Materials testing and material analysis



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Research

In the materials testing and analysis laboratories, a wide variety of materials tests are carried out in close cooperation with the HOFZET application centre of the Fraunhofer WKI for the development and investigation of conventional materials and in particular plastics as well as bio-based materials (biopolymers, natural fibre-reinforced composites, paper, etc.) or other products made from renewable raw materials.

In materials testing, for example, a wide variety of mechanical test methods (tensile, compression or flexure test, hardness test and notched bar impact test, heat deflection temperature, computer tomography) are carried out. In addition, chemical stability and long-term properties are analysed through various weathering tests.

Within the scope of material analysis, e.g. particle and fibre analyses, surface analyses as well as tribological tests are carried out.

Various supplementary microscopic analyses (scanning electron microscopy including EDX, light microscopy, heating table microscopy), thermal examinations (rheology, dynamic differential calorimetry, pyrolysis) and optical measuring methods (Fibershape) enable the results to be better interpreted.

Interesting techniques

Computer tomograph Procon X-Ray CT-AlphaDuo

Technical data:

  • 240-kV microfocus and 225-kV high-power X-ray tube
  • 4MP detectors
  • Samples: Maximum diameter 500 mm, maximum height 400 mm, maximum weight 25 kg
  • In-situ-stage for 4-point bending tests
  • Z-shaft for further in-situ set-ups (e.g. fluids, pressure, etc.)
  • Scan volume depends on recording mode:
  • 500 mm diameter, 250 mm height
  • 250 mm diameter, 400 mm height
  • Minimum voxel size: < 1 μm

In conjunction with the HOFZET application centre of the Fraunhofer WKI, a wide range of CT measurement issues can be addressed.

Scanning electron microscopy incl. EDX for elemental analysis, line scans and mapping

A scanning electron microscope (SEM) is an electron microscope in which a primary electron beam is passed over a sample (scanned). This creates interactions between the electrons and the sample and thus an image is produced. The entire process usually takes place in a high vacuum to avoid interactions with atoms and molecules in the air. The main areas of application of an SEM are material and damage analysis.

Scanning electron microscopy has several advantages over traditional light microscopy:

  • High depth of field
  • Increased resolving power
  • Low effort for sample preparation
  • Simple adaptation of additional measuring devices for microanalysis

When the sample is bombarded with the electron beam, secondary products are produced that can be used for imaging as well as for material analysis. The secondary electrons (SE) and the backscattered electrons (RSE) are the signals used for image generation. For material characterisation, X-rays are used, which are analysed with an energy dispersive (EDX) spectrometer. Another development in SEM is the use of VP (variable pressure) apertures. This makes it possible to microscope highly gaseous, moist and non-conductive samples and to carry out non-destructive examinations.

Dynamic differential calorimetry (DDK/DSC): DSC 204 F1 Phoenix Netzsch

The dynamic differential calorimetry (DDK) or differential scanning calorimetry (DSC) is a method of thermal analysis that measures the specific heat of a sample as a function of temperature. Characteristic thermal properties of biopolymers such as melting points, glass transition temperatures and crystallisation processes can be determined and graphically displayed with the help of the DSC.

In plastics technology, this test method is used in the areas of development, production, incoming inspection, quality assurance and damage analysis of moulded parts.

Technical data:

  • Temperature measuring range: -180 °C to 700 °C
  • Heating rate range: 0.001 K/min - 200 K/min
  • Cooling rate range: 0.001 K/min - 200 K/min
  • Cooling: maximum 200 K/min; automatically controlled liquid nitrogen cooling.
  • Baseline optimisation: BeFlat®
  • Automatic sample changer: DSC 204 F1 Phoenix® ASC for 64 samples and reference beakers

 

 

Equipment

Mechanical testing laboratory

  • Universal testing machine Zwick/Roell Z100 Allround-Line
  • Universal testing machine Zwick/Roell Z020 Allround-Line
  • Bench tester Zwick/Roell Z2.5 TN zwicki-Line
  • Pendulum impact testing machine Zwick/Roell HIT25P

Thermal and rheological testing laboratory with weathering

  • HDT and Vicat test system CEAST HV500 Instron
  • Dynamic-mechanical analysis: DMA 242 E Artemis® Netzsch
  • Dynamic differential calorimetry (DDK/DSC): DSC 204 F1 Phoenix Netzsch
  • Rheology: High pressure capillary rheometer
  • MFR/MVR extrusion plastometer
  • Flow spiral
  • Climate change cabinet ARS-1100 ESPEC and UV rapid weathering unit

Imaging methods and optical analysis

  • Computer tomography
  • Various light microscopes
  • Heating table microscope Axio Scope.A1 Zeiss
  • Two scanning electron microscopes including EDX for elemental analysis, line scans and mapping
  • 3D digital microscope
  • Particle, fibre analysis and characterisation via Fibershape
  • Colour and gloss meter

Further testing devices

  • Contact angle measuring device and tensiometer DCAT 21
  • Moisture analysis with Aquatrac + and Aquatrac-3E
  • Density determination with electronic analytical balance EL204/01
  • Microtome

Impressions

The team

Team leader for thermomechanical tests and rheology

Non-Public Person