Surface treatment with plasma

The demand for special functional coatings for products and semi-finished products is very high in many industrial sectors - from automotive production and plastics processing to medical technology or biotechnology. Fraunhofer IFAM is researching and developing plasma-assisted coating processes which decisively improve the range of properties of these (semi-finished) products almost independently of the material used. And without the use of chemicals! This makes these processes particularly interesting at present, because it helps companies to comply with regulations such as the REACH regulation or the HSE guidelines.

 

The three advantages of plasma coatings: thin, chemical-free and material-independent

Plasma coatings enhance the properties of many products and semi-finished products: targeted plasma treatment provides their surfaces with a variety of functions such as adhesion promotion, corrosion protection or aging protection. Depending on the function, plasma coatings offer different advantages. However, all plasma coatings have three major advantages in common.

1. Extremely thin: plasma technology can be used to produce thin layers with a thickness typically between 10 nanometers and 1 micrometer. The component geometry therefore remains virtually unchanged.
2. Chemical-free: the plasma layers are produced in a dry chemical process. The use of wet chemical substances such as primers or release agents can therefore be dispensed with.
3. Virtually independent of materials: whether metals, polymer plastics or fiber composites - plasma-supported coating processes can be used on almost all materials.

 

Plasma: the environmentally friendly alternative for many industries

Plasma coating processes provide an economical and environmentally friendly alternative to wet chemical treatment processes for many different industrial manufacturing processes. Table 1 shows a selection of possible applications.

If wet chemical coating processes are to be dispensed with due to employee and environmental protection (REACH, HSE), industry-specific regulations or cost savings, it is worth considering the use of plasma technology. The researchers at Fraunhofer IFAM provide advice on this and, if necessary, carry out feasibility studies.

Industries	Selection of possible functional coatings
Automotive and aircraft construction	Adhesion promoters for adhesives and coatings Infiltration-resistant sealing adhesives Protection against hydrothermal aging Release coatings for plastics processing Antibacterial surface coatings for interiors Friction reduction, e.g. for radial shaft seals
Energy sector	Hydrogen barriers for LOHC technology Release coatings for the production of rotor blades in wind energy Adhesion promoters for solar modules Anti-aging coatings for photovoltaics Abrasion and corrosion protection for reflectors of solar thermal power plants
Medical technology	Antibacterial coatings Coatings for the storage of antibiotics, e.g. on implants Coatings for controlling cell adhesion
Maritime technologies	Active anti-fouling Corrosion protection
Plant and mechanical engineering	Blank corrosion protection for production lines Particularly interesting for food production and processing, where flaking of protective coatings must be avoided at all costs.

 

Functional layers for different applications

Different functional layers can be produced by means of plasma coating. The table shows a selection of functions and benefits which the experts at Fraunhofer IFAM have often realized for customers from different industries and in publicly funded projects.

It should be emphasized that these functions can often be combined. For example, plasma coatings can be produced for electronic components, which combine electrical insulation, corrosion protection, and aging protection. In medical technology, it is possible to produce implant coatings that are antibacterial and at the same time can store antibiotics that promote acceptance of the implant by the body.

Function	Advantages (selection)	Possible applications
Adhesion promotion	Chemical-free improvement of long-term adhesion (substitute for primer!)	Metallization of plastics Structural bonding of light metals Painting of composite materials with water-based paints
Release coating	Release agent-reduced or even release agent-free demolding of molded parts	Can be implemented for various plastic and FRP processing methods, including: In-mold coating (IMC) process Injection molding Rigid foam Slush process Thermoplastic injection molding Wax injection molding Get to know the ReleasePLAS® release coating system developed by Fraunhofer IFAM!
Easy-to-Clean	Chemically exceptionally stable layer Can be combined with other functions, such as corrosion protection or wear protection	Fraunhofer IFAM has developed Easy-to-Clean coating systems for various applications, including: PermaCLEANPLAS® for easy cleaning of surfaces contaminated by coatings BestSKINPLAS® as a non-stick coating in the food processing industry
Corrosion protection	Plasma polymer corrosion protection coatings have a high thermal and chemical resistance Coating of narrow, complex components (e.g. heat exchangers) possible Can be combined with, among other things, electrical insulation, antimicrobial effectiveness or release properties	Anodizing replacement or combination with anodizing finishing Heat exchanger Plant engineering and fixture construction Automotive supply industry Building equipment Musical instruments
Protection against aging and insulation	No emission of Volatile Organic Compounds (VOC; volatile organic substances) No need for protective coatings or potting compounds	Especially in electronics:   Coating of sensors Replacement of protective coatings on electronic boards Local aging protective coatings on conductive tracks and contacts
Friction reduction and abrasion protection	Extending the service life and increasing the mobility of interacting components	FrictionPLAS and FrictionPLASblack, for example, for small and large components such as radial shaft seals, o-rings, plastic rails or metallic components (e.g. made of aluminum, copper, titanium, steel or stainless steel) in all industries
Antibacterial	Create a competitive advantage: enhance your product surface with preventive protection against the transmission of bacteria! Biocompatible design for medical technology applications	Particularly interesting for interior fittings in public buildings and transport Special possibilities for medical technology, including implants
Storage	Biocompatible design for medical technology applications	Particularly interesting for medical technology: antibiotic-containing coatings with adjustable release behavior

 

Plasma coating process supplemented by laser technology

Both plasma-enhanced chemical vapor deposition (PECVD) and physical vapor deposition (PVD) can be used to create new application-specific surface properties without significantly changing the geometry of the component. In combination with laser treatments, be it structuring or smoothing, these properties can be optimized in many ways, for example in adhesion (bonding), tribology, or wetting (superhydrophilicity, superhydrophobicity). Fraunhofer IFAM has the corresponding know-how in laser technology.

Dr. Ralph Wilken is head of the department "Plasma Technology and Surfaces" at Fraunhofer IFAM. With his team of researchers, he offers extensive knowledge of all aspects of the use of plasma, laser, and VUV technologies in surface engineering. In close cooperation with customers from industry, they develop customized plasma coatings. Many of them are already successfully implemented in manufacturing in a wide range of industries.