolved WC particles trapped in larger M6C, Cr-rich lamellar M23C6, and M3C2 in the austenite matrix. M23C6 and M3C2 precipitates are formed in both the γ/M6C grain boundary and the matrix. These large-sized and lamellar brittle phases tend to weaken the wear resistance of the composite coatings. The wear behavior is controlled simultaneously by both abrasive wear and adhesive wear. Among them, abrasive wear plays a major role in the wear process of the coating sintered at 1175℃, while the effect of adhesive wear is predominant in the coating sintered at 1225℃.

Reduction of Sensitivity to Sintering Temperature for Nd-Fe-B Magnets through Zr and Nb Additions

To reduce the sensitivity of grain growth to sintering temperature for improving property consistency of sintered Nd-Fe-B magnets, combined additions of Zr and Nb were investigated. It was found that when Zr content was increased to 0.07 at. pct, abnormal grain growth was effectively hindered even when the sintering temperature reached 1100℃. With combined additions of 0.07 at. pct Zr and 0.07 at. pct Nb, the sensitivity of grain growth to sintering temperature was greatly reduced consistency than the magnets containing no Zr and also improved. The magnets sintered at 1100℃ showed higher property Nb. In addition, the magnetic properties of magnets were also improved.

Effect of Sintering Temperature on Microwave Absorbing Behaviour of Mn-Zn Ferrite

The microwave absorbing behaviour of Mn-Zn ferrite sintered at 1100,1200,1300,1400 and 1500℃ has been investigated.The phase constitution of the ferrite was analyzed by X-ray diffraction.The results show that the ferrite sintered at 1 500℃ has better microwave absorbing prop- erty than those prepared at other temperatures,due to the increase of turbulent loss generated by the formation of excessive Fe^(2+) in deoxidizing of Fe_2O_3 at high temperatures.

Effect of sintering temperature in argon atmosphere on microstructure and properties of 3D printed alumina ceramic cores

Alumina ceramics with different sintering temperatures in argon atmosphere were obtained using stereolithography-based 3D printing.The effects of sintering temperature on microstructure and physical and mechanical properties were investigated.The results show that the average particle size,shrinkage,bulk density,crystallite size,flexural strength,Vickers hardness,and nanoindentation hardness increased with the increase in sintering temperature,whereas the open porosity decreased with increasing sintering temperature.No change was observed in phase composition,chemical bond,atomic ratio,and surface roughness.For the sintered samples,the shrinkage in Z direction is much greater than that in X or Y direction.The optimum sintering temperature in argon atmosphere is 1350℃with a shrinkage of 3.0%,3.2%,and 5.5%in X,Y,and Z directions,respectively,flexural strength of 26.7 MPa,Vickers hardness of 198.5 HV,nanoindentation hardness of 33.1 GPa,bulk density of 2.5 g/cm^3,and open porosity of 33.8%.The optimum sintering temperature was 70℃higher than that sintering in air atmosphere when achieved the similar properties.

Development of Test Method for Measuring Sintering Temperature of Mould Fluxes

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.

Effect of sintering temperature on microstructure and nonlinear electrical characteristics of ZnO varistor

The nonlinear properties of ZBMCCS-based varistors,which are composed of ZnO-Bi_(2)O_(3)-MnO_(2)-Cr_(2)O_(3)-Sb_(2)O_(3)-Co_(3)O_(4) and SiO_(2) are studied inrelation to sintering temperature,in the range of 1280–1350℃.The samples are investigated for grain morphology by using scanning electron microscope(SEM).These samples were examined by using X-ray diffraction patterns(XRD)and DC electrical measurements.X-ray diffraction analysis of the samples show the presence of ZnO,Zn_(2)SiO_(4) willemite phase and Co_(2.33)Sb_(0.67)O_(4) spinel phases.The average grain size of ZnO increased as the sintering temperature increased from 2.57 to 6.84
m.In the examined temperature range,the breakdown field decreased from 2992 to 127 V/cm with the increase of sintering temperature.This system gives a relatively high nonlinearity coefficientα=33.61(at a sintering temperature of 1280℃)with a low leakage current of 0.21 mA/cm^(2).

Electro-catazone treatment of an ozone-resistant drug:Effect of sintering temperature on TiO_(2) nanoflower catalyst on porous Ti gas diffuser anodes

Electrochemical heterogeneous catalytic ozonation(E-catazone) is a promising and advanced oxidation technology that uses a titanium dioxide nanoflower(TiO_(2-NF))-coated porous Ti gas diffuser as an anode material.Our previous study has highlighted that the importance of the TiO_(2-NF)coating layer in enhancing*OH production and rapidly degrading O_(3)-resistant drugs.It is well known that the properties of TiO_(2-NF)are closely related to its sintering temperature.However,to date,related research has not been conducted in E-catazone systems.Thus,this study evaluated the effect of the sintering temperature on the degradation of the O_(3)-resistant drug para-chlorobenzoic acid(p-CBA) using both experimental and kinetic modeling and revealed its influence mechanism.The results indicated that the TiO_(2-NF)sintering temperature could influence p-CBA degradation and*OH production.TiO_(2-NF)prepared at 450 C showcased the highest p-CBA removal efficiency(98.5% in 5 min) at a rate of 0.82 min^(-1),and an*OH exposure of 8.41 x 10^(-10) mol L^(-1) s.Kinetic modeling results and interface characterization data revealed that the sintering temperature could alter the TiO_(2) crystallized phase and the content of surfaceadsorbed oxygen,thus affecting the two key limiting reactions in the E-catazone process.That is,≡TiO_(2) surface reacted with H_(2) O to form TiO_(2)-(OH)_(2),which then heterogeneously catalyzed O_(3) to form *OH.Consequently,E-catazone with a TiO_(2-NF)anode prepared at 450°C generated the highest surface reaction rate(5.00 x 10^(-1) s^(-1) and 4.00 x 10^(-3) L mol^(-1) s^(-1),respectively),owing to its higher anatase content and adsorbed oxygen.Thus,a rapid O_(3)-TiO_(2) reaction was achieved,resulting in an enhanced*OH formation and a highly effective p-CBA degradation.Overall,this study provides novel baseline data to improve the application of E-catazone technology.

Behaviour of micro-and nano-alumina-reinforced Mg-3Zn-0.7Zr-1Cu alloy composites processed at different sintering temperatures

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.

Influence of sintering temperature on electrical properties of(K_(0.4425)Na_(0.52)Li_(0.0375))(Nb_(0.8825)Sb_(0.07)Ta_(0.0475))O_(3) ceramics without phase transition induced by sintering temperature

Lead-free(K_(0.4425)Na_(0.52)Li_(0.0375))(Nb_(0.8825)Sb_(0.07)Ta_(0.0475))O_(3)(KNLNST)piezoelectric ceramics are synthesized by the conventional solid-state reaction method.The sintering temperature and poling temperature dependence of ceramic properties are investigated.Previous studies have shown that variation of sintering temperature can cause phase transition,similar to the morphotropic phase boundary(MPB)behavior induced by composition changes in Pb(Zr,Ti)O_(3)(PZT).And the best piezoelectric performance can be obtained near the phase-transition sintering temperature.In this research,phase transition induced by sintering temperature cannot be detected and excellent piezoelectric properties can still be obtained.The sintering temperature of the largest piezoelectric coefficient of such composition is lower than that of the highest density,which is considered in composition segregation as a result of intensified volatilization of alkali metal oxides.Combined with the effect of poling temperature,the peak values of the piezoelectric properties are d_(33)=313 pC/N,k_(p)=47%,ε_(r)=1825,tanδd=0.024,T_(o-t)=88℃,and TC=274℃.