Novel Series of Low‐Firing Microwave Dielectric Ceramics: Ca5A4(VO4)6 (A2+ = Mg,Zn)

Using a conventional solid‐state reaction Ca₅A₄(VO₄)₆ (A²⁺ = Mg, Zn) ceramics were prepared and their microwave dielectric properties were investigated for the first time. X‐ray diffraction revealed the formation of pure‐phase ceramics with a cubic garnet structure for both samples. Two promising ceramics Ca₅Zn₄(VO₄)₆ and Ca₅Mg₄(VO₄)₆ sintered at 725°C and 800°C were found to possess good microwave dielectric properties: ε_r = 11.7 and 9.2, Q × f = 49 400 GHz (at 9.7 GHz) and 53 300 GHz (at 10.6 GHz), and τ_f = ?83 and ?50 ppm/°C, respectively.     

聚氨酯预聚体接枝环氧树脂的制备及固化性能研究

采用分步法合成了聚氨酯(PU)预聚体/环氧树脂(E-51)接枝共聚物(g-PU/EP),以自制二聚酸聚酰胺为固化剂,对固化体系的固化性能进行了研究。结果说明:当PU预聚体/E-51质量比为20∶100时,固化体系的剪切强度(铝-铝)最大为14.1 MPa;SEM分析结果表明,接枝后固化物呈典型韧性断裂;TG分析表明,接枝改性对固化物耐热性的影响较小。     

污泥热干燥粘结的特征和影响因素

污泥热干燥过程中在干燥设备内部表面的粘结是影响干燥设备性能的重要因素。通过热干燥模拟实验,分析了污泥含水率、加热温度、加热方式、加热界面性质等因素对污泥粘结的影响。结果表明,含水率是影响污泥粘结最主要的因素,污泥含水率较高时,粘结量较少,随着污泥干燥程度增加,含水率降低,粘结量逐渐增加,当含水率达到60%左右时粘结量达到最大,之后转而减少;加热温度不超过120℃时,温度对污泥粘结的影响不明显,加热温度高于120℃时,污泥粘结量随温度升高而显著增加;传导加热方式比对流加热方式更易导致污泥粘结;加热接触界面的表面粗糙度越大则污泥粘结量越大。     

应用三级分离技术改造褐藻酸钠传统工艺

在褐藻酸钠的生产中,应用新的三级机械分离技术改进传统工艺,可以大幅度降低自来水和氯化钙消耗,削减COD排放,并有助于提高产品得率。全年实现节水353500m3,节液体氯化钙2695t,减少COD排放159．075t,经济效益和社会效益显著。一年多的实际应用表明,该新技术的应用是成功的。     

Microwave hydrothermal synthesis and photocatalytic properties of TiO2/BiVO4 composite photocatalysts

TiO₂/BiVO₄ composite photocatalysts with heterojunction structures were synthesized by the one-step microwave hydrothermal method. The physical and photophysical properties of the as-prepared photocatalysts were fully characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), UV–vis diffuse reflectance spectra, photoluminescence (PL) and BET surface area analysis. The photocatalytic activities were evaluated by the decolorization of rhodamine B under UV and simulated sun-light irradiation. The results reveal that the as-prepared TiO₂/BiVO₄ composites exhibit higher photocatalytic activities than pure BiVO₄. The 20% TiO₂/BiVO₄ sample shows the best photocatalytic activity. The enhancement of photocatalytic activity is mainly attributed to the increasing separation rate of photogenerated charge carriers. The possible photocatalytic mechanism is discussed on the basis of the calculated energy band positions.     

Microstructure and electrical properties of (Pb0.87Ba0.1La0.02)(Zr0.68Sn0.24Ti0.08)O3 anti-ferroelectric ceramics fabricated by the hot-press sintering method

(Pb_0.87Ba_0.1La_0.02)(Zr_0.68Sn_0.24Ti_0.08)O₃ anti-ferroelectric ceramics with various amounts of excess PbO have been fabricated by the conventional solid-state reaction process and the hot-press sintering method, and the dependence of microstructure, ferroelectric and dielectric properties on sintering approaches and lead volatilization conditions has been studied. When an appropriate quantity of excess PbO is added, the lead volatilization effect can be compensated and the content of pyrochlore phase is decreased. Hot-pressed anti-ferroelectric ceramics exhibit much higher densities than conventionally sintered samples. The spontaneous polarization and maximum dielectric constant of the AFE ceramics decrease when the hot-press sintering method is used. The dielectric loss can be obviously reduced by using the hot-press sintering method and adding a proper amount of excess PbO. The systemic investigation of the lead volatilization effect and the hot-press sintering method will contribute to the development of high properties of anti-ferroelectric ceramics in practical applications.     

An experimental study of flow and heat transfer of supercritical carbon dioxide in multi-port mini channels under cooling conditions

This paper presents the fluid flow and heat transfer characteristics of supercritical CO₂ in a horizontal multi-port extruded aluminum test section consisting of 10 circular channels with an inner diameter of 1.31 mm. Both local and average pressure drop and heat transfer coefficients were measured as CO₂ was cooled in the multi-port circular channels with pressures ranging from 7.4 to 8.5 MPa, inlet fluid temperatures ranging from 22 to , and mass velocity ranging from 113.7 to 418.6 kg/m² s. The results indicate that the operating pressure, the mass velocity and the temperature of CO₂ had significant effects on fluid flow and heat transfer characteristics. The pressure drop and the average heat transfer coefficient increased greatly with increasing the average temperatures of CO₂ in the near-critical region; the average heat transfer coefficient attained a peak value near the corresponding pseudocritical temperature; and the maximum heat transfer coefficient decreased as the pressure increased. Both the pressure drop and the heat transfer coefficient increased with the mass velocity, but decreased with the operating pressure. The measured average heat transfer coefficients were compared with the experimental data reported in the literatures and a large discrepancy was observed. Based on the experimental data collected in the present work, a new correlation was developed for forced convection of supercritical CO₂ in horizontal multi-port mini channels under cooling conditions.     

废旧锂离子电池回收处理技术与资源化再生技术进展

近年来,随着消费电子商品、电动车和大规模储能市场的快速发展,作为目前占据最多市场份额的锂离子电池的产量也随之快速增长,随之产生的废旧锂离子电池的数量和重量呈现出了井喷式的上涨。从其巨大的数量、环境保护和资源再生的角度来看,废旧锂离子电池都具有很高的回收价值和潜力。本文主要从实验室研究和工业应用两个角度总结了目前主要的回收处理方法和流程,重点介绍了利用废旧锂离子电池电极材料重新再生和合成新的电极材料的研究进展。目前废旧锂离子电池回收处理存在的问题主要是：电极材料的复杂多样性导致分离提纯过程困难,回收过程易产生二次污染以及回收的经济激励不足。未来的发展趋势在于结合绿色环保和低成本经济,研究高效的回收处理工艺流程。     

2 500 t/d新型干法水泥生产线热工标定与分析

对AXNW水泥厂2500t/d生产线进行热工标定并分析,该厂熟料产量平均在2850t/d,超过设计产量的14%。系统烧成热耗3308.69k J/kg,高于全国平均水平。C1筒出口温度为290℃,处于国内先进水平,其氧含量达到4.9%,偏高。篦冷机冷却效果欠佳,风室存在风短路现象,直接影响了熟料质量和余热发电量,热回收效率偏低。该烧成系统还有较大的提升潜力,如果通过改进和优化,精细化管理和操作,熟料产能还可以得到进一步的提高,热耗及电耗可明显下降。     

Study of Cu/Mn Catalysts for Coreactions of NH3-SCR and CO Oxidation

Catalysis Letters - To explore the possibility of coreaction of selective catalytic reduction with NH3 (NH3-SCR) and CO oxidation (CO-O), bimetallic doping catalysts of Mn and Cu were synthesized...