Sains Malaysiana 47(6)(2018): 1251–1257

http://dx.doi.org/10.17576/jsm-2018-4706-21

Kesan Suhu Celupan ke atas Mikrostruktur dan Kekerasan Salutan Aluminium

pada Keluli Karbon

(Effect of Dipping Temperature on Microstructure and Hardness of Coating Aluminium

on Carbon Steel)

EMEE MARINA SALLEH², ZAIFOL SAMSU², NORINSAN KAMIL OTHMAN^1*

& AZMAN JALAR¹

¹School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia

43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

²Institute of Microengineering and Nanoelectronic (IMEN), Universiti Kebangsaan Malaysia

43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

Diserahkan: 15 September 2017/Diterima: 17 Januari 2018

ABSTRAK

Keluli karbon amat mudah terkakis dalam pelbagai persekitaran terutamanya dalam keadaan berudara lembap dan suhu tinggi. Oleh sebab itu, permukaan keluli karbon perlu dilindungi dengan bahan atau logam yang mampu menangani serangan kakisan yang agresif dengan membentuk lapisan oksida dan lapisan antara logam yang bersifat pelindung. Kajian ini dijalankan untuk menentukan mikrostruktur permukaan dan kekerasan salutan aluminium (Al) tulen yang telah dihasilkan melalui teknik celupan panas. Celupan panas dalam leburan Al tulen dilakukan pada suhu berbeza untuk mendapatkan lapisan salutan yang optimum. Keputusan teknik celupan panas menunjukkan dua lapisan utama terhasil iaitu lapisan luar Al dan lapisan dalam aluminit (Fe-Al). Manakala lapisan dalam aluminida terdiri daripada dua lapisan yang berbeza iaitu lapisan nipis luar FeAl3 dan lapisan tebal dalam Fe2Al5. Keputusan daripada ujian mikrokekerasan Vickers menunjukkan bahawa nilai kekerasan lapisan aluminida meningkat dengan peningkatan suhu leburan Al manakala lapisan Al tidak menunjukkan sebarang perubahan yang ketara.

Kata kunci: Aluminida; celupan panas; kekerasan; keluli karbon

ABSTRACT

Carbon steel can easily be corroded in various environments, particularly in wet environment and at high temperature. Thus, the surface of the carbon steel must be protected by a material or metal that can form oxide surface and intermetallic layer that can preserve the carbon steel from aggresive corrosion attack. This study was performed to determine microstructure and hardness of aluminium (Al) coating that produced by hot dipping technique. The hot dipping coating using pure Al was conducted at different molten temperatures in order to attain an optimized coating layer. Two layers were formed on the surface of Al hot dipped carbon steel, the outer Al layer and the inner aluminide layer (Fe-Al). The inner aluminide layer consisted of two distinct layers which were thin FeAl3 at the outer layer and thicker Fe2Al5 on the inner layer. Microhardness of the aluminide layer values increased with increasing molten Al temperatures used and no apparent change of hardness of Al layer was obtained.

Keywords: Aluminide; carbon steel; hardness; hot dipping

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