Papers by Author: P. Limsuwan

Abstract: Titanium dioxide (TiO₂) was prepared by Sol-Gel technique that was coated on the grade 304-stainless steel. Effect of dip coated speed, number of coated cycles and annealed temperature on films properties were investigated. The optimum condition for film preparation was at dip coated speed of 0.12 cm/s, number of coated cycles of 20 cycles and annealed temperature of 500 °C. TiO₂ film was crystal structure in anatase phase that had the main plane (101). Surface morphology of the TiO₂ films formed grain that look like knobby shape. nanograin sizes were slightly difference that showed in the range of 10-50 nm. Under optimum condition, TiO₂ film was used as photocatalyst to treat domestic wastewater. TiO₂ film was coated on the paddles of water wheel and 24 paddles were used to create water wheel. Films surface area were contact to wastewater and the light around 0.504 m² under working volume and working area of 0.0135 m³ and 0.09 m², respectively. Under irradiation of the near UV with average intensity of 0.89 mW/cm² over 24 hrs., and rotational speed of 17 rev/min. that were controlled by microcontroller box set. To compare treatment efficiency, uncoated TiO₂ - water wheel (UTWW) was run in the same condition of coated TiO₂ - water wheel (CTWW). The result showed that the CTWW had higher treatment efficiency than the UTWW. Especially for COD, TS, TDS and PO₄^3-, CTWW had greater treatment efficiency than the UTWW that percentage difference were greater than 90%.

Abstract: This research aims to investigate the effects of heat treatment on color and clarity of ruby. The ruby were heated at 1200, 1300, 1400, 1500 and 1600°C in oxygen atmosphere for 40 hours, respectively. Each ruby before heated and after heated, the color measurement by spectrophotometer, to observe color changing and clarity. Found that, the samples had beautiful red and clarity more than before heated. So that, heat treatment of ruby at high temperature in oxygen atmosphere, could to increment valuated of natural ruby.

Abstract: Rutile TiO₂ films are normally used as biomaterial that synthesized on unheated stainless steel type 316L and glass slide substrates by dual cathode DC unbalanced magnetron sputtering. The influence of the substrate bias voltages (V_sb), from 0 V to-150V, on the structure of the as-deposited films was investigated. The crystal structure was characterized by grazing-incidence X-ray diffraction (GIXRD) technique, the films thickness and surface morphology was evaluated by atomic force microscopy (AFM) technique, respectively. The results show that the as-deposited films were transparent and have high transmittance in visible regions. The crystal structure of as-deposited films show the XRD patterns of rutile (110) with V_sb at 0V and shifted to rutile (101) with increasing V_sb. The films roughness (R_rms) and the thickness were 3.0 nm to 5.7 nm and 420 nm to 442 nm, respectively.