Zheng Guang Zou

The Study of Self-Propagating High-Temperature Synthesis of TiC-Al2O3/Fe Composites from Natural Ilmenite

In the paper, natural ilmenite (FeTiO3) was used as the main green material to synthesize TiC-Al2O3/Fe composite powder by Self-propagating High-temperature Synthesis (SHS) technology and densified TiC-Al2O3/Fe composites were prepared in a vacuum hot-pressoven. The reaction mechanism in the synthesis process was studied through theoretical thermodynamical analysis and experiment research .The effect of different synthesis conditions on the products was discussed. The relations among synthesis conditions,sintering conditions, phases composition, microstructure and properties of composites were also studied in details. A new way to synthesize the advanced TiC-Al2O3/Fe composites with relatively lower cost was practiced.

One-Step Electrodeposition of CIGS Thin Films from Alcohol Solution on Flexible Substrate

CuIn1-xGaxSe2 (CIGS) precursor films were fabricated on Mo foils by one-step electrodeposition in water and alcohol solutions. The precursor films were annealed in Ar atmosphere at 450°C to synthesize the polycrystalline thin films. The current density vs. potential curves of Cu2+, In3+, Ga3+ and Se4+ was studied by cyclic voltammetry. The compositions of CIGS, were analyzed by energy dispersive X-ray spectrum. The morphology and phase structure of films was characterized by scanning electron microscopy and X-ray diffraction, respectively.

Steel-Bonded Cemented Carbide GT35 by In Situ Reduction of Natural Ilmenite

Steel-bonded cemented carbide GT35 was fabricated from natural ilmenite by in-situ synthesis and vacuum pressureless sintering. The thermodynamics of the synthesis process were analyzed. The results indicated that the stable phases were TiC and iron in the FeTiO3-C system. During the synthesis process, ilmenite was reduced by graphite via a series of titanium oxides to obtain hard phase (TiC) and the steel matrix as the ultimate products. The experimental results shown that GT35 had a reasonable phase composition and fine TiC particles embedded uniformly in the steel matrixes. The composites exhibited excellent mechanical properties: the relative density was higher than 97%, the hardness reached HRC 61.5 and the maximal bending strength was about 1270MPa.

Effects of Mo(Ni) on Valence Electron Structures of TiC/Fe Cermets

Based on the empirical electron theory (EET) of solids and molecules, the valence electron structures (VESs) of TiC-Mo(Ni)-Fe system were calculated by building proper structure model. The results indicate that additives of Mo and Ni improve the interface conjunction factors of the cermets in different ways. By adding Mo, the VESs of the ceramic phase are improved for the formation of the rim phase (Ti1-xMox)C, which leads to the enhancement of the interface conjunction, while the improvement of the VESs on metal phase by adding Ni is due to the formation of the Fe100-yNiy. Mo and Ni additives increase the interface electron density of cermets, that is, the adding of the Mo and Ni enhance the overlapping grade of the electron cloud on interface and increase the binding energy of the interface, which is propitious to the wettability. The best wettability was found at x=0.5 or y=30.

Improved Electrodeposition of CuIn1-xGaxSe2 Films

CuIn1-xGaxSe2(CIGS) precursor films are fabricated on Mo foil by coelectrodeposition. The influence of the applied potential and the electrolyte additive in the process of electrodeposition are discussed. The precursor films are annealed in Ar for a short time to synthesize the polycrystalline thin film. The annealed layers are only phase-pure CuIn0.7Ga0.3Se2 and show a good crystallinity.

Nonlinear Dynamic Analysis and Nonlinear Structure of Self-Propagating High-Temperature Synthesis Process

The Self-propagating High-temperature Synthesis(SHS) process is a nonlinear one far from thermodynamic equilibrium, many nonlinear structures present in the process. After SHS processes of Ti-C-Fe and Ni-Si systems have been studied by the numbers, the effects of initial parameter conditions on nonlinear structure have been gained. On the base of establishing the model of combustion reaction dynamic characteristics, backward finite-difference approximation equations and central finite-difference approximation equations were applied to numerically calculate and simulate the characteristics of combustion wave and its’ change rules in the SHS process. All the experimental results are consistent with the simulative results.