Studi Perilaku Coating Epoxy Mastic-Polyurethane dengan Variasi Ketebalan Polyurethane pada Baja ASTM A36 di Larutan (NH4)2SO4 + NaCl

Cahyono, Kezia Anandita (2024) Studi Perilaku Coating Epoxy Mastic-Polyurethane dengan Variasi Ketebalan Polyurethane pada Baja ASTM A36 di Larutan (NH4)2SO4 + NaCl. Other thesis, Insitut Teknologi Sepuluh Nopember.

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Abstract

Baja ASTM A36 sering digunakan dalam industri karena murah, kuat, tangguh, serta mudah diproses pemesinan dan dilas, namun baja ini memiliki ketahanan korosi yang lemah. Dalam industri pupuk, yang mengandung senyawa korosif seperti ammonium sulfat (NH₄)₂SO₄ dan natrium klorida (NaCl), korosi dapat menjadi masalah serius. Penelitian ini bertujuan mengetahui perilaku coating epoxy mastic sebagai primer dan polyurethane sebagai topcoat pada baja ASTM A36 di lingkungan yang mengandung ammonium sulfat. Epoxy mastic dipilih karena penetrasi dan adhesinya yang baik, sementara polyurethane dipilih karena ketahanan kimia dan cuacanya yang unggul. Variasi ketebalan topcoat polyurethane yang digunakan adalah 0, 75, 100, dan 200 μm. Spesimen diuji dengan simulasi korosi atmosfer salt spray menggunakan larutan 0,35% ammonium sulfat dan 0,05% NaCl selama 7 hari. Evaluasi dilakukan melalui observasi visual, pengukuran ketebalan coating, dan pengukuran persentase rust pada permukaan. Hasil penelitian menunjukkan bahwa penambahan ketebalan polyurethane sebagai topcoat pada baja ASTM A36 dengan primer epoxy mastic meningkatkan ketahanan terhadap penurunan ketebalan coating (bleeding), meningkatkan ketahanan kimia, serta mengurangi kontaminasi rust staining. Namun, peningkatan ketebalan topcoat juga meningkatkan risiko cacat delaminasi akibat sifat mekanik polyurethane yang kaku dan keras. Berdasarkan data, variasi EmP75 merupakan pilihan yang lebih baik. Cacat delaminasi sebelum coating lebih sering muncul pada spesimen EmP200 dan EmP100. Penurunan ketebalan pada periode pengamatan terakhir (168 jam) menunjukkan bahwa EmP75 memiliki penurunan yang relatif rendah sebesar 13,7 μm dibandingkan dengan EmP200 dan Em yang masing-masing sebesar 16 μm. Rating korosi pada EmP75 setara dengan EmP100 dan EmP200 pada periode pengamatan terakhir, yaitu bernilai 8. Meskipun persentase rust staining pada EmP75 (15,05% pada 168 jam) lebih tinggi dari EmP100 (4,7% pada 168 jam) dan EmP200 (0,63% pada 168 jam), hal ini tidak memengaruhi kinerja coating dalam melindungi substrat, hanya mempengaruhi visual permukaan coating.
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ASTM A36 steel is frequently used in industry due to its affordability, strength, toughness, and ease of machining and welding. However, it has poor corrosion resistance. In the fertilizer industry, which contains corrosive compounds like ammonium sulfate ((NH₄)₂SO₄) and sodium chloride (NaCl), corrosion can be a significant issue. This research aims to investigate the performance of epoxy mastic as a primer and polyurethane as a topcoat on ASTM A36 steel in an environment containing ammonium sulfate. Epoxy mastic was chosen for its excellent penetration and adhesion, while polyurethane was selected for its superior chemical and weather resistance. The variations in polyurethane topcoat thickness used were 0, 75, 100, and 200 μm. Specimens were tested using an atmospheric corrosion simulation with a salt spray containing 0.35% ammonium sulfate and 0.05% NaCl for 7 days. Evaluations were conducted through visual observation, coating thickness measurement, and rust percentage measurement on the surface. The results showed that increasing the thickness of the polyurethane topcoat on ASTM A36 steel with an epoxy mastic primer improved resistance to coating thickness reduction (bleeding), enhanced chemical resistance, and reduced rust staining contamination. However, increasing the topcoat thickness also heightened the risk of delamination defects due to the stiff and hard mechanical properties of polyurethane. Based on the data, the EmP75 variation was found to be the best choice. Delamination defects before coating were more frequent in EmP200 and EmP100 specimens. Thickness reduction in the final observation period (168 hours) showed that EmP75 had a relatively low reduction of 13.7 μm compared to EmP200 and Em, each at 16 μm. The corrosion rating of EmP75 was equivalent to EmP100 and EmP200 in the final observation period, with a value of 8. Although the rust staining percentage on EmP75 (15.05% at 168 hours) was higher than EmP100 (4.7% at 168 hours) and EmP200 (0.63% at 168 hours), this did not affect the coating’s performance in protecting the substrate, only the visual appearance of the coating surface.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Baja ASTM A36, Korosi Atmosfer, Epoxy Mastic Coating, Polyurethane Coating, Salt Spray, ASTM A36 Steel, Atmospheric Corrosion
Subjects:	T Technology > TJ Mechanical engineering and machinery > TJ174 Maintenance and repair of machinery T Technology > TS Manufactures > TS699 Powder coating of metals
Divisions:	Faculty of Industrial Technology and Systems Engineering (INDSYS) > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User:	Kezia Anandita Cahyono
Date Deposited:	22 Aug 2024 07:09
Last Modified:	22 Aug 2024 07:09
URI:	http://repository.its.ac.id/id/eprint/114042

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