Laser surface texturing is one of the promising surface modification techniques to reduce wear and friction properties of materials. In this study, we report the comparative effect of laser surface texturing on commercial nickel, electrodeposited nickel and Ni-SiC composite coatings. Hemispherical dimples, with 80-200 mm dimple spacing, were created and examined on the surfaces of the materials studied. The results revealed that microsurface texturing with 150 mm dimple spacing considerably improved the coefficient of friction. Electrodeposited nickel has shown improved coefficient of friction under identical texturing and tribological conditions when compared to commercial nickel. Furthermore, incorporation of SiC nanoparticles in nickel, by codeposition processes, resulted in the increase in microhardness of the coating, which in turn prevented the dimples from being deformed after wear testing. Dimple spacing accuracy and incorporated second phase ceramic particles both contributed significantly to reduction in coefficient of friction of electrodeposited Ni-SiC composite coatings.

This study attempted to manufacture an Y 2 O 3 ceramic coating layer on a ceramic (AlN) substrate using aerosol deposition (AD) and investigated its macroscopic properties. Pure Y 2 O 3 powder with a polygonal shape and average size of 5.0 μm was used as initial feedstock. Using aerosol deposition with suitable process conditions, an Y 2 O 3 coating layer was successfully fabricated on aluminum nitride (AIN). The thickness of the manufactured coating layer was approximately 10 mm. The coating layer consisted of Y 2 O 3 phase identical to that in the initial powder, and no additional oxides were identified. In regard to the roughness of the Y 2 O 3 coating layer, the average roughness (R a ) measured 1.32 μm, indicating that the surface roughness was relatively even compared to the initial powder size (5 μm). Mechanical properties of the Y 2 O 3 coating layer were measured using nano indentation equipment, and the indentation modulus of the Y 2 O 3 coating layer fabricated by aerosol deposition measured 136.5 GPa. The interface of the coating layer was observed using TEM, and the deposition mechanism of the Y 2 O 3 coating layer manufactured by aerosol deposition was also discussed.

This study investigated the high temperature oxidation property of SiC coated layer fabricated by aerosol deposition process. SiC coated layer could be successfully manufactured by using pure SiC powders and aerosol deposition on the Zr based alloy in an optimal process condition. The thickness of manufactured SiC coated layer was measured about 5 μm, and coating layer represented high density structure. SiC coated layer consisted of α-SiC and β-SiC phases, the same as the initial powder. The initial powder was shown to have been crushed to the extent and was deposited in the form of extremely fine particles. To examine the high temperature oxidation properties, oxidized weight gain was obtained for one hour at 1000°C by using TGA. The SiC coated layer showed superior oxidation resistance property than that of Zr alloy (substrate). The high temperature oxidation mechanism of SiC coated layer on Zr alloy was suggested. And then, the application of aerosol deposited SiC coated layer was also discussed.

Recently, with the increase in the application of UHSS plates in automobiles, the service life of existing molds is being shortened, and directed energy deposited type 3D printing technology is being considered as a way to extend the service life. In this study, in order to improve the service life of cold molds, the wear characteristics of the deposited parts using composition systems were analysed, and the possibility of practical application was estimated through evaluation with shear molds.</br>Since the high hardness of AM layer can be reached without additional heat treatment, it was expected to improve the service life when applied to the surface of the mold. Through the wear evaluation of the ball-on-disk method, it was confirmed the wear performance improvement of M4, and as a result of the shear mold life evaluation of 1.5 GPa class high-strength automotive steel plate for the M4 deposited, it was found that shear up to 17,000 strokes were possible. When the number of strokes was increased, a fracture layer due to deposition was observed in the cross-section of the mold surface, and it is believed that additional heat treatment research is required to improve the life of the AM mold.