Materials Science Forum Vol. 840

Abstract: α-Cordierite glass ceramic was synthesised through crystallization of glass compacts made of milled glass frits. The effect of temperatures and colorants were studied. The crystal structure of α-cordierite was analysed using X-ray diffraction technique and Rietveld structural refinement method. Density, porosity and shrinkage analysis, Vickers hardness and SEM were also performed. The result revealed that at higher sintering temperatures, the properties of α-cordierite was getting better. Low apparent porosity level and high hardness dense α-cordierite was fabricated at temperature 1350oC. The low porosity level may lead to high thermal conductivity which suggested that cordierite was candidates for FIR therapy instrumemts.________________________________________________________________________

Abstract: The transition from non-living to living matter has been reported can be achieved in the laboratory via designing and constructing the protocell models [1]. Protocell is a study of origin of life theory whereby it is not a true cell, but a term used to refer to early cells or primitive cells. There are two types of protocell model; vesicles and coacervates. Vesicles are biological membranes; provide a semi-permeable boundary between the internal and external environment of a cell and are constructed via self-assembly of lipid and fatty acid molecules [2-5]. While vesicles are made of self-assembly of lipid molecules, coacervates are mixtures of two or more polymers in aqueous solution that spontaneously phase separated to form droplets. Coacervate droplets ^have been proposed as a potential alternative protocell model because of compartmentalization properties [6-11].

Abstract: Anodic oxidation is a well-established surface modification method which combines electric field driven metal and oxygen ion diffusion to produce protective oxide layer on metals. This method has been widely used to modify the surface properties of titanium and its alloy. This present study aims to investigate the effect of agitation speed on the surface properties of anodised titanium. At first, the high purity titanium foils were anodised in mixture of 0.04 M β-glycerophosphate disodium salt pentahydrate (β-GP) and 0.4 M calcium acetate monohydrate (CA) at 350 V and 30 mA.cm^-2 for 10 minutes at different agitations speed (300 rpm - 1500 rpm). Next, surface properties of anodised titanium were characterised by digital single-lens reflex camera (DSLR camera), field emission scanning electron microscopy (FESEM) and glancing angle X-ray diffractometer (GAXRD). At lower agitation speed (≤ 900 rpm), surface of anodised titanium covered by small donut-shaped pores. With increasing of agitation speed (≥ 1100 rpm), the oxide layer became more porous and covered by larger donut-shaped pores. Rutile TiO₂ peaks were detected at agitation speed more than 1100 rpm. Agitation condition is believed to be an effective method to enhance the surface properties of anodised titanium for biomedical applications.

Abstract: Recent studies revealed the incorporation of sodium removal treatment in between alkali and heat treatments to prepare a sodium-free bioactive surface on titanium. This method has been reported to be more effective than conventional alkali and heat treatments to promote titanium osteointegration. This study aims to investigate the surface properties of high purity titanium after subjected to alkali treatment and subsequent sodium removal treatment. High purity titanium foils were immersed in 5 M NaOH at 60 °C for 24 hours followed by immersion in diluted HCl acid and/or distilled water at 40 °C for a period of time. The surface morphology and composition were examined using Field Emission Scanning Electron Microscope/Energy-Dispersive X-Ray Spectroscopy (FESEM/EDS). The surface wettability was evaluated by water contact angle. The surface functional groups were analysed using Fourier Transform Infrared Spectroscopy (FTIR). It was revealed that alkali and subsequent sodium removal treatments have rendered these samples high wettability and surface energy with the introduction of hydroxyl groups. Furthermore, diluted HCl treatment, water treatment and combination of both treatments removed sodium from the surfaces of alkali-treated titanium effectively (<5wt% Na) without altering existing hydroxyl groups.

Abstract: Metal foam is the cellular structures that made from metal and have pores in their structures. Metal foam also known as the porous metals, which express that the structure has a large volume of porosities with the value of up to 0.98 or 0.99. Porous 316L stainless steel was fabricated by powder metallurgy route with the composition of the SS316L metal powder as metallic material, polyethylene glycol (PEG) and Carbamide as the space holder. The powders were mixed in a ball mill at 60 rpm for 10 minutes and the mixtures were put into the mold for the pressing. The samples were uniaxially pressed at 3 tons and heat treated by using box furnace at 870 °C. There are several tests that have been conducted in order to characterize the physical properties of metal foam such as density and porosity testing, and the morphological testing (Scanning Electron Microscopy (SEM)). The results show that the composition of 85 wt% SS316L of metal foam show high in porosity which suitable for implants application.

Abstract: The uniformly cross-linked gellan gum hydrogel with sodium montmorillonite (Na-MMT), organo-montmorillonite (CTAB-MMT) and Cloisite 15A were successfully prepared. The compression performances of the hydrogels were investigated. The results show that the GG hydrogels containing Cloisite 15A required smallest volume to achieve optimum compression stress, modulus and compression strain at 5% (w/w) compared to both Na-MMT and CTAB-MMT at 10% (w/w), respectively. The decrease in compression performances of gellan gum hydrogel at higher concentration containing those clays could be due to agglomeration process which created the entangled structure and bring up the brittleness of hydrogel properties. Overall, the presence of the clays significantly improved the mechanical performances of gellan gum hydrogels which beneficial to be used in tissue engineering.

Abstract: Titanium (Ti) is widely used in dental and orthopedic implants because of its good biocombatibility and high corrosion resistance. Titanium oxide (TiO₂) has shown to exhibit strong physicochemical bonding between Ti implant and living bone because of its ability to induce bone-like apatite in a body environment. Ti is always coated by an oxide surface layer of 1.5-10 nm thickness. TiO₂ crystalline structures; anatase and rutile present several distinctive features, such as photocatalytic behaviour, superhydrophilicity and biocompatible properties. Anodic oxidation is used to modify the surface of pure titanium in a phosphuric acid electrolyte in order to maximize and characterize the TiO₂ anatase crystalline phase. In the present work, thick films of the anatase polymorph of TiO2 were formed on commercially pure Ti foil under potentials 200 V-350 V at current densities 40 and 60 mA/cm² for 10 min. Multiple characterization techniques were used. Glancing angle X-ray diffraction (GAXRD) is used to obtain crystalline phases, field emission scanning electron microscope (FESEM) is used to obtain surface images and water contact angle (WCA) is used to obtain the wettability of the oxide surface. According to GAXRD results the intensity of the major peak increased with increasing applied voltage and current density while decrease with molar concentration. This means that the amount and/or crystallinity of anatase are/is influenced with these parameters. The coated oxides obtained small amount of anatase is comparing to films anodized in H₂SO₄ electrolyte. Which confirm that slower crystallization in H₃PO₄ than in H₂SO₄. FESEM images obtained that as the voltage increased, the film breaks down locally and results in a porous surface. The porosity and the pore size increase with the increasing voltage. The pore size diameter at 300V for 0.3 M can reach up to 1μm. As for WCA results the coated samples at higher voltages (250 V, 300 V and 350 V) and molar concentration 0.3 M have shown more hydrophilic surface, with sample anodized at 350 V at 0.3 M have the lowest contact angle, thus the highest surface energy. While samples anodized at 200 V voltage observed more hydrophobic surface with sample anodized at 200 V at 0.1 M have the lower wettability, thus the lowest surface energy.

Abstract: The composite cathode Ba₀.₅Sr₀.₅Co_0.8Fe_0.2 (BSCF)–samarium-doped ceria carbonate (SDCc) was reviewed based on different (Li/Na)₂ carbonate molarities (67:33, 62:38, and 53:47 (mol.%)). Effects of (Li/Na)₂ carbonate on BSCF was studied in terms of chemical, thermal, and physical properties. Composite-cathode powders were prepared using high-energy ball milling (HEBM) and calcined at 750 °C for 2 h before uniaxial pressing to form a pellets. Afterwards, the pellets were sintered at 600 °C for 90 min to obtain porous composite-cathode pellets. Powders behaviors were examined based on particle size and thermal expansion by using Image J software, field-emission scanning electron microscopy (FESEM) and dilatometry respectively. Cross-section morphology of the pellets were characterised by FESEM to examine grain positions and by the Archimedes principle to identify the porosity, respectively. The quantitative elements for the BSCF-SDCc pellet were identified using energy-dispersive spectroscopy (EDS). HEBM enabled the cathode to achieve a nanocomposite state. Cathode cells obtained became porous when porosity values were between 26% and 30%. These results showed that BSCF–SDCc has high potential for low-temperature solid oxide fuel cell (LT-SOFC) applications.

Abstract: Zinc Oxide (ZnO) is well known for its wide band gap semiconductor with large excitation energy that serves various application. These unique characteristics had gained much research attention on ZnO nanostructure synthesis and physical properties. In this study, ZnO thin films were deposited on ITO/PET substrate by a spin coating sol-gel process. The starting solution were prepare by dissolved zinc acetate dehydrate (ZnAc) and diethanolamine (DEA) in water (H₂O) and 2-propanol (2-PrOH). Acid Citric (C₆H₈O₇) from 0.2 to 1.0 M were dropped into 100 ml sol-gel solution to study effect of sol-gel environment condition. ZnO thin films were obtained after pre-heating the spin coated thin films at 100 °C for 5 minutes after each coating. The coated substrates were undergone for Hot Water Treatment (HWT) process at 90 °C for 6 hours to grow ZnO nanostructures. The effects of sol-gel environment condition by drop different concentrations of C₆H₈O₇ into the solution were studied. Nanoflakes ZnO were obtained after hot water and hydrothermal treated at 90 °C for 6 hours with 0.2 till 1.0 concentration of C₆H₈O₇ dropped directly in the sol-gel solution. On the basis of the changes in morphology and microstructure induced by hot water treatment, it is concluded that the nanosheets were highly transparent with the visible range (350 – 800 nm) with 70%-90% of Transmittance spectra. Growth of ZnO nanosheet influenced by increment of C₆H₈O₇ mol concentration also with value of roughness RMS.

Abstract: Banana stem (BS) was used as the natural cellulose source. It must undergo an alkali treatment and bleaching process before continuing with an acid hydrolysis. Then, the Nanocrystalline cellulose (NCC) was synthesized via acid hydrolysis with four different concentrations of sulfuric acid (H₂SO₄) at 50 %, 52 %, 54 % and 56 % respectively at 50 0C for 1 hour. The influence of acid concentration of morphology, thermal and chemical properties of the NCC was studied in this project. The morphology dimension of the NCC was determined by using field emission scanning electron microscope (FESEM) and thermal stability of the NCC was determined by using thermal gravimetric analysis (TGA). Chemical composition and structural analysis were measured by using Fourier transform infrared (FT-IR) and X-ray diffraction (XRD).