No abstract

This paper investigates the physical properties and electrochemical properties of the innovative non-precious metal catalyst using different carbon types. The cathode catalyst for PEMFC (Proton Exchange Membrane Fuel Cell) is an important part of fuel cell because the reaction of the cathode is three times lower than the anode. Otherwise, the high cost of Pt/C catalyst for cathode needs to be replaced using low-cost material. Therefore, this research fabricated Pt free catalyst. FeCl3.6H2O was used as a metal precursor. Urea and PVP as a nitrogen (N) source were mixed with carbon. The variations of carbon are Graphite (Gt), Charcoal Active (CA), and Calcined Petroleum Coke (CPC). As prepared catalysts, were noted as Fe/N-Gt, Fe/N-CA, and Fe/N-CPC. Catalysts without nitrogen addition also were synthesized such as Fe-Gt, Fe-CA, and Fe-CPC for comparison. The electrochemical properties can be evaluated form Cycle Voltammograms (CV) curve. Graphite supported catalyst has anodic and cathodic peak otherwise has the lowest capacity. It means that the redox reaction occurs during CV measurement for Fe/N-Gt and Fe-Gt catalyst. Nitrogen addition of graphite supported catalyst has a higher current density than Fe-Gt catalyst. The morphology of the catalyst was identified by Scanning Electron Microscope (SEM). Different particle shape for carbon types can be observed by SEM image of obtained catalyst. Energy Dispersive X-Ray EDX to identify the chemical composition. Nitrogen-doped carbon caused the formation of Fe2O3 and it was determined by X-ray diffraction (XRD).

ABSTRACT

Salah satu jenis proses pengelasan yang banyak digunakan di dunia industri Kereta Api adalah proses <em>resistance spot welding</em>. Proses pengelasan ini mempunyai banyak keunggulan pada pengelasan pelat tipis dengan menggunakan sambungan tumpang yang diaplikasikan pada <em>side wall</em> kereta api. Penelitian ini dilakukan dengan tujuan untuk mengetahui pengaruh variasi parameter pengelasan yang meliputi <em>current</em>, <em>weld time</em>, dan <em>pulsation</em> terhadap <em>shear strength</em>, struktur mikro dan diameter <em>nugget</em>. Material yang digunakan adalah material SA-240 tipe 304 dan SA-240 tipe 201 dengan ketebalan 2 mm untuk material SA-240 tipe 304 dan tebal 3 mm untuk material SA-240 tipe 201. Pengujian <em>shear strength</em> diperoleh parameter<em> resistance spot welding</em> semakin tinggi, maka nilai <em>shear strength </em>juga semakin tinggi. Strukturmakro didapatkan semakin tinggi <em>current</em>, <em>weld time</em>, dan <em>pulsation</em>, maka <em>nugget</em> semakin lebar. Sedangkan pada hasil uji mikro pada daerah <em>base metal</em> struktur yang tebentuk adalah <em>austenite</em>, sedangkan pada daerah HAZ dan <em>weld metal</em> adalah struktur <em>ferrit</em> dan <em>austenite</em>. Ukuran butir pada daerah HAZ yang semakin mendekat ke daerah <em>weld metal</em> ukuran butirnya menjadi semakin besar. Struktur mikro yang terbentuk pada <em>weld metal</em> bentuknya memanjang (<em>columnar grains</em>) ke daerah yang mengalami pembekuan paling akhir.

Dissimilar joint commonly applied on pressure vessel application in power plan field as joining between the tank and the stanchion of pressure vessel. This paper presents the investigations carried out to study the influence of groove angles and filler metals on 304L Stainless Steel to AISI 1040 Carbon Steel dissimilar joints. Gas Tungsten Arc Welding with 120 A of current was used on this research, joined the two different metals. The 30°, 45°, and 60° were used in this welding as parameters of V-groove angles. ER 308L-16 filler metal of stainless steel and ER 70S-6 filler metal of carbon steel were used as filler metals. Tensile test was conducted to obtain tensile strength of joint and to analysis of the effect of the welding parameters to the mechanical properties. The highest tensile strength was obtained from the 60° groove angle using ER 308L-16 filler metal of 614.54 MPa. In the other hand, 45° groove angle using ER 70S-6 filler metal obtained the lowest tensile strength of 578.66 MPa. The joining process of dissimilar welding using ER 308L-16 filler metal, filler metal for stainless steel, has obtained the highest tensile strength with wider groove angle as well.