| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a glass ceramic which realizes both of a good surface property compatible to the contact recording system and stable low floating of a magnetic head and in which alkaline components are reduced and deposition of lithium disilicate causing surface defects (pits) when the ceramic is polished or of a crystal phase, or the like, exhibiting a negative or low thermal expansion is suppressed. <P>SOLUTION: The glass ceramic contains, as a main crystal phase, at least one kind selected fromα-cristobalite,α-quartz and solid solutions of them and substantially does not contain lithium disilicate, lithium silicate or a crystal exhibiting a negative or low thermal expansion, and further the glass ceramic is substantially free from B, Cr and Mn components and has an average coefficient of linear thermal expansion in a temperature range of -50 to +70°C of +65 to +140 (10<SP>-7</SP>/°C). The deposited crystal has an aggregate secondary particle structure, in which an average primary crystal particle diameter is <0.1μm and an average aggregate secondary particle diameter is 0.3 to 2.0μm. <P>COPYRIGHT: (C)2003,JPO</p> |
