How next-generation composite materials are manufactured and analysed

By Luigi Raspolini - March 7, 2019

The technical specifications of next-generation materials are taking our technology to a completely new level, allowing us to create products with outstanding properties that were impossible to achieve in the past. These materials are the result of a huge drive toward innovation in material science and could only be achieved because of the invention of the first composite materials and their introduction into the industrial landscape.

In this article, I describe how these next-generation materials are being developed — and equally important: how their chemical composition is analysed, and their performance is measured.

Learn how a desktop SEM was used to observe fibers and leather details without damaging the samples
Download the case study on examining archeological grave goods here

How beneficial properties of composite materials are created and preserved

Certain materials have outstanding properties that offer the perfect fit with a specific application. Sometimes, unfortunately, the environment is affecting these materials to such an extent that they cannot be easily used. They also require continuous replacement and fixing, thereby compromising all the advantages that come from their use.

By creating multiple layers, or applying a coating, such delicate materials can be shielded and used, with all the benefits that they bring.

next generation composite material analysis
Figure 1: Glass sheet coated with different materials. The multiple layers add specific properties to the product.

For example, introducing nanofibers in a slab can dramatically improve its resistance to traction, flexion or torsion. These materials normally feature a matrix (the external part of the material, directly exposed to the stress) that is supported by a network of fibers. When the stress is applied to the material, this is transferred to the fibers. The fibers can easily handle the applied force, responding with an
elastic deformation. As soon as the stress is removed, the fibers will bring the material back to its original state.

This stress-transfer process is what led to the creation of self-healing materials. A typical example is the plastic covers of some smartphones that, when scratched, can recover from the condition in a matter of minutes. If the scratch is not too deep, it will completely disappear and the ‘brand-new’ feeling of the phone will last longer.

The crafting of these materials requires high-level engineering and is the result of a big investment in research. In particular, scientists have focused their attention on how to transfer the stress from the matrix to the fiber, without having the latter slipping inside the structure. Several different solutions were taken into account and investigated, such as creating a complex fibrous skeleton or coating the fibers with a material that improves the shear stress transmission at the fiber-matrix interface.

          next generation composite material manufacturing next generation composite material research

Figure 2 & 3: Different kinds of fiber weaving offer different resistance to stress. The appropriate weaving technique is chosen according to the application.

How next-generation composite materials are analysed and measured

As these investigations were performed on nano-scaled materials, electron microscopes were employed for the analysis and measurements. With a desktop scanning electron microscope (SEM), it is in fact possible to evaluate the diameter of the fibers and monitor how they change along the structure. At the same time, it is also possible to locally analyse the quality and chemical composition of the coating in order to verify that the adhesion of the fiber to the matrix is optimized. This can be done with an energy dispersive X-ray analysis (EDS).

Composite materials are not a recent invention, by the way. The ancient population inhabiting the European continent were already mixing different types of materials for decorative or practical uses. One example is the discovery of archaeological grave goods in the imperial and royal tombs in the Speyer Cathedral in Speyer, Germany, which showed that textile fibers were mixed with golden threads.

Within the KUR-Project “Conservation and restoration of mobile cultural assets” in Germany, electron microscopy has been successfully used to perform numerous analyses of the tombs’ contents. Download this free case study to discover how a desktop SEM was used to investigate fiber and leather details without damaging the samples or performing additional sample preparation, it's very interesting:

Download the Case Study on archaeological grave goods

About the author

Luigi Raspolini is an application engineer for the Thermo Scientific Phenom Desktop SEM product range at Thermo Fisher Scientific. Luigi is constantly looking for new approaches to materials characterization, surface roughness measurements, and composition analysis. He is passionate about improving user experiences and demonstrating the best way to image every kind of sample.

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