Papers by Dewi Idamayanti
Exploring the Influence of Temperature on Sodium Titanate Mineral Formation Using X-Ray Diffraction
Journal of physics. Conference series, Mar 1, 2024
Peningkatan Kekerasan Permukaan Ferro Casting Ductile (FCD) 700 Melalui Proses Nitridasi Dengan Media Urea
CR journal (creative research for West Java development), Jun 29, 2015
IOP Conference Series: Materials Science and Engineering, 2019
Water pump machine impeller is made of gray cast iron with some variation of wall thickness. The ... more Water pump machine impeller is made of gray cast iron with some variation of wall thickness. The thin part undergoes consequently a very rapid cooling and promotes the formation of hard ledeburite, This study removes the already formed ledeburite ((α + Fe3C) + Fe3C) by mean of heat treatment. By calculating the mass fraction of iron carbide at the level of 5%, heating the material at the austenite temperature, holding it for 2 hours and cooling it subsequently in the air, ledeburite changes to ferrite and graphite. Graphite is formed discrete along the grain boundaries of previous pearlite after the completion of heat treatment. The graphite resembles a randomly oriented eutectic undercooling type D and this is associated with a decrease of hardness to 115HV at the tip of the impeller blade.
Advances in physics research, Dec 31, 2022
This study investigated the properties of mesocarbon anodes in the half-cell of sodium-ion batter... more This study investigated the properties of mesocarbon anodes in the half-cell of sodium-ion batteries. The behavior of mesocarbon was examined using electrochemical methods. Cyclic voltammetry (CV) was applied with various scan rates to reveal the anodic-cathodic voltage and peak current. The CV profile allowed for predicting the energy storage mechanism of sodium ions in mesocarbon. The CV measurement of the half-cell Na | mesocarbon demonstrated the intercalation and de-intercalation of sodium ions in the graphene interlayer at 0.01 V and 0.12 V, respectively. Based on the Power law, the kinetics of sodium ion movement was controlled by the diffusion-dominant reaction. After 25 cycles, the electrochemical impedance spectroscopy (EIS) spectra exhibited increasing resistances in the solid-electrolyte interface (R SEI ) and charge transfer (Rct), ranging from 53.8 to 65.6 and 42.6 to 229 , respectively. Considering the charge/discharge rate capability in the first five cycles, the mesocarbon could deliver a specific capacity of discharge of 42 mAh/g at 0.1 C and retain 73% of its capacity after 25 cycles.
Free-standing hard carbon anode based on cellulose nanocrystal-reinforced chitosan substrate for eco-friendly sodium-ion batteries
Journal of energy storage, Jun 1, 2024
Cellulose
This work successfully fabricated flexible substrates made of cellulose nanocrystal-reinforced ch... more This work successfully fabricated flexible substrates made of cellulose nanocrystal-reinforced chitosan (CNC-Ch) through a simple water-based casting method. The rice husk cellulose nanocrystals (CNCs) were employed to reinforce the chitosan (Ch) matrix in the range of 10-50 wt%. The CNC-Ch substrates produced compact homogenous film with good dispersion and distribution of CNCs within the chitosan matrix. Afterward, the CNC-Ch substrate was applied to form a self-standing hard carbon anode with a mass loading of 5 mg/cm 2. As an anode, the hard carbon with 10 wt% of CNC showed the highest electronic conductivity of 0.9774 S/cm and ionic conductivity of 2.12 × 10-5 S/cm in half-cell of hard carbon | NaClO 4 1 M EC: DMC (1:1) | Na, with acceptable mechanical properties. These characteristics indicate a promising CNC-Ch substrate candidate for flexible hard carbon anodes for advanced sodiumion battery applications.
The Influence of Intercritical Annealing Holding Time on Mechanical Properties of AISI 4340 Steel
IOP Conference Series: Materials Science and Engineering, 2019
A low-high austempering process can be referred to as the application of undercooling condition i... more A low-high austempering process can be referred to as the application of undercooling condition in the austempering process of Austempered Ductile Iron (ADI). Undercooling condition promote more grain nucleation and producing finer grains with good mechanical properties. This study aims to investigate the influence of the first stage of lower temperature austempering holding time on its mechanical properties and find the best holding time which can produce the highest toughness of ADI materials. The experiment began with the heating of the nodular cast iron sample up to 927 °C and held for 120 minutes. Then it quenches to a liquid salt bath with a temperature of 260 °C as a lower temperature of the first austempering stage with a variation of holding time at 30, 60 and 90 minutes. Then it was transferred to a second salt bath medium of 400 °C as the second austempering stage with a holding time of 120 minutes then it was given the air cooling. The sample was tested by hardness, tens...
The Effect of Two-Step Austempering Heat Treatment Holding Time to The Mechanical Properties of Austempered Ductile Iron (ADI)
Synthesis of sodium iron oxide from sodium carbonate and ilmenite-based iron hydroxide via a wet milling method
Nucleation and Atmospheric Aerosols, 2022
Synthesis of sodium iron oxide from sodium carbonate and ilmenite-based iron hydroxide via a wet milling method
Nucleation and Atmospheric Aerosols, 2022
IOP Conference Series: Materials Science and Engineering, 2019
The Pulverizer pipe made of mild steel had erosion failure due to coal dust impacting, thus its s... more The Pulverizer pipe made of mild steel had erosion failure due to coal dust impacting, thus its service life also reduces. The ceramic coating overlay on the surface of mild steel is one of the appropiate ways to protect the mild steel from erosion. This research is aimed to perform a ceramic coating over the surface of the mild steel using a dipping method to improve its erosion resistance by using the alumina-phosphate ceramic coating. The coating layer is formed by the reaction between monoaluminum phosphate (MAP) as a binder and Al2O3 particles. It transforms into berlinite phase when heated at an elevated temperature. The observation is carried out with the variation of the MAP binder composition Al:P 25:75, 28:72, 30:70 and the Al2O3/MAP slurry is given at 40/60. Scanning electron microscopy is used to characterize the coating morphology. X-ray diffraction is applied to investigate the ceramic coating phases. The gas erosion jet measures erosion resistance of the ceramic coati...
IOP Conference Series: Materials Science and Engineering
This research is focused on the application of the Al2O3-phosphate ceramic coating on mild steel ... more This research is focused on the application of the Al2O3-phosphate ceramic coating on mild steel surface to protect mild steel from erosion in coal dust environment. Erosion resistance of mild steel could be improved by overlay it with SiC in the Al2O3-phosphate ceramic coating. As a filler, Al2O3 was mixed with 20%, 40%, and 60% SiC by using aluminium phosphate as a binder and heated at 220 °C for 5 hours. X-ray diffraction testing was conducted to observe the phase of Al2O3-SiC phosphate ceramic coating. Meanwhile, surface morphology and adhesion characteristic of Al2O3-SiC phosphate ceramic coating were analyzed by scanning electron microscope. To analyze the erosion resistance quantitatively solid particle impingement test by applying gas jets at the right angle (90°) against a sample surface has been conducted. The results showed that Al2O3-SiC phosphate ceramic coating is strongly bound to the mild steel surface without the presence of any void. The higher the SiC content can ...
PENGARUH PROSES TEMPERING GANDA TERHADAP SIFAT MEKANIK MATERIAL BAJA COR PADUAN Ni-Cr-Mo
Pengaruh Waktu Heat Treatment Terhadap Karakteristik Ceramic Coating Berpengikat Fosfat pada Baja Karbon Rendah
Low carbon steel is commonly used in the coal handling industry, but has low erosion and corrosio... more Low carbon steel is commonly used in the coal handling industry, but has low erosion and corrosion resistance. Hence, there is often a performance decrease due to the work environment that causes erosion and corrosion. Therefore, phosphate-bonded ceramic coating is applied. Al (OH) 3 and H3PO4 are used as a base material of binder. SiC (silicon carbide) and alumina are ceramic particles which is used in this research. The heat treatment was carried out for 1 hour, 3 hours and 5 hours to determine the effect of heat treatment time on phosphate bonded ceramic characteristics. The SEM results show that the longer of the heat treatment time, the more vacancies are formed. To determine erosion resistance of ceramic coating, erosion test is conducted, and the result show that erosion rate of ceramic coating with addition of SiC particles was 7.5 mg/Kg and without SiC was 14.2 mg/Kg. To make sure of berlinite, water resistance test was carried out, because berlinite is not soluble in water...
Peningkatan Kekerasan Permukaan Ferro Casting Ductile (FCD) 700 Melalui Proses Nitridasi Dengan Media Urea
Ferro Casting Ductile (FCD) 700 digunakan untuk produk yang memerlukan kekuatan, duktilitas dan k... more Ferro Casting Ductile (FCD) 700 digunakan untuk produk yang memerlukan kekuatan, duktilitas dan ketahanan impak, misalnya pada poros engkol. Untuk meningkatkan kinerja material dapat dilakukan pengerasan permukaan antara lain dengan proses nitridasi. Proses nitridasi dengan menggunakan urea sebagai sumber nitrogen dilakukan untuk meningkatkan kekerasan permukaan hingga 700 HV (60 HRC). Pada penelitian ini proses nitridasi dilakukan berdasarkan rasio urea per luas permukaan nitridasi. Variabel parameter yang diaplikasikan adalah temperatur (530 0C, 550 0C, 580 0C, 600 0C, dan 620 0C) dan waktu proses (1 jam dan 2 jam). Parameter yang digunakan secara konstan adalah rasio ketersediaan urea per luas permukaan sebesar 0,25 g/mm2 dan tekanan ruangan nitridasi 0,3 Mpa. Verifikasi hasil dilakukan dengan pengujian kekerasan dan struktur mikro. Berdasarkan analisa struktur mikro yang didapat, pada variasi temperatur dan waktu nitridasi (580 0C, 600 0C, dan 620 0C dengan waktu proses nitridas...
The influence of flushing time on the bonding quality of liquid white cast iron on the solid surface of similar material
Hard metal castings are widely used in the coal mill pulverizer as construction material for coal... more Hard metal castings are widely used in the coal mill pulverizer as construction material for coal crushers. During its operation crushers and mills experience degradation caused by abrasion load. This research dealed with the surface overlaying of similiar material on the surface of white cast iron by mean of gravity casting. The die blank casting was preheated prior to the casting process of outer layer made of Ni-Hard white cast iron to guarantee bonding processes and avoid any crack. The preheating temperature of die blankin ther range of 500C up to 850C was set up to reach the interface temperature in the range of 887°C -1198°C and the flushing time was varied between 10-20 seconds. Studies carried on the microstructure of sample material revealed a formation of metallurgical bonding at the preheating temperature above 625 °C by pouring temperature ranging from 1438 °C to 1468 °C. Metallographical and chemical composition by mean of EDS examination were performed to observed the...
The effect of a single quenching double tempering process on the mechanical properties of NiCrMo alloyed steel casting
IOP Conference Series: Materials Science and Engineering
This research aimed to improve the mechanical properties of NiCrMo alloyed steel casting, especia... more This research aimed to improve the mechanical properties of NiCrMo alloyed steel casting, especially in terms of toughness. Toughness is a combination of tensile strength, yield strength, and elongation. The method used was a multi-heat treatment process involves normalizing, tempering, double tempering, and an additional intermediate process of quenching. The results obtained through the normalizing process followed by single quenching on oil media and double tempering (single quenching double tempering) produced the best-combined result of tensile strength, yield strength, and elongation. The modulus of toughness increased by up to 745 % compared to the as-cast condition from 20 N.mm/mm3 to 149 N.mm/mm3. The best mechanical properties were obtained from tempered martensite microstructure. It is free from rest martensite and secondary carbide.
Shifting of the neutral line at a v-bending process of AISI 1015 steel plate
Journal of Physics: Conference Series
During a forming process of steel plate microstructural changes occurs in the material. The outsi... more During a forming process of steel plate microstructural changes occurs in the material. The outside part of the material experiences tension while compression stress takes place in the inner side. Constant uniaxial load, speed and temperature were applied on the V bending of 4 mm thick low carbon steel plate. Microstructural observation and hardness test were carried out on the cross-section area of the plate to assess the changes within the material. It is revealed that an offset of the imaginary neutral line to the inner side has occurred. The elongation of stretched material on the outer side, which is associated with microstructural changes of grain shape, orientation and hardness value does not exceed the proportional plastic area.
Metal casting commonly uses silica sand with water glass as a binder for mold and core. Water gla... more Metal casting commonly uses silica sand with water glass as a binder for mold and core. Water glass binder that overlays grain sand was harden by CO2 gas to form silicate bonding.nbsp Thenbspnbsp waste silica sand was not able to benbsp reused as mold and core because its properties changed due to high temperature exposure during casting process that converted silicate bonding become refractory compound. Recently, several methods were developed to recyclenbsp waste silica sand. The methods recommended were mechanical, thermal and wet methods. In this research, wet method has been selected to reclaimenbsp wastenbsp silica sand due to good properties result.nbsp The research methodology involved several processes. Lumps ofnbsp wastenbsp silica sand was crushed mechanically then mixed with water at the ratio of 1nbsp : 1 by weight andnbsp stirred at the speed of 1400 RPM. The mixing and washing steps have been done gradually until five times. The properties of reclaimed silica sand res...
Uploads
Papers by Dewi Idamayanti