Functional Coatings and Surface Technology

Functional Coatings and Surface Technology

Highly Porous Bioglass Layer on Metallic Hollow Spheres (316L)
© Fraunhofer IFAM Dresden
Highly Porous Bioglass Layer on Metallic Hollow Spheres (316L)

At the Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM) in Dresden, special, low-cost processes are being developed with which even complicated geometries can be coated in a reproducible way. A particular focus is the development of new technologies that can significantly increase the performance and functionality of metallic materials (e.g. temperature resistance, corrosion resistance, specific surface, biofunctionalization, catalytic activity and selectivity, sensory properties, etc.). For coatings, especially wet-chemical processes such as Liquid Phase Deposition (LPD), e.g. dip or spray coating, are used. However, other methods such as chemical vapour deposition (CVD) or galvanic processes can be used, if required.

 

 

Applications

TiO2 Coating on Open Cell Metal Foam
© Fraunhofer IFAM Dresden
TiO2 Coating on Open Cell Metal Foam
Filled SiCN Coating for High Temperature Oxidation Protection of Mild Steel (ST37)
© Fraunhofer IFAM Dresden
Filled SiCN Coating for High Temperature Oxidation Protection of Mild Steel (ST37)
  • Oxidation and Corrosion Protection
    Functional coatings allow the application of processed materials at elevated temperatures and under corrosive conditions.
  • Catalyst Technology
    Combines light, ductile catalyst supports with highly porous coatings with a large surface area, defined pore size and shape and active centers.
  • Adsorption
    Permeable materials with large surfaces for gas drying and gas cleaning.
  • Medical and Implant Technology
    Permanent and degradable coatings for implants.
  • Biotechnology and Food Technology
    Immobilization of microorganisms and enzymes.
  • Sensor Technology
    Gas analysis and process monitoring.
  • Chemical Process Technology
    Highly porous coatings with defined pore size and shape for microreactors.
  • Interface Materials
    Interface layer with adjustable electrical and thermal conductivity or insulation.

Technology

Liquid Phase Deposition (LPD)

Cost-effective method, approved from paint technology, also allows the coating of larger components with demanding geometry.

  • Dip Coating
  • Spray Coating
  • Sol / Gel - Methods

Structure

Coatings above and below
© Fraunhofer IFAM Dresden
Coatings above and below

Diffusion of elements from the coating into the substrate leads to the formation of an intermediate layer - the reason for the good adhesion compared to physically applied coatings.

 

Materials

Highly Porous Bioglass Layer on Metallic Hollow Spheres (316L)
© Fraunhofer IFAM Dresden
Highly Porous Bioglass Layer on Metallic Hollow Spheres (316L)
AgO Coating on Fibre Structure (Highly Porous, Catalyst Carrier)
© Fraunhofer IFAM Dresden
AgO Coating on Fibre Structure (Highly Porous, Catalyst Carrier)

Substrate Structures

  • Open cell metal foams, metallic hollow spheres, sintered hollow sphere structures, metallic fibre structures
  • Metal plates and profiles


Coating Material (Precursor)

  • Inorganic polymers: polysilazanes, polysiloxanes, polycarbosilanes
  • Metal alkoxides
    (M(OR)x)M = Si, Al, Ti, Zr…
  • Bioglasses


Filler Systems

The use of filler systems increases the functionality of coatings with regard to thermal expansion, hardness, electrical and thermal conductivity. Filler systems are developed individually for each application.

 

Properties

Oxidation Test: 1100 °C, Air, 400 h
© Fraunhofer IFAM Dresden
Oxidation Test: 1100 °C, Air, 400 h
  • Dense or porous ceramic coatings or hybrids of organic-inorganic coatings
  • Tickness: 100 nm up to 200 µm
  • Very good adhesion to the substrate
  • High temperature stable
  • Oxidation- and corrosion resistant
  • Adjustable pore size and shape

Examples

BET Surface of Coated Metallic Hollow Spheres after Pyrolysis at 800 °C
© Fraunhofer IFAM Dresden
BET Surface of Coated Metallic Hollow Spheres after Pyrolysis at 800 °C

Density SiCN - Coating

  • Coating material: SiCN - polysilazane ceramic
  • Substrate: sintered hollow sphere structure
  • Material 1.4767 (Fe-20Cr-6Al)
  • Coating tickness: 7 µm


High Porous Ceramic Coatings

  • Substrate: metallic hollow sphere
  • 316L
  • Coating thickness: 10 µm