磷酸镁水泥固化铜污染土的工程特性

为研究不同水泥固化重金属污染土的处理效果和工程特性,取掺重金属铜的高岭土作为研究对象,考虑磷酸镁水泥(magnesium phosphate cement,MPC)掺量、养护龄期、初始铜离子浓度三种因素,研究了MPC固化后重金属铜污染土的固化效果及特性.基于无侧限抗压强度试验和扫描电镜试验,分析了三种因素对固化铜污染土...     

High-strength wrought magnesium alloy with dense nano-scale spherical precipitate

This paper reported the influences of Yb addition on the precipitate and mechanical properties of wrought magnesium alloy ZK60. The ingots of ZK60-1.78Yb (wt%, 0.26 at%) alloys were cast using permanent mould and extruded at 370℃ . By means of TEM and HRTEM, it was observed that Yb affected the precipitate and precipitation of ZK60-1.78Yb alloys significantly. Dynamic precipitation occurred in the as-extruded alloy and spherical nano-scale precipitate with high density and homoge-neity exhibited in the aged alloys. The precipitate particles were about 5-20 nm in diameter, 10-30 nm in average space length. The tensile test results showed that the ZK60-1.78Yb alloy had excellent pre-cipitation strengthening response with the maximum tensile strength 417.5 MPa at ambient tempera-ture.     

稀土烯丙基化合物的研究（Ⅺ）──钆、镝、钬、铒和镱的镁烯丙基四甲基乙二胺配合物的合成

低温时，以四甲基乙二胺（ｔｍｅｄ）作稳定剂，用无水稀土氯化物与烯丙基氯化镁在四氢呋喃中反应，合成了对空气和湿气相当敏感的稀土镁烯丙基四甲基乙二胺配合物（Ｃ３Ｈ５）２ＬｎＣｌ５Ｍｇ２（ｔｍｅｄ）２（Ｌｎ＝Ｇｄ，Ｄｙ，Ｈｏ，Ｅｒ，Ｙｂ）配合物的组成经元素分析、红外光谱、质谱等鉴定以及摩尔电导的测定．还进行了配合物与二氧化碳或含活泼氢的化合物的反应．     

亚微米氮化钛粉末燃烧合成研究的理论分析

对氮化钛粉末的自蔓延高温还原合成过程进行了理论分析，热力学计算表明，反应最合适的温度范围为１４００～２０００Ｋ，这一温度可借ＭｇＯ稀释剂进行调节，使之达到抑制氮化镁副产物的形成和防止产物出现液相烧结的作用，从而获得粒径细小均匀的氮化钛合成粉末。动力学分析指出，在反应物中添加少量含氮化合物可以有效降低高氮压的临界条件。     

特殊液相沉淀法制备镁的钛酸盐

采用特殊液相沉淀法制备了镁的钛酸盐。经TEM和XRD表征,镁的钛酸盐前驱体,粒径为3-4nm,经焙烧至1200℃时,有MgTiO3,MgTi2O5,Mg2TiO4出现,此时这混品的粒径为500nm左右,MgTiO3为主晶相;对不同温度段粒子的相结构进行XRD表征,探讨了生成MgTiO3和Mg2TiO4的条件和历程。     

碳化法从菱镁矿中提取高纯氧化镁的研究

采用碳化法,对低品位菱镁矿进行磨矿、浸出,可获得MgO含量大于99%的高纯(4MgCO3·Mg(OH)24H2O)产品,MgO回收率大于85%。其最佳工艺条件如下:煅烧时间为60min,煅烧温度为800℃,磨矿时间为3min,浸出温度为22℃,浸出压强为3kPa,搅拌排气量为0.6m3/h,液固比为50∶1。     

锰矿石氧化-磷酸铵镁沉淀-A/O联合处理焦化废水

以锰矿石氧化-磷酸铵镁沉淀-A/O组合工艺联合处理焦化废水.利用锰矿石氧化去除水中挥发酚等有机物,进水p H=2.0,水力停留时间22 min,挥发酚去除率达98.8%,COD去除率64.8%.出水经磷酸铵镁(MAP)沉淀处理,去除和回收大部分氨氮,在最佳p H=10.5时氨氮去除率达81.4%.以A/O工艺生物处理,混合液回流比200%,COD和氨氮去除率为93.8%和97.3%.焦化废水经组合处理后,挥发酚、COD和氨氮去除率分别达98.8%、97.8%、99.6%.     

Solidification,microstructure, and mechanical properties of the as-cast ZRE1 magnesium alloy with different praseodymium contents

The influence of praseodymium (Pr) content on the solidification characteristics, microstructure, and mechanical properties of ZRE1 magnesium (Mg) cast alloy was investigated. The obtained solidification parameters showed that Pr strongly affected the solidification time, leading to refinement of the microstructure of the alloys. When the freezing time was reduced to approximately 52 s, the grain size decreased by 12%. Mg₁₂Zn (Ce,Pr) was formed as a new phase upon the addition of Pr and was detected via X-ray diffraction analysis. The addition of Pr led to a substantial improvement in mechanical properties, which was attributed to the formation of intermetallic compounds; the ultimate tensile strength and yield strength increased by approximately 10% and 13%, respectively. Pr addition also refined the microstructure, and the hardness was recovered. The results herein demonstrate that the mechanical properties of Mg alloys are strongly influenced by their microstructure characteristics, including the grain size, volume fraction, and distribution of intermetallic phases.     

镁质碱式盐对污泥力学性能的影响

采用一种镁质碱式盐(MOC)进行了改善浓缩污泥力学性能的实验研究.结果表明,在MOC和污泥的质量比为5/100～20/100,MgO和MgCl2质量比为3/1～5/1时,可以使污泥无侧限抗压强度提高到85.14kg.cm-1,50kPa下的污泥渗透性能可达到2.17×10-3cm.s-1;塑性指数(IP)最低可降到7.9.同时污泥的粒径呈线性增加,当污泥粒径在45～72μm之间时,污泥比阻的下降较明显.采用X射线衍射(XRD)和扫描电镜(SEM)进行微观分析,发现MOC在污泥中发生胶凝水化反应.在Mg2+和OH-激发下,MOC与污泥中的Si2+,Al3+,Cu2+形成了Mg-Si-Al凝胶体系,并以晶体结构的形式存在,对污泥的稳定化起到了积极的作用.     

CO2盐水层埋存条件下Mg^2+对油井水泥石腐蚀的影响

为探索CO2盐水层埋存条件下Mg^2+对油井水泥石腐蚀的影响,采用X射线衍射(XRD)、热重分析(TGA)和背散射电子像(SEM-BSE)等分析方法对腐蚀后的水泥石进行分析。结果表明:Mg^2+会减小CO2对水泥石的腐蚀速率;Mg^2+存在的情况下,水泥石表层生成的菱镁矿会一定程度上减缓碳酸钙的溶解,水泥石表面淋滤作用并不明显,内部生成的水镁石、菱镁矿和膨胀性矿物碳酸钙造成水泥石内应力增大而产生多条裂隙;Mg^2+存在的情况下,水泥石表层生成的菱镁矿及其内部生成的水镁石均会阻碍水泥石与外部腐蚀离子的反应,Mg^2+对CO2腐蚀水泥石的过程具有“减缓效应”。