The Added Value of SEM-Technology for Industrial Applications

In this interview, AZoM speaks to Alexander Bouman, Product Manager for Thermo Fisher Scientific, about SEM technology and the advantages of chemical classification using EDX analysis, and the capabilities and applications of the Phenom ParticleX.

What is Phenom ParticleX?

Phenom ParticleX is one of the products from Thermo Fisher Scientific. It’s a versatile desktop SEM solution which gives you great analysis results in-house and it also supports automated analysis, testing, and classification, which results in a process that is around 10 times faster than outsourcing. Next to that, all your confidential data stays within your company instead of outsourcing it to external laboratories. The system is simple to operate and easy to learn, meaning a lot of people within your company can benefit from SEM capabilities. Phenom ParticleX offers technical cleanliness reports, including those necessary for ISO 16232 and VDA-19 compliancy, as well as reports for additive manufacturing for metal powders including particle morphology and powder purity.

How does an SEM work?

An SEM starts at the electron source, where electrons are emitted by heating the source, which in our case is the long-life CeB6. The electrons are emitted, and the resulting electron beam is guided through the so-called SEM column. By moving the electron beam in the x- and y-direction, it scans the surface of the sample.

Surface of a metal with a hole observed with an electron microscope. Image Credits: Roberto Lo Savio/shutterstock.com

The interaction between the electron beam and the sample, generates electrons and x-rays. The electrons can be distinguished between backscattered electrons (basically the electrons from the beam that bounce back) and secondary electrons, which are those that are being “knocked out” by the e-beam at the surface of the sample. Via specific detectors, these electrons can be converted into signals which are shown as grayscale values. As the scan generator scans over the surface of the sample, an image is created.

Grayscale values allow us to distinguish particles by looking at differences in contrast. The background appears black, whereas the particles turn out to be much brighter. With this contrast, we can look at the transition from dark to bright and that means we can start detecting the particles, including their size and shape, as well as their quantity.

What is the added value of EDX analysis?

With EDX analysis, the incoming electron beam hits the sample and in addition to the backscattered and secondary electrons, we also get x-rays. The energy level of these x-rays is unique for each material so we can use it to classify the materials that are present in the sample. This will be visualized via a so-called EDX spectrum. The peaks in the EDX spectrum show which elements are present and allow for quantification as well.

The height of the peak shows how much is present from a specific element and thus can correlate to the concentration to solidify those quantifications.

The ability to look at an SEM image and count the particles, detect the morphology and the chemical classification using EDX, makes it a very powerful analysis tool, particularly if the sample has a lot of particles with an unknown classification; we can use an SEM to make it clear what kind of particles we have, and how many are present, and what morphology they have.

What is technical cleanliness and how is it achieved with your products?

Technical cleanliness is an issue in (automotive) industry. Scratching of sliding surfaces, such as inside a gearbox, can happen if there are very small particles of, for example, corundum in between two gearing wheels. Eventually, they will end up damaging the gearbox. Other potential risks are obstructing nozzles or short-circuiting electronic boards. In short, the lack of cleanliness on a microscale level is a big issue.

We start looking at the part to certify whether it is clean enough for the application. This part is placed within a washing machine which will rinse the part using very strict washing guidelines and the water with the particles will leave the machine to be collected on a filter. The wet filter is then inserted into an oven, so the result is a dried filter with the particles on top of it and that can be placed inside the SEM, such as a Phenom ParticleX.

Phenom ParticleX

Using our software, automated analysis can be started to look at all the particles that are on the filter and to classify them. The particles can be classified by size and chemistry. Size-wise, it counts particles and classifies them in a certain size range. For chemical classification, every particle is analyzed with the EDX detector and using classification, we can determine if the particles belong to corundum, aluminum alloy with copper, aluminum oxide, silicon-rich, mineral, mineral fiber, aluminosilicates or silicon oxides. A report then represents what it has found during the analysis of this specific filter and it gives you insightful data whether your product fulfils the cleanliness requirements to prevent future warranty claims. This can be set up for ISO standards, like 4406 and 4407, for the cleanliness of oils and other motor fluids as well as for VDA 19 or ISO 16232 for technical cleanliness in the automotive industry.

What other major applications does ParticleX have?

ParticleX can also play a huge role in gaining insightful data when looking at additive manufacturing. We see several challenges in the additive manufacturing industry. If the particle morphology is not good, then it will affect thermal properties. This can result in a potential fracture in the printed product. Next to that, the purity of the metal powder has to be as homogeneous as possible and if that is not the case then it will change the physical properties of the powder, which results in potential points of fracture during the printing process.

Powders in this industry are very expensive and printing is not 100% efficient. Therefore, unused powders are recycled as often as possible, which results in quality that gets worse over time due to the formation of satellites (particles with smaller particles attached to it) and chemical impurities. If you have a bad-quality powder you will end up with potential fragile printed parts.

The good thing with the Phenom ParticleX is that it can focus on the specific requirement of particle morphology that is necessary for this industry. We can offer an additive reporting format displaying a histogram of the average of the particles that have been analyzed. So, it looks at all the particles on the sample stub and it will differentiate between spheres, satellites, and agglomerates (several particles together). This is then represented with its specific size ranges, which will tell you the particle morphology homogeneity. Afterwards, once the tested powder has been used in the printer, the printed part can be inspected using the Phenom ParticleX, showing the versatility of this tool.

What would you say are the biggest benefits of Phenom ParticleX?

As mentioned, it is a versatile desktop SEM solution that gives you the possibility to do all your quality analysis, as well as R&D SEM work, and in both cases keeping your confidential data in-house. Next, it is up to ten times faster compared to outsourcing because you can run the analysis yourself instead of shipping it to an external laboratory. It is simple to operate, so a lot of people can make use of it, and it is versatile with standard reports to fulfill the ISO 16232 or VDA-19 reporting and insightful reporting for additive manufacturing. In our view, seeing is believing and therefore personal demonstrations can be booked at discover.phenom-world.com/demo.

About Alexander Bouman

Alexander Bouman is a Product Manager at Thermo Scientific Phenom Desktop SEM. He has an MSc in Chemical Engineering, and his background is in product management in industrial lighting and Phenom desktop SEM.