Carbonization of biomass is a type of pyrolysis that allows for the formation of byproducts that have applications in many other industries [1]. In the field of materials science concerned with environmental impact intersecting with desirable material properties and performance, the process of carbonization in particular with commonplace biomass such as food waste is of great interest. In this thesis, pistachio shell was used as the organic biomass of choice for carbonization, and reinforcement was provided by titanium powder. These two materials were milled together at two different compositions and milling times. Experimental conditions consisted of replicates of three bulk samples made from uniaxially pressed powder mixtures heat treated from 800 °C up to 1200 °C in increments of 100 °C. Heat treatment occurred in a tube furnace with a heating rate of 5 °C/min up to the heat treatment temperature, holding the temperature for 1 hour, then ramping back down to room temperature, all in an inert atmosphere. XRD was performed on heat treated samples before polishing, while optical microscopy and SEM were performed after mounting and polishing. TGA was performed on the milled powders, while hardness was performed on the heat treated bulk samples after mounting and polishing. Results obtained suggested that increasing heat treatment temperature and milling time decreased carbon matrix porosity. In addition, greater amounts of titanium seemed to result in increased porosity. However, at increased temperature, more surface cracking was observed, leading to the conclusion that an excessively high temperature is detrimental to mechanical properties. Finally, rutile TiO2 was formed as a result of the heat treatment process. In considering environmental impact, cost, and mechanical properties, a balance must be maintained between higher temperature processing, duration, milling time, and porosity present due to these factors. Future work includes further investigations into processing parameters and characterization such as XPS and abrasion testing. / Master of Science / Carbonization of organic materials such as wood or nut shells can be explained in short as a decomposition that occurs when those materials are heated up without allowing them access to oxygen as in a normal combustion like a fire. Because of that, carbonization can produce useful products and materials of interest to many. Adding titanium to pistachio shell powder, performing compaction and carbonization, then further heating up those samples, resulted in composite materials consisting of mostly carbon char and particles inside that improve the properties. After testing multiple experimental conditions and analyzing them using equipment such as X-Ray Diffraction (XRD), Thermogravimetric Analysis (TGA), optical microscopes, Scanning Electron Microscopy (SEM)/Energy Dispersive Spectroscopy (EDS), and a hardness tester, some trends in properties and structure were observed. Generally, increasing heat treatment temperature and milling time will reduce porosity in the matrix. On the other hand, decreasing amount of Ti powder added seems to reduce porosity. However, too high of a heat treatment temperature seems to have a detrimental effect on the part manufactured (i.e. surface cracking). In addition, considering processing costs and time costs could discourage one from using a very high temperature to heat treat these samples. Therefore, it is important to balance amount of energy used to heat treat, time spent, and resulting porosity of the final product for its applications. Future work should be done to further determine the effects of processing parameters by making more samples to test the properties of. Other characterization techniques like X-Ray Photoelectron Spectroscopy (XPS) and abrasion testing could be good to determine the exact makeup of the particles in the composite as well as see the sample's performance in its intended application (i.e. brake pads).
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/112307 |
| Date | 27 October 2022 |
| Creators | Shen, Jacklyn Dana |
| Contributors | Materials Science and Engineering, Aning, Alexander O., Elmkharram, Hesham Moh, Suchicital, Carlos T. A. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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