The functional configuration of surfaces

Tribology and surface design

Component surfaces can often be damaged by the stresses of the manufacturing process as well as in normal use. Yet the condition of the surfaces can determine the functionality of a technical system. Scientists at the Fraunhofer IWM have extensive know-how combined with methods and processes which assure that specific properties belonging to the surfaces of parts and components, such as a low coefficient of friction, provide a specific surface energy or a desired visual appearance.

Specific developments for clients and project partners usually begin with an investigation of the failure mechanisms related to the surfaces involved using modern testing stations or by creating entirely new analysis techniques in order to determine the surface characteristics. The application of special simulation methods is useful for interpreting the experimental observations and evaluating damage events, thus helping to reduce the time required for subsequent development of coatings and techniques. These involve high-performance coating technologies together with specific edge-layer modifications and new processing methods.

Experts at the Fraunhofer IWM examine a wide range of problems. An example is the manufacture of bearings, where typical objectives would be to obtain stable friction conditions as quickly as possible, to assure particular dry-running properties or to achieve the longest possible service life. In plant construction and mechanical engineering the Fraunhofer IWM deals with questions concerning corrosion mechanisms, efficiency improvements and the possibilities for material pairing. In optics manufacturing and injection molding, methods are developed for damage-free demolding, online temperature measurement for molding tools and surfaces for forming tools that can realize the component surface properties required. In addition to the classification of layers, the Fraunhofer IWM develops coating techniques designed to achieve specific layer properties such as surface topography and microstructure.


How to work with the Fraunhofer IWM

Possibilities for measurement and analysis; surface treatment techniques
 

The Fraunhofer IWM works with the most up-to-date equipment available and develops special testing systems and experimental setups for individual customer queries.

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Surface functionalization


Characterization and control of wear, wetting behavior, visual appearance, gloss level and haptics of component surfaces

 

  • Characterization of surface contours and topography:
    • Atomic force microscope AFM
    • Scanning electron microscope REM
    • Profilometer and roughness measurement devices
    • Optical microscope
    • Confocal laser scanning microscope CLSM
    • White light inferometer WLI
    • Inferometer with phase modifier
  • Determination of surface conductivity and wavelength-dependent measurement of reflection, transmission and color:
    • High-resistance ohmmeter
    • 4-point resistance measurement
    • Glass fiber spectrometer
    • Wavefront measurement facility
  • Coating and plasma treatment of surfaces by various methods:
    • Reactive magnetron sputtering (HF, DC, pulsed DC)
    • Ion radiation techniques
    • Electron beam evaporator
    • PECVD systems
    • Plasma etchers

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Chemical and mechanical properties
 

Evaluation, modification and optimization of corrosion stability, adhesion, catalysis, material compatibility and diffusivity of component surfaces

 

  • Determining the composition of the chemical structure of surfaces and layers, spatially resolved and depth-dependent, plus phase analyses:
    • Confocal Raman microscope
    • FTIR spectrometer
    • ECP-OES optical emissions spectroscope
    • Glimmer discharge spectrometer GDOES
    • Energy-dispersive x-ray spectroscope EDX
    • X-ray photoemission spectroscope XPS
    • Quadrupole mass spectrometer
  • Surface energy and contact behavior measurement:
    • Test rigs for glass and plastics contact
    • Contact angle measurement device with temperature probe
  • Direct measurement of corrosion behavior:
    • Atlas cell test rig (cold-wall effect)
    • Elcometer 266 high-voltage holiday detector
    • Test rig for electrochemical noise
    • Electrolysis cell for hydrogen diffusion measurement
    • Test rig for corrosion in hot melted salts
  • Application-specific surface conditioning:
    • Coatings
    • Blasting processes (metals, ceramics)
    • Heat treatment processes

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Mechanical properties
 

Optimization of tribo pairs; determining of friction coefficient, wear resistance, dry-running behavior, lubricant stability and fretting behavior of components in use

 

  • Determination of tribological properties using application-specific tribo test rigs:
    • Piston-ring liner simulator with radionuclide technology RNT
    • Pin-on-disc tribometer with RN-T technology
    • Bearing and component test rig with RN-T
    • Pin-on-disc, rolling wear and ball bearing test rigs
    • Oscillating sliding abrasion test unit
    • Microtribometer
    • Tribocorrosion test rig
    • Hysitron TI 950 TriboIndenter
    • Tetra BASALT MUST, BASALT HOMAT surface testers
    • In house-developed UHV microtribometers and multiscale tribometers
    • Ice tribometer
    • Rheometer
    • Engine test rig
  • To determine the mechanical properties of edge layers and coatings, such as layer thickness, hardness, adhesion, inherent stresses and elastic modulus:
    • Layer thickness measurement (eddy current, magneto-inductive)
    • ScanningScratchTest SST
    • Rupture test
    • Nano indenter
    • Rockwell indentation, ball indentation
    • Scratch
    • Zygo interferometer for warp measurement
    • Ball impact test
    • Micromechanics test rig

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Surface coating and conditioning
 

Processes for development and application of application-specific coatings, in combination with suitable surface conditioning where appropriate:

  • Reactive magnetron sputtering (HF, DC, pulsed DC) with HF substrate biasing
  • Ion radiation techniques
  • Electron beam evaporator
  • PECVD systems
  • Plasma CVD coating systems CCP/ICP
  • Multi-chamber coating system for multiple-layer coatings and hybrid coatings
  • Plasma etching systems
  • Wet chemical coating systems (spin coating, knife coating, dip coating)
  • Ion etching unit for sample preparation and surface treatment
  • Ultra-precision turning, grinding and milling machine for diamond machining of forming tools
  • Shot peening systems for surface hardening and structuring

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