A new method was presented to determine the iron content in the coating of galvanized steel sheet based on laser-induced breakdown spectroscopy. The zinc-iron coating was characterized with a series of single laser pulses irradiated on the traversing sheet steel, each on a different steel sheet position. The influences of laser fluence and elemental depth distribution were studied and analyzed. To protect the corrosion performance of the coating and meet requirements for small-invasive measurement, the ablation size of the crater under different laser fluences was studied. Under the optimized experimental parameters, the diameter of ablation craters is about 50 lm, and then, the Fe content in the coating was calibrated and analyzed by the linear standard calibration method. The calibration result, however, is not good. Considering that the Zn content in the coating was high and relatively constant, curve calibration was then carried out with the intensity ratio (I Fe404:58 =I Zn468:01) instead of the net line intensity of Fe, and then, the determination coefficient of calibration curve increases from 0.7713 to 0.9511, and the root-mean-square error decreases from 0.4832% to 0.1509%. The results prove that the laser-induced breakdown spectroscopy is an effective way for the analysis of the Fe content in the coating of galvanized steel sheet. Keywords Laser-induced breakdown spectroscopy Á Galvanized steel sheet Á Quantitative analysis Á Small-invasive analysis Á Iron content

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The improved resistively-heated furnace with two heaters established a vertical thermal gradient to control nucleation during AlN single crystals Physical Vapor Transport (PVT) growth on polycrystal tungsten substrates. During the high temperature (> 1850 °C) heating process, the reverse temperature field (i.e., the temperature difference between the sublimation zone and the crystalline zone ΔT < 0) was obtained to reduce the number of nuclei on the tungsten substrate. During growth, the proper positive values of ΔT T were chosen to content the supersaturation values (0.25 < S < 0.3). The reverse temperature condition during high temperature (> 1850 °C) cooling was fulfilled to avoid recrystallization on grown AlN crystal. AlN single crystals made through the method were characterized by X-ray diffractions (XRD) and Raman spectroscopy.