In the current work, the influence of calcium carbonate (CaCO 3 ) filler loadings on the physical, mechanical, thermal, and morphological properties of pine fiber (PF) reinforced polyester composites were analyzed. The fillers loaded PF/polyester composites were fabricated using casting technique. The results revealed that the volume percentage voids in the filler-loaded composites was less as compared to neat PF/polyester composites due to filler occupancy in the air gaps of fabricated composites. The tensile strength increment in neat PF reinforced composites (10-30 vol%) was prompted by the polyester's ability to wet PF per-

Stress corrosion cracking (SCC) is known as a major factor that should be considered in the assessment of welding joint structure integrity. Despite the promising and wide application of dissimilar metal joints, the currently available SCC mitigation technique of dissimilar metal joints is not adequate. The challenge is to obtain a good joint while different melting points exist. This article reports a novel SCC mitigation method on a brass–steel dissimilar metal joint by modifying the geometry of the surface. It is evidenced that the sharpened steel (α1 specimen) significantly improves the SCC resilience of the joint. The evaluation of SEM/EDS photos reveals that the α1 geometry induces a smaller pore area around brass–steel micro-joint interfaces which in turn produces stronger joints.

No abstract

No abstract

No abstract

CoCr alloy is mostly used as biomaterial implant. However, it still has several weaknesses. Therefore, it is necessary to modify the surface to improve its biocompability. This research is a preliminary study on CoCr coated with Hydroxyapatite (HA)/Zirconium Dioxide (ZrO2) using Thermal Flame Spray method. 5 % -20 % ZrO2 was mixed with HA. Besides improving the biocompatibility, ZrO2 is believed to be able to enhance the antibacterial properties. Characterization test was performed using FE-SEM. The coating was analyzed for corrosion rate, surface roughness and antibacterial activity. Adding ZrO2 to HA has been proven to be able to improve corrosion rate. Combination of 80HA-20ZrO2 is the most effective bioceramic mixture, producing lowest corrosion rate of 0.213 mm/year in HBSS media. This is due to the increased reactivity value and better passivation reaction than CoCr without coating. Antibacterial activity test revealed that the coating could form inhibitory area around the sample meaning that the coating can provide bacterial resistance for the implant.

Organic chitosan synthesized from fish scales and food-grade chitosan were investigated, via the potentiodynamic polarization method, as potential corrosion inhibitors on ASTM A36 iron in 3.5% NaCl solution. The results of the study revealed that chitosan, both food-grade and that synthesized from fish scales, inhibited the corrosion of ASTM A36 iron in 3.5% NaCl solution. The source of the chitosan did not have any effects on the chitosan’s behavior or potential. The inhibitor efficiency value increased as the chitosan concentration increased. The optimum concentration of the two types of chitosan was 3000 ppm; the inhibitor efficiency value decreased when the inhibitor concentration was increased to4000 ppm. This inhibitor efficiency value change occurred because at 4000 ppm, the inhibitor concentration exceeded the best conditions to form a protective layer on the surface of ASTM A36 iron. Chitosan is cathodic, regardless of the source, and both types of chitosan were similar in terms of polarization type, adsorption, and isothermal adsorption. The isothermal adsorption interaction of chitosan (from either source) followed Temkin-type kinetics with the ASTM A36 iron and had chemisorption characteristics.

This study aims to find material steel for animal feed chopper machine which is not easily corroded with method of hot dip galvanizing (HDG). Steel as machinery components or construction often gets broken before the predicted time because of corrosion. The HDG method was begun by pre-treatment process which were polishing, degreasing, rinsing I, pickling, rinsing II, fluxing, and drying. The main process of galvanizing was done by dipping in 98% of zinc solution with temperature variation of 430, 450, 470, and 490°C. The coating thickness measurement was run with Coating thickness NOVOTEST TP-1M. The corrosion was tested with electrochemical method of potentiodynamic polarization with AUTOLAB PGSTAT 128. The highest value of coating thickness was at galvanized temperature of 490°C which was 88.9 ± 3.24%. The value of standard deviation was indicated by how much the coating homogeneity formed. This was in line with the amount of corrosion rate at galvanized temperature of 490°C. The highest corrosion rate values in H2SO4 and NaCl environment were 1.18 and 0.21 mm/year. The highest hardness value of Zn layer is galvanizing temperature of 490°C which rises 41.71% of the base metal. The coating thickness, corrosion and surface hardness test have thee good agreement.