Preparation and hydrogen sorption properties of Mg-Cu-Y-H systems

Mg-xwt.%CuY (x=15, 20, 25) composites were successfully prepared by reactive mechanical alloying (RMA).X-ray diffraction (XRD) measurement shows that main phases of the as milled composites are MgH2 and Mg2Cu, and they converted into Mg and MgCu2 after dehydrogenation, respectively.Pressure-Composition-Isotherm (PCI) test shows that the composites exhibit double pressure plateau at each isothermal desorption process.The hydrogen absorption and desorption kinetics of the composites become worse with increasing x content, indicating that Mg-Cu phase has a negative effect on the hydrogen sorption properties of the composites.It is supposed that the good hydrogen sorption properties of the composites attribute to the catalyst effect of yttrium hydride distributed in Mg substrate and the particles size reduction and crystal defects formed by RMA.     

TRPM7-Mediated Calcium Transport in HAT-7 Ameloblasts

TRPM7 plays an important role in cellular Ca²⁺, Zn²⁺ and Mg²⁺ homeostasis. TRPM7 channels are abundantly expressed in ameloblasts and, in the absence of TRPM7, dental enamel is hypomineralized. The potential role of TRPM7 channels in Ca²⁺ transport during amelogenesis was investigated in the HAT-7 rat ameloblast cell line. The cells showed strong TRPM7 mRNA and protein expression. Characteristic TRPM7 transmembrane currents were observed, which increased in the absence of intracellular Mg²⁺ ([Mg²⁺]_i), were reduced by elevated [Mg²⁺]_i, and were inhibited by the TRPM7 inhibitors NS8593 and FTY720. Mibefradil evoked similar currents, which were suppressed by elevated [Mg²⁺]_i, reducing extracellular pH stimulated transmembrane currents, which were inhibited by FTY720. Naltriben and mibefradil both evoked Ca²⁺ influx, which was further enhanced by the acidic intracellular conditions. The SOCE inhibitor BTP2 blocked Ca²⁺ entry induced by naltriben but not by mibefradil. Thus, in HAT-7 cells, TRPM7 may serves both as a potential modulator of Orai-dependent Ca²⁺ uptake and as an independent Ca²⁺ entry pathway sensitive to pH. Therefore, TRPM7 may contribute directly to transepithelial Ca²⁺ transport in amelogenesis.     

青海镁产业专利导航发展分析

通过对盐湖提镁技术与镁合金等重点技术的专利分析,得到全球镁产业链不同环节的技术优势国家;从镁合金的专利权人排名来看,日本和韩国的企业展现出优势;基于专利权人的分析,挖掘中国镁技术领域的主要研究团队等重要情报信息;通过对中国及青海镁产业的专利布局分析,确定中国镁产业技术优势省、相关研发机构,总结青海省在镁产业领域的当前水平与可能的突破点,对镁产业关键技术进行导航探究,深度剖析镁产业研究价值与发展空间。同时对青海盐湖产业发展的优劣势条件进行分析,提出青海镁产业未来发展应该结合本地特色增加专利申请量,综合开发利用资源,提升关键技术,加强人才引进,促进产学研深度融合等发展建议。     

六水氯化镁在六种多元醇中溶解度的测定和关联

六水氯化镁的溶解度是镁盐综合利用的重要基础数据。采用静态平衡法测定了六水氯化镁在1,2-丙二醇、1,3-丙二醇、1,3-丁二醇、一缩二乙二醇、二缩三乙二醇、一缩二丙二醇6种多元醇中的溶解度（278.15~328.15 K）。实验结果表明,六水氯化镁在6种多元醇中的溶解度均随着温度的升高而增大,其中在一缩二乙二醇中的溶解度最大,在二缩三乙二醇中的溶解度随着温度的变化较其他多元醇变化更为明显。使用Apelblat方程、λh方程、Van′t Hoff方程和多项式方程对溶解度数据进行了关联,结果良好,其中Apelblat方程和多项式方程拟合结果优于其他方程。利用Van′t Hoff方程计算了6种体系的溶解焓、溶解熵和吉布斯自由能。这些结果对镁盐的分离提取及镁基功能材料的制备具有重要的参考价值。     

LaMgAl11O19-La2Ce2O7 复合陶瓷的高温相稳定性

La2Ce2O7(LC) 和 LaMgAl11O19(LMA) 是两种新型热障涂层材料。 LC 具有优良的热物理及抗腐蚀性能, 但 其断裂韧性差。 LMA 具有良好的综合性能, 特别是力学性能优良。 基于复合材料设计理念, 为充分利用 LC 和 LMA 的优势, 本文探究了制备 LMA-LC 双相复合陶瓷的可行性。 采用高温固相法合成了 LMA 和 LC 粉末, 重 点研究了 LMA 和 LC 的高温稳定性, 初步研究了 LMA-LC 复合陶瓷块材的力学性能。 结果表明： LMA 和 LC 在 高温下发生了化学反应, 反应程度随温度升高而加剧, 主要反应产物为 LaAlO3, 其在低温下的铁弹性可能是复 合陶瓷在室温下具有良好力学性能的原因。     

Mold-filling characteristics of AZ91 magnesium alloy in the low-pressure expendable pattern casting process

The magnesium (Mg) alloy low-pressure expendable pattern casting (EPC) process is a newly developed casting technique combining the advantages of both EPC and low-pressure casting. In this article, metal filling and the effect of the flow quantity of inert gas on the filling rate in the low-pressure EPC process are investigated. The results showed that the molten Mg alloy filled the mold cavity with a convex front laminar flow and the metal-filling rate increased significantly with increasing flow quantity when flow quantity was below a critical value. However, once the flow quantity exceeded a critical value, the filling rate increased slightly. The influence of the flow quantity of inert gas on melt-filling rate reveals that the mold fill is controlled by flow quantity for a lower filling rate, and, subsequently, controlled by the evaporation of polystyrene and the evaporation products for higher metal velocity. Meanwhile, the experimental results showed that the melt-filling rate significantly affected the flow profile, and the filling procedure for the Mg alloy in the low-pressure EPC process. A slower melt-filling rate could lead to misrun defects, whereas a higher filling rate results in folds, blisters, and porosity. The optimized filling rate with Mg alloy casting is 140 to 170 mm/s in low-pressure EPC.     

镁合金及其复合材料超塑性的研究现状

以等通道角挤压和粉末冶金等方法为例，讨论了镁合金晶粒细化的处理工艺。在室温下晶粒细化可使镁合金同时具有较高的强度和韧性，而在较高的应变速率或较低的温度下，晶粒细化的镁合金具有一定的超塑性，这说明晶粒细化对改善镁合金的力学性能十分重要。镁合金超塑性变形的主要机制仍然是晶界滑移，但晶界滑移总会在晶界三叉区或材料增强相与基体的相界处产生应力集中，使晶界滑移受到阻碍，这就需要有另外的协调机制来协调晶界进一步滑移。镁合金在超塑性变形过程中更容易发生动态再结晶使晶粒细化，使晶界滑移能够继续进行。镁基复合材料中增强体颗粒很细小且弥散分布，稳定了镁合金在高温下的组织，颗粒与晶粒界面可以充当原子扩散通道，很好地协调了晶界滑移。     

Flow stress and softening behavior of wrought magnesium alloy AZ31B at elevated temperature

1　INTRODUCTIONThewroughtmagnesiumalloyshaveexcellentspecificstrengthandstiffness ,machinability ,dampcapacity ,dimensionalstability ,lowmeltingcostsandare ,hence ,veryattractiveinsuchapplicationsasau tomobile ,aviation ,electronicandcommunicationin dustry[16 ] .Investigationsontheflowstressandsofteningbehaviorofmagnesiumalloysathigherformingtem peratureandstrainratehavebeenanimportantsub jectinwroughtmagnesiumalloysforming[710 ] .InthispapertheflowstressandsofteningbehaviorofAZ31Bdeform…     

镁合金激光焊接技术的研究现状与应用

镁在自然界中是大量存在的,我国的镁资源非常丰富,镁及其合金均具有许多优点,如重量轻、比强度和比刚度高、消震性能好、优良的机械加工性能和抛光性能、无毒性、无磁性、高热导率以及可回收利用等,已在汽车、精密仪器、电子、体育器械、核电、国防以及航空航天等许多领域得到了广泛的应用,具有广阔的应用前景.主要论述了镁合金激光焊接技术的现有水平与发展趋势以及镁合金激光焊接技术的应用领域及应用前景.