Papers by Author: Salina Muhamad

Abstract: Carbon nanotubes (CNTs) were fabricated from palm oil using the thermal chemical vapor deposition technique utilizing a two furnace system. The effect of precursor vaporization temperature of the first furnace, in the range of 300-600°C was systematically studied with the synthesis temperature (second furnace) fixed at 750°C for a total time of 30 min. The samples were characterized using field emission scanning electron microscopy and micro-Raman spectroscopy. CNTs of various packing densities and diameters were synthesized with the varying precursor vaporization temperature. Based on micro-Raman measurements nanotube defect level and the presence of SWCNT were dependent on the vaporization temperature. Vertically aligned CNTs (VACNTs) were found to grow within the vaporization temperature range of 400-500°C, with well graphitized and higher yield obtained at 450°C with excellent lateral alignment, uniform nanotubes diameter (~15 nm), orientation and distribution within the CNT bundles. At vaporization temperatures of 300-350°C and 500-600°C, lower growth rate, bigger nanotubes diameter and higher ID/IG ratio were observed which indicated lower nanotubes quality that produced at both temperature ranges.

Abstract: The effects of synthesis temperature on the quality and quantity of vertically aligned carbon nanotubes (VACNT) were studied using high resolution scanning electron microscopy, and micro-Raman spectroscopy. The VACNT was synthesized by Fe catalytic decomposition of palm oil deposited on silicon substrate by thermal chemical vapour deposition method. The analysis shows that the growth rate increases from 3.8 to 5.5 µm/min as the temperature was increased from 750 to 800°C. The nanotube diameters were observed bigger at low temperature range. Smaller and uniform diameter (~15 nm) was found at 750°C and the increment in diameter size was seen at higher temperature range. Smaller graphite Raman “G” peak width, low ID/IG ratio (~0.52) indicated higher crystallinity of the nanotube and moderate I2D1/ I2D2 ratio for second order Raman peak was also detected at synthesis temperature of 750°C. These results indicated that the optimum synthesis temperature for higher quality VACNT production was at 750°C.

Abstract: Metal Injection Molding (MIM) is a cost-effective technique for producing small, complex, precision parts in high volumes. MIM consists of four main processing steps: mixing, injection molding, debinding and sintering. In the mixing step, the powder titanium alloy (Ti6Al4V) medical grade is mixed with a binder system based on palm stearin to form a homogeneous feedstock. The rheological studies of the feedstock have been determined properly in order to success during injection into injection molding machine. After molding, the binder holds the particles in place. The binder systems then have to be removed completely through debinding step. Any contamination of the binder systems will affect the final properties of the parts. During debinding step, solvent extraction debinding has been used to remove partly of the binder systems. The debound part is then sintered at high temperature under control atmosphere furnace. The properties of the sintered craniofacial implants then was measured and compared. The sintered craniofacial implants also then were determined in term of in-vitro cytotoxicity study using mouse fibroblast lines L-929. The results show that the sintered craniofacial implants of titanium alloy produced by MIM fullfill the in-vitro cytotoxicity test.