Ceramics and glasses · Workhorse
Macor machinable glass-ceramic
Macorvalues describe: Macor
Why it wins
Mill it Tuesday, bake it Wednesday: the prototyping insulator, stable to 800 C, CTE close to hard glasses so it mounts optics without cracking them.
Why not the alternative
Alumina is stronger and cleaner but needs grinding; PEEK dies at bake temperatures.
Watch out
Weaker than fired ceramics; not for high load or high voltage margins.
Properties
The values below are candidate: compiled from the sources named, not yet individually validated. Provisional provenance: CoorsTek, CeramTec, Kyocera technical ceramic data.
Wet cleaning
| Recipe | solvent degrease then long bake: machined surfaces are porous and hold cutting fluid |
|---|---|
| Forbidden | cutting fluid left in the pores; aqueous soak |
| Limit | machined porosity, so the bake matters more than the wash |
Vacuum and outgassing
| Outgassing, unbaked (10 h) | 5e-9 mbar·L/s/cm² |
|---|---|
| Outgassing, baked | 5e-12 mbar·L/s/cm² |
| Vapour pressure | none |
Temperature
| Bake, assembled | 450 °C |
|---|---|
| Vacuum degas | 800 °C |
| Metallurgical limit | continuous 800 °C, softens 1000 °C |
Thermal
| CTE | 9.3 ppm/K |
|---|---|
| Thermal conductivity | 1.46 W/m·K |
| Specific heat | 790 J/kg·K |
| Emissivity | 0.9 |
| Melting / softening | 1000 soft. °C |
Mechanical
| Strength | 94 flex MPa |
|---|---|
| Elongation | nil |
| Young's modulus | 66.9 GPa |
| Hardness | 250 HV |
| Density | 2.52 g/cm3 |
Electrical and magnetic
| Relative permeability | 1.0 |
|---|---|
| Resistivity | >1e14 Ω·cm |
| Dielectric strength | 40 kV/mm |
Engineering
| Corrosion | good |
|---|---|
| Joining | not brazeable; mechanically clamped |
| Process notes | machines on a normal lathe, which is its whole point |
| Availability and cost | Corning, stock bar and plate |
Outgassing
4 sourced measurements for this card. A rate means nothing without the pumping time it was read at, so each one states it or declares it missing. The whole base, filters included, is at /tools/outgassing/.
Signature: no unbaked reading unbaked to 1e-12 baked.
| Material as published | Species | State | Pumping time | Rate |
|---|---|---|---|---|
| Macor machinable glass ceramic rods | total | baked | NOT STATED by the source | less than5.20e-13mbar·L/s/cm² |
| Macor machinable glass ceramic rods | total | baked | NOT STATED by the source | less than9.10e-13mbar·L/s/cm² |
| Macor machinable glass ceramic rods | total | baked | NOT STATED by the source | less than1.50e-12mbar·L/s/cm² |
| Macor machinable glass ceramic rods | total | baked | NOT STATED by the source | less than3.20e-12mbar·L/s/cm² |
Sources: S-CERN-THESIS-2019-061. Full citations and conditions at the base and in /data/outgassing.json.
Grades
| Macor (Corning MGC) | the single canonical grade |
|---|