Papers by Author: Johny Wahyuadi Soedarsono

Abstract: Lithium demand has increased rapidly in the last few years because lithium is a metal that is important in technology, like electronic equipment and electric vehicles. One of the primary lithium resources is lithium ore, which contains minerals such as spodumene and lepidolite. Mica schist is one of the lithium ore sources that is indicated to contain lithium. The mica schist used in this research was from Kebumen, Central Java, Indonesia. This raw material indicates a lithium mineral called lepidolite. The aims of this research were to find out the potential of local Indonesian minerals as raw materials for lithium extraction processes in lithium-ion battery (LiB) applications, with the effect of leaching time and solid/liquid ratio. The leaching agent used in this research was 2 M chloride acid (HCl). Variables of this research were-100 mesh for particle size of raw material, 1:5, 1:10, 1:15, and 1:20 (g/ml) for solid/liquid ratio, 30, 60, 90, and 120 minutes for leaching time, and 70 °C for leaching temperature. Inductively Coupled Plasma (ICP-OES) analysis was done on this research to determine the mica-schist composition. The optimum lithium percentage that was obtained in this research was 40.65% on a solid/liquid ratio of 1:5 (g/ml) and a leaching time of 120 minutes.

Abstract: Acidizing is one of the stimulation technologies in the oil and gas industry by removing scale, rust, debris or other acid-soluble particulates on the pipe tubing internal surface. The most common acid used is HCl. To avoid problems such as pipe or casing tubing leak due to acidic corrosion, during the acidizing normally applied with inhibition treatment by inorganic corrosion inhibitor with various compositions including quaternary ammonium salts, solvent and often some surfactant to strip oil from acid reactive surfaces. However, most of these compounds are not only expensive but also toxic to the marine environment. It is an obvious remark to point out the importance of low cost, green corrosion inhibitors which is safe to the environment. The wood extract has become important as an environmentally acceptable, readily available and renewable resource for wide range of inhibitors. A Caesalpinia Sappan L modified imidazoline has been synthesized and used as a corrosion inhibitor for carbon steel in API 5L X60 in HCl 1M environment.The aim of the investigation is to find low dosage-high efficiency green corrosion inhibitor.The testing techniques include wheel test weight loss measurement, Tafel polarization and Electrochemical Impedance Spectroscopy (EIS), Fourier Transform Infra-red Spectroscopy (FTIR). The results of weight loss studies correlated well with those of polarization and Impedance Spectroscopy. Inhibition performance for both Caesalpinia Sappan L modified imidazoline ( CS IMI) and Imidazoline (IMI) increases with increasing inhibitor concentration. The formulated Caesalpinia Sappan L modified imidazoline ( CS IMI), and Imidazoline (IMI) inhibitors give a greater than 90% inhibition efficiency with dosage 25 ppm at a temperature of 90-140°F. Caesalpinia Sappan L modified imidazoline (CS IMI), and Imidazoline (IMI) show comparable inhibition performance. However, at temperature 140 ^oF, Imidazoline (IMI) seems to have a slightly better performance, indicating better thermal stability. Caesalpinia sappan bioactive agents are brazilein and chalcone, and its inhibition mechanism by physisorption obey Langmuir Isotherm, this mode will control charge transfer at surface metal and electrolyte.This result confirms that Caesalpinia sappan modified imidazoline is very promising for the development of green corrosion inhibitors for oil and gas application

Abstract: Cooling rate plays an important role in the formation of thin wall ductile iron microstructure due to their thickness, which is 3 mm below based on Stefanescu. Cooling rate is closely related to casting design and determines the microstructure. This paper discusses the effect of casting design modification to casting yield and microstructures. Modification was made on a patented design used previously to produce thin wall ductile iron plates. The design was minimized and casting simulation was used to analyze castability of the design. After that, the design were casted in several pouring temperatures. Improvement was made to casting design based on the failure during the experiment. Casting process took place after simulation analysis. The casting product was fully casted as shown by the simulation. The casting yield has improved to 28%. When all plates were examined for microstructure, the result showed that all the microstructure of the plates was not graphite in ferrite matrix as occurred in the patented design but it was graphite in pearlite matrix.

Abstract: Sugarcane bagasse has demonstrated its ability to act as a reductor in iron-reduction process. As a reductor, bagasse has specialties as double-acting reductor equiped with volatile matter. This is the first study of the use of bagasse as reductor in iron-reduction process. The parameter concluded from this study was used for the second study which report has been submitted for publication. The aim of this study is to discuss the effect of reduction process parameter to the use of bagasse as reductor. This study was divided into 2 step. The first step is determining the optimum reduction process temperature and weight ratio. The reduction temperature varied as 700, 800, 900 and 1000 °C and the weight ratio are 1:2 and 1:4. The process duration is 30 minutes. The second stape is determining the process duration. The process duration will be varied as 30, 45 and 60 minutes. The condition of bagasse is air dried basis. The result shows that the reduction process produced wustite (FeO).

Abstract: Iron ores should be separated from oxygen and impurities which are coming along during the mining process. The separation process is known as reduction. There are two types of reduction process, and the most common is direct reduction process (DRP). There are several parameters in DRP which will determine the quantities of the product known as direct reduction iron (DRI). This worked discussed the effect of reduction temperature and pellet heap to the quantities of DRI using single conveyer belt Hearth furnace. The worked was done in laboratory scale using composite pellets with 14 mm in diameter. The ratio of iron ore to coal in the composite pellet is 1 to 1. The reduction process temperatures are 500^oC, 700^oC and 900^oC. The reduction time is 25 minutes. While the pellets heap are also varied to 1, 3, 5, 7, 8 and 9 layers. The results show that DRI was formed in 700^OC and the quantities of DRI are in line with the reduction temperatures and layers of composite pellets heap.

Abstract: Anodizing process conducted in Al7xxx/SiC produced non-uniform thickness of porous anodic film with cavities, micro-pores and micro-cracks. Cerium sealing was chosen as a post treatment to remedy the poor anodic film by providing a composite layer in order to further enhance the corrosion resistance in aggressive environment. In this study, anodizing process was conducted in H₂SO₄ solution at current density values of 15, 20, and 25 mA/cm² at room temperature, 0°C and-25°C for 30 minutes. Subsequently, electroless sealing was conducted in CeCl₃.6H₂O + H₂O₂ solution at room temperature and pH 9 for 30 minutes. Integrated protection composed of anodizing at 0°C and cerium sealing process in Al7xxx/SiC produced cerium rich deposits in the diameter of 64 nm (± 3nm) on the surface of anodic oxide layer. These spherical deposits covered the entire surface of anodic oxide layer in accordance with the morphology of the oxide layer. Otherwise, almost no cerium deposit formed on the surface of the oxide layer by conducted integrated protection at room temperature and-25°C. The integrated process conducted at anodizing temperature of 0°C presented a highest protection degree. The cerium protective layer which leads to the decreasing of corrosion rate and current density up to 99,99% or four orders magnifications than that of bare composite.

Abstract: Cooling rate plays an important role in thin wall ductile iron solidification, due to their thickness. Casting simulation is use as a tool to estimate the cooling rate. In the other hand, every microstructure has its own cooling rate. This paper explores the similarity of solidification mechanism between simulation and graphite characteristics. Three types of casting design simulated and produced. Solidification mechanism is analyzed based on cooling rate sequence and trend line matching. Temperature gradient and thermocouple function represent simulation while graphite characteristic represent experiment. The result shows that similarity in solidification mechanism is not found between simulation with experiment due to lack of parameters in both sides.

Abstract: Using vitamin C or ascorbic acid as corrosion inhibitor has several weakness. In its liquid form ascorbic acid is easily oxidized and its anti oxidant properties unstable due to heat, light, oxidizer, dissolved oxygen and heavy metals. Purple sweet potato (ipomoea batatas L) with its high anthocyanin is one of alternative for green corrosion inhibitor. Extract of purple sweet potato has the ability to hold the enzyme reaction and oxidation proses of ascorbic acid. Purple sweet potato extract mixed with ascorbid acid is used as inhibitor of API 5L steel in 3.5%NaCl. This compound is classifid as mixed type inhibitor. The adding of purple sweet potato extract will assist ascorbic acid to maintance its inhibition efficiency and increases surface layer corrosion resistant of steel. Polarization methods and electrocehmical impedance spectroscopy (EIS) are used to investigate corrosion rate and mechanism of the steel. Appliaction of 4 ml purple sweet potato mixed with 10^-4M ascorbic acid inhibitor increases inhibition ability of API 5L steel from 23.5 to 57.52%. Purple sweet potato extract moves polarization curve to lower potential (below 82 mVolt) with tends to be more negative.

Abstract: Utilization of ascorbic acid as corrosion inhibitor has several weaknesses. These weaknesses are easy to oxidize in solution form and reduction of its antioxidant properties due to heat, light, oxidizing agent, dissolve oxygen, and heavy metals. Purple sweet potato extract is an alternative green corrosion inhibitor with major contains of anthocyanin compound. Anthocyanin will withstand enzymatic reaction and oxidation process of ascorbic acid. Addition of purple sweet potato extract in ascorbic acid will enhance inhibition efficiency of steel compare to the used of ascorbic acid alone. Interaction of purple sweet potato extract with 0.01M ascorbic acid in 0.1M FeCl₃ environment was analyzed using FTIR spectroscopy. The result shows that interaction of purple sweet potato extract with ascorbic acid in 0.1M FeCl₃ build ability to form iron chelate.

Abstract: AMC (Aluminum Matrix Composite) as a main material for automotive and aircraft applications has the keyadvantage that islighter thanaluminumalloys. So, it can be ascertained that fuel comsumption forthoseapplicationswill be reduced. However, AMC materials are generally suceptible to galvanic corrosion due to galvanic reaction between aluminum matrix and reinforcement, and the formation of microstructure at matrix/reinforcement interface as well. Anodizing is the most effective surface modification method in order to protect AMCs surfaces. This process produces porous anodic coating which has the characteristics of high corrosion resistance and hardness layer. However, the presence of reinforcement particles in AMC hinders the initiation and growth of the protective oxide layer by forming cavities and micro crack. Therefore cerium sealing has been done to remedy the poor anodic film in order to further enhance the corrosion resistance in aggressive circumstances. The material studied in this research was AMC Al7xxx/SiC. Anodizing process were conducted in H₂SO₄ solution at current densities 15, 20, and 25 mA/cm² at 0°C for 30 minutes. Subsequently, continuedwithelectro lesssealinginCeCl3.6H₂O+H₂O₂ solutionat room temperature atpH9 for 30 minutes. The morphologies of anodic coating and sealing layer were examined by means of FE-SEM, the corrosion resistance of composites was estimated in a 3.5 wt.% NaCl solution by potentiodynamic polarization test. Coating process conducted by anodizing and cerium sealing in various of anodizing current densities at 0°C results in protective layers which lead to the decreasing of corrosion rate and current density up to four orders magnifications than that of bare and anodizedAl7xxx/SiCcomposite.