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Acid Leaching of SHS Produced MgO/TiB2

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dc.contributor.authorLok, Jonathan Y.en
dc.contributor.committeechairLogan, Kathryn V.en
dc.contributor.committeememberKampe, Stephen L.en
dc.contributor.committeememberPickrell, Gary R.en
dc.contributor.departmentMaterials Science and Engineeringen
dc.date.accessioned2014-03-14T20:46:38Zen
dc.date.adate2006-11-06en
dc.date.available2014-03-14T20:46:38Zen
dc.date.issued2006-10-10en
dc.date.rdate2006-11-06en
dc.date.sdate2006-10-12en
dc.description.abstractThe stoichiometric Self-propagating High-temperature Synthesis (SHS) thermite reaction involving magnesium oxide (MgO), titanium dioxide (TiO₂), and boron oxide (B₂O₃) forms titanium diboride (TiB₂) and MgO as final products. Selective acid leaching is used to remove the MgO leaving high purity TiB₂ powder. The SHS method to produce TiB₂ is attractive because of the relatively low temperature required to initiate the reaction, fast reaction time, and product purity. This study investigates the acid leaching of SHS produced MgO/TiB2 and a stoichiometric mixture of commercial MgO and TiB₂ powders. Leaching was conducted at 90° C, 60° C, and 30° C at pH levels of 4.0, 2.5, and 1.0 by introduction of concentrated aliquots of HNO₃. This method maintains a minimum pH target throughout the leaching process, thereby sustaining a dynamic concentration to remove the oxide. The optimal leaching conditions were determined to be at 90° C at a minimum pH target of 2.5 for the SHS produced product. At these conditions, conversion percentages of 83%-84% of MgO were measured with only trace amounts of TiB2 measured in the solution (less than 100 ppm). Conversion percentages for each leaching condition and dissolution mass of solid MgO and TiB₂ at each pH are also reported. Results from powder XRD confirm the removal of MgO and minimal dissolution of TiB₂, and indicate the formation of unidentified compounds. Inductively coupled plasma mass spectrometry (ICP) was used to analyze the ionic composition and extent of leaching. Scanning electron microscopy (SEM) was used to observe the particle morphology of the leached powders.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-10122006-142938en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-10122006-142938/en
dc.identifier.urihttp://hdl.handle.net/10919/35366en
dc.publisherVirginia Techen
dc.relation.haspartLOK_ETD.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectTitanium Diborideen
dc.subjectAcid Leachingen
dc.subjectThermite Reactionen
dc.subjectMagnesium Oxideen
dc.titleAcid Leaching of SHS Produced MgO/TiB2en
dc.typeThesisen
thesis.degree.disciplineMaterials Science and Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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