研究目的
To prepare Zr-Al-Co (Ti) coatings using the laser cladding technology and reveal the influence of Ti on the phase composition, hardness and corrosion resistance.
研究成果
Metallurgically bonded amorphous-nanocrystalline coatings were fabricated by laser cladding with Zr-Al-Co (Ti) GRs on Q235 steel substrate. The coatings were composed mainly of AlN, ZrO2 and amorphous phases. Laser cladding of Zr-based coatings can improve the microhardness of the substrate. The hardness increased with the increasing of Ti content with the highest value at Ti = 15 at%. The higher content of ZrO2 brought about the higher hardness. The clad layer can significantly improve the corrosion resistance in comparison with the substrate. The coating with 5 at% Ti substitution for Zr presented the best corrosion resistance among the alloy systems.
研究不足
The crystallization of a coating may be the result of relative lower cooling rate or dilution from substrate. The participation of atmosphere may also be the cause for the crystallization in addition to the cooling rate and dilution effect.
1：Experimental Design and Method Selection:
Laser cladding technique was used to fabricate coatings with the nominal composition of Zr60-xAl15Co25Tix (x = 0, 5, 10, 15 at%) on Q235 steel substrate.
2：Sample Selection and Data Sources:
The substrate was grinded with SiC papers and cleaned with anhydrous ethanol. Zr-Al-Co (Ti) alloy ingots were prepared by remelting pure Zr, Al, Cu and Ti under a high-purity argon atmosphere.
3：List of Experimental Equipment and Materials:
Nd: YAG laser cladding machine with the wavelength of
4：064 μm (LSSK-009) was used. The diameter of the laser beam was 4 mm with the laser power of 750 W, the pulse duration of 35 ms and the pulse frequency of 14 Hz. Experimental Procedures and Operational Workflow:
The scanning speed for laser cladding is
5：8 mm s?The as-deposited specimens were cut and polished according to the standard procedure for x-ray diffraction (XRD), metallography, micro-Vickers hardness and corrosion resistance test. Data Analysis Methods:
The micro-Vickers hardness of the cross section of the specimens is studied at a load of 25 g for 10 s (FM-700/SVDM4R). The morphology was observed by the optical microscope (OM) and the field emission scanning electron microscope (FE-SEM, FEI Nova Nano SEM 450) respectively.
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