Coating with plasma is a versatile method to apply ultra-thin polymeric layers on a wide range of materials.
Plasma Coating - How it Works
Plasma coating can be performed either as PVD (physical vapor deposition) or PECVD (plasma-enhanced chemical vapor deposition). Plastics, metals, ceramics, glass, and a number of other materials can be finished by plasma coating.
PVD Coating (hydrophobic and hydrophilic)
In physical vapor deposition, the material for coating is evaporated with the aid of plasma. It condenses on the surface, forming a thin, strong layer that can be either hydrophobic or hydrophilic.
Plasma-enhanced chemical vapor deposition (PECVD) is an improved form of chemical vapor deposition (CVD). In CVD, the object to be coated is heated to high temperatures before the monomer is introduced into the plasma chamber. In PECVD, on the other hand, plasma is used to accelerate the coating process. In PECVD the desired results are easily obtainable and thermal stress upon the workpiece is lower.
Special Types of Layers
- PTFE coatings: Almost any type of material can be sealed with a layer of PTFE-like material by adding either carbon tetrafluoride (CF4) or fluorine (F2) to the plasma coating process.
- Functional layers: Layers with chemical functionality can be generated by plasma coating. One example is the functionalization of glass with amino groups which will chemically bind proteins.
- DLC (diamond-like carbon) films: By plasma coating, highly cross-linked hydrocarbon layers can be deposited on workpieces. They have diamond-like properties, being extremely hard, smooth, chemically resistant, and biocompatible.
Coating Plasma - Users and Uses
- Textile manufacturing: Coating by plasma can turn cotton hydrophobic and fibers dirt-repellent. Plasma coating is an essential first step in preparing yarns for the manufacturing of smart textiles.
- Manufacturing of biochips by plasma coating: Deposition of functional layers on glass for the chemical binding of bio-molecules.
- Friction bearings: Plasma coating of moving parts with diamond-like carbon films for lubricant-free systems.
- Fuel tank manufacturing: Protective layers of PTFE-like materials generated by plasma coating render plastic impenetrable and corrosion-resistant.