Authors: Yu Xin Gao, Cheng Zhao, Zhi Gang Fang, Jian Yi
Abstract: Micro-nanostructure coatings have been attempted to prepare by Electro-spark deposition (ESD) on cast iron substrate. The microstructures and properties of the coating were investigated by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and microhardness tester. The results show that micro-nanosized particles and fine equiaxed structures prevail in the coating. The primary phases of the coating contain Fe3W3C, Co3W3C, Fe7W6 and W2C. Its average microhardness reaches 1290.1 HV. The results of abrasive test demonstrated that the coating had an excellent sliding wear resistance because the superfine particles distributed dispersedly in the coating increased the resistance to micro-cutting and plowing during the wear test, which effectively improves the surface performance of cast iron substrate.
176
Authors: Sheng Zhu, Guo Feng Han, Xiao Ming Wang, Wen Bo Du
Abstract: In this study, Al-Si alloy protective coating was deposited on the surface of ZM5 magnesium alloy by cold spray technology. Researchers observed the surface morphology of the coating by SEM, and researched tribological properties of the substrate material and the coating. The results show that, the bonding mechanism of the Al-Si alloy coating and substrate is metallurgical bonding and mechanical interlocking. The abrasion mechanism of Al-Si alloy coating is adhesive wear. The friction coefficient of the coating is higher than magnesium alloy in different friction frequencies. Greater change in friction coefficient is caused by the inhomogeneous phase composition. But the wear track depth of the coating is smaller than magnesium alloy. Wear-resisting property is improved.
142
Authors: Zong Yin Duan, Dong Sheng Wang
Abstract: This paper deals with the microstructure and thermal shock behavior of laser remelting of yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) deposited by plasma spraying. The microstructures of the coatings were analyzed by scanning electron microscopy (SEM). It was found that the as-sprayed ceramic coating had laminated structure with high porosity. However, the coating exhibited a dense lamellar-like layer with segment cracks on the remained plasma-sprayed porous layer. Thermal shock experiments for the two kinds of TBCs were performed by water quenching method. Testing result showed that the laser-remelted TBC had better thermal shock resistance than the as-sprayed one. The damage mode of the as-sprayed TBC was great-size whole spalling. In contract, the failure mechanism of the laser-remelted one was mainly local pelling. Segmented cracks of the top ceramic coatings caused by laser remelting improved the stress accommodation and were mainly attributed to the enhancement for thermal shock life of TBC.
2502
Authors: San Ming Du, Yong Ping Niu, Yong Zhen Zhang
Abstract: In the present study, 20 Wt. % ZrO2-Al2O3-17 wt.% TiO2 powders were sprayed using a plasma-spray technique after a NiAl bond layer was deposited on plain carbon steel substrate. The produced coatings were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) including energy-dispersive spectroscopy (EDS). The tribological properties of coatings against hard alloy ball were investigated by using a pin-on-disc tribo-meter under dry environments. The predominant wear mechanism of coating is fatigue.
420
Authors: Ren Guo Song, Pu Hong Tang, Chao Wang, Guo Lu
Abstract: Al2O3 and Al2O3-40wt.%TiO2 ceramic coatings on H13 hot-worked die steel have been prepared by plasma spraying, and then the microstructure, micro-hardness as well as wear resistance of the prepared coatings have been investigated by means of x-ray diffraction (XRD), scanning electron microscope (SEM), Vickers hardness tester and ball-on-disk high temperature tribometer. The results showed that the plasma sprayed ceramic coatings are of higher hardness and wear resistance than H13 hot-worked die steel.
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