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Description
Much advancement has been made in processing methods in the field of material science. Spark plasma sintering (SPS) has become a viable option for generating dense materials using less energy and shorter time. SPS utilizes current to rapidly generate heat to sinter materials. Benefits from this method include smaller grain sizes, lower sintering temperatures, and faster sintering times. Research in this field has led to the synthesis of composite materials, reinforced by ceramics or metals, with unique properties due to the processing method. An ever growing choice for reinforcement is carbon nanotubes (CNT). With a bulk density lower than that of aluminum and mechanical properties far superior to that of steel, CNT are being implemented in many fields today. Electrical, bio, mechanical, and other fields are pushing forward to harvest the benefits CNTs can provide, but have yet to overcome matters for successful synthesis of CNT composites. The primary issue preventing reliable composite production is material dispersion. Melt-infiltration is a process that has been used to generate high volume fraction of reinforcement in composites. This method takes advantage of creating a well dispersed porous preform from the reinforcing material. The matrix, whether metal or other, is melted into the preform, to generate the composite material. The CNT utilized are MWNTs with average inside, outside diameter and length of 5-15 nm, 30-50 nm and 10-20 _m respectively. The present work utilized for the first time the Joule heating aspects of SPS to allow the successful melting and subsequent rapid infiltration of aluminum into CNT pre-forms. The focus of the project was directed at understanding an unusual phenomenon where fully consolidated processed samples disintegrate over time into fine powder. The work involves extensive characterization of the disintegration process covering scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and Raman spectroscopy.
