EFFECT OF TITANIUM IONS IMPLANTATION ON THE CORROSION RESISTANCE OF SS 304 IN A NaCl MEDIUM

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1 MATERIALS SCIENCE and TECHNOLOGY Edited by Evvy Kartini et.al. EFFECT OF TITANIUM IONS IMPLANTATION ON THE CORROSION RESISTANCE OF SS 304 IN A NaCl MEDIUM Diah Astuti Indarwati 1, Priyo Tri Iswanto 2, Tjipto Sujitno 3 1 Graduate Program, Dept of Mechanical Engineering Gadjah Mada University 2 Dept of Mechanical Engineering Gadjah Mada University, Yogyakarta Indonesia 3 Center for Accelerator and Materials Processes Technology-BATAN,Yogyakarta, Indonesia d.astuti09@gmail.com ABSTRACT Titanium ions implantation into SS 304 surface using 150 kev/2 ma Ion Implantation equipment has been carried out. The aim of this research is to study the effect of Titanium ions implantation on the resistance of SS 304. For this purpose, SS 304 with the 14 mm of diameters and 2 mm of thickness of were implanted with Titanium ions for several doses/time at certain energy (100 kev). The corrosion resistance of implanted and unimplanted samples were tested using Potential Galvanostat. It has been found that the corrosion resistance of unimplanted SS 304 is 178,96 µa/cm 2, while for implanted samples are 176,19 µa/cm 2, 144,62 µa/cm 2, 139,57 µa/cm 2, 125,58 µa/cm 2, 133,61 µa/cm 2, 161,92 µa/cm 2, and 162,95 µa/cm 2 respectively for samples implanted for 1 hours, 2 hours, 3 hours, 4 hours, 5 hours, and 6 hours. From these data it can be concluded that the optimum time for implantation processes is 3 hours. Keywords : Corrosion Resistance, Ion Implantation, SS 304 INTRODUCTION Stainless Steel 304 (SS 304) is a material widely used in industry because of its excellent resistance to corrosion in comparison to other metals. But, on certain condition this material is still susceptible to corrosion. One way to improve the corrosion resistance is to deposit a coat of thin layer on the surface of a material using the ion implantation method. In modern technology, ion implantation has turned out to be the most important technique to introduce dopant atoms into materials. The major advantage of the ion implantation technique is the high controllability and reproducibility of the process parameters influencing the doping distributions [1]. In a previous study, it was shown that the use of ion implantation method has been able to improve the corrosion resistance of SS 304. The copper ions implanted on the SS 304stainless steel increase the corrosion resistance of the material s surface. The increase is estimated to be 7.24 times compared with non-implanted stainless steel (in a corrosive media of chloride acid M). This condition was achieved with an ion dosage of x ion/cm 2 and energy of 100 kev with a corrosion rate of 2.25 mpy. Implanted cerium ions on SS 304 have also been observed to be able to increase the corrosion resistance by a factor of 2.68 compared with the unimpanted SS 304. While SS 304 implanted with lanthalum ions

2 Materials Science and Technology saw its corrosion resistance increased by a factor of 1.20 compared with the unimplanted SS 304 [1]. Titanium is a good candidate as a corrosion-resistant material because it has the capability to form a protective oxide layer. The oxide films formed on titanium are more protective than oxide films formed on stainless steel, and they often perform effectively in media that would cause pitting and crevice corrosion in the latter (e.g., seawater, wet chlorine, organic chlorides) [11]. In this research, the effect of titanium ion implantation on SS 304 will be studied. The material to be studied is a low carbon SS 304 stainless steel having a weight % composition of 18%/20% Cr, 8%/10.5% Ni, 0.08% C, 2.0% Mn, 0.045% P, 0.03% S, 1.0% Si and the remainder is Fe by balance. EXPERIMENTAL METHOD The initial step started with the sample preparation. Several SS 304 steels with a diameter of 1.5 cm and thickness of 2 mm are provided. The samples were polished using sandpapers. The coarseness number of the sandpapers ranges from 180 to Autosol paste has also been used to polish up the samples. Furthermore, the prepared samples were inserted into an ultrasonic bath of alcohol to ensure that they are completely cleansed from all contaminants. The next step was the process of ion implantation using a 150 kev/2 ma Ion Implantation equipment. In an ion implantation procedure, the important parameters that must be considered are the energy and the dosage used. Ion energy will determine the depth of ion implantation penetration, while the ion dosage determines the amount or percentage or concentration of implantation atoms in the target material. In this research, the depth of penetration or the energy required was determined by using the SRIM program. From the SRIM program, the energy required in this research is determined to be 100 kev. The dosage was determined by the value of the beam current and the duration of implantation process. Mathematically it can be written as follows: It D (1) qea where D is dopant ion dosage (ions/cm 2 ), I is ion beam current (Ampere), t is duration of implantation process (second), q is charge state (+1, +2, +3, ), e is electron charge (1.602 x C), and A is beam area (cm 2 ) [7]. In practice, the value of the ion dosage can be regulated using two different ways, namely by varying the size of the ion currents whereas the duration of implantation process is fixed, or the duration of implantation process was varied while the beam current ions is fixed. In this research the current was fixed and the duration process was varied. The next step was corrosion testing. The corrosion test was conducted in a sodium chloride media 0.6 % using a Potensiostat/Galvanostat PGS 201 T instrument. The information obtained from the corrosion test results is the amount of corrosion current density (icor) generated from each target. This result can be used to calculate the corrosion rate in mill inch per year (mpy) using the equation below: 0.13i BE cor (2) where is the corrosion rate (mpy), i cor is the current density (µa/cm 2 ), BE is the equivalent weight of the specimen (gram/equivalent), and ρ is the density (gram/cm 3 ). 86

3 Effect Of Titanium Ions Implantation On The Corrosion And finally the last step is microstructure measurement. The microstructure measurement was carried out by Scanning Electron Microscopy (SEM) method. RESULTS AND DISCUSSION During the ion implantation stage, ion dosage (D) was varied by varying the duration of implantation process (t), while the ion beam current (I) was kept constant. Ion dosage was calculated by using equation (1). In the corrosion rate measurement, the information obtained from corrosion test results is the corrosion current density (i corr ) originating from each target. By inserting the value of equivalent weight (BE) and density (ρ) that are already known, the corrosion rate could be obtained from equation (2). The test results are presented in Table 1 and Figure 1. Table 1: Corrosion test result for SS 304 implanted by titanium. No. Energi Current Time Ion dose E corr Corrosion Rate (kev) (µa) (hours) (x ion/cm 2 ) (mv) (µa/cm 2 ) (mpy) I corr Figure 1: Graphic ion dose vs corrosion rate of SS 304 implanted by titanium Figure 1 illustrates the effect of titanium ion implantation on the SS 304 steel. Addition of titanium ions until a certain dosage has been reached will decrease the corrosion rate. This means that addition of titanium ions in this range will increase the corrosion resistance. On the other hand, after reaching the optimum point, addition of titanium ions would increase the corrosion rate. This means that in this range addition of titanium ions would decrease the corrosion resistance. From Table 1 the effect of addition of titanium ions has been calculated to decrease the corrosion rate in an unimplanted SS 304 steel by a factor of % compared to SS 304 steels implanted with titanium ions for one hour. The optimum condition was achieved with 87

4 Materials Science and Technology an ionic current of x ions/cm 2 (time duration = 3 hours). The corrosion rate for this condition is mpy. This means that titanium implanted SS 304 steels with this dosage will be subjected to surface corrosion, with a corrosion depth of mills per year or mm per year. The corrosion resistance at this optimum condition is improved by a factor of % compared to the corrosion resistance of unimplanted SS 304 steel. The SEM results shows the differences in the surface structure of the titanium implanted SS 304 steel and SS 304 unimplanted steel. (a) (b) Figure 2: Microstructure of SS 304 before corrosion test. (a) unimplanted sampe. (b) implanted sample 88 (a) (b) Figure 3: Microstructure of SS 304 after corrosion test. (a) unimplanted sample. (b) implanted sample Microstructure tests shows that the titanium ion implantation would reduce the level of corrosion in the sample. This can be seen from a comparison of the existing black spots on the implanted sample with the same black spots on the non-implant sample. The number of black spots in the Ti implanted sample is fewer than the number of black spots in the unimplanted sample, which means that this sample is more resistant to corrosion. Decrease in the corrosion rate, which means an increase in SS 304 corrosion resistance of ion implanted titanium may occur due to the formation of a stable protective layer so that the surface is passive, therefore it is not easily corroded. CONCLUSION 1. Surface treatment using titanium ion implantation method in SS 304 material can be used to improve the corrosion resistance. 2. The optimum dosage of titanium occurs in the process of implantation during the three hours (dosage x ions/cm 2 ), with mpy corrosion rate. Thereby

5 Effect Of Titanium Ions Implantation On The Corrosion increasing the corrosion resistance by a factor of % compared with the unimplanted SS 304 steel. REFERENCES [1]. Abbas, A.A., Forming A Protecting Layer For Corrosion In Stainless Steel Surface With Implantation Techniques, Disertation, Gadjah Mada University, 2007 [2]. Abbas, A.A., Prayoto, Anggraita, P., Efek Implantasi Ion Tembaga Terhadap Sifat Ketahanan Korosi baja Tahan Karat Austenitik Dalam Media Asam Khlorida, Proceeding, Pertemuan dan presentasi Ilmiah Penelitian Dasar Ilmu Pengetahuan dan Teknologi Nuklir, BATAN, 2005 [3]. Ebrahimian, H., et.all, Effect of nitrogen ion implantation on corrosion resistance of Ti films deposited on steel 304 by ion beam sputtering, J. Plasma Fusion Res. SERIES, Vol. 8, 2009 [4]. Fontana, M.G., Corrosion Engineering, McGraw-Hill Book Company, 1987 [5]. Khasanah, U., Efek Implantasi Ion Aluminium Nitrida Terhadap Sifat Ketahanan Korosi Baja Tahan Karat Tipe SS 304, Final Project, Sebelas Maret Univeristy, 2006 [6]. Sujitno, T., Aplikasi Implantor Ion Untuk Non Semikonduktor dan Semikonduktor, Materi Kuliah, Pelatihan Akselerator dan Pemanfaatannya, BATAN, 2003 [7]. Sujitno, T., Pemanfaatan Implantor Ion 150 kev/2ma Untuk Surface Treatment, Proseding Pertemuan dan Presentasi Ilmiah Teknologi Akselerator dan Aplikasinya, BATAN, 2006 [8]. Trethewey, K.R. and Chamberlain, J., "Korosi untuk Mahasiswa Sains dan Rekayasa", PT. Gramedia Pustaka Utama, Jakarta, 1991 [9]. Vardiman, R. G., et.all., The Effect Of Nitrogen Implantation On Martensite In 304 Stainless Steel, Metastable Materials Formation By Ion Implantation, Elsevier Science Publishing Company, Inc., 1982 [10]. download date 28 July