Type of Document Master's Thesis Author Dykema, Christopher Patrick URN etd-03192012-142230 Title Reaction Synthesis of HfB2 in a Variety of Metallic Environments Degree Master of Science Department Materials Science and Engineering Advisory Committee
Advisor Name Title Kampe, Stephen L. Committee Chair Aning, Alexander O. Committee Member Pickrell, Gary R. Committee Member Keywords
- hafnium diboride
- reaction synthesis
Date of Defense 2009-07-30 Availability restricted AbstractThis project investigated the reactive formation of hafnium diboride (HfB2) in a variety of metallic environments, including blends with Bi, Cu, Ni, and Sb. HfB2 has garnered interest for a variety of applications due to its hardness, stability at elevated temperatures, as well as electrical and thermal conductivity. Experimental testing included differential scanning calorimetry (DSC) to reveal reaction initiation temperatures and enthalpies of reaction; and optical pyrometry to measure maximum reaction temperatures.
Overall, DSC results indicated melting preceded reaction initiation; suggesting that the reaction initiation temperature for a certain blend occurred soon after melt formation, and could be broadly approximated by examination of binary phase diagrams. However, compositions containing bismuth ignited almost 200 ºC above the expected melting temperature.
The maximum temperature measurement did not appear to correlate with reaction enthalpies as might be expected. This lack of correlation may be a result of an inability to capture the true maximum temperature due to the measurement frequency of the pyrometer, the disparity of heating rates between the two experimental methods, and/or to the influence of intermediate reactions on the temperature increase.
Filename Size Approximate Download Time (Hours:Minutes:Seconds)
28.8 Modem 56K Modem ISDN (64 Kb) ISDN (128 Kb) Higher-speed Access Dykema_CP_T_2009_1.pdf 3.35 Mb 00:15:29 00:07:57 00:06:58 00:03:29 00:00:17 Dykema_CP_T_2009_Copyright.pdf 2.24 Mb 00:10:23 00:05:20 00:04:40 00:02:20 00:00:11indicates that a file or directory is accessible from the Virginia Tech campus network only.
If you have questions or technical problems, please Contact DLA.