| 摘要 |
<p>MACHINABLE GLASSES The present invention relates to glass articles which have compositions within the Li2O-ZnO-PbO-B2O3-SiO2-TiO2-Al2O3 system, which exhibit a dense white opal appearance and which have good machinability characteristics. The latter property enables the articles to be sawed and drilled with hand tools without spalling or breakage and, in addition, to be polished to a relatively high gloss. The glasses are rendered opaque by their separation into a lead oxide rich phase and a B2O3-SiO2 rich phase. The glasses may be converted to glass-ceramic materials, either before or after machining, if desired.</p> |
