Thesis Archive
Carbon Nanotubes Synthesis Using Iron Catalyst on Magnesium Oxide Substrate Through Microwave Plasma Chemical Vapor Deposition (2015-2016)
Rizette Dane F. Pajarillaga
I-ris B. Supan
Abstract:
-Carbon nanotube is another allotrope of carbon, possessing lightweight property, uniquely combined with strength. It sparked the interest of the scientific community due to its great potential for wide industry applications. Since its discovery, the challenge has been selecting the means of producing in a large-scale setup. Several methods have arisen in response to devising a method to generate CNTs with better quality and higher yield, that is, with smaller diameters and greater lengths. Another issue on CNT manufacturing is the cost of production, which is greatly dependent by high-temperature requirement. Consequently, this study intended to produce CNTs using Microwave Plasma Chemical Vapor Deposition that essentially utilizes plasma to further decrease synthesis temperature. Correspondingly, the effects of varying several synthesis parameters were investigated. The experiment consisted of 9 runs based on the L9 Taguchi design examining 4 factors, each with 3 levels: synthesis time (15, 20, 25 mins), catalyst concentration loading on substrate (1%, 2%, 3%), microwave power output (229.5, 280.5, 340 W), and feed gas to carrier gas ratio (60:40, 50:50, 40:60) using a common catalyst-substrate combination: Fe/MgO. The percentage yield, average diameter, and average length of CNTs produced were the responses measured for each run. The diameters and lengths of CNTs were measured using SEM whereas the composition was analyzed using EDX. CNTs were successfully produced using all parameter combinations. Additionally, the highest percentage yield at 89.79% was produced using 840.5 Watts power output, 1% catalyst concentration, 50:50 feed gas-carrier gas ratio, and 25 minutes synthesis time; whereas the highest length/diameter or aspect ratio obtained was 44.5 at 840.5 Watts power output, 2% catalyst concentration, 60:40 feed gas-carrier gas ratio, and 20 minutes run time. It was found that microwave power output, catalyst concentration on substrate, and synthesis time all have significant effect on the percentage yield of CNTs produced.
Adviser:
Dr. Joseph L. Auresenia