Papers by Author: Fan Xiu Lu

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Authors: Fan Xiu Lu, Yu Mei Tong, X.H. Gao, Wei Zhong Tang, Cheng Ming Li, Guang Chao Chen
Abstract: In the present investigation a specially designed ceramic interlayer, which is able to supply suitable protection of the ZnS substrate against chemical attack by atomic hydrogen, and is helpful to reduce the thermal stress, has been developed. Nano-crystalline diamond films were successfully deposited on to the pre-coated multi-spectrum ZnS. It was found that diamond nucleation on the ceramic interlayer could be greatly enhanced by a metal or semiconductor mask placed on top of the pre-coated ZnS substrate, whereas diamond nucleation will not happen even by long time seeding in ultrasonic bath with fine diamond powder suspension. It was found that diamond nucleation is induced by the presence of the metal or semiconductor mask. To our knowledge this kind of phenomena of induced nucleation has not been reported. Detailed results and discussions were presented.
Authors: Fei Chen, Hai Zhou, Jia Qing Chen, Fan Xiu Lu
Abstract: The plasma sprayed gradated coating with the bottom layer of NiCrAlY and the top layer of (ZrO2+CaO) was prepared on the 1Cr18Ni9Ti steel surface by the plasma spraying technique. The phase structure and morphology of the gradated coating were analyzed by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The high temperature oxidation resistance of the plasma sprayed samples at 800°C was investigated. The oxidation kinetics curve was worked out. The wear-resistance behavior of the graduated coating under dry sliding against GCr15 steel was evaluated on a ball-on-disc test rig. The results show that the thickness of gradated coating is about 320μm. The plasma sprayed gradated coating on stainless steel surface can improve the high temperature oxidation resistance of stainless steel. The oxidation rate of stainless steel is less than that of plasma sprayed gradated coating. The oxidation coating of plasma sprayed sample was very dense and is not easily exfoliated. The dense oxidation coating prevents the stainless steel from more oxidation. The friction coefficient of the 1Cr18Ni9Ti substrate was about 0.33 on dry sliding against the GCr15 steel, while the graduated coating experienced abated friction coefficient to 0.21 on the same testing condition.
Authors: Leng Chen, Wei Min Mao, Fan Xiu Lu, Ping Yang
Abstract: The residual stress and crystallographic texture of diamond films were investigated in the present work. The diamond films were synthesized on (100) silicon wafer by Microwave Plasma Chemical Vapor deposition (MPCVD). Then the residual stresses of the films were measured by X-ray diffractometer equipped with the two-dimensional detector. The residual stresses can be classified into two categories, i.e., the intrinsic stresses and the thermal stresses. It was shown that the thermal stresses were compressive in the temperature range studied and the intrinsic stresses were tensile. The crystallographic textures of the films were measured by X-ray diffractometer with the method of pole figure and orientation distribution function (ODF). The experimental results suggest that the crystallographic textures of the films depend upon the deposition temperature and methane flow rates, and the components and intensity of crystallographic textures have effect on the residual stresses in diamond films to a certain extent.
Authors: Fei Chen, Hai Zhou, Chen Chen, Fan Xiu Lu, Fan Xiu Lu
Abstract: Oxidation ceramic coating was directly synthesized on LY12 aluminium alloy by micro-arc oxidation (MAO) process in Na2SiO3 electrolyte solution with the Na2WO4-KOH-Na2EDTA addition. The corrosion resistance of the coating was tested using CS300P electrochemical corrosion workshop in 3.5% NaCl solution. Using the scanning electron microscopy (SEM) and X-ray diffraction (XRD), the cross-section microstructure, the surface morphology and the phase structure of the micro-arc oxidation ceramic coating were analyzed. The results showed that the corrosion resistance of the micro-arc oxidation ceramic coating in 3.5% NaCl solution was enhanced remarkably, the corrosion velocity was obviously slowed down. The thickness of micro-arc oxidation ceramic coating was about 11μm. The final phases in the coating were found to be α-Al2O3 and γ-Al2O3. The mechanism of the oxidation ceramic coating formation was investigated too.
Authors: Leng Chen, H.P. Feng, Fan Xiu Lu
Abstract: The crystallographic textures of the free-standing diamond films which were synthesized by the chemical vapor deposition (CVD) using a CH4/H2/Ar gas mixtures have been investigated. Texture components of the diamond films are analyzed with pole figures and orientation distribution function (ODF). The surface morphology of the diamond films grown at different substrate temperatures as well as different gas concentrations is observed with scanning electron microscopy (SEM). The experimental results indicate that the intensity of {110} fibre texture becomes much higher with the increase of the substrate temperature. It is considered that the higher multiplicity of <110> crystallographic direction in diamond octahedron leads to the higher appearance possibility of {110} fibre texture and the final texture components of the diamond films depend upon the CVD deposition parameters.
Authors: S.G. Wang, P.J. Sellin, Q. Zhang, Fan Xiu Lu, Wei Zhong Tang, A. Lohstroh
Abstract: In this study, X-ray detectors with coplanar metal-semiconductor-metal structure, were fabricated employing high quality chemical vapour deposited (CVD) diamond film grown by a direct current arc jet plasma system. In which the electrical contacts with dimension of 25 µm in width with a 25 µm inter-electrode spacing, were patterned on the growth side of the diamond film using lift-off technology. The performance of the fabricated detectors was evaluated by steady-state X-ray illumination. The photoconductivity of the diamond detectors was found to linearly increase with increase in the X-ray photon flux. This demonstrates that high quality CVD diamond can be used for X-ray detectors.
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