TiNvalues describe: PVD TiN
Big science (accelerators, light sources, public fusion)
Why it wins
The anti-multipacting skin: sputtered nanometers of TiN drop secondary electron yield on RF ceramic windows and couplers, and armor NdFeB undulator magnets against desorption and dust.
Why not the alternative
Bare alumina windows multipactor and punch through; bare magnets shed.
Watch out
Thickness is a compromise: too thick heats in RF fields.
Properties
The values below are candidate: compiled from the sources named, not yet individually validated.
Provisional provenance: CERN Accelerator School, vacuum and materials proceedings; CERN vacuum group compilations and coating programme.
Wet cleaning
| Recipe | substrate cleaned to UHV standard before coating; the film tolerates a solvent wipe |
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| Forbidden | abrasives: the film is thin |
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| Limit | adhesion, set by substrate preparation not by the film |
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Vacuum and outgassing
| Outgassing, unbaked (10 h) | 5e-10 mbar·L/s/cm² |
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| Outgassing, baked | 5e-13 mbar·L/s/cm² |
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| Vapour pressure | none |
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Temperature
| Bake, assembled | 400 °C |
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| Vacuum degas | substrate |
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| Metallurgical limit | oxidises above 550 °C in air |
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Thermal
| CTE | 9.4 ppm/K |
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| Thermal conductivity | 29 W/m·K |
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| Specific heat | 600 J/kg·K |
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| Emissivity | 0.4 |
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| Melting / softening | 2930 °C |
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Mechanical
| Strength | coating |
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| Elongation | nil |
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| Young's modulus | 250 GPa |
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| Hardness | 2000–2400 HV |
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| Density | 5.22 g/cm3 |
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Electrical and magnetic
| Relative permeability | 1.0 |
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| Resistivity | 25 µΩ·cm |
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Engineering
| Corrosion | good |
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| Joining | PVD onto a finished part |
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| Process notes | SEY 1.4–1.7 after conditioning |
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| Availability and cost | commodity PVD service |
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Grades
| Reactive sputtered TiN, 2 to 10 nm | RF window and coupler coating |
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| TiN on NdFeB | in-vacuum undulator magnet protection |
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Sources · 1
- CERN Accelerator School, RF and vacuum
← The Matter