Investigating the impact of nanoparticles on additive manufacturing

Due to the increasing availability of commercial printing systems and various research activities in recent years, additive manufacturing has become increasingly important. The advantages of additive manufacturing are the very high degree of freedom in component design, as well as the very short-term production of spare parts. In terms of efficient logistics, this means e.g. low inventory and fast just-in-time spare parts availability. Primarily with regard to the logistical challenges of existing weapon systems, this can open up new opportunities. The pure polymer materials mainly used up to now usually have only a low filler content in the form of color pigments. By incorporating nanoparticles, properties can be specifically improved for specific applications. These properties include electrical and thermal conductivity, strength and stiffness, crack propagation, fire behavior and radar absorption properties.

Literature research

• Availability of nanoparticles and their properties
• Possible incorporation methods
• Influence of nanoparticles on the properties of polymers
• Nanoparticles in additive manufacturing
• Manufacturing possibilities of filaments, dispersions and powders

Investigation of possible insertion processes of nanoparticles

• Investigation of possible methods of introducing nanoparticles into a polymer matrix
• Selection of suitable additive manufacturing processes

Investigation of the starting material

• Investigation of the starting material for manufacturing-relevant properties

Investigation of the processability by means of additive manufacturing

• The base material modified with nanoparticles is to be investigated for printability

Material characterization

• Additively manufactured test specimens are to be characterized for the expected property changes.

A powdered, semi-crystalline and generally chemical-resistant thermoplastic was selected as the base polymer for initial preliminary tests in FFF printing on the basis of its general proven performance in SLS printing by the German armed forces. From this polymer, which is available as a fine powder, it was possible to produce a filament using a filament extruder, which was then printed using an FFF printer. The selected material could be identified as a suitable polymer for mixing with nanoparticles. In contrast to the polymer used in the preliminary tests, the material selected for mixing with nanoparticles does not contain any additionally added nanoparticles such as titanium dioxide, which means that unwanted interactions with nanoparticles introduced in the future can be avoided.

In addition to the positive effects that nanoparticles have on various material properties, however, nanoparticles generally also pose health risks, which in many cases have not yet been adequately researched. In particular, some of the nanoparticles that are promising from a technical point of view - such as carbon nanotubes (CNTs) - have been classified by the International Agency for Research on Cancer (IARC) as Group 2B ("possibly carcinogenic"). Considering current studies on health effects of nanoparticles, there is therefore still a need for clarification on the subject of occupational safety.

The research project is based on the study "Investigation of the influence of nanoparticles on additive manufacturing" by WIWeB (Wehrwissenschaftliches Institut für Werk- und Betriebsstoffe).

Project duration: November 2021 to October 2024