Papers by Author: Agus Geter E. Sutjipto

Abstract: High silica MFI zeolite membrane was synthesized by hydrothermal method at 313 K on asymetri pore structure alpha alumina substrate, utilizing natural rice husk as the sources of silica. The top layer of substrate was about 0.1 µm. The calcination was conducted at 773 K to remove the organic template. This membrane has a good stability at high temperature and in organic solvent. The membrane structure was identified by X-ray diffraction (XRD). The permeation of some pure gases was carried out to detect pinhole or cracking by studying mass transfer mechanism in the membrane. The pervaporation performance of as-synthesized membrane showed good results. This process was able to produce fuel grade bioethanol (99.2%) with the separation factor about 14.

Abstract: AZO is an ideal replacement transparent conducting oxide (TCO) for ITO to all corresponding applications. The typical applications include: transparent electrodes for solar cells, flat panel displays, LCD electrodes, electro-magnetic compatibility (RF-EMI shielding) coatings, touch panel transparent contacts, static discharge dissipation. The production of useful and commercially attractive thin films using different deposition processes is very important parameter to investigate. A systematic study of the sputtering condition and their influenced on electrical and structural were studied. In this work, AZO films were deposited by RF magnetron sputtering at 200 °C. The result shows that the deposited time has influenced the characteristic of deposited AZO films. For a longer deposition time, thin film shows a uniform grain growth. The resistivity found minimum at the deposition time of 45 minutes. It can be considered that by reducing of the grain boundaries which enable the electron carries to conduct smoothly.

Abstract: Copper-based composite now is a potential material for various applications, while powder metallurgy processing technique is an alternative for high temperature processing materials and net shape component. In this research, Cu-based composite containing 10-50 vol% SiC fibers was fabricated by employing the powder metallurgy route. The mixtures of SiC fibers and Cu particles were blended in a ball milling machine with the addition of ethanol at 150rpm. Then, the mixtures were uniaxially compacted into a ɸ13.5mm cylindrical pallet and followed by sintering in vacuum furnace from 800-950°C for 4 hours. The density of the composite decrease with increasing SiCf and density as high as 87% for 10vol% SiCf/Cu matrix sintered at 800°C had been achieved. The Vickers hardness of 774MPa also had been achieved for 10vol% SiCf/Cu matrix but sintered at 900°C.

Abstract: Advanced development of computer network through Internet brings the technology to Manufacturing. Increasing the demand for effectively use of the production facility requires the tools for sharing the manufacturing facility by remote operation of the machining process. This paper introduces the methodology of machining technology for direct remote operation of networked milling machine. The tools including virtual simulation using CAD model, remote desktop protocol and Setup Free Attachment for remote operation of milling process are proposed. Accessing and monitoring of machining operation is performed by remote desktop interface and 3D virtual simulations. Capability of remote operation is supported by an auto setup attachment with a reconfigurable pin type setup free technology installed on the table of CNC milling machine to perform unattended machining process. The system is designed using a computer server and connected to a PC based controlled CNC machine for real time monitoring. A client will access the server through internet communication and virtually simulate the machine activity. The result has been presented that combination between real time virtual simulation and remote desktop tool is enabling to operate all machine tool functions and as well as workpiece setup.

Abstract: High purity MgO is a common ceramic material used as a protecting layer in an alternating current plasma display panel (AC-PDP). In this work, pure MgO was added by CaO for a better protecting layer. The effect of CaO addition was discussed according to the changes in the microstructure, mechanical strength and the ability of the sample to withstand surface breakdown (flashover) with various CaO addition in the powder mixture. In addition, it was found that 2.5 wt% CaO-addition shows a better electrical discharge. Since secondary electron emission coefficient contributes in the electrical discharge, it could be predicted that the 2.5 wt% CaO added MgO has a higher secondary electron emission constant and becomes a promising candidate for a protecting layer in AC-PDP.

Abstract: In the present investigation, low temperature nitriding has been attempted on AISI 316L austenitic stainless steel by using a laboratory fluidized bed furnace. The nitriding was performed in temperature range between 400°C and 500°C. X-ray diffraction, metallography, and corrosion tests were used to characterize the resultant nitrided surface and layers. The results showed that fluidized bed process can be used to produce a precipitation-free nitrided layer characterized by the S phase or expanded austenite on austenitic stainless steel at temperatures below 500°C. But there exists a critical temperature and an incubation time for effective nitriding, below which nitriding is ineffective. The corrosion behaviour of the as-nitrided surfaces is significantly different from that previously reported for low temperature plasma nitriding. This anomaly is explained by the formation of iron oxide products and surface contamination during the fluidized process.