Eco-friendly composite made of Timoho Fiber (TF) continuously developed to get the best performance to replace plastic-based synthetic fibers. This study focuses on investigating physical characteristics, mechanical properties, thermal analysis, and the morphology of TF-reinforced polyester composites by adding organic (egg shell powder-ESP) and inorganic (aluminum powder-AP) fillers. Hot press method was used in the composite fabrication with considered volume fraction of TF, organic, and inorganic fillers. The results showed that the density of TF-polyester composites decreases with the increasing volume fraction of the fibers. For additional fillers, it was shown that AP was more effective to be used to improve density than ESP. The tensile and impact strength of the composite increased with increasing TF volume. However, the addition of ESP and AP fillers into the composite caused different mechanical characteristics. Filler addition increased the elasticity modulus, toughness, thermal resistance increased, while the tensile strength decreased. ESP and AP fillers provided the best thermal resistance due to the relatively high thermal conductivity of ±1700 C compared to composites without fillers and amorphous ESP fillers. SEM observation supported the analysis of TF-polyester composite mechanical characteristics.

The effect of Mo on the corrosion behavior of Ni20Cr–xMo alloys in an oxidizing chlorine‐containing atmosphere using air mixed with the salt‐vapor mixture of NaCl–KCl–CaCl2 at 570°C was investigated. The results revealed that the corrosion performance of the Ni20Cr alloys in the oxidizing chlorine atmosphere was improved by Mo addition of up to 3 wt%. The Mo‐free alloy formed a potassium chromate during corrosion as a result of the reaction between the Cr2O3 scale and KCl vapor. The chromate formation increased the chlorine potential at the scale surface and induced the breakdown of the protective Cr2O3 scale, resulting in internal chromium chloride precipitates and a Cr‐depleted zone. In contrast, the presence of Mo resulted in the formation of a NiO scale, which did not react with the salt vapors and, therefore, prevented the formation of chromates. The beneficial effect of Mo on the high‐temperature chlorination of Ni–Cr alloys in salt‐vapor‐containing atmospheres was ascribed to the suppression of chlorine generation due to NiO scale formation.

Organic inhibitors have been considered as an effective way to control the corrosion of carbon steel weldment in an acidic environment. This work proposes a new green organic inhibitor made of extract of rambutan fruit (Nephelium lappaceum) peel and aims at analyzing its corrosion inhibitor properties and protection mechanism. Specimens of carbon steel weldment were tested for their corrosion by using electrochemical and immersion methods in 1 M HCl solution containing 0 to 6 g/L of Nephelium peel (NP) extract. Results showed that, in the same solution, the corrosion rate was measured to be higher on the weld metal zone than that of base metal zone, which could be related to the coarser grain of the weld metal zone and the stability of the formed oxide layer. The addition of NP extract was found to increase the stability of the oxide layer, thus increasing the corrosion resistance of the specimens. The maximum inhibition efficiency of the NP extract was reached at 97% for weld metal with 5 g/L of extract, at 80% for the heat affected zone with 5 g/L, and at 70% for base metal with 4 g/L. This work reveals the particularity of different weldment zones to the different needs of inhibitor concentration for obtaining the optimum corrosion protection.

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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.

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The effect of Fe on the corrosion behavior of Ni20CrxFe alloys in an oxidizing chlorine-containing atmosphere using air mixed with the salt vapor mixture of NaClKClCaCl 2 at 570°C was investigated. The results revealed that the corrosion performance of the Ni20Cr alloys in the oxidizing-chlorine atmosphere was improved by Fe addition. The oxide scale structure formed on all of the alloys containing Fe was similar with that formed on the Fe-free alloy. The potassium chromate and the internal precipitate zone were observed on all of the alloys. However, the internal Cr-chloride penetration and the Cr-depletion zone became thinner on the alloys with Fe addition. The Fe-oxide formed above Cr 2 O 3 scale on the alloys with Fe addition helped Fe inhibit the chromate formation and maintained low chlorine potential at the alloy surface. Thus, a protective Cr 2 O 3 scale can be maintained for a longer corrosion period.

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