电磁场作用下高铁渣对MgO-C耐火材料的侵蚀

电磁场会促使熔渣中的铁、锰离子与MgO-C耐火材料反应形成锰掺杂镁铁尖晶石相,为进一步研究锰掺杂镁铁尖晶石的生成形貌及特征,采用Fe2O3质量分数为53.62%、CaO与SiO2质量比为0.8的高铁渣,分别在有、无电磁场环境下,对碳质量分数为14%的MgO-C耐火材料进行渣蚀试验。结果表明:感应炉存在电磁场,使熔渣中部分Fe2+/Fe3+与镁砂中Mg2+发生置换形成镁铁尖晶石,其含有少量Mn2+离子;镁铁尖晶石中铁含量从渣蚀层到渗透层急剧降低,锰含量几乎维持不变;侵蚀后试样渗透层较明显。电阻炉无电磁场,则侵蚀后试样没有形成镁铁尖晶石,熔渣中Si、Ca渗透到方镁石晶格中,形成钙镁榄橄石低熔相,将镁砂溶解到熔渣中;渣蚀层有明显的MgAl2O4生成。     

机场水泥混凝土道面隔离式加铺层板厚合理性分析

通过实例,对机场水泥混凝土道面隔离式加铺层厚度与疲劳应力的关系进行分析,发现旧水泥混凝土道面疲劳应力随着加铺层厚度增加而减小,而加铺层疲劳应力却出现一个峰值。分析了旧道面不同计算厚度与加铺层疲劳应力峰值出现点对应的加铺层厚度的关系,提出当旧道面计算厚度小于20 cm时,加铺层厚度应比综合疲劳应力峰值对应的厚度大1～2 cm;当旧道面计算厚度大于20 cm时,加铺层厚度应比综合疲劳应力峰值对应的厚度小1～2 cm,为机场道面隔离式加铺设计提供参考。     

数控车床精密进给传动的预加载装置

一种高效预加载装置,利用碟形弹簧受压变形储备的能量压缩传动轴端的螺杆、推杆、转动钢球组成的预加载系统,迫使传动轴上的斜齿轮在轴上发生轴向移动,来达到使相啮合的斜齿轮上的另一轴产生相对转动,从而消除传动链间隙,达到补偿磨损及动态误差.     

电火花加工铝花纹块工艺技术的应用

铝花纹块的硫化膨胀量是决定合模后的花纹圈圆度和轮胎是否存在胶边的关键尺寸。通过将膨胀量值均匀分配于各花纹块之间的工艺,使电火花加工花筋连接无错台,花纹块加工质量好。     

Li、Sb、Ta共掺杂对铌酸钾钠基无铅压电陶瓷相结构和压电性能的影响

采用固相法及常压普通烧结方法,制备了Li、Sb、Ta共掺杂的铌酸钾钠基无铅压电陶瓷(Na0.52K0.44Li0.04)(Nb1-x-ySbxTay)O3,通过调节x、y在0至0.10之间的取值,研究Sb、Ta两种元素共掺杂对铌酸钾钠基陶瓷相结构、压电和介电性能的影响,获得优化的掺杂比例。在研究的组成范围内,随着Sb含量的增加,所得样品均存在一个由正交相向四方相的O-T相变,而随Ta含量的增加,相组成没有变化,且存在一个成分窗口,对应一系列具有较优压电性能的组分。在x=0.05,y=0.06的组分附近时,性能达到最优,d33～334pC/N,Kp～0.35,介电常数约为1900,介电损耗约为2.7%,Pr～16.4μC/cm2,Ec～8.4kV/cm。     

Effects of heat treatment on microstructure and mechanical properties of TiC/TiB composite bioinert ceramic coatings in-situ synthesized by laser cladding on Ti6Al4V

To improve the wear resistance of titanium alloy, in this work, TiC/TiB composite bioinert ceramic coatings were synthesized in-situ via laser cladding using Ti and B₄C mixed powders as precursor materials. And to decrease the impact of the excessive residual tensile stress generated by the uneven temperature distribution on the performance of coatings, the coatings were then subsequently heated for 3 h at different temperatures (400 °C, 600 °C, and 800 °C) and then air cooled. The effects of heat treatment on the microstructure, residual stress, micro-hardness, fracture toughness, and wear resistance of the coatings were investigated. The results showed that phase compositions and microstructure of the heat-treated coatings were virtually identical to that of the untreated coatings; however, the precipitation of acicular TiB enhanced mechanical properties of the heat-treated coatings. In addition, the average residual tensile stress values of the coatings decreased as the heat treatment temperature increased, which improved fracture toughness of the coatings from 3.95 to 4.68 MPa m^1/2. Moreover, wear resistance of the coatings was greatly enhanced by heat treatment; as the wear volume of the heat-treated coatings decreased by 50% at 800 °C compared with that of the untreated coatings. Lastly, the coatings showed good biocompatibility after being evaluated in vitro, and therefore had broad application prospects in the field of orthopedic implants.     

Preparation of a modified phosphate-based adhesive and its hot bonding performance on 316L stainless steel

In this study, a novel phosphate-based adhesive was prepared by using homemade aluminum phosphate as a matrix and by adding different fillers simultaneously. The effects of calcination temperature and filler composition on the bonding mechanism and high-temperature bonding strength of the adhesive for high-temperature alloys were studied. The results indicated that the crystalline transformation of AlPO₄ occurred at 500 °C. AlPO₄ has two crystalline forms at 500 °C: orthorhombic and hexagonal. The addition of CuO to the fillers resulted in the exchange of Fe and Cu at the substrate interface and enhanced the high-temperature bonding strength of the specimens. The maximum tensile strength of the specimens reached 3.9 MPa at 500 °C. These composites have potential applications in aviation, aerospace, and other fields.     

Kinetics of Hydrogen Absorption for Ti33V20Cr47 Alloy Powder

研究了温度、初始压力、粒度对Ti33V20Cr47合金吸氢动力学性能的影响.研究发现,合金的吸氢过程控速环节为三维扩散,表观活化能为25.7±0.8 kJ/mol.合金的反应速度随温度的升高而加快.由于Ti33V20Cr47合金有2个吸氢平台,在1.5 MPa和2.5 MPa压力下比在3.5 MPa压力下更先完成吸氢.合金反应速度随合金粒度的增大而加快.原因是合金吸氢过程为放热过程,粒度越大,吸氢产生的热量越不容易耗散,温度越高,导致吸氢越快.     

基于LMDI-Attribution的江苏省水足迹效率变化驱动力分析

在长江经济带各省市中,江苏省水足迹总量和人均量最大,缺水程度最严重,较低的水资源可持续发展能力制约了江苏省经济社会的发展。从水足迹视角,聚焦江苏省水足迹效率变化,分析水足迹效率变化的驱动因素和大小,为江苏省水资源可持续发展提出建议。基于2010—2019年江苏省水足迹计算结果,扩展Kaya恒等式构造出驱动水足迹效率变化的实际用水效率、水资源利用技术水平和水足迹结构3个因素,借助LMDI-Attribution模型计算各因素驱动力大小,并得到三大用水部门的具体贡献度。结果表明：研究期间江苏省水足迹效率增长幅度较大,从2010年的32.78元/m3增加到2019年的88.91元/m3,增幅为171.25%,其中实际用水效率为水足迹效率变化的最大驱动力,贡献了167%,其次为技术水平,贡献了26.15%;由于农业部门水足迹占比增大,水足迹结构对变化的影响为-21.67%;从用水部门来看,工业部门和生活部门的实际用水效率是最关键的驱动力,分别为91.19%和75.07%,农业部门仅为0.73%;技术水平驱动力中贡献最大的为生活部门的21.40%,其次为工业部门的4.79%,而农业部门为-0.04%;水足迹结构驱动力中仅农业部门是正向的,为0.06%,生活部门为-2.13%,工业部门为-19.60%。建议江苏省建立健全节水型农业体系,提高农业用水效率,降低农业部门水足迹所占比例,保持各用水部门灰水足迹的下降趋势,限制高污染企业的投资建设,支持绿色企业的发展;刺激省内消费需求,不断优化对外贸易结构,提升水资源可持续发展能力。