Sains Malaysiana 42(12)(2013): 1793–1798

Surface Morphology Studies of Low Carbon Steel Treated in Aqueous Lignin

(Kajian Morfologi Permukaan Terhadap Keluli Berkarbon Rendah Terawat dalam Lignin Berakueus)

S. YAHYA, N.K. OTHMAN*, A.R. DAUD & A. JALAR

School of Applied Physics, Faculty of Science & Technology, Universiti Kebangsaan Malaysia

43600 Bangi, Selangor, Malaysia

Diserahkan: 19 November 2012/Diterima: 1 April 2013

ABSTRACT

The effect of corrosion inhibition of low carbon steel in water based medium containing lignin was investigated via weight loss method. The evolution of surface morphology has been carried out for 7 to 42 days via optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron microscopy (XPS). Immersion of metal specimen without lignin shows that significant increase in the surface roughness. The longer the immersion time, the more the oxide crust formed. The surface degradation of metal specimen was well protected by immersion in lignin solution. A protective layer containing of lignin was formed on the surface of metal specimens after 7 and 21 days immersion. The corrosion inhibition gives about 13 and 53% inhibition for both 7 and 21 days immersion, respectively. The protective layers were spalling and separated from the metal surface after 42 days immersion in lignin solution possibly due to the increase in corrosion attack after long time immersion according to the increase in dissolved oxygen and may also due to the thermal mismatch between oxide and substrate. The adsorption of protective layer containing lignin was temporary adsorbed on the surface.

Keywords: Adsorption; corrosion; low carbon steel; weight loss method

ABSTRAK

Kesan perencatan kakisan keluli berkarbon rendah dalam medium air yang mengandungi lignin telah dikaji melalui kaedah penurunan berat. Evolusi morfologi permukaan telah dijalankan selama 7 hingga 42 hari melalui mikroskop optik (OM), mikroskopi elektron imbasan (SEM), spektroskopi penyerakan tenaga X-ray (EDX) dan fotoelektron mikroskopi x-ray (XPS). Penyerapan spesimen logam tanpa lignin menunjukkan bahawa peningkatan yang ketara pada kekasaran permukaan. Semakin lama masa rendaman, semakin banyak kerak oksida terbentuk. Degradasi permukaan spesimen logam dapat dikawal dengan merendamkan spesimen dalam larutan lignin. Lapisan pelindung yang mengandungi lignin telah terbentuk pada permukaan spesimen logam selepas rendaman selama 7 dan 21 hari. Perencatan kakisan memberikan perencatan kira-kira 13 dan 53% untuk 7 dan 21 hari rendaman. Lapisan pelindung mengalami pengelupasan dan terpisah dari permukaan logam selepas 42 hari rendaman dalam larutan lignin mungkin disebabkan oleh peningkatan serangan kakisan selepas masa rendaman yang lama menyebabkan peningkatan oksigen terlarut dan mungkin juga disebabkan oleh ketidakpadanan haba antara oksida dan substrat. Penjerapan lapisan pelindung yang mengandungi lignin merupakan perjerapan sementara pada permukaan logam.

Kata kunci: Kaedah kehilangan berat; kakisan; keluli berkarbon rendah; penjerapan

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*Pengarang untuk surat-menyurat; email: insan@ukm.my