The formation of interfacial phases is highly probable
and depends upon chemical reactions and mass transport
on both sides of the interface. Wetting and matching
of coefficients of thermal expansion (CTE) of oxide
glasses and non-oxide ceramics can also be an issue.
The largest recommended difference in CTE is ±0.5 ·
106
K1 to prevent stresses generated with in the glass
and/or substrate that may lead to cracking and either
cohesive or adhesive types of failure.