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Pores and weak bonding are the inherently drawbacks for thermally sprayed coating. Laser beam is an attractive approach to remelt thermal spray coating for obtaining fully dense coating with metallurgical bonding with substrate. However, defects of holes or cracks are highly inevitable with unmatching remelting processing parameters. In this work, a thermally sprayed Cr3C2-NiCr cermet coating by high velocity oxygen fuel spraying was post-processed by laser remelting with a series of varying beam energy densities from 37.5 J/mm2 to 225 J/mm2. The defect evolution was investigated by both experimental and numerical simulation methods. Large holes and through-thickness cracks were typical defects observed in the remelt coating by optical microscopy. The experimental results show that remelting-induced defects evolve into three stages with laser energy density. The effect of energy density on remelt structure was further verified with the temperature field by numerical simulation with ABAQUS code. The stress field interpreted the crack formation at periodical formation sites. The results on the defect evolution shed light on obtaining functional coatings for industrial applications.

Numerical simulation of cooling roller in planar flow melt spinning process was accomplished using CFD software, Get cooling water flow characteristics and the cooling roller wall temperature and pressure distribution with cooling roller rotation speed range 0-50r/s, The results show that: heat transfer coefficient h and Nusselt number between the cooling water and the inner wall surface of a copper roller creases with the increase of the cooling roller rotate speed, but the increase rate is relatively small; Effect of cooling roller rotate speed on inner wall pressure is large, cooling roller inner wall pressure increases with the rotation speed increase. This study provided a theoretical reference of amorphous cooling roller design and optimization.

In the paper, the relationship between the grain size and fatigue life are studied. To specify the initial and short crack propagation life of low carbon steel material, three methods are used in the simulation. At first, the K. Tanaka’s model is introduced to calculate the fatigue life of a grain. Then, the Voronoi Diagram is used to generate the microstructure of grains. At last, a criteria to specify the short crack is proposed. Based on these methods, the numerical simulation is conducted. With the help of the process, the grain sizes are generated randomly in order to specify how grain sizes effect fatigue life. The computational results are in good agreement with the experimental data. The results show that the randomness of fatigue life is closely related to the randomness of grain sizes.

Honing experiments were carried out for nickel-based superalloy Inconel718 bore. The significance analysis of the four honing parameters: spindle speed, stroke speed, wedge feed per stroke cycle and grain size on the surface roughness, was studied with the orthogonal design method. And the significant degree under the rated conditions was determined. The results showed that: wedge feed per stroke cycle and grain size have a significant influence on surface roughness while spindle speed and stroke speed had no significant effect. Also, there was a positive correlation between surface roughness and wedge feed per stroke cycle and grain size. Furthermore, the honed surface topography was analyzed by the meaning of microscope.

Orpiment (As2S3) is one of the major arsenic sulfide minerals, which can be dissolved by ferric ion and proton produced by the bacteria, and the main intermediates were polysulfides and elemental sulfur. In this study, two strains (Acidithiobacillus thiooxidans and Acidthiobacillus caldus) were used to bioleach the orpiment without iron ions addition. The experimental results show that both the two strains can grow in the pulp and dissolve the orpiment. In the bioleaching, it was found that pH decreased, the concentration of arsenic increased significantly and no elemental sulfur is detected on the surface of the residuals. At the same time the density of the planktonic bacteria increased obviously. These results indicate that the orpiment can be dissolved by the bacteria easily in absence of Fe3+. This study suggests that the release of arsenic which is from orpiment in the mining tailings can be faster than expected in open air.