., Munasir (2015) Komposit Aluminium Berpenguat Partikel Nano SiO2 dari Pasir Kuarsa sebagai Material Anti-korosi pada Medium Geotermal. Doctoral thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Partikel nano SiO2 dapat disintesis dari bahan alam pasir kuarsa Bancar Tuban dengan metode kontinu melalui dua tahap: (i) penyiapan larutan prekursor sodium silikat Na2 O.xSiO2 yang dapat dilakukan dengan metode basah (hydrothermal) dan (ii) pembentukan buburan silisit Si(OH)4 melalui metode kopresipitasi. Partikel nano SiO2 yang berhasil disintesis mempunyai kemurnian 97-98,9 wt% dengan fase amorf dan poliamorfi (quartz dan crystobalite). Bentuk partikel SiO2 adalah spherical like dan berdiameter partikel ~ 26-29 nm. Metode ini efektif dan tidak mahal sebagai alternatif dalam mendapatkan partikel nano SiO2 dari bahan mineral alam.
Fabrikasi komposit sistem Al/SiO2 untuk fraksi volume (Vf) SiO2 5-30% dilakukan dengan metode metalurgi serbuk (dengan pencampuran basah, dan kompaksi tanpa pemansan). Penggunaan larutan aktif N-Butanol (polar) dan TMAH (ionik) sebagai media pencampur serbuk Al dan partikel nano SiO2 terhadap produk material komposit Al/SiO2 dikaji dalam laporan disertasi ini. Pola difraksi sinar-X menunjukan terbentuknya fase γ-Al2 O 3 sebagai efek media aktif saat proses mixing dan sintering. Fase SiO2 memiliki puncak difraksi yang sangat rendah dibanding fase Al, sehingga tidak teridentifikasi pada pola difraksi komposit Al/SiO2 . Berdasarkan pengamatan foto elektron, SiO2 mengalami aglomerasi di daerah batas butir. Semakin besar fraksi volum SiO2 , aglomerasi semakin besar dan tidak homogen, sehingga memicu pembentukan ronga (voids) di daerah batas butir matriks. Peningkatan fraksi volum SiO2 cenderung menurunkan densitas dan meningkatkan porositas
Analisis performa anti-korosi material komposit Al/SiO2 dilakukan dengan metode polarisasi linier pada medium elektrolit NaCl 1M. Penambahan fraksi volum filler partikel nanosilika SiO2 pada sistem komposit Al/SiO2 sangat berpengaruh terhadap sifat ketahanan korosinya; selain penggunaan jenis medium aktif pencampunya (N-butanol dan TMAH). Sampel Al/SiO2 (t) dan Al/SiO2 (b) memiliki performa anti-korosi yang berbeda: (i) sebelum ekspose posisi EKor kedua jenis sampel terpisah agak jauh (~0,65 Volt), untuk sampel Al/SiO2 (t) posisinya lebih positip dari sampel Al/SiO2 (b) dan laju korosi sampel Al/SiO2 (t) tren laju korosinya lebih rendah dibanding Al/SiO2 (b); SiO2 5% memiliki ferforma anti korosi terbaik dengan laju korosi 0,034680 mm/y (sampel #5-T) dan 0,039618 mm/y (sampel #5-B); (ii) setelah ekspose posisi EKor kedua jenis sampel berhimpit, dan mengalami pergeseran ke kanan (potensial semakin positif), seperti sampel #5-T bergeser ke kanan sejauh 0,11 Volt dan untuk sampel #5B bergeser ke kanan sejauh ~
0,74 Volt (lebih positif dari posisi sampel #5-T); performa anti korosi SiO2 5% adalah yang terbaik dengan laju korosi 0,00005804 mm/y (sampel #5-T) dan 0,00001169 mm/y (sampel #5-B). Produk korosi Al/SiO2 di dalam larutan elektrolit NaCl 1M (~90ºC) adalah fase γ-Al2 O3 dan γ-Al(OH)3
(berdasarkan data difraksi sinar-X) atau terbentuk produk korosi dengan unsur O, Al, Na, dan Cl
(berdasarkan analisis SEM-EDX).
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SiO2 nanoparticles can be synthesized from natural quartz sand from Bancar, through the following routes: (i) preparation of sodium silicate (Na2 O.xSiO2 ) precursor solution which can be done by wet (hydrothermal) method and (ii) formation of silicic acid Si(OH)4 gel via coprecipitation method. The produced SiO2 contained purity of 97-98.9 wt% with amorphous and polymorphs (quartz and crystobalite). The grains of SiO2 were spherical shaped with diameter of
~29-100 nm. This method is effective and inexpensive as an alternative in obtaining SiO2
nanoparticle from natural material.
Fabrication of Al/SiO2 composites for SiO2 volume fraction of 5-30% were conducted by means of powder metalurgical method (including wet mixing and nonheating compaction). The use of active solution in terms of N-Butanol (polar) and TMAH (ionic) as mixing medium for Al and SiO2 in producing Al/SiO2 composites were studied in this report. X-ray diffraction pattern showed the formation of γ-Al2 O 3 as a r esult of the effect of active medium during mixing and sintering processes. SiO2 tends to have much lower diffraction peaks compared to Al, so that SiO2 peaks were not clearly identified in Al/SiO2 X-ray diffraction pattern. Based on electron photography observation, SiO2 was agglomerated in the grain boundaries with not uniform characteristic. As the SiO2 volume fraction increased, the larger inhomogeneously agglomeration was observed, that implied voids formation in the grain bundaries matrix region. The increasing SiO2 volume fraction seemed to lead to reducing density and increasing porosity.
The analyses of anticorrosion performance of Al/SiO2 composites were done by means of
linear polarization method in 1M NaCl electrolite medium, to simulate a geothermal medium. The
addition of SiO2 nanoparticles in the composite has strongly affected the corrosion properties, besides the use of N-Butanol and TMAH as active mixing media. The performances of Al/SiO2 (t) and Al/SiO2 (b) were different: (i) before exposure, Ecor for both composites types were at (~0.65
Volt), Ecor of Al/SiO2 (t) was more positive than of Al/SiO2 (b) and the corrosion rate of Al/SiO2 (t) was lower than of Al/SiO2 (b); 5% SiO2 showed the best anticorrosion performance with corrosion rate of 0.034680 mm/y (sample #5-T) and 0.039618 mm/y (sampel #5-B) and (ii) after expposure, Ecor for both composites types were at close quarters and more positive, sample #5-T shifted to
0.11 volts and sample #5-B shifted to 0.74 volts; 5% SiO2 showed the best anticorrosion
performance with corrosion rate of 0.00005804 mm/y (sample #5-T) and 0.00001169 mm/y
(sampel #5-B). The corrosion products of Al/SiO2 in 1M NaCl electrolite medium (~90 ºC) were were γ-Al2 O3 and γ-Al(OH)3 (based on X-ray diffraction data) or in the elemental forms of O, Al, Na, and Cl (based on SEM-EDX analysis).
| Item Type: | Thesis (Doctoral) |
|---|---|
| Additional Information: | RDFi 620.5 Mun k |
| Uncontrolled Keywords: | Pasir kuarsa, Nano partikel silika, Komposit Al/SiO2 , Metode kontinu, Metalurgi serbuk, Korosi, Geotermal, Potensiodinamik (Tafel Plot), Quartz sand, Silica Nanoparticles, Al/SiO2 Composites, Continu method, Powder metalurgy, Corrosion, Geothermal, Potentiodynamic (Tafel Plot) |
| Subjects: | Q Science > QC Physics T Technology > TA Engineering (General). Civil engineering (General) > TA418.74 Corrosion and anti-corrosives T Technology > TA Engineering (General). Civil engineering (General) > TA418.9 Composite materials. Laminated materials. |
| Divisions: | Faculty of Mathematics and Science > Physics > 45001-(S3) PhD Thesis |
| Depositing User: | Eny Widiastuti - |
| Date Deposited: | 26 Mar 2018 05:34 |
| Last Modified: | 26 Mar 2018 08:25 |
| URI: | http://repository.its.ac.id/id/eprint/51634 |
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