Titanium Nitride (TiN)
TiN is the original gold-colored PVD hard coating and the benchmark every later coating is measured against. It is a single-layer titanium nitride deposited by physical vapor deposition, and it exists to put a hard, inert, low-reactivity skin on tool and forming surfaces that would otherwise wear or cold-weld. Decades on, it is still the general-purpose default: not the hardest or the most heat-resistant option, but well-understood, widely available, and biocompatible enough for medical and food-contact use.
What the numbers say
- Hardness ~2,000–3,000 HV (typical ~2,300). A genuine spread across microhardness loads and datasheets; the GPa nanoindentation figures and bulk-TiN values are kept out of this range. [brycoat, eifeler, surfacesolutions]
- Max service ~450–600°C, oxidation-limited in air (typical ~550°C). Cited sources disagree — oxidation onset is quoted at ~454°C, 500°C, and 600°C — so this is a soft ceiling, not a single number. [brycoat, eifeler, balzers, surfacesolutions]
- Coefficient of friction ~0.6 against steel. Counterface is hardened bearing steel (100Cr6), dry and unlubricated, ball-on-disc per ASTM G99. All four cited pages converge on 0.6, though friction is a system property and the true envelope is wide. [eifeler, balzers, brycoat, surfacesolutions]
- Thickness 1–5 µm (typical ~3 µm); deposited 400–500°C (typical ~450°C) as a standard PVD process temperature. [brycoat, eifeler, surfacesolutions, balzers]
Where it fits
TiN earns its place as the all-round starter coating: wear protection on drills, taps, milling cutters and inserts; forming, stamping and fine-blanking tooling; and plastic injection-mold components. Its inertness and biocompatibility also make it the go-to decorative gold finish and a coating for medical and food-contact parts. The trade-off is the modest heat ceiling — for dry, high-speed machining or hotter forming work, the harder carbon-alloyed and aluminum-bearing nitrides take over.
Vendor-neutral note: these are general process properties for understanding tradeoffs — not a specification for your application. Real selection needs a coating house with your substrate, geometry, and duty data.