Browsing by Author "Anasyida A. S"

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    Characterization of molybdenum-modified aluminide coating on 304 stainless steel via slurry
    (Published by EDP science, 2026-05-30) AMBALI IBRAHIM OWOLABI; Anasyida A. S; Abdullah, T. K; AbdulRazak, K; Dhindaw., B. K; Shuaib-Babata, Y. L
    This study investigates the microstructural changes and growth kinetics of intermetallic compounds in Mo-modified aluminide coatings on 304 stainless steels with varying temperatures and times. Molybdenum and alumina were introduced via slurry aluminizing. Heat treatments were conducted at 750 °C, 800 °C, and 850 °C for varying times (6, 8, and 10 h). Aluminide coating was characterized with SEM, EDX, and XRD, revealed the presence of multilayer phases comprising of Fe-Al and Mo-Al intermetallic compounds, along with an alumina scale on the coating surface. Samples heated at 750 °C showed uniform coatings, while those at 800 °C and 850 °C exhibited voids and cracks. The growth kinetics of the coating obey a parabolic law conforming to diffusion-controlled growth. The activation energies calculated for FeAl and Fe3Al were 360 kJ/mol and 237 kJ/mol, respectively, which is higher than that of coatings containing aluminium (FeAl layer: 180 kJ/mol and and Fe3Al layer: 260 kJ/mol). The total activation energy (Q) was 26 kJ/mol for coatings containing molybdenum and 53 kJ/mol for coatings with only aluminium. Hardness of the intermetallic layers varied from 378 to 966 HV for Mo-modified coatings as compared to aluminide coating (380 to 1030 Hv). The corrosion behaviour of Mo-aluminide coatings was investigated in 3.5% NaCl using polarization and electrochemical impedance spectroscopy (EIS) tests. Results show improved performance of corrosion resistance due to Mo-rich intermetallic phases, with the 6 h sample exhibiting the best corrosion resistance.
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    Low-Temperature Slurry Aluminizing: Investigating the Influence of Aluminizing Time on the Corrosion Performance of Aluminide Coating on 304 SS
    (Published by IOP Science UK,, 2024-12-26) AMBALI IBRAHIM OWOLABI; Anasyida A. S; Abdullah T. K
    The surface of austenitic stainless steel (304 SS) was modified with aluminium and alumina powders using a slurry aluminizing route to enhance its lifespan at high temperatures. The substrate was subjected to low heat treatment temperature (680°C) at various aluminizing times (4, 6, 8, and 10 hours). The corrosion resistance of the aluminide coating was evaluated by exposing them to a mixture of molten solar salt containing 60 wt.% NaNO3 and 40 wt.% KNO3 at 600°C for 100 hours. The coatings were characterized using FESEM, EDX, and XRD. Coating thickness, hardness, multi-layered phases, and corrosion products were determined before and after corrosion. The results indicated that a dense and continuous inner layer made up of FeAl-based intermetallic improved the corrosion resistance of 304SS. Coating thickness increased with increasing aluminizing time, with a maximum thickness of 75.12 μm observed for samples with 10 hours of aluminizing. The highest coating hardness of 1060 HV was observed on Fe2Al5 of aluminide layer heat treated at 10 hours. The corrosion product found on the aluminide layer was NaAlO2 and the sample heat treated for 6 hours exhibited the lowest corrosion rate of 0.21 mm/year.
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    Microstructural evolution and hardness properties of Si-modified aluminide coating on 304 stainless steel via slurry aluminizing: effect of aluminizing temperatures
    (Published by the Universiti Putra Malaysia, Malaysia, 2024-06-16) AMBALI IBRAHIM OWOLABI; Anasyida A. S; Abdullah, T.K
    Surface modification of austenitic steel with a Si-modified aluminide coating enhances its lifespan by improving resistance to corrosion, oxidation, and high-temperature strength. To achieve this, a slurry composed of silicon, alumina, and aluminium was applied on the surface of 304 stainless steel (304SS) substrates. The samples were subjected to aluminizing at 750 °C, 800 °C, and 850 °C for 6 hours. Microstructural analysis was carried out using a field scanning electron microscope (FESEM) equipped with energy-dispersed X-ray spectroscopy (EDX), while X-ray diffraction (XRD) was employed for phase identification. The hardness of the coating was measured using Vicker microhardness. The study revealed the presence of various binary intermetallic compounds, including Fe2Al5, Fe3Al, and FeAl, as well as ternary phases like Al3Fe2Si3 and Fe1.7Al4Si, within the coatings. The addition of silicon reduced the intermetallic compound (IMC) layer thickness by occupying vacancy sites along the crystal structure c-axis of Fe2Al5, thereby restraining the growth of this brittle IMC in favor of more ductile phases. Notably, specimens heat treated at 850 °C exhibited the highest thickness of Fe-Al IMC layers. As temperature increases, the number of voids at the interface between the aluminide layer and the steel substrate also grew. Microhardness measurement revealed that Fe2Al5, FeAl, and Fe3Al layers had a hardness value of about 850-990 HV, 570-630 HV, and 320-410 HV respectively for all the temperatures. Fe2Al5 has the lowest toughness and is confirmed to be the hardest zone in the aluminide coating. Si-modified aluminide coatings on 304 stainless steels could be considered as a material candidate for high temperature application.