The Alumina Film Nanomorphology Formed to Improve the Corrosion Resistance of Al-2.0 wt% Fe Alloy as Result of the Laser Surface Melting Technique Applied

The laser surface remelting (LSR) treatment was performed to Al-2.0 wt% Fe alloy with a 2 kW Yb-fiber laser (IPG YLR-2000S). The substrate and laser-treated material characterization were executed using different techniques. Among them, the microstructure was analyzed by optical microscope, SEM, low-angle X-ray diffraction (LAXRD) and the corrosion test was made in aerated solution of 0.1 M H2SO4 at a temperature of 25°C ± 0.5°C. As result was shown, the micrograph of LSR-treated material displaying can be a fine cellular structure and the existence of certain nano-porosities and a similar to a nano-dendritic growth was observed too. The characteristic of melted zone was constituted of metastable phases according to the result of x-rays and the behavior corrosion as a result of the LSR-treated sample, which it was shown to be more resistant to corrosion than the untreated sample. A comparative study was carried out of the cyclic polarization of the laser-treated and untreated samples, demonstrating that the reduction and oxidation reverse peaks were not observed and being the cyclic polarization behavior was of irreversible character in both samples, however, the LSR-treated sample propitious the passivity on the surface also reduced the corrosion phenomena. Wherefore, this type of laser-treated alloy can be applied in the aerospace, aeronautic and automobilist industries.

Applicability Evaluation of a Laser Light-Mater Interaction Based Computational Tool on Status Identification of Applied Micro-Structured Coatings

The current work aims at evaluating a proposed method based on a computational tool developed using Object-Oriented Programming to identify the status of micro-structured surfaces. In this case, these are micro-structured coatings with riblet microstructure developed by Fraunhofer Institute–IFAM, by building a graphical reproduction of the analyzed surface and calculating an expected laser reflection intensity acquired by a laser sensor device, the proposed method is assessed by using the simplest case: a flat surface, and an optimal case: an intact riblet surface. The results corroborate the calculations to be applied to further steps from more complex cases of degradation and to diverse riblets geometries. Based on Huygens-Fresnel and Fraunhofer diffraction theories, the calculations developed and demonstrated in this paper improved the nondestructive tests to support the status identification of the micro structured coatings, e.g. riblet structures based on shark skin used in shipping and aerospace industries. This work is assured required quality of the riblet coating identifying the number of structures and expected geometry using implemented calculations to foresee the laser reflection intensity acquired by a laser sensor device with 3 detectors, for instance, a riblet structure could be graphically reproduced, analyzed and completely identified based on the application of the theoretical optics applied on this work.

Soil Pore Characterization Using Free Software and a Portable Optical Microscope

Total porosity （TP）, determined by image analysis, pore type and pore size distribution were evaluated on impregnated soil blocks from an undisturbed Brazilian sandy loam soil using a digital portable optical microscope. The free software Image J （version 1.40g） was used for image analysis. Procedures for soil image collection and analysis were presented. The image analysis allowed the evaluation of pore sizes with diameters ranging from 20 to 〉 1 000 μm. The following types of pores were also obtained： rounded, elongated and intermediate. The results M[owed the characterization of the soil as moderately porous （TP = 21.6%）. Rounded, intermediate and elongated pores were responsible for 11.6%, 31.7% and 56.7% of TP. In relation to pore size 51.1% of TP was in the 100-500μm size class and a third of TP came from the pores larger than 500μm.