Authors: Hai Li Yang, Ping Ju Hao, Guo Zhang Tang, Yun Gang Li
Abstract: The siliconized layer on low silicon steel substrate was produced under pulse current conditions from KCl-NaCl-NaF-SiO2 molten salt and the effects of frequency on the composition and microstructure were investigated. The results showed that at the same average current density and other experimental conditions, Si content in the surface and the layer thickness decreased with increasing frequency. Low pulse frequency (500 Hz) and high frequencies (1500, 2000Hz) produced coarse grain and bigger surface roughness. There was a flat fine grain structure and a relatively thick (30m) layer when the frequency was 1000Hz. However, the effect of pulse frequency on the structure of the layer was not obvious. The phase structure of the layer was composed of Fe3Si with (110) preferred orientation at all experimental frequencies.
1113
Authors: Zhao Jun Deng, Jing Liu, Zhi Hong Lu, Hui Wang, Cheng Jiang Lin
Abstract: The morphology of inhibition layer and adhesion of Zn coating about a 600MPa grade high Al dual phase steel were studied by grow discharge spectrometry (GDS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the inhibition layer is mainly composed of Fe2Al5-xZnx particles with a size of 0.5~1μm, and the adhesion is directly related to the density of the inhibition layer, the denser the inhibition layer, the better the adhesion. It is found: for the samples with good adhesion that besides the Fe2Al5-xZnx particles, there are also some small spherical Al-Mn oxides particles in sizes from 30 to 100nm uniformly distributed in the inhibition layer; for the samples with bad adhesion, the steel substrate is not fully covered by Fe2Al5-xZnx particles and large amount manganese oxides are detected at the non-covered positions.
1669
Authors: Kang Zhang, Tai Ping Lu, Shu Ti Li
Abstract: The effect of AlN buffer layer on the quality of GaN epilayer grown on Si substrate by metalorganic chemical vapor deposition (MOCVD) has been investigated. It was found that the quality of GaN epilayer strongly related with the crystal quality of AlN buffer layer. As the full width at half maximum (FWHM) of AlN (0 0 2) plane increased from 1.23 degree to 3.41 degree, the FWHM of GaN (0 0 2) plane varied from 432 arcsec to 936 arcsec and the FWHM of GaN (1 0 2) plane varied from 677 arcsec to 1226 arcsec. Besides, more cracks formed and threading dislocation (TD) density increased. The deteriorated AlN buffer layer also led to a rougher morphology of the GaN layer, as can be seen from the root mean square (RMS) roughness of GaN layer which varied from 0.178 nm to 0.476 nm. And the morphology of AlN and the quality of GaN epilayer are not appear to be relevant due to the ruleless values of RMS roughness of AlN.
201
Authors: Hong Fei Sun, Zhan Rui Niu, Can Ming Wang, Bo Yuan
Abstract: A bronze mirror dating of Han-dynasty was studied in this paper. The in-depth structure and the composition of the natural patina and substrate alloy were determined by Electron probe micro-analyzer (EPMA) observation and EDS cartographies on a cross-section, the mineral composition of patinas were analyzed using XRD. The results show the layer structure of the patina has two obvious layers, and the inner layer ranges from 90µm to 260µm. This bronze mirror is a typical ancient Chinese black mirror Heiqigu, and the formation of high tin layer is due to special surface treatment by the ancients. Tthe composition of the patinas on the mirror and that of substrate alloy were found to be highly heterogeneous, the thin black patina on the mirror containing is cassiterite.
743
Authors: Feng Tang, Jin Yong Xu, Yan Tang, Cheng Gao, Peng Gao, Bo Gao, Wei Heng Mo, Yuan Ming Li
Abstract: The Cu-Ce infiltration layer was formed on 304 Stainless Steel surface by double glow plasma surface metallurgy technology. The effects of source voltage and cathode voltage on surface alloying concentration, surface hardness and infiltration layer depth were analyzed by comparative test. The results showed: In the experimental range, the contents of Cu and Ce, surface hardness, deposition layer depth increase with the source voltage increasing, which is contrary to the cathode voltage; the diffusion layer depth increases with either voltage increasing in a certain range.
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