Papers by Author: Qing Cai Su

Abstract: The vapor and gas permeabilities of the polyethylene films, casting polypropylene films and nylon films were tested in the paper. The keeping fresh performances were analyzed. It was found that the life time of vegetable packaged by films with high gas permeability is longer. The films with high vapor permeability reduce the accumulation of water droplets, but the leaves of vegetable change from green to yellow for lack of oxygen. It shows that the gas permeability of the film is more important than its vapor permeability for the vegetable storage. The family should choose the films with high gas permeability and appropriate vapor permeability to store vegetables.

Abstract: The field emission scanning electron microscope is applied in this paper to analyze the surface topography of diamond crystal synthesized at high pressure and high temperature. The research shows that parallel steps, jagged steps, hexagonal hills exist on (111) plane of diamond. The topography has a relation to the growth way of diamond. The (111) planes of diamond crystal mainly grow in layer mode.

Abstract: The microstructure of catalyst discs and fracture topography of boron-doped diamond blocks are analyzed in this paper. The results show that boron can promote or inhibit the growth of diamond crystal. The battens of metal carbides in catalyst are the main carbon source in the nucleation and growth of diamond. Crystal nucleus can absorb the carbon atoms from metal carbide in catalyst disc, and continually grow. It is resulted that the carbon atoms around the diamond grains in catalyst disc reduce, and the battens of metal carbides are thin. The more diamond grains are produced, the thinner battens of metal carbides in catalyst disc are formed.

Abstract: The growth process of synthetic diamond single crystals under high-pressure and high-temperature (HPHT) was investigated using acoustic emission (AE) technique. And AE parameters corresponding to growth process were analyzed. However, the AE features of diamond growth are relativelyweak and easily obscured by other AE sources. So the fast Fourier transformation (FFT) was used to calculate the frequency spectra of AE signals for identifying different AE sources. The results showed that the variation of AE counts and energy is in a good agreement with the formation process of synthetic diamond crystals. And the AE signals pronounced from diamond growth are concentrated in the frequency range from 100 to 250 kHz. Thus, AE technique is an effective way to monitor and study the diamond growth, and the frequency analysis can be a useful way to identify different AE sources.

Abstract: Boron-doped diamond single crystals were synthesized with Fe-Ni-C-B System catalysts which content of boron carbide (B4C) were different, and their crystallographic features were tested with electron probe microanalysis (EPMA), X-rays diffraction (XRD), Raman spectrum and field emission scanning electron microscopy (FESEM). The experimental results showed that doped boron in the diamond could result in the changes of its crystallographic features. There were different X-ray peak intensities in the different boron-doped diamond crystals, and the intensities were changed with the content of B4C in the catalysts. With the increase of boron content in the diamond, the boron atoms resulted in the change of growing rate in different crystalline face of the diamond. The quality of diamond synthesized with catalyst which contained 0.2 w.t.% boron carbide was worse than others.