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The hydraulic column is the key component of the hydraulic support in the mining environment. To improve a hydraulic column's reliability and service life, the Fe-based laser clad layer was prepared on 27SiMn steel substrate using a high power diode laser (HPDL). The results show that the best process parameters are the laser power of 3000 W, the scanning speed of 5 mm/s, the feeding fraction of 16 g/min and the lapping rate of 50%. The macroscopic morphology of the laser clad layer has no cracks, pits and other defects. The laser clad layer has a fine and uniform microstructure and can form a metallurgical bonding with the 27SiMn steel substrate. Elements distribution is uniform and it appears fluctuation around the melting line. The cladding hardness is 1.3 times higher than the substrate and the wear resistance is 7.7 times higher than the substrate. The self-corrosion potential of the laser clad layer is significantly shifted positively and has a significant passivation region. After 96 hours of salt pray corrosion test, the surface of the laser clad layer is still smooth. The laser clad layer has better corrosion resistance and performance than the substrate, which can meet the requirements of hydraulic support in the mining environment. [ABSTRACT FROM AUTHOR]

The evaluation of basic mechanical properties are shown to be of importance for the solid composite propellant development and application. The numerical analysis approach termed the three-phase Voronoi cell finite element method, was proposed to evaluate of the interfacial transition zone effect. Numerical results showed that the performance of the effective modulus could be essentially enhanced by increasing the zone thickness. The module of the composite with the inhomogeneous zone was higher than that of the composite with the homogeneous one. The effect of different zones on volume fractions and matrix moduli was also calculated. The Voronoi method can also be helpful for analyzing the characteristic properties of other three-phase composites. [ABSTRACT FROM AUTHOR]

In this work, a simulated corrosion electrolyte was employed in order to assess the effect of sealing treatment on the corrosion resistance of arc sprayed zinc coatings in atmospheric environment. The microstructures and corrosion behaviours of unsealed and sealed coatings had been studied using scanning electron microscopy and electrochemical testing. Scanning electron microscopy observations revealed that the unsealed coating consisted of an outer coarse layer and an inner impact layer. As for the sealed coating, the sealing agent not only covered the surface but also permeated into the original microdefects on the outer coarse layer of the as sprayed coating. The results of electrochemical testing and corrosion morphology observations indicated that the corrosion resistance of the sealed coating was enhanced a great extent due to the blocking and shielding effect of the sealing layer. [ABSTRACT FROM AUTHOR]