Equipment & measurement methods

Field emission scanning electron microscope (FE-REM)

Since the spring 2016 is that Feldemission-Rasterelektronenmmicroscope (FE-REM) in the portfolio of analysis methods and corresponds to the latest technology available on the market. The new system provides an extremely powerful research methodology for R & D and quality assurance. The FE-SEM allows the investigation of very small structures and nanoparticles with up to 500.000 magnification of the samples. In addition, the visual representation in 3D format is possible. Here are the details: FE-SEM

To see the pictures in 3D, you need one 3D glasses, You do not have one and you want that impressive 3D effect experience? Then request a free copy here.

Melting point analysis

Differential scanning calorimetry (DSC) is a thermal analysis technique that involves subjecting samples to a defined temperature program, detecting the heat absorbed or released by the sample. Thus, material-specific properties as in some polymers, the melting point or the glass transition point can be determined.

The process is used in Rhenotherm especially for the identification of thermoplastic coating materials, but can also be used for the incoming goods inspection of paints. It is also possible with mixtures of polymers or addition of fillers that the melting behavior is significantly changed compared to the pure substance. These effects of additive admixtures can be detected by the DSC, which allows adjustment of the processing process (eg longer sintering time or changed sintering temperature).

DSC curve of PTFE powder
DSC curve of PTFE powder

Determination of contact angle & surface energy

Using a drop shape analyzer, defined volumes of liquid can be deposited on a surface and the contour of the resulting drop can be measured. This allows conclusions about the surface properties, such as the non-stick effect. In addition, pretreatment methods and the wettability of various materials can be tested and measured.

Infrared spectral analysis

IR spectroscopy enables the identification of liquid and solid materials. It uses the fact that the molecules of many organic substances and also individual groups of molecules are vibrated by irradiation with infrared light. These vibrations are molecular or molecule group specific and can be used for unequivocal identification.

The operation of the IR spectrometer is as follows:

The sample is irradiated with the entire IR light spectrum and absorbs certain frequencies of this spectrum. The unabsorbed residue then strikes a detector that detects the resulting difference. This results in a spectrum which is compared with reference spectra of known substances so as to arrive at an identification of the sample.

Among other things, the following provisions may be implemented:

  • Analysis of liquid lacquers => Determination of the composition
  • Identification of unknown coatings

Roughness measurement using a stylus instrument

In the roughness measurement, the surface is scanned with a probe which detects and detects the height change caused by the roughness of the substrate. Using special software, the measured data is converted into a roughness profile.

This can be done with a stylus tip with a diamond stylus or without contact with a laser stylus.

Execution:

  • Measurement of the sample according to DIN EN ISO 4288
  • Determination of all roughness parameters such as Ra, Rz, Rmax, Rq etc. possible
  • Recording individual profile lines or entire topographies

Adhesion test & sliding friction measurement by means of tensile testing machine

We test the properties of our coating with specially developed test methods in order to be able to compare all products and to offer the best solution for every application. With the help of our adhesion test, we can measure the adhesion of the coating to the substrate. For this purpose, sample plates are coated and the coating is peeled off with the aid of the tensile testing machine. The tensile testing machine detects the force required for the removal, which in turn is an indication of the adhesion of the coating. Frequently, the samples are also subjected to chemical or thermal stress to determine the effect on the adhesion of the coating.

The coefficient of sliding friction of our coatings is also determined on sample plates over which a defined weight is drawn with the aid of the tensile tester. The force required for this is detected and can be converted into the sliding friction coefficient with the weight force.

Sample plate after adhesion test
Sample plate after adhesion test

Cross sections & light microscopic examinations

Light microscopy allows a macroscopic view of the surface. Here relatively rough structures can be considered and evaluated. Light microscopy can be performed quickly and normally (see grinding as a special case) without preparation. It serves primarily as a method for initial screening for many questions.
Also examined under the light microscope are cross sections. For this purpose, the sample or fragments of this sample are embedded in a Einbettharz and ground flat with the aid of a grinder. Under the microscope, one can then look at the layer structure in cross section. With the help of this method, the layer thickness can be determined beyond doubt and most accurately. In addition, information such as the distribution of fillers in the coating can be obtained. The disadvantage of this method, however, is that it destroys the sample.

Micrograph of a corroded sample
Micrograph of a corroded sample

Cold finger test

This test method developed for and with Rhenotherm enables the corrosion resistance of coatings to be tested. For this purpose, a special, one-sided closed metal sleeve ("finger") is coated on the outside. This specimen is immersed in a special apparatus in the boiling test medium, which come as test media water, dilute acids or alkalis in question. The specimen is additionally cooled from the inside, resulting in a significant temperature difference, which means additional stress for the coating. At intervals (100 hours to several weeks running time) the cold finger is checked for blistering or other signs of corrosion. Once defects in the coating are detected, the test is terminated and the duration of the test is recorded in hours.
It is not a test method that gives absolute values, but a comparison of different coating systems. This serves to draw conclusions about their suitability in corrosive applications.

Experimental setup cold finger test
Experimental setup cold finger test
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