|
|
|
|
PRODUCTION AND CHARACTERIZATION OF MACHINABLE GLASS CERAMICS CONTAINING DIFFERENT RATES OF POTASIUM MICA AND CORDIERITE Machinable glass ceramics are materials produced by the similar production methods of melting and casting that all glass ceramics undergo with controlled nucleation and crystallization. In the first stage of the study, glass composition containing different ratios of potasium mica and cordierite have been prepared, mixed and casted at proper temperatures. 4% CeO2 as a stabilizer and 2%CaO as melting agent were added to glass compositions. In the second stage of the experimental studies, disc and cylindrical shaped samples were prepared to determine the microstructural and mechanical properties in terms of microhardness and machinability. Heat treatment methods were applied to the glass specimens in order to make microstructural characterization by using scanning electron microscope (SEM) and microhardness test for determining hardness values of the specimens and according to the obtained results, machinability test was applied by drilling. After machinability tests, chemical durabilities and electrical resistivities of produced materials were determined. As a result of experimental studies, it was determined that CeO2 addition promotes cordierite forming and CaO addition as a melting agent decreases the melting point of glasses. In selected glass compositions, curved mica that provides machinability and cordierite phases precipitated in glass base matrix. According to machinability tests, produced glass-ceramic materials have perfect machinability properties. Chemical durabilities of compositions have found relatively high and CaO addition has reduced the chemical durability. High electrical resistivities of glass-ceramic samples mean that these materials can be used as electrical insulator. |
|||
|
|