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Gammadata Instrument offers equipment, services and expertise in atomic and nuclear physics, laser and optical measurement technology, high-end microscopy systems, elemental analysis and material characterization, in addition to instruments and equipment for educational classrooms to help teach the future generation about science.


SEM as a fiber analysis method for filtration systems quality control

The production of filters and membranes undergoes several quality control steps to ensure that the properties of the product are up to specification. Different methods can be used for such fiber analysis, but only one can provide the best results. Find out in this blog how Scanning Electron Microscopes (SEM) can be used to investigate imperfections in metallic filters.

Different purpose – different filter

Whether we are aware of it or not, we use many filters on a daily basis – directly or indirectly. For example, tap water is filtered several times before undergoing chemical treatment, prior to becoming drinking water. This is to remove all kind of particles, from big rocks to small sand grains. In extreme cases, the filters can become so thick that they can catch bacteria.

Air conditioners also employ filtering systems. They are mostly used to trap dust and small particles, but combined with activated carbons, they can catch odors and purify the air.

Also, some chemical reactions catalysts are typically shaped as metallic meshes with micropores to let the chemicals flow while, at the same time, maximizing the exposed surface and minimizing the pressure required for the fluid to flow in the reactors.

Comparison between BSD (left) and SED (right) image of a metallic mesh. In BSD images the color contrast highlights differences in the atomic weight of the analyzed material, making contamination detection easier. SED signal enhances the sample topography and the surface structure of the sample.

Deeper inspections with SEM

The easiest way to investigate a filter is obviously to observe it. Optical microscopes can, in many cases, provide plenty of information on larger filters, but in other cases the resolution that they provide is not sufficient for in-depth inspection. Scanning electron microscopes, therefore, prove to be the best analysis technique to inspect any kind of filter thanks to the higher magnification and better resolution. SEM show not just the size of the pores in-between the fibers, but also the surface of the fibers themselves, their roughness and much more. So exactly what kind of data can be obtained?

One tool for multiple analysis

An SEM enables the user to perform a highly detailed visual inspection of the imaged samples. Modern image processing techniques and advanced from Phenom have turned these devices into automated analysis tools.

An example of this is the automated system to measure the diameter of fibers displayed in the image below. Here, Phenom Fibremetric software can reconstruct the direction of the fiber and measure it — an operation that would require tremendous efforts and a huge amount of time from an operator.

Example of automatic detection of fibers (left) and results displayed in a diameter size distribution histogram (right).

In the case of multi-layer materials or coated fibers, the SEM can be used to determine that the size of each layer has the right size, the distribution of the material on the substrate is homogeneous and the roughness is within specifications.

Filtration efficiency and product lifetime, as well as resistance to washing processes, can largely benefit from the improvements derived from knowing this information.

See video customer example below.



Thermo Scientific is the leading global supplier of desktop scanning electron microscopes and imaging solutions for submicron scale applications. Phenom SEM-based systems are used in a broad range of markets and applications. Phenom produce the most advanced desktop SEMs available on the market with a complete family of products,from the entry level Pure model through to the class leading ProX, XL and now worlds beating desktop FEG-SEM the Pharos.

 

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