Meaning
Glass-ceramic material characterized by an extremely low, near-zero coefficient of thermal expansion constitutes the preferred substrate for ultra-precision optics and metrology standards. Manufactured by Schott, Zerodur combines a crystalline phase with a negative thermal expansion and a vitreous phase with a positive expansion. This combination achieves an overall expansion coefficient that approaches zero over a wide temperature range.
Material Synthesis
The production process requires controlled crystallization of a parent glass to grow lithium-aluminum-silicon oxide crystals. These crystals must be distributed uniformly to ensure isotropic mechanical properties throughout the bulk material. The unique structure of Zerodur provides exceptional long-term dimensional stability, resisting micro-structural changes over years of thermal cycling.
Thermal Property
Dimensional change is almost immeasurable when this ceramic is exposed to typical laboratory temperature variations. Its coefficient of thermal expansion remains below 0.05 times 10 to the minus 6 per Kelvin. This extreme resistance to thermal deformation prevents drift in laser interferometer mounts and semiconductor lithography stages.
Unlike metals, the material does not exhibit delayed mechanical relaxation after thermal shifts, providing immediate measurement stability.
High Precision Application
Metrology laboratories and aerospace manufacturers utilize this material for mirror substrates and reference scales. Choosing Zerodur for the structural loop of a coordinate measuring machine eliminates the need for active thermal compensation during long scans.
