稀土钕对激光快速成形TC4合金组织及性能的影响

针对氢化脱氢钛合金粉末氧含量较高的问题，研究了添加稀土钕对激光快速成形TC4合金组织及性能的影响。结果发现，添加稀土Nd后，激光快速成形TC4合金的宏观晶粒尺寸变化不大；但随稀土添加量的增加，初始β列状晶逐渐转化为全β等轴晶，晶粒内部的魏氏α组织逐渐转变为网篮α，粗化α条不断增多，呈现团束聚集趋势，晶界α集束体积分数也不断增大；随稀土添加量的增加，激光快速成形TC4合金的室温塑性先大幅度提高，然后急剧降低；稀土添加量为0．1％～0．2％（质量分数，下同）时，氧含量为0．26％的氢化脱氢TC4合金粉末激光快速成形件沉积态的抗拉强度达975MPa，延伸率9．5％，满足锻件标准要求。     

固氟氯化铵焙烧法从包头稀土矿中回收稀土的动力学

研究了固氟氯化铵焙烧法分解包头混合型稀土精矿回收稀土的动力学.结果表明:固氟焙砂的氯化反应过程符合Bagdasarym提出的区域反应速率模型,氯化反应过程经过了两个串联反应步骤,且反应生成物的核按一个方向长大;反应速率方程遵从Erofeev方程的串联反应步骤模型,反应表观活化能Ea为36.831 KJ·mol-1,过程控制步骤是内扩散控制.     

二元稀土系AB5型贮氢电极合金的放电容量与晶胞体积和4f电子浓度的关系

制备了6个系列通式为AαA‘1-αB5的RE(NiCoMnTi)5贮氢电极合金(其中，AαA‘1-α为La，Ce，Pr，Nd4个元素中任意2个的组合)，测定了它们在100次循环中的最大放电容量Cmax及部分合金的晶胞体积Vcell．结果表明：Cmax主要由Vcell决定，Cmax先随Vcell的增大而增加，在Vcell≈85．66x10^-^3。nm^3时达到一极大值，然后又随Vcell的增大而减小；同时，Cmax还与4f电子浓度ne4f／naRE有关，A侧具有相同4f电子浓度的合金其Cmax随4f电子浓度的变化趋势相似．     

Mg-Al-Zn（RE）镁合金轧制变形行为及强化机制

针对典型的Mg-Al-Zn系AZ31变形镁合金以及添加了0．8％Ce和0．8％Nd的AZ31镁合金，研究了合金在轧制加工过程中组织与性能的变化以及稀土元素对合金的影响，并探讨了合金的主要强化机制。结果表明：Mg-Al-Zn系合金轧制加工过程中加丁硬化严重，容易发生脆性断裂。添加稀土元素后的合金强度和塑性都有明显提高，稀土元素可形成Al4ce等含稀土化合物，起到细晶强化和第二相强化作用。     

Reaction process of monazite and bastnaesite mixed rare earth minerals calcined by CaO-NaCl-CaCl2

The decomposition reactions of monazite and bastnaesite mixed rare earth minerals calcined by CaO-NaCl-CaCl2 were studied by means of TG-DTA and XRD. The results show that the process of the minerals decomposed by CaO involves two steps. The first step occurs in the temperature range of 425-540 ℃, and the main reactions are bastnaesite decomposition, i.e. REOF reacts with CaO to produce RE2O3 and CaF2, and Ce2O3 is oxidized to CeO2. During this step, CaCO3 is formed at about 500 ℃. The second step takes place in the temperature range of 610-700 ℃, and the reactions are monazite decomposition into RE2O3, Ca5F（PO4）3 and Ca3（PO4）2 by CaO and CaF2. In this process, the decomposition ability is improved because CaO from CaCO3 decomposing has high chemical activity. In calcining process, the new formed Ca5F（PO4）3 restrains fluorine that can escape in form of gaseous compound. The decomposition ratio of the mixed rare earth minerals reaches 90.8% at 700 ℃.     

Photocatalytic syngas synthesis from CO2 and H2O using ultrafine CeO2-decorated layered double hydroxide nanosheets under visible-light up to 600 nm

The rational design of photocatalyst that can effectively reduce CO₂ under visible light(l>400 nm),and simultaneously precise control of the products syngas(CO/H2)ratio is highly desirable for the Fischer-Tropsch reaction.In this work,we synthesized a series of CeO₂-decorated layered double hydroxides(LDHs,Ce-x)samples for photocatalytic CO₂ reduction.It was found that the selectivity and productivity of CO and H₂ from photoreduction of CO₂ in conjunction with Ru-complex as photosensitizer performed an obvious“volcano-like”trend,with the highest point at Ce-0.15 and the CO/H₂ ratio can be widely tunable from 1/7.7 to 1/1.3.Furthermore,compared with LDH,Ce-0.15 also drove photocatalytic CO₂ to syngas under 600 nm irradiation.It implied that an optimum amount of CeO₂ modifying LDH promoted the photoreduction of CO₂ to syngas.This report gives the way to fully utilize the rare earth elements and provides a promising route to enhance the photo-response ability and charge injection efficiency of LDH-based photocatalysts in the synthesis of syngas with a tunable ratio under visible light irradiation.     

Sulfuric acid recovery from rare earth sulphate solutions by diffusion dialysis

1 Introduction As an important industrial chemical, sulfuric acids are widely used in metallurgical and chemical processes, in which some waste solutions containing free sulfuric acids and metallic ions are therefore produced[1, 2]. If these waste acids …     

臭氧脱硝技术在稀贵多金属烟气治理中的应用

主要介绍在面临环境保护要求不断提升,废气排放指标不断降低的情况下,使用臭氧氧化+液碱脱硝技术对稀贵卡尔多炉和旋转顶吹炉生产回收金、银、硒、碲、铅、铋等金属产出的烟气的治理。治理后二氧化硫指标小于50mg/m3、氮氧化合物小于60mg/m3、尘指标小于10mg/m3,满足A类企业环保要求,同时其他重金属指标都满足国家国控指标要求,达到超低排放要求。     

Ce对440C不锈轴承钢夹杂物演变的影响

为探究稀土Ce对440C不锈轴承钢中夹杂物的改性作用,利用实验室MoSi₂电阻炉对440C不锈轴承钢进行稀土Ce处理,采用OM、SEM等系统分析了Ce的添加对440C不锈轴承钢脱氧及夹杂物演变的影响。结果表明,随着Ce加入量的增加,其收得率逐渐升高。Ce的加入使钢中TO质量分数由0.002 5%降低至0.001 2%。未加入Ce的钢中夹杂物主要为Al₂O₃、MnS以及镁铝尖晶石;加入质量分数为0.011 5%的Ce后,夹杂物被改性为以Ce-Al-O为主的夹杂物;当Ce的添加量达到0.036 4%时,夹杂物被完全改性为Ce-O-S夹杂物。适量的Ce可以降低夹杂物尺寸及面积比例,但过量加入会使夹杂物尺寸变大。在本试验条件下,当Ce质量分数为0.011 5%时,钢中夹杂物细小弥散效果最明显。以上结论可为Ce在高碳铬不锈轴承钢中的应用提供参考。