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EFFECT OF NICKEL PULSED ELECTRODEPOSITION PARAMETERS ON DEPOSIT MICROSTRUCTURE AND CORROTION RATE AISI 410
Full text linkNickel pulse electrodeposition is one of the coating methods that used to increase the corrosion resistance and improve the mechanical properties. In this study, nickel was used as the anode and martensitic stainless steel 410 was used as the cathode. The solution used in the method of nickel pulse electrodeposition include nickel sulfate, nickel chloride, and boric acid. Pulse electrodeposition parameters are variation of duty cycle of 70, 80, 90% and frequency variations valued at 0.1, 1, 10, and 20 kHz. Temperatures used in research nickel pulse electrodeposition at 50 ° C, with a current density of 15 A / dm² and 18 minutes. The Scanning Electron Microscopy analysis determine the microstructure and grain size changes after a nickel pulse electrodeposition. The polarization test determine optimum rate of corrosion when 90 % duty cycle and 20 kHz frequency
MODELING OF SEPTIC TANKS SEEPAGE NEAR DUG WELLS IN MARGAHAYU VILLAGE, BANDUNG REGENCY
Full text linkDense settlements have an impact on pollution, one of which is domestic pollution which results in groundwater and soil water pollution at ground level. Identification of pollution that occurs below the soil surface (groundwater contamination) is more difficult to detect, so modeling is needed to find out how the rate of groundwater pollution rate. Modeling is done by using water sampling method at dug well at location adjacent to septic tank. Sampling ground water and infiltration modeling is done by using Geostudio SEEP/W software. The research area is in Margahayu village, Bandung regency. The results of laboratory analysis and physical observation in the field show that the Margahayu region has ammonium (NH4-N) content which is above the standard quality threshold. This condition is reinforced by modeling simulation results that there has been domestic sewage from septic tanks to dug wells. Pollution has reached groundwater level with depth ranged between 4-5 meters. The distance of wells adjacent to the septic tanks affects the quality of groundwater. In the KB area 17 it is indicated that the contamination in the residents' wells in harike-3i, KB new on the 32-40 day time frame, and KB new 2 on the 24th day. Distance sources of contaminants and soil permeability play an important role in determining the travel time of contaminants
ANALYSIS OF CLIMATOLOGICAL THERMAL COMFORT IN DKI JAKARTA USING HEAT INDEX (HUMIDEX)
Full text linkInteractions between human and environment about the influence of the physical atmosphere’s state or weather on human is expressed in com- fort level. The complex relationship between health and weather factors with human comfort is defined as biometeorological index. One of the biometeorological indices is heat index called as Humidex. Studies about Humidex in Jakarta were conducted using climate data stations of Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG), namely air temperature, relative humidity and wind speed daily average during 1985 to 2012. The purpose of this study was to determine the level of thermal comfort using heat index Humidex in Jakarta and its climatological trends during 1985 to 2012. Comparative analysis between Humidex and the wind speed and also with the number of vehicles in Jakarta were conducted to determine their impact to the heat index in Jakarta. The results showed that the Humidex monthly average in Jakarta ranged between 36,1 °C and 39,5 °C. Humidex monthly pattern had two peaks with the first peak was on May and the second one was on November, while the lowest value was recorded on August and January. Humidex in Jakarta tended to increase between 0.05 °C and 0.08 °C with its coefficient of determination (R2) was between 0.36 and 0.71. The effect of wind speed to Humidex was lowering the value of Humidex which increased the thermal comfort. Meanwhile, the number of vehicles showed a tendency to grow exponentially, which affected the further decline in thermal comfort level in Jakarta
PERILAKU SENSITASI PADA LOGAM STAINLESS STEEL SERI J4 AKIBAT PERLAKUAN PANAS
Full text linkThe failure of austenitic stainless steel during the industrial aplications is place sensitization due to heat treatment. The investigation of that failure has been investigated by researchers in particular for stainless steel 2XX and 3XX types, while there isno or little investigation for stainless steel J4 type.Furthermore, the investigation of the presence of sensitization on stainlees steel was conducted by referring to American Society for Testing and Materials (ASTM) A262-02a, which the caracterization of metal surface morphologies dan chrom content used optical microscope andscanning electron microskop, and Energy-dispersive X-ray spectroscopy, respectively. The results elucidate that sensitization is produced in temperature range from700oC up to 900oC .There isgrain boundaries attack onsurface morphologies after sensitization test in the temperature range from700oC up to 900oC ,whichis unlikely to happenat temperature of 600oC. The possibility of chromium difusion to grain boundaries took place from the decrease of chromium content adjancent with grain boundaries and the increase of chromium content in grain boundaries, whichimplies the formation of intermetallic compound of carbide
CORROTION RATE AND MORPHOLOGY OF POROUS METAL ALLOY Mg-Ca-Zn WITH CaCO3 AS FOAMING AGENT
Full text linkMagnesium alloy is a material that has been developed as a biodegradable implant material in orthopedic applications. Magnesium alloys have good biocompatibility, biodegradability, and good mechanical properties which make them have the potential to be used as a biomedical material. The main objective of this paper is to investigate corrotion rate and morphology after corrotion of biocompatibility of implant-based alloys Mg-Ca-Zn with CaCO3 as a foaming agent. Mg-Ca-Zn Alloy was made by the method of powder metallurgy with the addition of CaCO3 as a foaming agent with three variations of composition (96Mg-Ca-3Zn-CaCO3, 91Mg-Ca-3Zn-5 CaCO3, and 86Mg-Ca-3Zn-10 CaCO3 wt%). Sintering process was carried out at 600 °C and 650 °C with a holding time of five hours. Corrosion test was performed using G750 Gamry Instrument in accordance with ASTM standard G5-94. Simulated body fluid electrolyte used is Hank's solution with a pH value of 7.4 and a temperature of 37 °C. Then the analysis of the microstructure after corrosion test was conducted using scanning electron microscopy (JEOL, JSM-6390A Japan) equipped with energy dispersive spectrometry data (EDS). Alloy corrosion rate of Mg-Ca-Zn-CaCO3 increases with the amount of CaCO3 in the alloy and the temperature rise in the sintering. From the test results, the smallest corrosion rate is in the alloy 91Mg-Ca-3Zn-CaCO3 at 600 °C sintering (58.3045 mpy) and the highest occurs in alloy 86Mg-Ca-3Zn-10CaCO3 at 650 °C sintering (91.4007 mpy). Surface morphology of the alloy after the corrosion process is the type of volcano. This localized corrosion occurs where an electrochemical reaction takes place to form a distinctive structure with a circle and a hole in the middle
LOCAL MATERIAL TESTING FOR PAVEMENT MATERIAL ON REMOTE AND OUTMOST ISLAND
Full text linkRoad infrastructure development in remote and outmost islands such as Mentawai, Aru, and Morotai faced a problem i.e. dificulty in the availability of standard material. The standard material had to be transported from other areas that taking a long time and high cost of transportation. In fact, the three islands had abundant materials. However, there was no study conducted to examine the properties of the local material. The study aim was to find out the physical properties of pavement material that will be the basis of pavement design. The research began with the selection of material, discussion with experts, coordination with involved parties, site observation, and laboratory test. The analysis of testing result used comparative analysis that compared test result to certain standard. Based on the analysis, local material from Mentawai Islands was suitable for foundation layer with cement stabilization 6%. Coral from Aru Island and limestone from Momojiu Morotai Island could also be utilized for foundation layer. Limestone from Rau Morotai Island utilized for aspalt mixture. Sand from Aru Island and sea sand from Morotai Island could be used for aspalt mixture and concrete cement mixture
A STUDY OF STRESS CORROSION CRACKING RESISTANCE FOR COLD FORMING PLASTIC DEFORMED Cu-30Zn ALLOY
Full text linkCu-30Zn alloy has good atmospheric corrosion resistance. It is mainly used as automotive radiator cores, ammunition component, lamp fixture, flashlight shells and kickplates. Cold rolled Cu-30Zn with deformation degree 33,87% at 300OC was tested its Stress Corrosion Cracking (SCC) property. Stress corrosion cracking (SCC) of a Cu–30Zn has been investigated using Mattsson solutions 0,5 M (NH4)2SO4 + 0,05 M CuSO4 in room temperature by using a constant load method. Cu-30Zn has a weakness on stress corrosion cracking in ammonia environment (mattson solution). Scanning electron microscope (SEM) testing indicated the failure of cold roll Cu-30Zn was a transgranular cracking. Furthermore, cracking occued at stress below yield stress. Energy dispersive Spectroscopy (EDS) test exhibited dezincification indication on fracture surface. The visual examination of surface morphology on alloy showed discoloration from yellow to red. Homogenized Cu-30Zn showed better SCC resistance than cold rolled Cu-30Zn
WASTEWATER SPECIFIC EMISSION FACTOR FROM COMMUNAL WASTEWATER TREATMENT PLANT (WWTP)
Full text linkGreenhouse gasses (GHG) that produced by anaerobic digestion of wastewater consists of CH4 gas and NO2 gas. Beside the data of specific activity, the specific emission factor also plays important part to determinate GHG emission. The aim of this paper is to know specific emission factor value from communal wastewater treatment plant (WWTP), as an input to determinate GHG emission for determination of GHG emission reduction rate. The data was collected by taking sample of BOD, CH4 gas, and CO2 gas from communal WWTPs. Sampling location were communal WWTPs in Jakarta City, Bandung City, and Yogyakarta City. Those WWTPs using anaerobic baffle reactor as their treatment system with capacity varied between 40-200 EP. The parameters were BOD and CH4 that measured using grab sampling in the morning and evening. Data analyzed by quantitative methods. The specific emission factor value was determined from CH4 gas measurement which affected by wastewater treatment unit dimension, gas catcher chamber, and air suction pump capacity. The analysis results showed specific emission factor for communal WWTPs from the three cities is 0.00171 kg CH4/kg BOD. The value has bid difference when compared to IPCC’s default that is 0.48 kg CH4/kg BOD. This is due to the formation of CH4 gas and CO2 gas was strongly influenced by environmental condition in real time condition. This factor is not taken into consideration in IPCC’s default