Fabrication of a Protective Hybrid Coating Composed of TiO2, MoO2, and SiO2 by Plasma Electrolytic Oxidation of Titanium

This work examined the influence of dual incorporation of MoO2 and SiO2 on the corrosion behavior of pure titanium treated via plasma electrolytic oxidation (PEO). To achieve this purpose, pure titanium substrate was treated via PEO in an alkaline-molybdate electrolyte without and with SiO2 nanoparticles. The microstructural observation revealed that the addition of SiO2 nanoparticles into the electrolyte during PEO helped to seal the structural defects in the PEO coating so that a rougher, thicker, and denser coating rich in SiO2 was successfully obtained. From the electrochemical measurements in a 3.5 wt.% NaCl solution, the TiO2-MoO2-SiO2 hybrid coating exhibited a higher corrosion resistance than the TiO2-MoO2 coating which was attributed to the sealing effect by stable SiO2 nanoparticles.

Investigation on Microstructural Characteristics and Mechanical Properties of Thermally Sprayed Fe-Base Composites Reinforced with Different Ceramic Particulates

Three different coatings were deposited using the Detonation Gun Spraying (DGS) technology from steel powders alone; and steel powers mixed with Fe3C and SiC particles; respectively. The microstructural characteristics of these coatings were examined and the hardness of each type of coating was studied. The morphology and structure of the feedstock powders were affected by the exposure to high temperature during the spraying process and rapid solidification of steel powders that resulted in the formation of an amorphous structure. The unreinforced steel coating had the highest hardness among the three types of coatings; possibly due to a higher degree of amorphization in the coating compared to the other two samples. The microstructural observation confirmed the formation of dense coatings with a layered structure with good connectivity between layers with minimum defects and porosities in the interfacial regions.

MYCELIAL AMYLASE AND CELLULASE CHARACTERIZATION AS WELL AS BASIDIOMA PHYSICOCHEMICAL ANALYSIS OF LINGZHI MUSHROOM

Karakterisasi Amilase dan Selulase Miselial Serta Analisis Fisikokimia Basidioma Jamur Lingzhi (Ganoderma lucidum) Lingzi mushroom (Ganoderma lucidum) synthesizes enzymes which have anti-hyperglycemic and anti-diabetic activities. This preliminary study aims to characterize the amylase and cellulase activities of mycelial culture, and to analyze the physicochemical compounds in the basidioma of G. lucidum InaCC F11 and G. lucidum InaCC F106. The enzymes were characterized spectrophotometrically using DNS method, and the basidioma was subjected to proximate and high performance liquid chromatography (HPLC) analysis, as well as microstructural observation using scanning electron microscope. Results showed both strains demonstrated amylase activity, but not cellulase activity. The optimum activity of amylase in G. lucidum InaCC F11 mycelial cultures was achieved on the 3rd incubation day, at pH 5.5, 35 ºC temperature, and 1.5% substrate concentration, whereas that of G. lucidum InaCC F106 on the 7th incubation day, at pH 5, 40 ºC temperature, and 1.75% substrate concentration. Dried basidioma of G. lucidum InaCC F11 contained 93.72% carbohydrates, 3.06% protein, 0.85% fat, 0.768% crude fiber, 0.54% ash, and 1.83% moisture. In addition, HPLC detected the presence of phenols (0.036%), steroids (0.014 mg 100 mL-1), and active triterpenoid compounds. Jamur lingzi (Ganoderma lucidum) mensintesis enzim yang memiliki aktivitas anti-hiperglikemik dan anti-diabetes. Studi pendahuluan ini bertujuan mengkarakterisasi aktivitas amilase dan selulase kultur miselium, serta menganalisis senyawa fisikokimia pada basidioma G. lucidum InaCC F11 dan G. lucidum InaCC F106. Enzim dikarakterisasi secara spektrofotometri menggunakan metode DNS. Basidioma dianalisis secara proksimat, menggunakan kromatografi cair kinerja tinggi (KCKT), serta diamati mikrostrukturnya menggunakan mikroskop elektron. Hasil menunjukkan kedua strain tersebut memiliki aktivitas amilase, dan tidak ada aktivitas selulase. Aktivitas amilase optimum pada kultur miselium G. lucidum InaCC F11 dicapai pada inkubasi hari ke-3, pH 5,5, suhu 35 ºC, dan konsentrasi substrat 1,5%, sedangkan pada kultur miselium G. lucidum InaCC F106 dicapai pada inkubasi hari ke-7, pH 5, suhu 40 ºC, dan konsentrasi substrat 1,75%. Basidioma kering G. lucidum InaCC F11 mengandung karbohidrat 93,72%, protein 3,06%, lemak 0,85%, serat kasar 0,768%, abu 0,54%, dan kadar air 1,83%. Selain itu, KCKT mendeteksi adanya fenol (0,036%), steroid (0,014 mg 100 mL-1), dan senyawa triterpenoid aktif.

Brazing of Stainless Steel Using Electrolytic Ni-P Plating Film and Investigation of Corrosion Behavior

Electrodeposited Ni-11 mass%P alloy plating film was fabricated on the surface of stainless steel SUS304 to conduct brazing of SUS304 plates for a heat exchanger. Brazing of SUS304 plates with electrodeposited Ni-11P layers was carried out using a hydrogen reducing furnace. The microstructure and joint strength of the brazed joint were also investigated. From the result of the microstructural observation of the cross section of the joint, it was found that the brazing filler metal is homogeneously distributed without defects such as voids between the SUS304 plates. The results of electrochemical measurements showed that the P-concentrated phase in the Ni-11P alloy is preferentially dissolved in NaCl aqueous solution.