Modifikasi Pengujian Kekuatan Lekat Lapisan Hvof Thermal Spray Dengan Serbuk Wc Pada Nosel Roket

Modification of Bonding Strength Test of WC HVOF Thermal Spray Coating on Rocket Nozzle. One way toreduce structural weight of RX-100 rocket is by modifying the nozzle material and processing. Nozzle is the main targetin weight reduction due to the fact that it contributes 30 % to the total weight of the structur. An alternative for this is bysubstitution of massive graphite, which is currently used as thermal protector in the nozzle, with thin layer of HVOF(High Velocity Oxy-Fuel) thermal spray layer. This paper presents the characterization of nozzle base material as wellas the modification of bonding strength test, by designing additional jig to facilitate testing processes while maintaininglevel of test accuracy. The results showed that the material used for RX-100 rocket nozzle is confirmed to be S45Csteel. Modification of the bonding strength test was conducted by utilizing chains, which improve test flexibility andmaintains level of accuracy of the test

Peran 1 Dan 9 Wt. % Zn Dalam Proses Pengerasan Presipitasi Paduan Aluminium Aa319

The Role of 1 and 9 wt.% Zn in Precipitation Hardening of AA319 Aluminium. Aluminium alloys are widely used for automotive application due to its low density and high corrosion resistance. For economic reason, casting of automotive products always uses aluminium scrap as charging materials that may result in fluctuation of content of alloying element, such as Zn. This research studies the role of Zn in precipitation hardening of AA319 aluminium alloys. Hardness and tensile testing were conducted to study the mechanical properties of the alloys, while ageing response was followed by hardness measurements. Evolution of microstructures was observed by using optical microscope and SEM (scanning electron microscope) equipped with EDS (energy dispersive spectroscopy). Distribution of solute elements was detected by x-ray mapping and formation of nanoprecipitates was observed by using TEM (transmission electron microscope). Research results showed that addition of 1 and 9 wt. % Zn on AA310 alloys increases strength and hardness. Morphology transformation of Al-Fe-Mn-Si phase from chinese script into needle shape was detected, and may be due to dissolution of Zn in aluminium matrix that change the interfacial stress between the matrix and interdendritic phases. Addition of Zn also increased response of alloys to natural ageing but no significant change was detected for artificial ageing at 200 oC. Age hardening was contributed by the formation of θ’ (Al2Cu) nanoprecipitates. Zn was segregated on the periphery of Al2Cu phase

Effects of quenching methods on shape memory properties of Cu-28Zn-3Al wt. % alloy produced by gravity casting

100-107In recent years, Cu-Zn-Al alloys are studied intensively due to their excellence in shape memory effect (SME), good mechanical properties, along with accessible production process and cost. Cu-Zn-Al Shape Memory Alloy easily form stabilization in martensite phase that leads to SME properties reduction, but can be minimized by applying alternative quenching methods. In this research, several quenching methods are proposed to minimize the phase stabilization of martensite. The Cu-28Zn-3Al alloy was produced by gravity casting and homogenized at 800 ℃ for 2h followed by air cooling. Furthermore, as-homogenized plate was betatized at 850 ℃ for 30 minutes and then subsequently quenched using three different methods: direct quench (DQ), up quench (UQ), and step quench (SQ). Morphology, phase transformation, hardness, and strain recovery characterization are examined using an optical microscope, SEM-EDS, XRD, DSC, Vickers, and bending tests. The results showed that the DQ and UQ samples consist of V-shape βˈ[M18R] martensite as a matrix and retained α[A1] as the second phase. The volume fraction ratio of βˈ[M18R]: α[A1] is (98.4:1.6) and (92.9:6.1) for DQ and UQ, respectively. However, the SQ sample did not indicate the presence of the martensite phase and did not show any recovery rate. Bending test showed that DQ and UQ had 27.2% and 36.3% of recovery rate, respectively

Seroepidemiologic Assessment Of Malaria Using An Elisa For Ring-infected Erythrocyte Surface Antigen Of Plasmodium Falciparum

Zat anti terhadap antigen permukaan dari sel eritrosit yang terinfeksi dengan parasit bentuk cincin (Ring-infected Erythrocyte Surface Antigen/RESA) Plasmodium falcipa­rum telah diukur dari sera yang dikumpulkan di Jawa Tengah, Jawa Timur, dan Irian Ja­ya. Untuk mendeteksi IgG terhadap RESA tersebut digunakan ELISA (Enzyme Linked Immuno Sorbent Assay). Dari pengukuran tersebut menunjukkan adanya korelasi antara RESA ELISA dengan pengukuran epidemiologis transmisi malaria secara konvensional. Pada tulisan ini diuraikan tentang prosedur standar untuk melakukan RESA ELISA dan membahas hal-hal yang menguntungkan maupun keterbatasan-keterbatasan dalam ekstrapolasi data untuk menggambarkan perkiraan transmisi malaria