Experimental Study of the Corrosiveness of Ternary Blends of Biodiesel Fuel

Biodiesel is an alternative renewable resource to petroleum-based diesel. The aim of using biodiesel is to reduce environmental pollution and combat global warming. Biodiesel application in compression ignition engines has shown its compatibility with better combustion characteristics and high engine performance. Many advantages can be obtained by using biodiesel, including reducing exhaust gases, reducing air toxicity, providing energy security, and being biodegradable. However, biodiesel’s disadvantage involves oxidation stability, corrosion, degradation, and compatibility with other metallic materials. The present study investigates the corrosive behavior of the ternary blend (waste cooking-Calophyllum inophyllum biodiesel-diesel) fuel that occurs in contact with mild steel and stainless steel 316. The observation study for mild steel and stainless steel 316 material under the static immersion method was performed for 7,200 h and 14,400 h, respectively, at room temperature (25°C–30°C). In every 720 and 1,440 h of immersion time, the coupon’s profile was analyzed by scanning electron microscopy (SEM)/electron-dispersive spectrometer (EDS), and the mass loss was observed, for corrosivity investigation. Based on the obtained results, the average corrosion rate of mild steel and stainless steel 316 is 0.6257 and 0.0472 nm/year at 7,200 h, respectively; the difference in corrosion rate for these metallic materials is approximately 92.46%. The degradation of the fuel properties such as kinematic viscosity, density, refractive index, and acid value was monitored. In this study, stainless steel 316 was more resistant to corrosion attack with some micro pitting and showed better compatibility with the ternary blend than mild steel. The regression analysis and the correlation of corrosion rate were studied.

Cytotoxicity of Ti/SS316/Mg Particles on Human Osteoblasts

Daily walking or exercise of the bone implant recipients may generate particles due to wear and tear. Reports have mentioned that particles could circulate in the human body and trigger aseptic loosening, inflammation, and other potential complications. The mechanism of these phenomena remains mostly unclear. This study is to investigate the cytotoxicity of titanium (Ti), stainless steel 316 (SS316), and magnesium (Mg) particles due to these materials are the most commonly used biomaterials based on their adequate mechanical properties and excellent biocompatibility. Human osteoblasts (SAOS2 cells) were exposed directly to different concentrations of Ti/SS316/Mg particle during the direct cytotoxicity test. Together with the previous study, we found out that Ti particles showed cytotoxicity to osteoblasts at different dosages and times, while SS316 particles and Mg particles (low dosage) can reduce the cytotoxicity induced by Ti particles and boost cell viability. Mg particles can be toxic to osteoblast at a higher dosage, while SS316 particles are “safer” than Mg particles at higher dosages. Cell viability and cell morphology of SAOS2 cells under different treatments were observed at 2/3/5 days. This study found out that cell viability could be enhanced with certain combinations of Ti/SS316/Mg particles. This can give us certain guideline on how to design and fabricate a hybrid bone implant. However, how to quantify the particles inside the human body in real-time, and the exact interaction among particles, cells, tissues, and even organs require further research.

Corrosion Studies on Stainless Steel 316 and their Prevention – A Review

Corrosion is a process that causes a change of metal to chemically stabled form, by reacting with a solution or with the atmospheric air. There are various types of corrosions such as crevice corrosion, intergranular corrosion, stress corrosion, pitting corrosion, galvanic corrosion and uniform corrosion. These types of corrosion and the prevention methods are investigated in this review paper. Stainless steel 316 has excellence in corrosion resistance, due to the presence of molybdenum content. From the literature survey, stainless steel 316 has been tested in various experiments to improve the properties of the material. In the present review, several coating processes and additives which are added on SS 316 to improve the material properties are studied. The advantages of these improvements are reduced cost of change of material, reduced loss of material due to corrosion and increase in materials durability. Hence, stainless steel 316 is used for all corrosion applications which causes less damage and high durability compared with other austenitic steels.

Effect of the variation of the electrodeposition time of hydroxyapatite/chitosan coatings on AISI 316L SS

Type AISI 316 L Stainless Steel (316 L SS) plays a crucial role in bone replacement surgery due to its excellent mechanical features, availability at low cost, and ease of fabrication, but its performance is low when in contact with the aggressive conditions of the human body fluids. Chitosan (CTS) is a biopolymer that blended with hydroxyapatite (HAp) could form coatings to improve surface properties of a metallic orthopedic prosthesis, i.e., corrosion-resistance to the base metal and biocompatibility of the ceramic on the metal surface. This work aims to obtain and evaluate HAp/CTS composite coatings deposited on the surface of AISI 316 L SS substrate by electrophoretic deposition (EDP) technique. The influence of the time of deposition on the coating’s characteristics and properties was characterized and discussed. The coatings were structural, elemental, and chemically characterized using X-Ray diffraction and Raman spectroscopy. HV values in a range of 64.7 to 111.5 were observed, showing the lowest HAp/CTS-30.0 coating values for all the loads applied. The lowest HV value was nearby to the reported value for human bone’s hardness, around 47HV; considering that the coating will be in constant contact motion with the bone surface, the contact with a softer surface could decrease the wear on the human bone. The hardness decreases with the coating thickness’s increment because the coating presented a higher plastic deformation than the 316 L SS surfaces. A decrease in the roughness average (Ra) was well noticed as the deposition time increased; meanwhile, the thickness increased as the deposition time increased.