What is Thin Dense Chrome?
Thin Dense Chromium and is a low-temperature (~60°C), surface coating process based on chrome-plating technology, but displays higher hardness along with better lubricity and corrosion than other chromium coatings on the market. Through a proprietary chemical solution, TDC is produced as a hard, thin, dense chrome coating, where its micro-nodular surface texture boasts benefits that other coatings can't produce, enhancing use, and reducing wear. A further MLP process can be applied to reduce friction and improve the corrosion resistance.in South Africa the TDC available is the Armoloy® coating.
Properties of TDC
- High hardness at >72 HRc
- Nodularity – A key property of TDC is a nodular effect which increases lubricant retention and reduces surface contact area. This in turn improves the wear life and reduces friction.
- The dense nature of the coating means high corrosion resistance as the coating is almost free of micro-cracks
- High adhesion strength – TDC coating is highly resistant to chipping, flaking, cracking and peeling from the base metal under standard ASTM bend tests.
- Uniform deposits with minimal thickness or edge build-up
- No requirement for post finishing (except special applications)
- Matt silver satin chrome finish
- Can be applied locally to a specific area only
- Typical thickness 2.5 – 5.0 µm (max).
Safety & Cleanliness
FDA/USDA approved for use, without concern on food processing equipment, in clean room environments and medical/pharmaceutical applications. Independent testing has proven no issue of toxicity or skin irritation in TDC coated parts.
- Excellent adhesion to the base metal
- Reduces fretting and pickup or galling
- Reduced wear and friction of moving parts
- Enhanced corrosion resistance, in some cases replacing stainless steel.
- Improved release characteristics on moulds and dies
- Reduced maintenance and machinery replacement costs
- Smoother, faster and quieter running equipment
- Complies to AMS-2438a (10/98)
- Can be applied to internal and external geometries
- Protects expensive replacement parts such as stainless steel and tool steels
- TDC can be applied to nitrided surfaces, but all components must be clearly defined as being nitrided before coating.
The TDC Advantage
- Although TDCis not the hardest micro-coating available, it has its own distinct advantages when compared to other micro-coatings available.
- Size flexibility – from coating of needle size components up to 3 meter shafts, TDC can handle a large range of sizes that often limit other solutions.
- Low process temperature- since the coating is performed at low temeperatures there is no threat that the coating will affect the underlying material's heat treatment. Thus even unknown steels can be coated with confidence.
- Insignificant Hydrogen diffusion – for many electroplated coatings hydrogen gas evolution and long plating times threaten heat treated components due to Hydrogen Embrittlement. Due to the extremely rapid deposition rate, hydrogen exposure is typically only a few minutes meaning post baking is unnecessary for all but the most critical of components.