Guides / Finishes

PVD Coatings Explained: TiN, CrN and DLC for Hardened Parts

October 13, 2026

PVD, physical vapor deposition, coats a part inside a vacuum chamber by vaporizing a solid source material and letting it condense on the surface as a thin, hard film. It is the process behind the gold-colored TiN coating on cutting tools and the dark, low-friction DLC coatings on precision components. This guide explains how the process works and which of the common PVD coatings fits which job. This overview is part of our guide to PVD coating services, which takes the buying decision from coating choice to verification and RFQ.

How PVD differs from plating

Electroplating and electroless plating deposit metal from a liquid solution, using either electric current or a chemical reducing reaction. PVD happens in a vacuum chamber: a solid source material is vaporized, sometimes reacted with a gas such as nitrogen to form a compound coating, and the vapor condenses on every exposed surface of the part.

The result is a thin, dense, hard coating, typically 1 to 5 µm, well below the thickness of most electroplated finishes. PVD coatings are valued for hardness and low friction rather than for corrosion protection or thickness the way zinc or powder coat are.

Titanium nitride, TiN

TiN is the most common PVD coating, recognizable by its gold color. It is hard, wear resistant and has been used on cutting tools and dies for decades, which gives it the longest track record of the common PVD coatings.

Use it for cutting tools, dies, molds and wear surfaces where a proven, moderately priced hard coating is enough.

Typical thickness: 1 to 4 µm. Typical hardness: in the range of 2000 to 2500 HV, well above hardened tool steel.

Watch for: color is cosmetic as well as functional; if the gold appearance matters to your application, confirm the shop’s process gives a consistent shade batch to batch.

Chromium nitride, CrN

CrN runs at a lower process temperature than TiN in many deposition systems and tends to perform better against corrosion and adhesive wear, at somewhat lower hardness. It is a common choice where TiN’s process temperature is a concern for the substrate, or where corrosion resistance alongside wear resistance matters.

Use it for molds, dies and wear parts in corrosive environments, and substrates more sensitive to process heat than tool steel.

Typical thickness: 1 to 5 µm. Typical hardness: generally somewhat below TiN, in the range of 1750 to 2200 HV depending on the specific process.

Watch for: confirm actual process temperature with the shop if your substrate has a low tempering temperature; “lower than TiN” is relative, not universally low.

Diamond-like carbon, DLC

DLC coatings are amorphous carbon films that combine high hardness with very low friction, closer to a solid lubricant than a conventional hard coating. Several DLC variants exist, differing in hydrogen content and added elements, which changes friction and hardness balance.

Use it for sliding and rotating parts where friction reduction matters as much as wear resistance, such as precision shafts, pins and components running against another metal surface without external lubrication.

Typical thickness: 1 to 3 µm. Typical hardness: can exceed 3000 HV depending on the specific DLC variant, though the coating’s low friction is often the more relevant property than raw hardness.

Watch for: DLC variants differ meaningfully between shops and equipment. Describe the friction and wear requirement rather than naming “DLC” alone, and let the shop propose the specific variant they run.

Process temperature and hardened steel

Most PVD processes run hot enough, commonly in the range of 150 to 500 °C depending on the specific coating and equipment, to matter for hardened steel substrates. A part tempered at a lower temperature than the PVD process runs can lose hardness during coating. Ask the shop what process temperature their specific PVD coating requires and compare it against your steel’s tempering temperature before committing.

This is a different concern from hydrogen embrittlement, which is an electroplating risk. PVD does not carry the same hydrogen uptake mechanism, but process heat is a real substrate consideration in its place.

Coverage and geometry limits

PVD is a line-of-sight process: material vapor travels in straight lines from source to part inside the chamber, so deep bores, blind holes and sharply undercut features coat thinner than exposed faces, or not at all without part rotation and careful fixturing. If your part has internal features that need the coating, confirm with the shop how they handle coverage in those areas before assuming uniform thickness the way you might with electroless nickel.

Cost and lead time relative to plating

PVD generally costs more per part than conventional electroplating, largely because vacuum chamber time is expensive relative to a plating tank, and batch sizes per chamber load are often smaller than a plating rack or barrel. Lead time follows a similar pattern: PVD runs are frequently scheduled in batches around chamber availability, rather than a continuous line a part can join at any time, which can mean a longer queue than a comparable plating process.

The cost is usually justified by what conventional plating cannot deliver: a thin, hard, low-friction film that adds negligible dimensional change, which matters on precision-fit parts where any electroplated thickness would need to be accounted for in the design. If the part does not need PVD’s specific combination of properties, a conventional wear coating such as hard chrome or electroless nickel is often the lower-cost route to similar wear performance.

Substrate preparation and adhesion

PVD coating adhesion depends heavily on the condition of the surface entering the vacuum chamber. Parts are typically cleaned and sometimes etched in-chamber immediately before deposition, since any contamination, oxide layer or residual machining oil left on the surface becomes trapped under the coating and can cause adhesion failure.

Surface finish going in matters more for PVD than for a thicker electroplated coating, since PVD films are thin enough to closely follow the existing surface topography rather than filling it in. A rough or scratched surface will show through a PVD coating in a way it might not show through a thicker deposit. If a smooth final appearance matters, confirm the required starting surface finish with the shop before the part is machined or ground.

Specifying PVD on a drawing

There is no single dominant published spec for PVD the way ASTM or MIL-PRF specs exist for plating and anodize. Most PVD callouts are customer-specific, naming:

• Coating type (TiN, CrN, DLC or a named variant).
• Thickness range.
• Hardness requirement, if critical to function.
• Any process temperature limit tied to the substrate’s heat treatment.

Because the spec landscape is less standardized than plating, describing the function the coating has to perform, alongside any coating type preference, gets a more useful quote than a bare coating name alone.

See also: PVD coating reference: coating types, thickness, temperature and tests.

How we help

We are a matching service, not a plating shop. Describe what the part has to survive, sliding wear, abrasive wear, high temperature or low friction, and we pass your RFQ to up to three shops running PVD that can recommend and quote the right coating. See which finish fits your part for how PVD compares with plating and anodize more broadly, or go straight to the RFQ form.

Frequently asked questions

Keep reading

• Zinc Flake Coatings for Fasteners: When to Specify Them and What to Check
• Wear Surfaces: Choosing Between Hard Anodize, Nitriding and Hard Chrome