Sol-Gel Synthesis of LaMO3 (M = Cr, Mn, Fe, Co, Ni) Nanocrystalline Powders

Sol-gel synthesis of LaMO3 ( M = Cr, Mn, Fe, Co, Ni) nanocrystalline Powders was investigated. DSC measurement shows that precursors decomposed at about 403 K and 620 K to bum out of N, C, and H. The calcined samples at 1073 K were determined by XRD to be single phase. SEM observation shows that the prepared samples are nanocrystalline powders in broad sense. The average grain size of LaM'O3 (M'= Cr, Mn, Fe, Ni) is 150 ～700 nm,and the grain size of LaCoO3 is about 30 nm.     

Structure formation in binary Al-TM (TM = Mn,Co, Ni,Cu) melts

The structures of binary Al-TM (transition metal TM = Mn, Co, Ni, Cu) melts at near-liquidus temperatures are studied by X-ray diffraction and simulation using the reverse Monte Carlo method. The melts are found to have chemical local atomic ordering, and this ordering depends on the nature and content of TM. Chemical local atomic ordering leads to a medium-range order as a result of TM atom localization at distances of 0.4–0.5 nm in the composition of polytetrahedral clusters having icosahedral symmetry. A medium-range order in the melts is identified due to the presence of an additional maximum (prepeak) in the left slope of the first peak in experimental structure factor curves. The local atomic orders in the melts and the corresponding crystalline and quasicrystalline phases are found to correlate with each other.     

A correlation between stability of compounds and structure of hydrogen-induced amorphous alloys in GdM2 (M = Fe,Co, Ni)

Enthalpy changes ΔH for hydrogen absorption and desorption, hydrogen-induced amorphization (HIA) in C15 Laves phases c-GdM₂ (M = Fe, Co, Ni) and crystallization of the resultant amorphous alloys a-GdM₂H_x have been measured by differential scanning calorimetry (DSC). Furthermore, structures of a-GdM₂H_x have been investigated by X-ray diffractometry (XRD) to correlate their structures with the stabilities of the original compounds. Both a-GdFe₂H_3.0 and a-GdCo₂H_3.4 prepared from the less stable compounds show the strong tendency for the same kinds of metal atoms to cluster and crystallize to GdH₂ and Fe(Co). Correspondingly, the sum of ΔH for all reactions become equal to that for the formation of GdH₂. On the contrary, a-GdNi₂H_3.5 prepared from the stable compound shows a rather homogeneous structure and crystallizes to GdH₂ and GdH₂ and GdNi₅. As a result, the sum of ΔH shows a large negative value in comparison with that for the formation of GdH₂.     

湿法冶金(包括Zn、Mn、Cu、Ni、Co等)除铁的几种主要方法

论述了湿法冶金除铁的几种主要方法,包括中和水解法、黄钾铁矶法与针铁矿法除铁的化学反应、热力学分析及技术条件等.     

Thermodynamics of oxygen solutions in liquid Ni,Co, Fe,and Mn metals

Pure gaseous oxygen at a pressure $p_{O_2 }^{1/2} = 1$ is taken as the standard state of oxygen dissolved in a liquid metal. In the case of such a standard state of oxygen, its activity is equal to the equilibrium oxygen partial pressure in the vapor, which is risen to a power of 1/2. This allowed us, using two thermodynamic functions, i.e., the standard Gibbs energy for the oxidation reaction of liquid metal with oxygen to form a lower oxide and the experimentally determined oxygen solubility in a liquid metal, to obtain equations for the energies of mixing of each metal with oxygen and to calculate them, to find linear temperature dependences of the energies of mixing, and to describe oxygen solutions in liquid metals by pseudoregular-solution model equations. Linear dependences of the solubility functions on the standard Gibbs energies for oxidation reactions of liquid metals are found. The aim of the study is to suggest the energies of mixing of four metals (Ni, Co, Fe, and Mn) with oxygen and their temperature dependences for the calculations of the activity coefficients and the activity of oxygen in the solutions of these liquid metals by the pseudoregular-solution model equations.     

WC-8(Fe, Co, Ni)RE合金性能研究

用不同比例的Fe和Ni部分代替WC-8Co合金中的粘结剂Co，再添加微量的碳粉和稀土氧化物Y2O3制得WC-8(Fe，Co，Ni)RE硬质合金，测试了其物理机械性能，研究了粘结剂各种成分及烧结温度、烧结气氛对硬质合金性能的影响。在一定的烧结工艺下，以Fe和Ni部分代替Co所制得的WC-8(Fe，Co，Ni)RE硬质合金，其性能可以达到甚至超过YG8的标准，同时对影响WC-8(Fe，Co，Ni)RE硬质合金性能的一些因素进行了讨论。     

Effect of water vapor on the CO and CH4 catalytic oxidation over CeO2-Mox (M=Cu,Mn,Fe,Co,and Ni) mixed oxide

CeO2-MOx (M=Cu, Mn, Fe, Co, and Ni) mixed oxide catalysts were prepared by a citric acid complexation-combustion method. CeO2-MOx solid solutions could be formed with M cations doping into CeO2 lattice, while NiO and Co3O4 phases were detected on the surface of CeO2-NiO and CeO2-Co3O4 by Raman spectroscopy. The presence of M in CeO2 could obviously promote its catalytic activity for CH4 catalytic combustion and CO oxidation. Among the prepared samples, CeO2-CuO exhibited the best performance for CO oxidatio...