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Coal gangue is an inevitable coal waste from coal mine, which results in serious environmental problems. Oxy-fuel firing of coal waste and biomass waste is an alternative technology for efficient and clean utilization and CO2 reduction of coal waste. In this study, the oxy-fuel combustion characteristics and interactions of coal gangue and pine sawdust were investigated using thermogravimetric analysis, with a focus on the effect of oxygen concentration on interactions between coal gangue and pine sawdust during oxy-fuel combustion. The oxy-fuel combustion of pine sawdust had two obvious stages, including the release of volatile matter and the combustion of the remaining char, which differed from oxy-fuel combustion of coal gangue with one overlapped stage of devolatilization and char oxidation. Moreover, the addition of pine sawdust could improve the oxy-fuel combustion reactivity of coal gangue. The significant deviations between the experimental derivative thermogravimetric curves and theoretical derivative thermogravimetric curves for the blends indicated that interactions between coal gangue and pine sawdust had occurred in the temperature range of 400-600 °C. The interaction mechanism was primarily thermal effect between coal gangue and pine sawdust during oxy-fuel combustion. The oxygen concentration had a significant effect on the interactions between coal gangue and pine sawdust. The increase of oxygen concentration from 20% to 40% could improve interactions between coal gangue and pine sawdust obviously. However, relative small improvement of interactions was detected between coal gangue and pine sawdust when oxygen concentration was further increased from 60% to 80%. This was related to the difference of rate controlling factor for oxy-fuel combustion reaction under various oxygen concentrations.

In order to precisely measure the ion parameters in a microwave electron cyclotron resonance plasma using an ion sensitive probe, the dependences of the current-voltage (I-V) characteristics on the shielding height (h) and the potential difference between inner and outer electrodes (VB) have been investigated at different working pressures of 0.03 Pa and 0.8 Pa. Results show that the I-V curves at higher pressure are more sensitive to the variation of h than those at lower pressure. The influence of VB on ion temperature (Ti) measurement becomes more prominent when the pressure is increased from 0.03 Pa to 0.8 Pa. Under both pressures, the optimized h is obtained at the condition where the current reaches zero in the positive voltage region with a suitable VB of −1.5 V because of effective shielding of the electron E×B drift.

Magnetoelectric heating was used to heat ions in an ECR plasma with a magnetic mirror field. The temperature and density of ions were measured by an ion sensitive probe (ISP) before and after magnetoelectric heating in order to investigate the influence of the anode ring's radius, axial position and working pressure on magnetoelectric heating. Results showed that a suitable radius of the anode ring could improve the ion temperature effectively and the optimal size of the anode ring depended on the cyclotron radius of ions. The radial uniformity of the ion density was improved by increasing the radius of the anode ring after heating. The magnetic mirror field could reduce the loss of ions caused by collision with the wall of the chamber and it was beneficial to increase the ion temperature and the ion density. It was suitable to heat the ions when the anode ring was set at the center of the magnetic mirror field where there was a weaker magnetic field strength. Lower pressure contributed to the increase in the ion temperature and efficiency of magnetoelectric heating.

The nano-sized particles of anatase titanium oxide (TiO2) were obtained by hydrolysis of titanium ester (TNB) in basic media and dehydrated in acid media. And then the anatase titanium oxide was treated with nitrogen plasma. The effect of nitrogen plasma treating time on the activity of photo-catalytic reduction of the Cr2O72− for sample obtained was investigated. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Transmission Electron Microscope (TEM) and Ultraviolet (UV). A peak of 396 eV in the N 1 s XPS spectra of sample obtained with nitrogen plasma treated TiO2 showed that nitrogen-doped titanium oxide (TiO2−xNx) has been obtained. The spectra of UV showed that the light absorption of TiO2−xNx obtained by nitrogen plasma treated TiO2 for 10min. had moved to the visible region. The picture of TEM and spectra of XRD indicated that the crystallographic forms and particle dimension had no apparent change for both the modified and the unmodified TiO2. When the TiO2 sample was treated for 7 min with nitrogen plasma, it exhibited best photo-catalytic activity.

Thick diamond films with a thickness of up to 1.2 mm and a area of 20 cm2 have been grown in a homemade 5 kW microwave plasma chemical vapor deposition (MPCVD) reactor using CH4/H2/H2O gas mixtures. The growth rate, radial profiles of the film thickness, diamond morphology and quality were evaluated with a range of parameters such as the substrate temperature of 700 oC to 1100 oC, the fed gas composition CH4/H2 = 3.0%, H2O/H2 = 0.0%~ 2.4%. They were characterized by scanning electron microscopy and Raman spectroscopy. Translucent diamond wafers have been produced without any sign of non-diamond carbon phases, Raman peak as narrow as 4.1 cm?1. An interesting type of diamond growth instability under certain deposition conditions was observed in a form of accelerated growth of selected diamond crystallites of a very big lateral size, about 1 mm, and of a better structure compared to the rest of the film.

A technique of improvement on diamond nucleation based on pulsed arc discharge plasma at atmospheric pressure was developed. The pulsed arc discharge was induced respectively by nitrogen, argon and methanol gas. After the arc plasma pretreatment, a nucleation density higher than 1010 cm-2 may be obtained subsequently in chemical vapor deposition (CVD) on a mirror-polished silicon substrate without any other mechanical treatment. The effects of the arc discharge plasma on the diamond nucleation were investigated by scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR) and Raman spectroscopy. The enhancement of nucleation is postulated to be a result of the formation of carbon-like phase materials or nitrogenation on the substrate surface without surface defect produced by arc discharge.

Diamond films with very smooth surface and good optical quality have been deposited onto silicon substrate using microwave plasma chemical vapor deposition (MPCVD) from a gas mixture of ethanol and hydrogen at a low substrate temperature of 450°C. The effects of the substrate temperature on the diamond nucleation and the morphology of the diamond film have been investigated and observed with scanning electron microscopy (SEM). The microstructure and the phase of the film have been characterized using Raman spectroscopy and x-ray diffraction (XRD). The diamond nucleation density significantly decreases with the increasing of the substrate temperature. There are only sparse nuclei when the substrate temperature is higher than 800°C although the ethanol concentration in hydrogen is very high. That the characteristic diamond peak in the Raman spectrum of a diamond film prepared at a low substrate temperature of 450°C extends into broadband indicates that the film is of nanophase. No graphite peak appeared in the XRD pattern confirms that the film is mainly composed of SP3 carbon. The diamond peak in the XRD pattern also broadens due to the nanocrystalline of the film.

Flat adherent diamond films on copper substrates have been prepared using a nickel interlayer. The structure of the interface between the substrate and the diamond film has been investigated using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). XRD shows that a Cu–Ni alloy is formed on the substrate surface after a hydrogen plasma annealing treatment. XPS demonstrates that some chemical bonds such as CO, CC and C-metal appear on the surface of the substrate. The adhesion of the diamond film on the copper substrate is improved due to the formation of Cu–Ni alloy and C–Ni bonds at the interface. The optimum thickness of the nickel interlayer for the adhesion improvement is 5∼10 μm. To minimize the deformation of the specimen owing to the largely thermally-induced stress, a new three-step-method has been adopted to relax this stress. In the three-step-method, the intrinsic stress of the diamond film characterized by micro-Raman spectroscopy is controlled and adjusted by the deposition conditions. By balancing the tensile intrinsic stress and compressive thermal stress, a flat diamond film/copper substrate composite is obtained when the substrate temperature falls from the deposition temperature to room temperature.

Growth of carbon nanotubes (CNTs) at low temperature is very important to the applications of nanotubes. In this paper, under the catalytic effect of cobalt nanoparticles supported by SiO2, CNTs were synthesized by microwave plasma chemical vapor deposition (MWPCVD) below 500°C. It demonstrates that MWPCVD can be a very efficient process for the synthesis of CNTs at low temperature.

High-density Polyethylene Elucidated by Energy-tunable Positron Annihilation and Water Contact Angle Measurements Zhe Chen1,2,∗, Zhi Wang1,2, Qiuming Fu1,2, Zhibin Ma1,2, Pengfei Fang3, and Chunqing He3 1Hubei Key Laboratory of Plasma Chemistry and New Materials, Wuhan Institute of Technology, Wuhan, 430073, China 2School of Material Science and Engineering, Wuhan Institute of Technology, Wuhan, 430073, China 3School of Physics and Technology, Wuhan University, Wuhan, 430072, China

The deposition of high-quality diamond films and their adhesion on cemented carbides are strongly influenced by the catalytic effect of cobalt under typical deposition conditions. Decreasing Co content on the surface of the cemented carbide is often used for the diamond film deposition. But the leaching of Co from the WC-Co substrate leading to a mechanical weak surface often causes a poor adhesion. In this paper we adopted an implant copper layer prepared by vaporization to improve the mechanical properties of the Co-leached substrate. The diamond films were grown by microwave plasma chemical vapor deposition from CH4:H2 gas mixture. The cross section and the morphology of the diamond film were characterized by scanning electron microscopy (SEM). The non-diamond content in the film was analyzed by Raman spectroscopy. The effects of pretreatment on the concentrations of Co and Cu near the interfacial region were examined by energy dispersive spectrum (EDS) equipped with SEM. The adhesion of the diamond on the substrate was evaluated with a Rockwell-type hardness tester. The results indicate that the diamond films prepared with implant copper layer have a good adhesion to the cemented carbide substrate due to the recovery of the mechanical properties of the Co-depleted substrate after the copper implantation and the formation of less amorphous carbon between the substrate and the diamond film.

The direct deposition of diamond films on copper substrate has been suffered from adhesion problems due to the mismatch of the thermal expansion coefficients of diamond and copper. In this paper, nuclei with valuable density were directly introduced through a submicron diamond powder layer. The diamond grits partially were buried in the copper substrate leading to better adhesion. Another method with nickel intermediate layer for enhancing the adhesion was studied here in detail. It was suggested that Cu-Ni eutectic between the copper substrate and Ni interlayer might contribute to the adhesion improvement. The quality of the diamond films deposited with nickel interlayer was investigated by scanning electron microscopy and Raman spectroscopy.

The preparation of crystalline C3N4 films was investigated using pulsed arc discharge from mixed methanol and ammonia water at atmospheric pressure. The X-ray diffraction (XRD) patterns of the films prepared at a substrate temperature of 450oC suggested that the film was composed of α-C3N4 and β-C3N4 crystallites. Raman spectra exhibited distinct peaks which are in good agreement with those predicted theoretically for C3N4 crystallites.

Aligned carbon nanotubes (CNTs) were synthesized on glass by microwave plasma chemical vapor deposition (MWPCVD) with a mixture of methane and hydrogen gases at the low temperature of 550 °C. The experimental results show that both the self-bias potential and the density of the catalyst particles are responsible for the alignment of CNTs. When the catalyst particle density is high enough, strong interactions among the CNTs can inhibit CNTs from growing randomly and result in parallel alignment.

A novel approach, which was based on pulsed arc discharge with applied potential of 4 kV at atmospheric pressure and substrate temperature of 300 °C, had been developed to deposit carbon films with diamond phase from methanol solution. The surface morphology of the deposits was observed by scanning electron microscopy (SEM). The deposits were characterized with micro-Raman spectroscopy, infrared (IR) spectroscopy and X-ray photoemission spectroscopy (XPS). It was confirmed from Raman and XPS spectra that the deposit contains micro-grains of diamond phase.

The deposition of diamond films on cemented carbides is strongly influenced by the catalytic effect of cobalt under typical deposition conditions. Decreasing the content of Co on the surface of the cemented carbide is often used for the diamond film deposition. But the leaching of Co from the WC-Co substrate leads to a mechanical weak surface, often causing poor adhesion. In this paper we adopt a copper implant layer to improve the mechanical properties of the Co leached substrate. The copper implant layer is prepared with vaporization. The diamond films are grown by microwave plasma chemical vapor deposition from the CH4/H2 gas mixture. The morphology and the quality of the diamond films have been characterized by scanning electron microscopy and Raman spectroscopy. A Rockwell apparatus has evaluated the adhesion of the diamond on the substrate. The results indicate that the diamond films have good adhesion to the cemented carbide substrate due to the recovery of the mechanical properties of the Co depleted substrate after the copper implantation and less graphite formation between the substrate and the diamond film.

The magnetoelectric heating is investigated on an ECR plasma device. The ion temperatures are measured by ion sensitive probe (ISP) before and after magnetoelectric heating. The influences of bias voltage of electrical ring, magnet field and pressure on ion temperature and the efficiency of ion heating are studied. The results indicate that the whole heating of the plasma is accomplished through the magnetoelectric heating of the ions in the sheath of the electric ring and the radial transport of the heated ions. The ion temperature in the axial area increases with the bias voltage of electric ring, and their relationship is nonlinear. The ion temperature increases more than 20 eV when the bias voltage is 1000 V. A heating efficiency is achieved to be as high as 2%2.5% and increases with the bias voltage increasing. The magnetic field strength plays an important role in the limitation and heating of the ions. The efficiency of the magnetoelectric heating increases with the increase of the magnetic field strength when the magnetic field strength changes from 6.310-2T to 8.710-2T. The efficiency of the magnetoelectric heating increases with the pressure decreasing when the pressure chenges in a range of 0.020.8Pa.