Pseudo Phase Diagram and Microwave Dielectric Properties of Li2O–MgO–TiO2 Ternary System

Li₂O–MgO–TiO₂ ternary system is an important microwave dielectric ceramic material with excellent properties and prospect in both scientific research and application. A phase diagram of the Li₂O–MgO–TiO₂ ternary system was established in this article, based on earlier research results and our present work. Microwave dielectric properties with compositions in different regions of the phase diagram have been analyzed. We found that the 0.33 Li₂MgTi₃O₈–0.67 Li₂TiO₃ ceramics sintered at 1200°C exhibited excellent dielectric properties: Q × f value = 80 476 GHz (at 7.681 GHz), ε_r = 24.7, τ_f = +3.2 ppm/°C. We also designed two ceramic systems in the Li‐rich region of the Li₂O–MgO–TiO₂ ternary system, which received little attention in the past decades, because many excellent single‐phase ceramics, such as Li₂MgTiO₄, Li₂MgTi₃O₈ and MgTiO₃, have been found in the Ti‐rich region. The ceramic systems have low sintering temperatures but also relatively poor dielectric properties.     

高海拔地区水泥厂利用劣质煤的测试及分析

正0前言根据煤炭资源的分布状况,云南、贵州等地的煤一般具有高灰分、低热值的特点,此类型煤由于运输距离短、价格低,受到周边地区水泥厂的青睐。云贵高原海拔较高,随海拔增高大气压力逐渐降低,高海拔对烧成系统会产生一定的不利影响。本文针对中     

镍铁渣微粉单掺及与粉煤灰复掺对混凝土性能的影响

在混凝土中分别单掺镍铁渣微粉、复掺镍铁渣微粉和粉煤灰,研究了其对混凝土工作性能、力学性能的影响,并通过XRD衍射分析、SEM分析等现代测试手段分析掺合料微粉对水泥水化性能的影响。试验确定了镍铁渣微粉、粉煤灰用作混凝土掺合料的最佳掺量:单掺镍铁渣微粉时,镍铁渣微粉的最佳掺量为15%;复掺镍铁渣微粉和粉煤灰可使两者在混凝土中发生"叠加效应",优势互补,当两者的总掺量为40%,其中镍铁渣微粉掺量为15%时,混凝土的后期强度仍然较高。     

10 000 t/d回转窑液压挡轮装置的优化设计

结合中国中材国际工程股份有限公司设计的某10000t/d熟料生产线的回转窑挡轮装置,介绍了挡轮装置的优化设计,其中创新设计了不同与以往1个挡轮的3个挡轮的设置;对其挡轮装置的结构也作了优化,采用了3组轴承,使挡轮受力更加合理,寿命延长。2012年该10000t/d回转窑装备被评为科技进步二等奖,至今已应用于国内外多条生产线,均取得了良好的业绩和效果。     

微纳米气泡技术在渔业水产行业的研究进展及应用综述

微纳米气泡技术是当前国内外的前沿科技,也是研究的热点。该文详细介绍了微纳米气泡在悬浮物的吸附去除、有机物的强化分解及促进生物活性等方面的最新研究进展与应用现状。综述了微纳米气泡发生装置的各种原理和结构,并对其应用进展进行了分析和探讨,特别介绍了在渔业水产相关领域的研究应用情况。指出了微纳米气泡技术目前面临的主要问题及对渔业研究领域的启示,以期为微纳米气泡在水产养殖、捕捞、加工等领域的理论研究和技术应用提供参考。     

夹杂物对F92/F22异种钢焊接接头冲击性能的影响

采用夏比摆锤冲击试验对同种焊接及焊后热处理工艺条件下的F92/F22异种钢焊接接头焊缝冲击性能进行了研究。结果显示,1号试样的冲击吸收能量(63 J)不足相同工艺条件下2号试样冲击能量(130 J)的1/2。通过扫描电子显微镜(SEM)和能谱(EDS)分析了冲击断口的形貌特征和微区成分,发现在1号试样冲击断口的裂纹形成区存在大小约25μm的复合氧化物夹杂。采用有效投影面积模型计算引发裂纹萌生的临界夹杂物尺寸,分析了夹杂物对F92/F22异种钢焊接接头冲击性能的影响,并确定了该夹杂是造成1号试样冲击吸收能量显著下降的主要原因。因此,应采取适当的工艺措施减少其内部的缺陷,以提高该异种钢焊接接头的冲击性能。     

Influence of MWCNTs modified by silane coupling agent KH570 on the properties and structure of MWCNTs/PLA composite film

Composite films based on poly(lactic acid)(PLA) filled with modified multiwalled carbon nanotubes (MWCNTs) were prepared by casting/solvent evaporation technique and investigated for their properties and structures. MWCNTs were modified by coupling agent KH570 which can improve the dispersion of MWCNTs and then enhance the comprehensive properties of PLA. The influences of modified conditions, including the amounts of KH570, the reaction temperature and time, were analyzed. And also the structures and properties of composite films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), fourier transform infrared (FTIR) and thermogravimetric analysis (TG). The two components of the composite films, WMCNTs and PLA, had excellent compatibility. The addition of MWCNTs modified by coupling agents KH570 was beneficial for the crystallization of PLA, and the toughness of composite films was also improved. When the reaction temperature was 70 °C, reaction time was 6 h, and the amount of KH570 was 3 % respectively, the obtained composite films had the perfect comprehensive properties.     

Performance of Sm<Subscript>0.7</Subscript>Sr<Subscript>0.3</Subscript>CoO<Subscript>3−<Emphasis Type="Italic">δ</Emphasis></Subscript> membrane under CO<Subscript>2</Subscript>-containing atmosphere

The permeability and stability of Sm_0.7Sr_0.3CoO_3?δ (SSCO) regarding the special requirements for carbon capture and storage (CCS) application were investigated. Pure CO₂ was used as the sweep gas at 900 °C, leading to that the oxygen permeation flux decreases by about 34 %. Several cycles of changing the sweep gas between helium and CO₂ indicate the good reversibility of this degradation. Both carbonate formation and adsorption of CO₂ on the membrane surface are responsible for the degradation of the membrane performance. The better CO₂ resistance results from the substitution of Sm for Sr due to the higher acidity of Sm₂O₃ (1.278) than that of SrO (0.978) and a discontinuous layer of carbonate.     

铝/钢电弧辅助激光对接熔钎焊铺展特性

采用小功率TIG电弧辅助激光热源进行5A06铝合金和热镀锌ST04Z钢的预置粉末对接熔钎焊工艺试验,通过SEM,Photoshop来研究预留间隙、背面填涂钎剂、激光热输入、辅助电弧电流、热源中心间距、填加焊丝对熔钎焊接头铺展宽度的影响. 结果表明,预留小于0.5 mm的间隙与背面填涂钎剂均可增大铺展宽度;在未焊穿的前提下,随激光热输入和辅助电弧电流的增加,铺展宽度增大;随热源中心间距的增大,铺展宽度先增加后减小. 焊接熔池中填加Al-Si焊丝较未填加焊丝的铺展性更好,获得连续、美观的焊缝表面形貌.