铈镍合金的“氢通道”和“氢溢出”效应协同改善氢化镁的储氢性能

氢化镁（MgH₂）因其储氢容量高(7.6wt%)、资源丰富、可逆性好等优势而在能源材料的开发方面得到了越来越多的关注。然而,MgH₂较强的金属–氢键导致其吸放氢反应动力学缓慢、热力学稳定性过高,难以获得广泛的实际应用。本文成功设计并合成了CeNi₅合金,有效改善了MgH₂的储氢性能。研究结果表明,氢化以及湿化学球磨处理后的CeNi₅ 合金呈现片层状结构,MgH₂–CeNi₅复合材料中CeNi₅含量的增加可以有效地降低MgH₂的起始放氢温度。 MgH₂–5wt%CeNi₅复合材料的初始放氢温度为174°C,比纯MgH₂的放氢温度降低了156°C。复合体系在275℃的温度下,10分钟内释放出约6.4wt%的H₂。此外,完全脱氢的样品在175℃的低温下吸收了4.8wt%的H₂,并且吸氢过程的表观活化能从(73.60 ± 1.79)下降到(46.12 ± 7.33) kJ/mol。微观结构分析表明,原位生成的Mg₂Ni/Mg₂NiH₄和CeH_2.73分别展现出“氢通道”和 “氢溢流”效应,从而有效增强了MgH₂–5wt%CeNi₅复合材料的储氢性能。     

B4C-TiB2-SiC复合陶瓷的SPS制备及组织性能研究

针对B₄C陶瓷烧结性能较差、成本较高的技术问题,提出了一种新型的B₄C基复合陶瓷的制备方法. 该方法以B₄C、Ti₃SiC₂及Si的混合粉作为初始粉体,通过放电等离子烧结技术（SPS）制备第二相（TiB₂+SiC）质量分数为30%的B₄C-TiB₂-SiC复合陶瓷,利用SPS特殊的烧结机制以及烧结过程中的原位放热反应,有效提升了B₄C陶瓷的烧结性能,降低了B₄C陶瓷的制造成本. 研究结果表明,在烧结温度为1650 °C,保温时间为5 min,烧结压力为50 MPa的条件下,制备得到了具有较高致密度（98.5%）的B₄C-TiB₂-SiC复合陶瓷. 随着烧结压力的增加,B₄C-TiB₂-SiC复合陶瓷的硬度逐渐增大,断裂韧性不断减小,而复合陶瓷的弯曲强度则呈现出先缓慢增加后迅速增大的变化趋势.      

改质钢渣中铁/磷富集相形核与长大行为研究

回收钢渣中的铁（Fe）和磷（P）,不仅可以减轻钢渣堆积带来的环境负担,而且是钢铁工业发展循环经济、实现可持续发展的必由之路。本文旨在通过研究B₂O₃改质钢渣中富铁相（Fe₃O₄）和富磷相（Ca₁₀P₆O₂₅）的结晶动力学规律确定Fe₃O₄与Ca₁₀P₆O₂₅晶体可控生长的温度制度。本研究采用高温激光共聚焦扫描显微镜（CLSM）在线观测CaO–SiO₂–FeO–P₂O₅–B₂O₃熔体的结晶行为,使用经典的结晶动力学理论计算Fe₃O₄与Ca₁₀P₆O₂₅晶体的形核和长大速率。研究结果表明,CaO–SiO₂–FeO–P₂O₅–B₂O₃熔体在冷却过程中初晶相Fe₃O₄析出温度范围为1300–1150°C,棒状的第二相Ca₁₀P₆O₂₅在1150–1000°C温度区间内析出,且Fe₃O₄相的结晶能力大于Ca₁₀P₆O₂₅相。综合考虑Fe₃O₄相与Ca₁₀P₆O₂₅相的形核与长大速率,最终确定两相选择性结晶长大的最佳温度区间为(1055 ± 25)°C,即在1080–1030°C温度范围内对CaO–SiO₂–FeO–P₂O₅–B₂O₃熔体进行缓慢冷却有利于Fe₃O₄与Ca₁₀P₆O₂₅晶体的结晶长大,从而为后续从渣中选择性分离Fe₃O₄相与Ca₁₀P₆O₂₅相创造了必要条件。     

高钙赤铁矿烧结的矿物特性、冶金性能及相结构演变

为了研究高钙赤铁矿的烧结特性，采用了化学分析、激光衍射、扫描电镜、X射线衍射和微型烧结等方法和手段分析了其矿物学特性，并设计烧结杯试验探究其与国产磁铁精粉的混合烧结行为，最后采用灰色关联数学模型计算和比较了不同高钙赤铁矿含量下的综合烧结性能。结果表明，高钙赤铁矿粒度较粗，所含Ca元素以方解石（CaCO₃）的形式存在，具有较强的自熔特性且自熔产生的液相结晶形态较好。在烧结过程中添加20wt%的含量后，能够提高利用系数、减少固体燃料消耗、提高烧结矿还原性指数和改善高炉的透气性指数的幅度分别为0.45 t/(m2·h)、6.11 kg/t、6.17%和65.39 kPa·°C。与全磁铁精粉烧结过程相比，高钙赤铁矿烧结还可以提高烧结烟气的热值，有利于烟气回收热量并进行二次利用。随着高钙赤铁矿含量的增加，烧结混合料在成矿过程中的聚合方式由以液相粘结为主转变为局部液相粘结伴随着铁氧化物连晶的共同作用。根据灰色关系模型的计算，在0–20wt%的配比范围内，高钙赤铁矿含量增加对烧结经济技术指标与烧结矿冶金性能综合表现的提升是有利的。     

高炉炼铁工艺中超高TiO2炉渣:密度和表面张力

针对高炉冶炼超高（>80%）甚至全钒钛磁铁矿工艺流程，为了优化高炉造渣制度，进行了一系列关于高钛型炉渣（BFS）物理化学性质方面的研究。本工作分别利用阿基米德原理和最大气泡压力法研究了高钛型炉渣的密度和表面张力。系统探究了TiO₂含量和MgO/CaO质量比对CaO–SiO₂–TiO₂–MgO–Al₂O₃炉渣密度和表面张力的影响规律。结果发现，随着TiO₂含量从20wt%增加到30wt%，炉渣密度逐渐降低，但随着MgO/CaO质量比从0.32增加到0.73，熔渣密度略有增加。从硅酸盐网络结构角度来看，炉渣密度与结构聚合度（DOP）具有一致的变化规律。TiO₂的加入会降低炉渣体系中(Q3)2/(Q2)比值（其中，Q2和Q3分别代表桥氧数为2和3的网络结构单元），进而降低炉渣结构聚合度，导致炉渣密度降低。随着TiO₂含量从20wt%增加到30wt%，CaO–SiO₂–TiO₂–MgO–Al₂O₃炉渣的表面张力显著降低。相反，随着MgO/CaO质量比从0.32增加到0.73，表面张力增加。此外，利用基于Butler公式的Tanaka模型获得了1723 K下含钛炉渣等表面张力图，为高炉冶炼超高比例（>80%）甚至全钒钛磁铁矿工艺中造渣制度的优化提供了数据支撑。     

不同温度下CeO2预煅烧对甲醇氧化反应中Pt/CeO2–C电催化剂性能的影响

Pt/CeO₂–C catalysts with CeO₂ pre-calcined at 300–600°C were synthesized by combining hydrothermal calcination and wet impregnation. The effects of the pre-calcined CeO₂ on the performance of Pt/CeO₂–C catalysts in methanol oxidation were investigated. The Pt/CeO₂–C catalysts with pre-calcined CeO₂ at 300–600°C showed an average particle size of 2.6–2.9 nm and exhibited better methanol electro-oxidation catalytic activity than the commercial Pt/C catalyst. In specific, the Pt/CeO₂–C catalysts with pre-calcined CeO₂ at 400°C displayed the highest electrochemical surface area value of 68.14 m2·g?1 and I_f/I_b ratio (the ratio of the forward scanning peak current density (I_f) and the backward scanning peak current density (I_b)) of 1.26, which are considerably larger than those (53.23 m2·g?1 and 0.79, respectively) of the commercial Pt/C catalyst, implying greatly enhanced CO tolerance.     

粉煤灰基多孔陶瓷膜的制备工艺研究

为了研究多孔陶瓷膜样品的主要实验影响因素,通过单因素试验法探究不同工艺条件对制备多孔陶瓷膜样品性能的影响,并作正交优化试验。以粉煤灰为主原料,经过研磨过筛处理后,添加少量Al_2O_3、造孔剂和TiO_2,均匀混合,模压成型,高温烧结后制得多孔陶瓷膜。在优化试验配方和工艺参数后,当粉煤灰80wt%、Al_2O_38wt%、淀粉10wt%、TiO_22wt%、模压强度为18MPa、烧成温度为1200℃、保温时间为0. 5 h时,烧结得到膜样品的平均孔径为2μm、孔隙率为41. 3%、抗折强度为8. 96 MPa、水通量为1201 L/(m2·h·MPa)、耐酸度为96.5%、耐碱度为95.1%、体积密度为1. 69 g/m L。探究结果表明,烧成温度和造孔剂含量对膜样品性能的影响较大。     

高硼多组分铸铁的组织及相元素分布

这种新提出的新型铸铁的化学成分为在0.7C–5W–5Mo–5V–10Cr–2.5Ti (wt%)中分别添加1.6wt% B和2.7wt% B。这项工作的目的是研究硼的含量对合金的结构状态和阶段元素分布对耐磨结构成分的形成影响。结果表明,当B含量为1.6wt%时,合金由三种共晶组成:(a) “M₂(C,B)₅+铁素体”具有“汉字”形貌 (89.8vol%), (b) “M₇(CB)₃+奥氏体”具有“莲座”形貌,(c) “M₃C+奥氏体”具有“莱氏体”形貌 (2.7vol%)。当硼含量为2.7wt%时,基体硬度由HRC 31提高到HRC 38.5。组织中出现了平均显微硬度为HV 2797的初生碳化物M₂(C,B)₅,体积分数为17.6vol%。共晶体(a)和(b,c)的体积分数分别降低到71.2vol%和3.9vol%。基体为“铁素体/奥氏体” (1.6wt% B) 和“铁素体/珠光体”(2.7wt% B),两种铸铁均含有致密析出碳化物(Ti,M)C和碳硼化物(Ti,M)(C,В),体积分数为7.3%–7.5%。基于能量色散X射线能谱,给出了元素相的分布和相应的相公式。     

不同结构和形态的天然镁硅酸盐:与K反应制备生物柴油的K2MgSiO4催化剂

In this work, different magnesium silicate mineral samples based on antigorite, lizardite, chrysotile (which have the same general formula Mg₃Si₂O₅(OH)₄), and talc (Mg₃Si₄O₁₀(OH)₂) were reacted with KOH to prepare catalysts for biodiesel production. Simple impregnation with 20wt% K and treatment at 700–900°C led to a solid-state reaction to mainly form the K₂MgSiO₄ phase in all samples. These results indicate that the K ion can diffuse into the different Mg silicate structures and textures, likely through intercalation in the interlayer space of the different mineral samples followed by dehydroxylation and K₂MgSiO₄ formation. All the materials showed catalytic activity for the transesterification of soybean oil (1:6 of oil : methanol molar ratio, 5wt% of catalyst, 60°C). However, the best results were obtained for the antigorite and chrysotile precursors, which are discussed in terms of mineral structure and the more efficient formation of the active phase K₂MgSiO₄.     

YSZ含量对多孔氧化铝支撑体断裂韧性的影响

针对陶瓷膜支撑体材料的脆性问题,研究添加适量氧化锆粉体来改善多孔氧化铝陶瓷支撑体的断裂韧性。采用干压成型法,分别在1400°C、1450°C、1500°C、1550°C、1600°C烧后得到相应的支撑体,考察各支撑体的断裂韧性,以及各支撑体的孔隙率和抗折强度随氧化锆添加量的变化规律,采用XRD(X-raydiffraction)物相分析手段对氧化锆增韧多孔氧化铝陶瓷的增韧机理进行了探讨。研究结果表明:1600°C热处理后,当YSZ含量为6wt%时,支撑体的抗折强度和断裂韧性值最大,分别为137MPa和2.5MPa.m1/2,其中,t-ZrO2转变为m-ZrO2是支撑体断裂韧性提高的根本原因。     

烧结温度对Ba0.96Ca0.04Ti2O5陶瓷的物相结构与电学性能影响探究

在改性Pechini法制备Ba_0.96Ca_0.04Ti₂O₅(BCT2)粉体的基础上,采用常压固相烧结工艺制备了BCT2陶瓷,详细探究了在不同烧结温度(1050～1250℃)下对BCT2陶瓷物相结构与性能的影响规律。采用X射线衍射仪、冷场发射扫描电子显微镜、电子比重天平和精密阻抗分析仪,分别测试了BCT2陶瓷的物相结构、断面形貌、致密化程度和电学性能。结果表明,随着烧结温度一定程度的升高,BCT2陶瓷的结晶度提升、致密化程度增加、介电性能和铁电性增强。最佳烧结温度(1200℃)下BCT2陶瓷的性能为ρ_r=96.64%、T_C=444.9℃、ε_m=619.3和γ=0.429。     

Desulfurization ability of refining slag with medium basicity

The desulfurization ability of refining slag with relative lower basicity (B) and Al₂O₃ content (B = 3.5–5.0; 20wt%–25wt% Al₂O₃) was studied. Firstly, the component activities and sulfide capacity (C_S) of the slag were calculated. Then slag-metal equilibrium experiments were carried out to measure the equilibrium sulfur distribution (L_S). Based on the laboratorial experiments, slag composition was optimized for a better desulfurization ability, which was verified by industrial trials in a steel plant. The obtained results indicated that an MgO-saturated CaO-Al₂O₃-SiO₂-MgO system with the basicity of about 3.5–5.0 and the Al₂O₃ content in the range of 20wt%–25wt% has high activity of CaO (a_CaO), with no deterioration of C_S compared with conventional desulfurization slag. The measured L_S between high-strength low-alloyed (HSLA) steel and slag with a basicity of about 3.5 and an Al₂O₃ content of about 20wt% and between HSLA steel and slag with a basicity of about 5.0 and an Al₂O₃ content of about 25wt% is 350 and 275, respectively. The new slag with a basicity of about 3.5–5.0 and an Al₂O₃ content of about 20wt% has strong desulfurization ability. In particular, the key for high-efficiency desulfurization is to keep oxygen potential in the reaction system as low as possible, which was also verified by industrial trials.     

钛磁铁矿和钛铁矿冶炼渣的相平衡研究

高炉冶炼含钛铁矿时,因强还原条件和高温会形成高熔点Ti(C,N),导致炉渣和铁水粘度增加,使高炉操作难以顺利进行。必须掺杂高品位铁矿稀释原料中的氧化钛,使高炉渣所含的20wt%~30 wt% TiO₂难以回收,造成资源浪费。HIsmelt是近年来开发的绿色炼铁新工艺,不需要焦炭和烧结矿。HIsmelt工艺中炉内的氧分压高于高炉中的分压,温度显著低于高炉风口,因此避免了Ti(C,N)的形成。HIsmelt炉的水冷内壁会造成大量热损失,增加能耗,而且有炉衬烧穿的潜在风险。在HIsmelt工艺中以CaO为助剂熔炼富含TiO₂的铁矿会产生Al₂O₃–MgO–SiO₂–CaO–TiO₂渣。利用高温平衡、冷淬和电子探针显微分析技术研究了该渣系的相平衡,探讨了处理钛磁铁矿以及钛磁铁矿和钛铁矿混合矿的过程中渣液相温度与助剂添加量的关系。在所研究的组成范围内观察到的初晶相有板钛矿M₃O₅（MgO·2TiO₂–Al₂O₃·TiO₂）、尖晶石（MgO·Al₂O₃）、钙钛矿CaTiO₃和金红石TiO₂。结果表明,在TiO₂和M₃O₅相区中,渣液相温度随着CaO含量的增加而降低,而在尖晶石和CaTiO₃初晶相区的液相温度则随CaO含量的增加而升高。通过控制渣液相温度可以在炉子内壁上形成保护渣层,减少热损失,降低内衬耐火材料消耗。此外,讨论了炉渣碱度对炉渣液相线温度的影响,发现冶炼钛磁铁矿和钛铁矿的混合矿可以获得低硫铁水和高TiO₂炉渣,具有显著的成本和资源优势。最后,将实验测定的液相温度和固溶体成分与FactSage计算结果进行了比较,指出目前含钛热力学数据库的局限性和改进方向。     

无机填料对聚氨酯仿瓷砖性能的影响

以聚氨酯为胶料、粉煤灰和CaCO₃为填料制备了仿瓷砖，进行力学性能测试和SEM扫描分析。结果表明，填料的添加量为72~78%、压制强度为21~109 MPa时，添加粉煤灰和CaCO₃的仿瓷砖的最大破坏强度为3 300 N和2 300 N，最大断裂指数为50 MPa和35 MPa，最小耐磨损体积分别为289 mm³和445 mm³，最小吸水率为0.95%和0.85%。粉煤灰的综合增强作用好于CaCO₃。     

基于低镁烧结矿和熔剂性球团的综合炉料熔滴性能研究

A low MgO content in sinter is conducive to reduce the MgO content in blast furnace slag. This study investigated the effect of MgO content in sinter on the softening–melting behavior of the mixed burden based on fluxed pellets. When the MgO content increased from 1.31wt% to 1.55wt%, the melting temperature of sinter increased to 1521°C. Such an increase was due to the formation of the high-melting-point slag phase. The reduction degradation index of sinter with 1.31wt% MgO content was better than that of others. The initial softening temperature of the mixed burden increased from 1104 to 1126°C as MgO content in sinter increased from 1.31wt% to 1.55wt%, and the melting temperature decreased from 1494 to 1460°C. The permeability index (S-value) of mixed burden decreased to 594.46 kPa·°C under a high MgO content with 1.55wt%, indicating that the permeability was improved. The slag phase composition of burden was mainly akermarite (Ca₂MgSiO₇) when the MgO content in sinter was 1.55wt%. The melting point of akermarite is 1450°C, which is lower than other phases.     

烧结温度和钙含量对CaNdTiNbO7型陶瓷固化体晶相结构的影响

萤石及其衍生结构陶瓷是高放废物固化的潜在基体材料,针对烧绿石型高放废物固化体CaNdTiNbO₇存在缺陷萤石相和钙钛矿杂相问题,设计了一系列温度与Ca含量效应实验,通过传统高温固相法在1 000～1 600℃下合成CaNdTiNbO₇固化体样品,并在1 400℃合成Ca_0.99NdTiNbO_6.99和Ca_0.9NdTiNbO_6.9陶瓷,通过XRD和SEM-EDS研究烧结温度与钙含量对合成CaNdTiNbO₇型纯相烧绿石固化体的影响。结果表明：随着烧结温度增加,固化体次生萤石相发生227型缺陷萤石向215型缺陷萤石相再到烧绿石结构的转变,在1 500℃以上合成近似单相的烧绿石样品,而不能去除钙钛矿杂相。降低Ca的含量可以实现钙钛矿杂相的去除,但会生成227型缺陷萤石而非215型缺陷萤石相。CaNdTiNbO₇型烧绿石固化体合成温度应不低于1 500℃且应适当减少钙元素的含量。     

Corrosion behavior of as-cast Mg–8Li–3Al+xCe alloy in 3.5wt% NaCl solution

Mg–8Li–3Al+xCe alloys (x = 0.5wt%, 1.0wt%, and 1.5wt%) were prepared through a casting route in an electric resistance furnace under a controlled atmosphere. The cast alloys were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The corrosion behavior of the as-cast Mg–8Li–3Al+xCe alloys were studied under salt spray tests in 3.5wt% NaCl solution at 35°C, in accordance with standard ASTM B–117, in conjunction with potentiodynamic polarization (PDP) tests. The results show that the addition of Ce to Mg–8Li–3Al (LA83) alloy results in the formation of Al₂Ce intermetallic phase, refines both the α-Mg phase and the Mg₁₇Al₁₂ intermetallic phase, and then increases the microhardness of the alloys. The results of PDP and salt spray tests reveal that an increase in Ce content to 1.5wt% decreases the corrosion rate. The best corrosion resistance is observed for the LA83 alloy sample with 1.0wt% Ce.     

全水解制氢用自支撑多孔NixFe–S/NiFe2O4异质结构双功能电催化剂

稳定的非贵金属双功能电催化剂是可再生能源驱动的波动全水电解面临的难题之一。本文在三维碳纤维布上电沉积制备了多孔Ni–Fe金属阵列,并在此基础上进行原位氧化和化学硫化,构建了一种新型的自支撑分级多孔Ni_xFe–S/NiFe₂O₄异质结构双功能电催化剂。研究结果表明,Ni_xFe–S/NiFe₂O₄异质结构催化剂对析氢反应(HER)和析氧反应(OER)都表现出良好的催化活性和稳定性,优异的催化性质与其大比表面积提供丰富的活性位点、异质结构的协同效应、超亲水表面和稳定的自支撑结构密不可分。分析结果证析氧过程异质结构中的Ni_xFe–S转化为金属氧化物/氢氧化物和Ni₃S₂。与商用20wt% Pt/C||IrO₂-Ta₂O₅相比,自支撑Ni_1/5Fe–S/NiFe₂O₄||Ni_1/2Fe–S/NiFe₂O₄在10-500mA/cm2的波动电流密度范围内表现出更好的稳定性和更低的槽电压。在500 mA/cm2的工业电流密度下,Ni_1/5Fe–S/NiFe₂O₄||Ni_1/2Fe–S/NiFe₂O₄的槽电压仅为约3.91 V,比Pt/C||IrO₂–Ta₂O₅ (约4.79 V)降低了约20%。     

Fabrication of Fe–TiC–Al2O3 composites on the surface of steel using a TiO2–Al–C–Fe combustion reaction induced by gas tungsten arc cladding

The aim of the present study was to fabricate Fe–TiC–Al₂O₃ composites on the surface of medium carbon steel. For this purpose, TiO₂–3C and 3TiO₂–4Al–3C–xFe (0 ≤ x ≤ 4.6 by mole) mixtures were pre-placed on the surface of a medium carbon steel plate. The mixtures and substrate were then melted using a gas tungsten arc cladding process. The results show that the martensite forms in the layer produced by the TiO₂–3C mixture. However, ferrite–Fe₃C–TiC phases are the main phases in the microstructure of the clad layer produced by the 3TiO₂–4Al–3C mixture. The addition of Fe to the TiO₂–4Al–3C reactants with the content from 0 to 20wt% increases the volume fraction of particles, and a composite containing approximately 9vol% TiC and Al₂O₃ particles forms. This composite substantially improves the substrate hardness. The mechanism by which Fe particles enhance the TiC + Al₂O₃ volume fraction in the composite is determined.     

Mineral transition and formation mechanism of calcium aluminate compounds in CaO?Al2O3?Na2O system during high-temperature sintering

The mineral transition and formation mechanism of calcium aluminate compounds in CaO?Al₂O₃?Na₂O system during the high-temperature sintering process were systematically investigated using DSC?TG, XRD, SEM?EDS, FTIR, and Raman spectra, and the crystal structure of Na₄Ca₃(AlO₂)₁₀ was also simulated by Material Studio software. The results indicated that the minerals formed during the sintering process included Na₄Ca₃(AlO₂)₁₀, CaO·Al₂O₃, and 12CaO·7Al₂O₃, and the content of Na₄Ca₃(AlO₂)₁₀ could reach 92wt% when sintered at 1200°C for 30 min. The main formation stage of Na₄Ca₃(AlO₂)₁₀ occurred at temperatures from 970 to 1100°C, and the content could reach 82wt% when the reaction temperature increased to 1100°C. The crystal system of Na₄Ca₃(AlO₂)₁₀ was tetragonal, and the cells preferred to grow along crystal planes (110) and (210). The formation of Na₄Ca₃(AlO₂)₁₀ was an exothermic reaction that followed a secondary reaction model, and its activation energy was 223.97 kJ/mol.