Analisis Pengaruh Penambahan Unsur Ytterbium Terhadap Efisiensi Anoda Korban Berbasis Aluminium Dalam Larutan NaCl 3,4% Pada pH 6 Dan 8

Widodo, Anastasia Stella (2025) Analisis Pengaruh Penambahan Unsur Ytterbium Terhadap Efisiensi Anoda Korban Berbasis Aluminium Dalam Larutan NaCl 3,4% Pada pH 6 Dan 8. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Korosi pada struktur logam di lingkungan air laut menjadi permasalahan serius yang dapat menurunkan masa pakai material. Salah satu metode proteksi korosi yang umum diterapkan adalah sistem proteksi katodik menggunakan anoda korban. Aluminium sering dipilih sebagai material anoda karena memiliki densitas yang rendah serta konduktivitas listrik yang baik. Namun demikian, efisiensi aluminium murni sebagai anoda korban masih tergolong rendah akibat terbentuknya lapisan pasif yang menghambat pelepasan elektron. Untuk mengatasi hal tersebut, penambahan unsur paduan seperti logam tanah jarang ytterbium (Yb) menjadi alternatif yang potensial dalam meningkatkan efisiensi anoda korban. Penelitian ini bertujuan untuk mengevaluasi pengaruh variasi konsentrasi Yb (1,2%; 1,48%; dan 1,54%) serta pengaruh pH elektrolit (6 dan 8) terhadap efisiensi anoda korban aluminium menggunakan acuan standar DNV-RP-B401. Pembuatan sampel dilakukan dengan metode pengecoran menggunakan crucible furnace pada suhu 850°C dan dituangkan ke dalam cetakan logam permanen (permanent mold casting). Pengujian meliputi karakterisasi komposisi dan struktur mikro (OES, XRF, XRD, metalografi, dan SEM-EDX), serta evaluasi ketahanan korosi melalui uji potensiodinamik, EIS, dan efisiensi anoda korban berbasis DNV-RP-B401. Hasil penelitian menunjukkan bahwa penambahan Yb menghasilkan presipitat fasa intermetalik Al3Yb yang terdistribusi di batas butir matriks aluminium selama proses solidifikasi, yang bertindak sebagai grain refiner sehingga mampu memperhalus mikrostruktur dan memperkecil ukuran butir. Kehadiran fasa ini berkontribusi terhadap peningkatan kestabilan elektrokimia sehingga meningkatkan efisiensi anoda. Efisiensi tertinggi diperoleh pada sampel Al-1,2%Yb pada pH 6 dengan nilai sebesar 85,97%. Namun, penurunan pH elektrolit yaitu pH 6 menyebabkan
penurunan efisiensi pada seluruh variasi, yang disebabkan oleh meningkatnya laju korosi. Hal ini terjadi karena tingginya konsentrasi ion H⁺ dalam larutan bersifat agresif terhadap lapisan pasif Al2O3, mempercepat pelarutan anodis dan meningkatkan laju korosi.
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Corrosion of metallic structures in marine environments poses a serious threat that can
significantly reduce the service life of materials. One common method for mitigating corrosion
is cathodic protection using sacrificial anodes. Aluminum is widely used as an anode material
due to its low density and good electrical conductivity. However, the efficiency of pure
aluminum as a sacrificial anode remains relatively low due to the formation of a passive layer
that hinders electron release. To address this issue, the addition of alloying elements such as the
rare earth metal ytterbium (Yb) has emerged as a promising alternative for enhancing sacrificial
anode efficiency. This study aims to evaluate the effect of varying Yb concentrations (1.2%,
1.48%, and 1.54%) and electrolyte pH (6 and 8) on the efficiency of aluminum-based sacrificial
anodes, based on the DNV-RP-B401 standard. The specimens were prepared by casting using
a crucible furnace at 850°C and poured into a permanent metal mold. The experimental
procedures included chemical composition and microstructure characterization (OES, XRF,
XRD, metallography, and SEM-EDX), as well as corrosion resistance evaluation through
potentiodynamic polarization, EIS, and DNV-RP-B401-based anode efficiency testing. The
results showed that Yb addition led to the formation of Al₃Yb intermetallic precipitates
distributed along the grain boundaries of the aluminum matrix during solidification, acting as
grain refiners that refined the microstructure and reduced grain size. The presence of this phase
contributed to improved electrochemical stability and enhanced anode efficiency. The highest
efficiency was obtained in the Al-1.2%Yb sample at pH 6, with a value of 85.97%. However,
decreasing the electrolyte pH to 6 resulted in a decline in efficiency across all compositions due
to increased corrosion rates. This was attributed to the high concentration of H⁺ ions in the
acidic solution, which aggressively attacked the Al2O3 passive layer, accelerating anodic
dissolution and increasing the corrosion rate.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Aluminium, Anoda Korban, Efisiensi, pH, Ytterbium, Sacrificial Anode, Efficiency
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) > TA418.16 Materials--Testing. T Technology > TA Engineering (General). Civil engineering (General) > TA418.75 Corrosion-resistant materials T Technology > TA Engineering (General). Civil engineering (General) > TA480.A6 Aluminum alloys.
Divisions:	Faculty of Industrial Technology and Systems Engineering (INDSYS) > Material & Metallurgical Engineering > 28201-(S1) Undergraduate Thesis
Depositing User:	Anastasia Stella Widodo
Date Deposited:	04 Aug 2025 08:35
Last Modified:	04 Aug 2025 08:35
URI:	http://repository.its.ac.id/id/eprint/126047

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