PERILAKU SENSITASI PADA LOGAM STAINLESS STEEL SERI J4 AKIBAT PERLAKUAN PANAS

The 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

EFFECT OF HEAT TREATMENT TEMPERATURE ON MICROSTRUCTURE CHARACTERISTIC AND HARDNESS PROPERTIES OF CASTED Ti-6Al-4V ELI

Ti-6Al-4V Extra Low Interstitial (ELI) alloys have been widely used for biomedical application as implant materials due to its excellent mechanical properties and good corrosion resistance. Furthermore, mechanical properties of this alloy could be improved by heat treatment process. In this research, it has been studied the effect of heat treatment temperature on microstructure and hardness properties of casted Ti-6Al-4V ELI alloy. After calculation of material balance to obtain this alloy composition, raw materials were melted using single arc melting furnace flowed with argon gas and melted alloy was casted. Then, it was heat treated by solution treatment for around 1 hour and subsequently quenched in water as medium. Solution temperature was given with temperature variables of  850oC, 950oC and 1050oC.  After that, it was aged at temperature of 500oC for 4 hours. Microstructures were observed using optical microscope and hardness value were obtained by Vickers hardness method. The results of microstructure observation showed that it was changed after heat treatment process, especially on morphology of α and β phase. Thus, the hardness of alloy significantly increased compared with as-cast condition after heat treatment process. The optimum value of hardness was obtained at temperature of 850oC that was 478 HVN.

HUBUNGAN ANTARA NERACA AIR LAHAN TERHADAP PRODUKSI KARET KLON BPM24

Secara umum produksi karet dipengaruhi oleh fluktuasi curah hujan setiap bulan. Penelitian bertujuan mengetahui pengaruh curah hujan, evapotranspirasi, dan ketersediaan air lahan terhadap produksi karet klon BPM 24. Penelitian ini dilaksanakan di Kebun Percobaan Balai Penelitian Sembawa, Sumatera Selatan dari tahun 2013 – 2015. Plot penelitian yang digunakan adalah tanaman menghasilkan klon BPM 24 tahun tanam 2002 berumur 14 tahun dengan tekstur tanah clay loam. Penelitian ini dilakukan dengan cara membandingkan produksi tanaman karet pada saat musim hujan dan musim kemarau dari tahun 2013-2015. Hasil penelitian menunjukkan bahwa kadar air tanah merupakan parameter yang paling berpengaruh terhadap hasil lateks tanaman karet klon BPM 24 dibandingkan dengan parameter curah hujan dan evapotranspirasi. Hasil lateks menurun dengan berkurangnya kandungan air tanah pada periode bulan kering. Kurangnya air pada bulan kering menjadi faktor pembatas untuk hasil karet yang optimal. Ketika kadar air tanah turun hingga di bawah 100 mm, hasil lateks maksimal yang dapat dicapai oleh tanaman karet adalah sebesar 20 g/p/s

PENGARUH SINTERING BERULANG TERHADAP STRUKTUR KRISTAL DAN MORFOLOGI PERMUKAAN BI,PB-SR-CA-CU-O YANG DIDOPING MG

Telah dilakukan sintesis pelet superkonduktor Bi1.6Pb0.4Sr2Ca1.8Mg0.2Cu3O10+δ menggunakan metode padatan dan proses sintering berulang.Benda uji yang dibuat dianalisis dengan menggunakan XRD (X-ray Diffractometer) dan SEM – EDS (Scanning Elektron Microscopy - Energy Dispersive Spectroscopy). Berdasarkan analisis XRD didapatkan fase yang terbentuk adalah (Bi,Pb)-2223, (Bi,Pb)-2212, CaPbO3, Ca2PbO4 dan MgO. Perlakuan sintering berulang pada benda uji BPSCCO doping Mg dapat meningkatkan fraksi volume (Bi,Pb)-2223 dari 37% menjadi 68%. Berdasarkan analisis SEM, didapatkan luas porositas pada morfologi permukaan benda uji sebesar 4,742%. Adapun dengan perlakuan sintering berulang menyebabkan terjadinya penurunan luas porositas dari 4,742% menjadi 2,132% hingga 1,589% untuk benda uji sintering 1 kali, 2 kali, dan 3 kali. Bentuk butir juga semakin lebih seragam akibat dari perlakuan sintering berulang yang diberikan pada sampel

PERFORMANCE ANALYSIS OF PSO-PD CONTROLLER IN CONTROLING THE RIGID GANTRY CRANE SYSTEM

Karya tulis ini membahas tentang algoritma particle swarm optimization (PSO) untuk mengoptimalkan penguat pengendali PD yang dinamakan pengendali PSO-PD. Efektivitas algoritma pengendali yang diusulkan diuji dengan menggunakan fungsi step dan dibandingkan dengan pengendali PD berbasis Zigler-Nichols (ZN-PD). Hasil simulasi yang didapatkan menunjukkan bahwa pengendali PSO-PD menghasilkan waktu naik dan waktu puncak yang lebih lambat dibandingkan dengan pengendali ZN-PD, tetapi memiliki waktu tunak yang lebih cepat dan nilai overshoot yang kecil di bawah trayektori yang didefinisikan.Kata kunci: Sistem gantry crane, PSO, Gain PD, Sudut ayunan AbstractThis paper presents the particle swarm optimization (PSO) algorithm to optimize the gains of the PD controller to form what so-called the particle swarm optimization (PSO-PD) controller. The effectiveness of the proposed control algorithm is tested under constant step function and compared with Ziegler-Nichols (ZN-PD) controller. Simulation results show that proposed controller has slower rise time and peak time than ZN-PD controller as well as small overshoot under the predefined trajectories

INFLUENCE OF CARBON AND NITROGEN ADDITION ON THE CORROSION RESISTANCE OF Co-28Cr-6Mo-0,8Si-0,8Mn-0,4Fe-0,2Ni ALLOYS

Cobalt alloys is one of the implant materials that is used in orthopedic and dentistry, because of its biocompatibility, good mechanical properties, and high corrosion resistance. The mechanical properties and corrosion resistance can be enhanced by thermomechanical treatment and addition of alloying element. Carbon and nitrogen were added to enhance mechanical properties and high corrosion resistance. Effect of carbon variation and nitrogen to the corrosion resistance in Co-Cr-Mo (CCM) alloys were measured by corrosion measurement system (CMS) device in Hank’s Solutions after thermomechanical treatment process. Corrosion rate of Co-Cr-Mo alloys with carbon variation dropped to 5.8 x 10-4 mmpy and 5.2 x 10-4 mmpy with carbon variation and nitrogen. Decreasing corrosion rate indicated that the corrosion resistance of alloys is increased with the addition of carbon and nitrogen

EFFECT OF NICKEL PULSED ELECTRODEPOSITION PARAMETERS ON DEPOSIT MICROSTRUCTURE AND CORROTION RATE AISI 410

Nickel 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

THE EFFECT OF CHARGING CONDITION FOR CONDUCTED EMISSION VALUE OF INFORMATION TECHNOLOGY EQUIPMENT

Currently, IT devices, especially mobile phone and notebook, have become a staple for humans. These devices can’t be separated from human activities. Mobile phone or notebook using those are too often can lead people to conduct any charging process when that device is being used. In general, there are three conditions for any devices when the charging process is being performed, such as: off, standby, and normal use (music on). This research objective is to compare the result on conducted emis- sion testing when mobile phone and notebook at the plugging charge for the conditions: off, stand by, and normal use (music on). Testing method refers to CISPR 22 Standards at Clause Mains Terminal Disturbance Voltage. Testing result for mobile phone and notebook show that all of testing sample perform conducted emission value with quasi peak value meet the requirement of CISPR 22. The amount of 80% testing sample, perform the highest quasipeak margin value when the off condition of devices