Boosting thermoelectric efficiency of Ag_(2)Se through cold sintering process with Ag nano-precipitate formation

Silver selenide(Ag_(2)Se)stands out as a promising thermoelectric(TE)material,particularly for applications near room temper-atures.This research presents a novel approach for the fabrication of bulk Ag_(2)Se samples at a relatively low temperature(170℃)using the cold sintering process(CSP)with AgNO_(3)solution as a transient liquid agent.The effect of AgNO_(3)addition during CSP on the micro-structure and TE properties was investigated.The results from phase,composition and microstructure analyses showed that the introduc-tion of AgNO_(3)solution induced the formation of Ag nano-precipitates within the Ag_(2)Se matrix.Although the nano-precipitates do not af-fect the phase and crystal structure of orthorhombicβ-Ag_(2)Se,they suppressed crystal growth,leading to reduced crystallite sizes.The samples containing Ag nano-precipitates also exhibited high porosity and low bulk density.Consequently,these effects contributed to sig-nificantly enhanced electrical conductivity and a slight decrease in the Seebeck coefficient when small Ag concentrations were incorpor-ated.This resulted in an improved average power factor from~1540μW·m^(−1)·K^(−2)for pure Ag_(2)Se to~1670μW·m^(−1)·K^(−2)for Ag_(2)Se with additional Ag precipitates.However,excessive Ag addition had a detrimental effect on the power factor.Furthermore,thermal conductiv-ity was effectively suppressed in Ag_(2)Se fabricated using AgNO_(3)-assisted CSP,attributed to enhanced phonon scattering at crystal inter-faces,pores,and Ag nano-precipitates.The highest figure-of-merit(zT)of 0.92 at 300 K was achieved for the Ag_(2)Se with 0.5wt%Ag dur-ing CSP fabrication,equivalent to>20%improvement compared to the controlled Ag_(2)Se without extra Ag solution.Thus,the process outlined in this study presents an effective strategy to tailor the microstructure of bulk Ag_(2)Se and enhance its TE performance at room temperature.

Ore-blending optimization model for sintering process based on characteristics of iron ores

An ore-blending optimization model for the sintering process is an intelligent system that includes iron ore characteristics, expert knowledge and material balance. In the present work, 14 indices are proposed to represent chemical composition, granulating properties and high temperature properties of iron ores. After the relationships between iron ore characteristics and sintering performance are established, the ＂two-step＂ method and the simplex method are introduced to build the model by distinguishing the calculation of optimized blending proportion of iron ores from that of other sintering materials in order to improve calculation efficiency. The ore-blending optimization model, programmed by Access and Visual Basic, is applied to practical production in steel mills and the results prove that the present model can take advantage of the available iron ore resource with stable sinter yield and quality performance but at a lower cost.

Basic characteristics of Australian iron ore concentrate and its effects on sinter properties during the high-limonite sintering process

The basic characteristics of Australian iron ore concentrate (Ore-A) and its effects on sinter properties during a high-limonite sintering process were studied using micro-sinter and sinter pot methods. The results show that the Ore-A exhibits good granulation properties, strong liquid flow capability, high bonding phase strength and crystal strength, but poor assimilability. With increasing Ore-A ratio, the tumbler index and the reduction index (RI) of the sinter first increase and then decrease, whereas the softening interval (Delta T) and the softening start temperature (T (10%)) of the sinter exhibit the opposite behavior; the reduction degradation index (RDI+3.15) of the sinter increases linearly, but the sinter yield exhibits no obvious effects. With increasing Ore-A ratio, the distribution and crystallization of the minerals are improved, the main bonding phase first changes from silico-ferrite of calcium and aluminum (SFCA) to kirschsteinite, silicate, and SFCA and then transforms to 2CaO center dot SiO2 and SFCA. Given the utilization of Ore-A and the improvement of the sinter properties, the Ore-A ratio in the high-limonite sintering process is suggested to be controlled at approximately 6wt%.

Research on sintering process of YSZ electrolyte

Yttria stabilized zirconia (YSZ) has widely been used as electrolyte in solid oxide fuel cell (SOFC). The microstructure of YSZ related to the fabrication process was discussed in the paper. With YSZ nano-powders about 40-100 nm as raw material, the YSZ adobe was manufactured by tape calendering process. The named three-step sintering process was performed at 1000 ℃ for 2 h, then raised the temperature with normal rate and as soon as up to 1400 ℃, the furnace was controlled at 1250-1300 ℃ for 10-20 h. The high dense YSZs with the relative density of 96%-99% were obtained; the grain size of YSZ could be reduced to 0.5-3 μm. The above result is benefited to co-fired in the electrode-supported SOFCs.

Sintering process as relevant parameter for Bi_2O_3 vaporization from ZnO-Bi_2O_3-based varistor ceramics

The relationship between sintering process and vaporization of the Bi2O3 in ZnO-Bi2O3-based varistor ceramics was investigated.The phase and microstructure evolution during the sintering process were examined.The results show that the higher the sintering temperature or the longer the sintering time is,the more the Bi2O3 is volatilized.The heating rate has little effects on the Bi2O3 volatilized in ZnO-Bi2O3-based varistor ceramics.This is in accordance with the relative X-ray diffraction peak area ratio analysis.The results also show that the sintering temperature has the greatest impact on the vaporization of the Bi2O3,then followed by sintering time,and the effect of the heating rate is the minimum.

Preparation of β-Sialon/ZrN bonded corundum composites from zircon by nitridation reaction sintering process

β-Sialon/ZrN bonded corundum composites were synthesized using fused white corundum,alumina micro powder,zircon and carbon black by nitridation reaction sintering process. Phase composition and microstructure of the synthesized composites were investigated by X-ray powder diffraction and scanning electronic microscope,and the formation process of the composites was discussed. The results show that the composites with different compositions can be obtained by controlling the heating temperature and contents of zircon and carbon black. The proper temperature to synthesize the composites is 1773 K.

Effect of sintering process on microstructure and magnetic properties of high frequency power ferrite

An oxide ceramic process was adopted to prepare high frequency manganese-zinc(MnZn)power ferrite.In combination with the microstructure analysis of material,the influences of sintering process on initial permeability(μ_(i))and high frequency loss in unit volume(P_(cv))of MnZn power ferrite were investigated.The results show that in order to obtain fine microstructure and high frequency properties,the preferable sintering temperature and atmosphere are 1230℃and oxygen partial pressure(P_(O_(2)))of 4%,respectively.

One-time sintering process to modify xLi2MnO3(1-x)LiMO2 hollow architecture and studying their enhanced electrochemical performances

To solve the critical problems of lithium rich cathode materials, e.g., structure instability and short cycle life, we have successfully prepared a ZrO2-coated and Zr-doping xLi2MnO3·(1–x)LiMO2 hollow architecture via one-time sintering process. The modified structural materials as lithium-ion cathodes present good structural stability and superior cycle performance in LIBs. The discharge capacity of the ZrO2-coated and Zr-doped hollow pristine is 220 mAh g-1 at the 20th cycle at 0.2 C(discharge capacity loss, 2.7%)and 150 m Ah g-1 at the 100 th cycle at 1 C(discharge capacity loss, 17.7%), respectively. However, hollow pristine electrode only delivers 203 m Ah g-1 at the 20 th cycle at 0.2 C and 124 mAh g-1 at the 100 th cycle at 1 C, respectively, and the corresponding to capacity retention is 92.2% and 72.8%, respectively.Diffusion coefficients of modified hollow pristine electrode are much higher than that of hollow pristine electrode after 100 cycles(approach to 1.4 times). In addition, we simulate the adsorption reaction of HF on the surface of ZrO2-coated layer by the first-principles theory. The calculations prove that the adsorption energy of HF on the surface of ZrO2-coated layer is about-1.699 e V, and the ZrO2-coated layer could protect the hollow spherical xLi2MnO3·(1–x)LiMO2 from erosion by HF. Our results would be applicable for systematic amelioration of high-performance lithium rich material for anode with the respect of practical application.

Preparation of ZrN(ZrON)-SiAION Composite Ceramics via a Pressureless Sintering Process

ZrN-SiAlON composite materials were synthesized at 1 550 ℃ for 6 h via a carbothermal reduction nitridation route using fly ash （≤74 μm）,zircon （≤ 44 μm） and active carbon as starting materials.The processed ZrN-SiAlON composite micropowders were mixed with polyvinyl alcohol as binder to prepare ZrN （ZrON）-SiAlON composite ceramics by carbon-embedded pressureless firing at 1 450,1 500 and 1 550 ℃ for 1 h,respectively.Influences of firing temperature on the phase compositions,microstructure and sintering properties of the ceramics were investigated.The results show that：（1） β-SiAlON based composite ceramics with different compositions can be prepared by controlling firing temperature,and the main crystalline phases of the specimen fired at 1 550 ℃ for 1 h involve ZrN,ZrON and β-SiAlON （z =2,Si4Al2O2N6）; （2） ZrN （ZrON）,β-SiAlON and a Fe-Si based compound can be observed in the microstructures of the specimens fired at different temperatures.ZrN （ZrON） particles distribute homogeneously in the β-SiAlON matrix; （3） raising firing temperature can increase the shrinkage ratio of the ceramics,and the volume shrinkage ratio increases from 19.4％ to 40.3％ when the firing temperature rises from 1 450 to 1 550 ℃.

Intelligent optimal control for lead-zinc sintering process state

The intelligent integrated predictive model of synthetical permeability was established using the fuzzy classifier to combine the time sequence predictive model with the craftwork parameter predictive model. Then, the estimation model of burn-through point(BTP) based on pipe stress point(PSP) method and the predictive model of BTP were proposed. The optimal control of permeability and heat states was implemented by using the fuzzy expert controller with self-studying mechanism. The application of the intelligent control technique suppresses 17% of the fluctuation of synthetical permeability and 12% of the fluctuation of BTP, stabilizes the output and quality of sinter and settles the basis for the optimization of output and quality of sintering process.

High Energy and High Coercivity Sintered NdFeB Magnets by Low Oxygen Process

Using ball milling and single direction pressing, we can produce high performance NdFeB sintered magnets. The oxygen content of sintered magnets can be controlled under 1500xl0^-6 and the magnetic performance can be improved by using low oxygen processing. The high preformance NdFeB sintered magnets with Br=(1.4 ± 0.2)T, iHc>796 kA/m and (BH)max=(390± 16) kJ/m^3, have been batch produced.

Properties and corrosion behavior of Al based nanocomposite foams produced by the sintering-dissolution process

The properties orAl based nanocomposite metal foams and their corrosion behaviors were investigated in this study. For this, the composite metal foams with different relative densities （porosity） reinforced with alumina nanoparticles were prepared using a powder me- tallurgy-based sintering-dissolution process （SDP） and NaC1 particles were used as space holders. Then, the effect of nanoparticle rein- forcement and different amounts of NaC1 space holders （corresponding porosity） on the microstructure, morphology, density, hardness, and electrochemical specifications of the samples were investigated. It was found that as the relative density increased from 60% to 70%, the wall thickness increased from about 200 to 300 pro, which led to a decrease in pore size. Also, the addition of nanoparticle reinforcement and the increased relative density result in increasing metal foam hardness. Moreover, electrochemical test results indicated that increasing the A1203 content reduced the corrosion rate, but increasing the porosity enhanced it.

Design and development of expert system for controlling sintering process

The general structure of expert system for controlling sintering process has been proposed. It includes knowledge base, inference engine, data acquisition system, learning system, knowledge base management system, explanation system and so on. The control functions consist of sintering chemical composition control centered on basicity and sintering process state control centered on permeability. The adaptive prediction of sintering chemical composition, the control strategy centered on basicity, the control strategy centered on permeability, the judgement of permeability and the prediction of burn through point were studied. The software of system, which includes about 1 000 expert rules, was successfully applied in off line control of sintering process in a sintering plant.

Effects of Activated Sintering Process on Properties and Microstructure of W-15Cu Alloy

The effects of activated sintering technology of H2 atmosphere sintering on the microstructure and properties of W-15Cu alloy using ultrafine W-15Cu composite powder fabricated by spray drying calcining-continuous reduction technology were investigated.The experimental results showed that W-15Cu alloy,consolidated by activated sintering technology of H2 atmosphere sintering for 1 h at 1300 ℃,with 98.5 % relative density,transverse rupture strength 1218 MPa,Vickers hardness HV0.5 378,average grain size about 1.2 μm and thermal conductivity 192 W/m·K,was obtained.In comparison to the normal sintering process,activated sintering process to W-15Cu alloy could be achieved at lower sintering temperature.Furthermore,better properties in activated sintered compacts were obtained,and activated sintering process resulted in finer microstructure and excellent properties.

Real-time operation guide system for sintering process with artificial intelligence

In order to optimize the sintering process, a real-time operation guide system with artificial intelligence was developed, mainly including the data acquisition online subsystem, the sinter chemical composition controller, the sintering process state controller, and the abnormal conditions diagnosis subsystem. Knowledge base of the sintering process controlling was constructed, and inference engine of the system was established. Sinter chemical compositions were controlled by the strategies of self-adaptive prediction, internal optimization and center on basicity. And the state of sintering was stabilized centering on permeability. In order to meet the needs of process change and make the system clear, the system has learning ability and explanation function. The software of the system was developed in Visual C++ programming language. The application of the system shows that the hitting accuracy of sinter compositions and burning through point prediction are more than 85%; the first-grade rate of sinter chemical composition, stability rate of burning through point and stability rate of sintering process are increased by 3%, 9% and 4%, respectively.

EXPERT SYSTEM FOR CONTROLLING THE STATE OF SINTERING PROCESS

In order to control sintering process,improve permeability and stabilize burn through point, a control scheme which combines thermal state with permeability state is proposed, and an expert system for controlling sintering process state is developed, the software which includes about 1000 expert rules is successfully applied to off line control of sintering process.

Research and industrial testing of dioxin emission reduction technology in the sintering process

Based on an analysis of the chlorine elements in each component of the sintering mixture,industrial tests of the use of dioxin reduction techniques in the sintering process were found to reduce the chlorine sources and inhibit the formation of dioxins.The dioxin reduction effect obtained in the industrial experiment was better than that in the sintering pot experiment,but their patterns were consistent.When urea is used as an inhibitor,the dioxins can be significantly reduced.When a 0.02%ratio of urea was added,a maximum dioxin emission reduction of 79%was obtained.Reducing the chlorine sources also had an obvious dioxin reduction effect,enabling a 69.49%reduction.In addition,when these two technologies were applied simultaneously,a significant emission reduction rate of 92.23%was achieved.The concentration of dioxins in flue gas dropped to 0.2421 ng TEQ/m^(3) before desulfurization,which meets the emission standard for dioxins in the final exhaust gas.

Fabrication of superhydrophilic surface on copper substrate by electrochemical deposition and sintering process

Superhydrophilic surfaces were fabricated on copper substrates by an electrochemical deposition and sintering process. Superhydrophobic surfaces were prepared by constructing micro/nano-structure on copper substrates through an electrochemical deposition method. Conversion from superhydrophobic to superhydrophilic was obtained via a suitable sintering process. After reduction sintering, the contact angle of the superhydrophilic surfaces changed from 155° to 0°. The scanning electron microscope （SEM） images show that the morphology of superhydrophobic and superhydrophilic surfaces looks like corals and cells respectively. The chemical composition and crystal structure of these surfaces were examined using energy dispersive spectrometry （EDS） and X-ray diffraction （XRD）. The results show that the main components on superhydrophobic surfaces are Cu, Cu2O and CuO, while the superhydrophilic surfaces are composed of Cu merely. The crystal structure is more inerratic and the grain size becomes bigger after the sintering. The interracial strength of the superhydrophilic surfaces was investigated, showing that the interfacial strength between superhydrophilic layer and copper substrate is considerably high.

Sintering and Electronic Conducting Properties of La_(0.7)Ca_(0.3)CrO_3 Perovskite Synthesized by a Glycine-nitrate Process

La0.7 Ca0.3 CrO3 powder consisting of superfine and uniform particles （ 100-200 nm ） were synthesized using a glycine-nitrate process （ GNP ）. The sintering and electronic conducting properties of La0.7 Ca0.3 CrO3 were invetigated in the sintering temperature range of 1 200-1 450 ℃. The desired morphology of the powder significantly improved its sinterability. La0.7 Ca0.3 CrO3 ceramics sintered at 1 250-1 450 ℃ show high relative densities above 95 % . The ceramics sintered at 1 250-1 400 ℃ have very similar electronic conduct- ing properties, providing electronic conductivities around 55 Ω^-1 cm^-1 at a measuring temperature of 800 ℃ . Further increasing the sintering temperature to 1450 ℃ led to an apparent degradation of electronic conducting properties. This research demonstrates the advantage of the GNP in producing La0.7 Ca0.3 CrO3 with respect to the enhanced sintering properties and superior electronic conducting properties.