Papers by Keyword: Hot Dip Aluminizing

Abstract: Copper and brass specimens were hot dipped aluminized using different times and temperatures conditions. Obtained coatings in a rich-aluminum matrix were characterized using microhardness test, metallographic analysis, electrochemical tests to evaluate corrosion resistance, and scanning electron microscopy/EDS analysis. Corrosion rate of hot dip aluminized copper varies according to processing parameters of molten aluminum. On the other hand, analysis and electrochemical results show that hot dipped aluminized brass increases its corrosion resistance at higher Al content within the coating.

Abstract: The growth of thin oxide layer due to the variation in temperature on the surface of aluminized carbon steel was investigated. Hot dip aluminizing of low carbon steel was carried out at 750 °C in a molten pure aluminum for 5 minutes. Aluminized samples were heat treated at 600 °C, 700 °C, 800 °C, and 900 °C for 1 hour. The formation of aluminum oxide layer was investigated in this study. Optical microscopy, Atomic Force Microscopy (AFM), SEM and EDAX were used in investigation. From the observation, the appearance of aluminum oxide layer increased with the increase in temperature. The result of EDAX analysis revealed the existence alumina phase. Surface roughness measurement showed increment with the increase in oxidation heat treatment temperature.

Abstract: The pure aluminized layer and RE-aluminized layer on industrial pure iron were prepared by hot dip aluminizing method, and the thickness and composition of the layer were investigated by means of scanning electronic microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. The results showed that the RE was permeated into the alloy layer after hot dip RE-aluminizing and the thickness of the alloy layer increases by about 30% as against hot dip pure aluminizing. The binding energy between the vacancy and aluminum atom was calculated. According to the energy condition of the solute-vacancy complex diffusion, it points out that the solute-vacancy complex diffusion is the main mechanism of aluminum atoms diffusion in hot dip RE-aluminizing and the main reason why the thickness of alloy layer increases after hot dip RE-aluminizing.

Abstract: Hot-dip aluminizing panels of Q235 steels were produced in laboratory. Then the hot-dip aluminizing samples were executed diffusion at elevated temperatures protecting with flowing argon gas. Metallographic microscope, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were employed for compositional analyses and graphical analyses of coating. The diffusion process was researched and the phase’s microstructure after diffusion was analyzed and discussed. The hot-dip aluminizing diffusion mathematical model was established with the finite element method. The results show that after diffusion in hot-dip aluminizing, the aluminum of the coating disappeared. The thickness of diffusion layer increased and the dentate frame disappeared. There are some iron-rich phases such as Fe2Al5, FeAl and Fe3Al in the diffusion layer. The phase Fe2Al5 decreases and the phase FeAl increases. The mathematical model corresponds with the actual situation. The diffusion coefficients of Al atoms diffusing in intermetallic compounds were calculated at 950°C, which were 0.29×10-12 m2/s for Fe2Al5, 0.7×10-12 m2/s for FeAl, and 0.27×10-12 m2/s for Fe3Al, respectively.

Abstract: A hot dip aluminising process was carried out with a 1mm steel sheet dipped into the Al-10at.% Si melt in an automatic hot-dip simulator. When steel and liquid aluminium are in contact with each other, a thin intermetallic compound (IMC) is formed between the steel and the aluminium. The analysis and identification of the formation mechanism of the IMC is needed to manufacture the application products. Energy dispersive X-ray spectroscopy (EDX) and electron probe microanalysis (EPMA) are normally used to identify the phases of IMC. In the Al-Fe-Si system, numerous compounds with only slight differences in composition are formed. Consequently, EDX and EPMA are insufficient to confirm exactly the thin IMC with multiphases. In this study, transmission electron microscopy (TEM) analysis combined with EDX was used. The TEM sample was prepared with focused ion beam (FIB) sampling. The FIB lift-out technology is used to slice a very thin specimen with minimum contamination for TEM analysis. It is clearly shown that the IMC consists of Al-27 at. % Fe-10 at. % Si and is identified as Al8Fe2Si with a hexagonal unit cell (space group P63/mmc). The cell parameters are a= 1.2404nm and c= 2.6234nm.