This research aims at investigating the corrosion behavior and hardness of AISI Stainless Steel 304 (AISI SS 304) in corrosive hydrochloric acid solution and temperature variation treatment. In this study, the samples of AISI SS 304 are immersed for six (6) days in the corrosive acid solution at the temperature of 30°C and 50°C. The solution used as the corrosive media are HCl, FeCl3, and NaCl in the concentration of 5%, 10% and 15%. The results show that the higher the concentration of the solution, the higher the corrosion rate of AISI SS 304 will be, and the higher the temperature, the higher corrosion rate will also occur in all corrosion media. The corrosion that occurs in AISI SS 304 is mostly in the form of uniform corrosion and some pitting corrosion, and the value of hardness decreases after corrosion.

MgB₂ superconductor is a superconductor with a critical temperature of around 39K and has the potential to replace Nb₃Sn and NbTi as superconducting coils to produce high magnetic fields. In this study, monofilament wires have been made to analyze the doping effect of SiC and Carbon Nanotubes (CNT) in its manufacture using Powder-In-Tube (PIT) method. Stainless Steel (SS-316) tube was used as a tube filled with powders of starting materials of Mg, B, SiC and CNT. A total of 8 samples were prepared with variations in the addition of SiC, and CNT as much as 5, 10, and 15 wt %, and also the variations in the addition of Mg composition by 0 and 10 mol % from normal stoichiometric values. The samples were rolled and sintered at 800°C for 3 hours. The samples then were analyzed using SEM (Scanning Electron Microscopy) to analyze the surface morphology, XRD (X-Ray Diffractometer) to analyze the formed phases and crystal structures, and then resistivity versus temperature using cryogenic systems to analyze their superconductivity properties. Based on the results of the XRD analysis, the MgB₂ phase is the major phase in the samples and the SiC doping causes the formation of minor phases of Mg₂Si and Fe₃C. The addition of SiC causes a decrease in crystalline properties of the MgB₂ phase due to reaction with SiC, while the addition of CNT does not cause the formation of a new phase. Based on the results of the analysis of resistance versus temperature, it is seen that the addition of SiC causes a decrease in T_C value. While the addition of CNT causes the improvement in the nature of superconductivity, but it also causes the decrease of its T_C values.

Magnesium diboride (MgB2) is a highly potential superconducting material, in substitution of Nb3Sn, which has a critical temperature of ~ 39 K. This synthesis and manufacturing of MgB2 wire were conducted by in-situ powder in tube (PIT). The method doped with silicon carbide (SiC) was aimed to study the effect of phase formation on carbon substitution and morphological characteristics with the motivation to improve superconductivity properties. Magnesium, boron, and SiC powders were synthesized and functionally processed with stainless Steel 304 tube. Heat treatment was conducted at 750℃, 800℃, and 850℃ for 2 hours followed by furnace cooling. Characterization was carried out by x-ray diffractometer (XRD), scanning electron microscopy (SEM), and cryogenic magnet testing. The results showed that 1% SiC optimally increased the zero critical temperature of MgB2 ~ 37.18 K along with the sintering at 750℃ for 2 hours.

Exposure to humid environments can influence the behaviour of the composite brake pad. The use of hazardous materials in brake pads poses health risks. Therefore, it is essential to utilise more environmentally friendly materials. The brake pads in this study, composed of 35 vol. % phenolic resin, 25 vol. % eggshell particles, 10 vol. % bamboo fibre, 5 vol. % bamboo particles, 10 vol. % alumina powder, 5 vol. % zinc powder and 10 vol. % graphite powder, underwent a rigorous manufacturing process involving cold compaction, hot compaction and post-curing. The samples were immersed in engine oil for 12, 24, 36 and 48 hours. The results of the study indicated that composites made from calcined eggshell and bamboo particles maintained their performance even after being exposed to engine oil. Following this exposure, the composites exhibited a coefficient of friction ranging from 0.33 to 0.36, a friction stability coefficient between 71.59 and 79.19, a flexural strength ranging from 7.23 to 8.25 MPa and a flexural strain ranging from 0.54 to 1.11 %. Additionally, the wear rate experienced a slight increase, measuring between 4.75 and 6.64 mm3/m. The flexural modulus was found to be between 4.44 and 5.49 GPa, while the hardness ranged from 43.35 to 91.05 HRR.

Carburizing is a method for obtaining a sturdy material surface. This hard surface is used for machine elements that intersect with other materials, so failure due to wear can be avoided. However, this increase in hardness has always been followed by decreased ductility. This condition certainly lowers the fatigue life of the material. For that, it is necessary to compromise between surface hardness and ductility. This study used AISI 1045 steel, which has a surface roughness of 0.4 and 4.7 μm with carburation media used, is a mixture of 80% coconut shell charcoal and 20% Barium carbonate. The sample was given the pack carburization treatment at 850°C and holding time for 3 hours, and then cooled in the open air. The samples were reheated at 850°C, holding time for 17 minutes, and then cooled with airflow at speeds of 10.34, 15.51, and 20.06 m/s for 30 minutes. This research shows that the surface of steel with a roughness of 0.4 μm has excellent performance with the hardness and corrosion level respectively 228.6 HV and 2.3586 mpy at cooling airflow rate of 20.06 m/s while the fatigue life of material occurs at the speed of airflow cooling 10.43 m/s.

STUDI KARAKTERISTIK SIFAT MEKANIK ALUMUNIUM MATRIX COMPOSITE (AMC) PADUAN AL, 5%Cu, 12%Mg, 15% SiC HASIL PROSES STIR CASTING DENGAN VARIASI TEMPERATUR PENGADUKAN