Sains Malaysiana 43(6)(2014): 935–940

Surface Morphology Study on Aluminum Alloy after Treated with Silicate-Based Corrosion

Inhibitor from Paddy Residue

(Kajian Morfologi Aloi Aluminium Selepas Dirawat dengan Perencat Kakisan

Berasaskan Sisa Padi)

N. MOHAMAD, A. JALAR & N.K. OTHMAN*

School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor D.E., Malaysia

Received: 21 March 2013/Accepted: 1 March 2014

ABSTRACT

Aluminum alloys have extensive applications in engineering structures like aircraft due to their high strength-to-weight ratio. However, these alloys are very reactive and prone to corrosion attack. Paddy waste is one of the beneficial natural sources that have a potential contribution on inhibiting the corrosion attack. At 600°C, silica was obtained from rice husk ash. The chemical reaction between silica powders with concentrated alkali generates formulation of potential silicate-based corrosion inhibitor. The potentiodynamic polarization, optical microscope (OM), infinite focus microscope (IFM) and scanning electron microscopy (SEM) were employed to investigate the corrosion behaviour of Al 6061 through electrochemical and surface study. The electrochemical measurement showed that the existence of silicate-based corrosion inhibitor in 0.5 M hydrochloric acid medium significantly mitigates the corrosion rates. SEM, IFM and OM showed that the morphology of untreated Al 6061 contributes more damage on the sample surface than that of Al 6061 treated with silicate-base corrosion inhibitor. The aim of this study was to attain better understanding of surface study on corrosion behaviour of aluminum alloy in acidic medium after treated and untreated with silicate-based corrosion inhibitor from paddy residue.

Keywords: Aluminum alloy; corrosion inhibitor; silicate

ABSTRAK

Aloi aluminium mempunyai aplikasi yang luas dalam bidang kejuruteraan struktur seperti pesawat kerana mempunyai nisbah kekuatan-kepada-berat yang tinggi. Walau bagaimanapun, aloi ini adalah sangat reaktif dan cenderung kepada serangan kakisan. Sisa padi adalah salah satu sumber semula jadi yang bermanfaat dan mampu memberi sumbangan yang berpotensi menghalang serangan kakisan. Pada 600°C, silika diperoleh daripada abu sekam padi. Tindak balas kimia antara serbuk silika dengan alkali pekat menjana formulasi berpotensi bertindak sebagai perencat kakisan berasaskan silikat. Pengutuban potentiodinamik, optik mikroskop (OM), infiniti fokus mikroskop (IFM) dan imbasan elektron mikroskop (SEM) telah digunakan untuk mengkaji perilaku kakisan Al 6061 melalui kajian elektrokimia dan permukaan. Pengukuran elektrokimia menunjukkan bahawa kewujudan perencat kakisan berasaskan silikat dalam medium 0.5 M asid hidroklorik menyebabkan kadar kakisan berkurangan secara ketara. SEM, IFM dan OM menunjukkan bahawa morfologi Al 6061 yang tidak dirawat menyumbang lebih banyak kerosakan pada permukaan sampel berbanding Al 6061 yang dirawat dengan perencat kakisan berasaskan silikat. Tujuan kajian ini adalah untuk mencapai pemahaman yang lebih jelas melalui kajian permukaan berdasarkan kelakuan kakisan aloi aluminium dalam medium berasid setelah dirawat dan tidak dirawat dengan perencat kakisan berasaskan silikat daripada sisa padi.

Kata kunci: Aloi aluminium; kakisan perencat; silikat

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*Corresponding author; email: insan@ukm.edu.my