Akademik Veri Yönetim Sistemi
JOURNAL OF MATERIALS SCIENCE, cilt.53, ss.14350-14360, 2018 (SCI-Expanded)
A study was carried out on the carbon encapsulation of a number of elements using a spark discharge generator. The study showed that elements W, V, Ti, and Si formed carbides which were encapsulated successfully by graphitic layers forming a sound core-shell structure. Copper formed a partially filled core-shell structure, attributed to its relatively low condensation temperature, where considerable shrinkage seemed to have occurred after the encapsulation. Mg could not be encapsulated in a core-shell form but rather yielded an embedded structure where Mg is condensed onto already condensed carbonaceous material. Analysis of current observations coupled with those already reported data imply a simple mechanism for encapsulation. Metals/compounds that are solid above the condensation temperature of carbon give rise to a sound core-shell structure. Elements whose condensation temperature is less than that of carbon could still produce core-shell particles but they may be partially filled. It is estimated that the process of graphitic encapsulation may be complete around 1900 K and partially filled core-shell structure might develop depending on the volume shrinkage upon cooling to room temperature. Elements/compounds whose condensation temperature is below the encapsulation temperature fail to develop core-shell structure. Instead, they form embedded composite structure.