Studi Pengendalian Korosi Pada Sambungan Bilah-Lengan Turbin Arus Laut Sumbu Vertikal

Musabikha, Siti (2021) Studi Pengendalian Korosi Pada Sambungan Bilah-Lengan Turbin Arus Laut Sumbu Vertikal. Doctoral thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Pengembangan teknologi turbin arus laut sumbu vertikal harus bisa menghadapi dan bertahan terhadap kondisi lingkungan laut yang agresif dan korosif. Suatu sistem pengendalian korosi yang tepat diperlukan agar turbin vertikal tetap bisa beroperasi secara optimal dan menghindari kerugian finansial. Masalah korosi timbul pada sambungan turbin Kobold setelah enam tahun pengoperasian. Hal ini disebabkan oleh coating yang digunakan pada turbin tersebut belum bekerja optimal. Apalagi, aliran arus laut yang berputar bersama turbin menimbulkan kondisi aliran turbulen. Oleh karena itu, suatu studi tentang pengendalian korosi yang lebih tepat pada sambungan turbin arus laut vertikal perlu dilakukan dengan tujuan untuk menganalisis jenis material dan coating, serta mengevaluasi pengaruh kecepatan fluida terhadap kedua metode pengendalian korosi tersebut. Studi pengendalian korosi pada sambungan turbin vertikal bisa dicapai pertama-tama dengan memilih material melalui studi literatur. Pemilihan ini mempertimbangkan sifat-sifat fisik, mekanik, korosi, biaya, dan ketersediaan. Metode pemilihan material ini menggunakan multiple attribute decision making (MADM). Kedua, studi literatur mengenai jenis coating yang tepat juga perlu dilakukan dan beberapa coating dipilih. Kemudian, uji adhesi, impact, dan abrasi dilakukan untuk membandingkan kandidat coating tersebut. Terakhir, beberapa kandidat coating juga diuji secara eksperimen elektrokimia dan diberi variasi kecepatan putar untuk mengevaluasi pengaruh kecepatan fluida turbulen. Tafel polarization, electrochemical impedance spectroscopy (EIS), dan linear polarization resistance (LPR) dilakukan sebagai uji elektrokimia pada tahap ini. Kesimpulan dari riset ini yakni AISI 1045 terpilih sebagai material terbaik untuk aplikasi sambungan turbin vertikal, dan fluoropolymer menunjukkan kinerja coating yang terbaik. Laju korosi material tanpa coating yakni 5,52 ×10−4 mm/tahun pada sampel statis menjadi 1,73 ×10−2 mm/tahun pada sampel 5400 rpm. Hal ini menampilkan adanya penambahan laju korosi sebesar 30 kali lipat dan menandakan bahwa kecepatan putar fluida berpengaruh terhadap kinerja material dan meningkatkan laju korosi. Juga, efek kecepatan putar fluida terhadap coating menunjukkan selisih penurunan nilai impedansi atau ketahanan coating terhadap korosi hingga 17% pada 5400 rpm. Di samping itu, coating antifouling dan fluoropolymer dengan nilai impedansi yang tinggi bisa disarankan untuk diaplikasikan sebagai coating pengendalian korosi pada sambungan turbin vertikal.
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The development of the vertical-axis tidal-current turbine technology should be able to overcome and withstand the aggressive and corrosive ocean environments. A proper corrosion control system is required for the vertical turbine in order to operate optimally and avoid financial losses. Corrosion problems emerged on the connecting arm joint of the Kobold turbine after six years of operation. This is caused because the coating used on the turbines did not work optimally. Moreover, the rotating flow around the vertical turbine is turbulent flow conditions. Therefore, a corrosion control study on the connecting arm joint of the vertical turbine is needed to be done in order to analyze the types of materials and coating, and to evaluate the effect of rotation speed against both the corrosion control methods. Corrosion control study on the connecting arm joint of the vertical turbine can be firstly achieved through material selection via literature study. This selection considers the physical properties, mechanical properties, corrosion rate, fees, and availability. This material selection method used Multiple Attribute Decision Making (MADM). Secondly, the literature study of suitable coating also needs to be done and some coatings were selected. Then, adhesion, impact, and abrasion test were done to compare the coating performances. Lastly, the coating candidates were also tested experimentally and varied the rotation speed in order to evaluate the effect of turbulent fluid flow. And, Tafel polarization, electrochemical impedance spectroscopy (EIS), and linear polarization resistance (LPR) were carried out as the electrochemical test at this stage. The conclusion of this research is AISI 1045 chosen as the best material, and fluoropolymer performance shows the best coating performance. The corrosion rate of the bare surface material of 1.73 ×10−2 mm/year at 5400 rpm is higher than that of the static sample of 5.52×10−4 mm/year. It shows a 30-fold increase in corrosion rate and indicates that the rotation speed affects the material performance and increases the corrosion rate. Also, the effect of rotation speed shows a decreasing margin in impedance coating value, as the value of coating resistance against corrosion, up to 17% at 5400 rpm. In addition, the antifouling and fluoropolymer coating with high impedance values can be recommended to be applied as the corrosion control coating on the connecting arm joint of the vertical turbine.

Item Type:	Thesis (Doctoral)
Uncontrolled Keywords:	Material, coating, corrosion, control, turbine, material, coating, korosi, pengendalian, turbin.
Subjects:	T Technology > TC Hydraulic engineering. Ocean engineering T Technology > TC Hydraulic engineering. Ocean engineering > TC1665 Offshore structures--Materials.
Divisions:	Faculty of Marine Technology (MARTECH) > Ocean Engineering > 38001-(S3) PhD Thesis
Depositing User:	Siti Musabikha
Date Deposited:	10 Mar 2021 04:14
Last Modified:	10 Mar 2021 04:15
URI:	http://repository.its.ac.id/id/eprint/84044

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