Pattarinee Klumdoung

Variation of Color in Zirconium Nitride Thin Films Prepared by Reactive DC Magnetron Sputtering

This study is to evaluate a color variation of the zirconium nitride thin film, prepared from deposition technique of different N2 flow rates, ranging from 0.0 to 3.0 sccm, whereas the Ar flow rate is fixed at 3 sccm. The thin film was deposited on an unheated silicon wafer (100) via a reactive DC magnetron sputtering. The deposition current and deposition time were 0.6 A and 15 minutes, respectively. In the study, colors of film were changed from silver, gold, dark brown, brown, purple, pink to blue, when N2 flow rate further increase. Interestingly, the results indicate that gold color occurs in a very small interval of N2 flow rate.

Synthesis of Nanocrystalline β-Tricalcium Phosphate from Chicken Eggshells by Precipitation Method

Nanocrystalline β-TCP was successfully synthesized by simple precipitation method using calcium nitrate obtained eggshell as the calcium source, ammonium phosphate as the phosphate source and ammonia solution as agents for pH adjustment via our synthesis condition. Also, the effect of calcination temperature in range of 200-1200°C on phase transformation was investigated. The synthesized powders were characterized by X-Ray Diffraction (XRD), Rietveld refinements and Fourier transform infrared (FT-IR) techniques. The results indicate that β-TCP was observed at the calcination temperature of 700 °C and above. Furthermore, their crystallinity and crystalline size increase with increasing temperature. The a/c ratio of lattice parameter at temperature of 700-1200°C is similar to the standard phase of β-TCP. The chemical structure confirmed via FT-IR showed the band positions and functional groups, which are similar to that of stoichiometric β-TCP. Finally, eggshells are the potential material for synthesizing nanostructured BCP and may be possible in a low-cost production.

The Development of Electrospinning Apparatus to Fabricate Nanofiber for Future Material Applications

This research examines the development of a low cost mobile electrospinning system for fabricating nanofiber. The electrospinning system developed in this study consists of a horizontal needle arrangement and a motor which supports the working system that controls the solution flow rate without an external syringe pump. In order to discover the equipment operating conditions for nanofiber fabrication, the distance from the needle to the target was studied. A PVA solution of 8wt% was used and voltage was applied at 13 kV. The needle to target distances were varied from 8-18 cm. At a distance of 10 cm, the SEM images showed that the smallest diameter of the fiber was 119 nm. The average diameter was in the range of 119-240 nm. Concentrations of the 3 different solutions of PVA, PEO and PCL with the variation of voltage at each concentration were studied. The results show the diameter of PVA at 8 wt% and 12%wt are in the range of 127-197 nm and 222-402 nm, respectively. The diameter of PCL solution at a 20 wt% concentration is in the range of 32-60 nm. PEO at 2 wt% and 4wt% was not able to form as a fiber.

Processing of Elastic Silk Sericin/Gelatin Composite Film for Future Cosmetic Applications

The silk sericin/gelatin composite films were successfully prepared for future cosmetic applications. The sericin was extracted from Thai raw cocoons of the Bombyx mori silk worm via boiling and drying. Gelatin was extracted from white perch scales through a chemical treatment. To prepare the silk sericin/gelatin composite film, the silk sericin and gelatin solutions with different volume ratios were blended in distilled water by stirring in a magnetic stirrer for 30 minutes. They were dropped on the plastic mold. The sample was kept at a temperature of 50 °C to let it dry. The prepared composite films were characterized using UV-VIS spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). The silk sericin/gelatin composite films showed elastic behaviour, a homogeneous surface and no porosity which could indicate possible future use for cosmetic applications.

A Study of the Preparation of Silk Sericin/Chitosan Composite Film for Future Wound Dressing Applications

Silk sericin/chitosan composite films were successfully prepared for possible future wound dressing applications. To prepare the chitosan, shrimp shells were first washed and finely ground to obtain a fine powder before extracting the chitosan using a chemical reaction method. The sericin was extracted from Thai raw cocoons of Bombyx mori silk worm via boiling and drying. To prepare the silk sericin/chitosan composite films, the silk sericin and chitosan solutions with varying volume ratios were mixed in a magnetic stirrer for 30 minutes. They were then dropped on to a plastic mold. The sample was dried at a temperature of 50 °C. The prepared composite films were characterized using UV-VIS spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). The results from our studies could provide a method for future composite film development.

Preparation of 2 wt% ZnFe2O4/HAp Ceramic for Future Biomedical Applications

In this study, 2 wt% ZnFe2O4/HAp ceramic was prepared to form a promising composite material for future biomedical applications. Firstly, HAp powder was synthesized by precipitation using Ca(NO3)2 as the Ca source, (NH4)2HPO4 as the P source and ammonia as a pH adjuster. To prepare 2 wt% of ZnFe2O4, ZnO and Fe2O3 powders were mixed in ethanol with sequent dehydration and then calcination (using stoichiometric ratio). Finally, 2 wt% of ZnFe2O4 powder was milled with 98 wt% of HAp powder for 10 minutes before uniaxial pressing and then sintering at 1200 °C for 3 hours to form 2 wt% ZnFe2O4/HAp ceramic. The prepared ceramic was characterized by X- ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM). The XRD results revealed the ZnFe2O4/HAp ceramic with only HAp and ZnFe2O4 phases obtained, indicating that no impurities phases occurred. The FT-IR results revealed vibration bands of standard HAp and indicated the interaction between ZnFe2O4 and HAp. For the VSM results, the magnetization of composite was 0.05 emu/g and its coercivity was 44 Oe. These results could lead us to the development of a method for ZnFe2O4/HAp ceramic optimized for specific biomedical applications.

Fabrication of 2 wt% NiFe2O4/HAp Composite Ceramic for Future Heavy Metal Removal Applications

In this study, 2 wt% NiFe2O4/HAp composite ceramic was fabricated by the solid state reaction method to form a composite with the future potentiality to remove heavy metals. HAp powders were synthesized by precipitation using Ca (NO3)2 as Ca source, (NH4)2HPO4 as the P source and ammonia as a pH adjuster. NiFe2O4 powders were prepared by mixing and milling NiO and Fe2O3 powders (using stoichiometry ratio) in ethanol and sequent dehydration and then calcination. 2 wt% of NiFe2O4 powders were milled with 98 wt% of HAp powders for 10 minutes before uniaxial pressing and sintering at 1200 °C for 3 hours to form 2 wt% NiFe2O4/HAp composite ceramic. The prepared ceramic was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). XRD result shown that 2 wt% NiFe2O4/HAp composite ceramic with only HAp and NiFe2O4 phases obtained. FT-IR results revealed vibration bands of standard HAp and indicated the interaction between ZnFe2O4 and HAp. For the SEM result, the morphology of the prepared ceramic revealed nanoand micro sized grains. These results could lead us to the development of a method for a NiFe2O4/HAp composite ceramic optimized for specific heavy metal removal applications.

Effect of Temperature on the Structural and Magnetic Properties of Co0.7Zn0.3Fe2O4 Ceramic Prepared from Solid State Reaction

In present study, the Co0.7Zn0.3Fe2O4 ceramic was prepared using solid state reaction. The crystal structure of prepared ceramic indicated as solid solution. The SEM result indicated the dense structure of prepared ceramic as increased sintering temperature. For VSM result of Co0.7Zn0.3Fe2O4 ceramic indicated the super paramagnetic behavior with high magnetization. These results could lead us to the development of Co0.7Zn0.3Fe2O4 ceramic preparation optimized for specific applications.

Reductive heat treatment of austenitic stainless steel substrate for growth of hybrid carbon nanostructures

Single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), and carbon nanofibers (CNFs) in hybrid structures were synthesized on austenitic stainless steel substrates (Type:304). The formation of nanoparticles on substrates occurred under hydrogen gas (H2) with temperature of 720 °C. The effects of reductive heat treatment on the growth of carbon nanostructures at 15, 45, 60, 75 and 80 minutes were examined with scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffractrometer (XRD) and thermogravimetric analysis (TGA). The samples were synthesized using thermal chemical vapor deposition (Thermal CVD) under atmospheric pressure of acetylene gas (C2H2). The combination of carbon nanotubes and carbon nanofibers in hybrid structure was synthesized on a substrate using a long time to adjust the surface by heating treatment. The hybrid structure of carbon could not be observed when used in surface treatment time was 80 minutes. Shorter (<;45 min) or longer (>75 min) substrate heat treatments did not produce hybrid carbon nanostructures at this temperature.