无起拱烧结机新理论的研究

通过多年的试验研究，发现烧结机台车起拱是由台车过剩力矩所引起，提出了一种利用液压阻力矩方法及装置自动消除烧结机尾部台车过剩力矩的理论。依据该理论所设计的烧结机消除了台车起拱，因而避免了台车磨损，减少了漏风率。     

Effect of neck formation on the sintering of air-plasma-sprayed thermal barrier coating system

Sintering neck is a featured microstructure that may have significant effect on the sintering behaviour of air-plasma-sprayed thermal barrier coating system (APS TBCs). Based on experimental observations, a multi-necking wedge-shaped model for the sintering of APS TBCs was proposed by considering the sintering stress as surface tension and by employing the thermal-elasto-viscoplastic constitutive relation. Deformation pattern, stress distribution, sintering induced shrinkage, stiffening behaviour and temperature field were analysed by using finite element method. It is shown that the formation of sintering neck significantly affects thermal and mechanical properties related to sintering. Mechanisms of thermal and mechanical degradation induced by sintering were further elucidated.     

提高韶冶烧结氧化物料处理能力的研究与应用

介绍韶冶在氧化物料对工厂生产经营和现场环境造成不利影响的条件下,通过设备、工艺两方面的研究,提高氧化物料处理能力,从而增强烧结工艺对原料的适应性,使干精矿含硫降低,烧结机产能大幅度提升,烧结块质量保持较高水平,年创效益约2 500万元。     

Hydrogen production from low temperature WGS reaction on co-precipitated Cu–CeO2 catalysts: An optimization of Cu loading

Low temperature water–gas shift (WGS) reaction has been carried out at the gas hourly space velocity of 72,152 h⁻¹ over Cu–CeO₂ catalyst prepared by a co-precipitation method. Cu loading was optimized to obtain highly active co-precipitated Cu–CeO₂ catalysts for low temperature WGS. 80 wt% Cu–CeO₂ exhibited the highest CO conversion as well as the most stable activity (X_CO > 46% at 240 °C for 100 h). The excellent catalytic performance is mainly due to a strong metal to support interaction, resulting in the prevention of Cu sintering.     

Effect of TiO2 addition on the sintering densification and mechanical properties of MgAl2O4–CaAl4O7–CaAl12O19 composite

Materials designed in the high-alumina region of Al₂O₃–MgO–CaO system have been widely used in many technological fields. However, their further applications are limited by the high sintering temperatures necessary to achieve densification due to the poor sintering ability of calcium hexaluminate (CaAl₁₂O₁₉) and spinel (MgAl₂O₄). Considering this aspect, the present work investigated the effect of TiO₂ addition on the sintering densification and mechanical properties of MgAl₂O₄–CaAl₄O₇–CaAl₁₂O₁₉ composite by solid state reaction sintering. The results showed that the CA₆ grains presented a more equiaxed morphology instead of platelet structure by incorporating Ti⁴⁺ into its structure, which greatly improved the densification after heating at 1600 °C. The flexural strength was greatly enhanced with increasing addition of TiO₂ due to the significant decrease in porosity and improvement in uniformity of grain size as well as the absence of microcracks in the presence of Al₂TiO₅. The increased content of TiO₂ also played an active role in toughening this composite attributed to the increase in resistance to crack initiation and propagation.     

Correlating phase and microstructure development versus dielectric properties in La and Er co-doped Bi4Ti3O12 ferroelectric ceramics

Bi_3.25La_0.75−xEr_xTi₃O₁₂ and Bi_3.25La_0.75Ti_3−xEr_xO_12−δ ceramics were prepared and studied in this work in terms of dopant-induced phase and microstructure development as well as dielectric response. The results show that introduction of Er³⁺ tends to reduce the materials’ sintering temperature and average grain size. Moreover, it was noted that in these systems the substitution site of this dopant is controlled by valence state and ionic radii mismatch effects. In particular, even when a nominal substitution of Ti⁴⁺ is conceived, here it is found that Er³⁺ also incorporates at the (Bi,La)³⁺ sites. These and other interesting concluding remarks from this work, including Er³⁺ tolerance, were possible only after comparing, especially, the X-ray diffraction results and the intrinsic ferroelectric characteristics extracted from the dielectric measurements.     

Microstructure and thermoelectric properties of Sb doped Hf0.25Zr0.75NiSn Half-Heusler compounds with improved carrier mobility

Half-Heusler (HH) semiconductor alloys are being widely investigated due to their promising potential for thermoelectric (TE) power generation applications. Sb is an effective doping element for n-type ZrNiSn half-Heuslers alloys. HH thermoelectric materials Hf_0.25Zr_0.75NiSn_1−xSb_x (0 ≤ x ≤ 0.03) were synthesized by induction melting combined with plasma activated sintering (PAS) technique. X-ray diffraction concluded that single-phase HH compounds without compositional segregations were obtained. Presence of bended lamellar structures was revealed by the FESEM. Sb doping significantly enhanced the electrical conductivity, power factor and carrier concentration of the alloys. An increase in the carrier mobility was also observed. Consequently, optimum values of 4.36 × 10⁻³ W/mK² and 4.7 × 10²⁰ cm⁻³ were achieved for power factor and carrier concentration, respectively. As a result, a ZT value of 0.83 at 923 K was obtained which is about 67% improvement compared to the un-doped sample.     

Microstructural characterization of spray-dried NiO-8YSZ particles as plasma sprayable anode materials for metal-supported solid oxide fuel cell

The plasma spray method is widely used to produce NiO-8YSZ (composed of nickel oxide (NiO) and 8 mol% yttria-stabilized zirconia) anode layers in metal-supported solid oxide fuel cell (SOFC). Flowability control of microsized particles is important for achieving consistent performance of the SOFC anode layer. When microsized particles are fabricated via spray drying and sintering, the most significant factors that influence flowability are their sizes, distribution, and surface conditions. Thus, the aim of this study is to analyze the fabrication conditions for microsized NiO-8YSZ cermet particles made from a nanoscale, sinterable NiO-8YSZ dispersion solution by using an appropriate spray-drying and sintering process. The characteristics of the as-sprayed and sintered NiO-8YSZ composite particles (such as size, distribution, roughness, and nanostructure) were analyzed via field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS), particle size distribution (PSD), Brunauer–Emmett–Teller (BET) surface area, and atomic force microscopy (AFM). The as-sprayed microsized NiO-8YSZ particles became smaller and more uniformly distributed as the rotational speed used for spray drying increased. As a result of sintering, the extent of shrinkage of as-sprayed microsized NiO-8YSZ particles generated at high RPMs was lower than that of particles formed at low RPMs. No significant difference was observed in the distribution of the nanosized NiO and 8YSZ particles at different rotational speeds. Furthermore, the highest BET surface areas were observed for particles generated at 8000 RPM before sintering at 13.74 m²/g. After sintering, the highest BET surface area was 0.94 m²/g for particles generated at 16,000 RPM. Differences in nanostructure and surface roughness between as-sprayed and sintered microsized NiO-8YSZ particles were identified via AFM. This study is expected to provide important fundamental information useful for optimizing SOFC efficiency by promoting flowability control during the production of SOFC anodes via plasma spraying.     

Reliability of Cu nanoparticle joint for high temperature power electronics

Power cycle reliability of Cu nanoparticle joint has been studied for high temperature operation of power devices. Al₂O₃ heater chips and Cu–65 wt% Mo baseplates were joined by Cu nanoparticles and Sn–0.7Cu and power cycle tests of 65/200 °C and 65/250 °C were carried out on the joints. The Cu nanoparticles were prepared by reducing Cu carbonate in ethylene glycol with dodecanoic acid + dodecyl amine (C12) and decanoic acid and decyl amine (C10) as capping agents. A power cycle test of 65/200 °C did not inflict severe damage on the Cu nanoparticle joints so that there were not many cracks formed after 3000 cycles. Vertical cracks were formed in the C12 Cu nanoparticle joint after 3000 cycles of 65/250 °C test, however the maximum temperature during the power cycle test did not change at all because vertical cracks did not have an effect on preventing heat flow. On the contrary, lateral cracks were completely formed in the Sn–0.7Cu soldered joint after 200 cycles of 65/200 °C test and in the C10 Cu nanoparticle joint after 360 cycles of 65/250 °C test. In these experiments, the maximum temperatures were rapidly increased because heat conduction was prevented across the formed lateral cracks.