Leadfree piezoelectric devices by additive manufacturing (3D printing and multilayer)

Europe has a large number of SMEs and industry that apply ultrasonic technology in their products and services, ranging from medical imaging to pipeline inspection and ship positioning systems. With very few exceptions, the ultrasound waves are generated and received by discs, slabs or films made of PZT ceramics containing toxic lead (Pb). The idea behind the MANUNET project 3D-PIEZO was to give these companies access to high performance/low-cost lead-free ceramics. Such access will give European SMEs a competitive edge in the international market. The availability of inexpensive 3D manufacturing of piezoelectric transducer components will further increase the advantage. The project had three partners, SINTEF (NO), Cerpotech (NO) and CERHUM (BE). Cerpotech was responsible for ceramic powder development, CERHUM for 3D printing, and SINTEF for the multilayer route, electrode application, poling and characterisation. Compositionally modified versions of two different lead-free materials, bismuth sodium titanate (BNT) and potassium sodium niobate (KNN), showed very good piezoelectric performance compared to state-of-the-art technology. Early 3D printing experiments showed that printing the piezoelectric materials was more difficult than expected due to severe UV scattering and absorption. The project worked intensively to solve this challenge, but with only partial success. All the components tested in the project were therefore made by the multilayer route. Reliable procedures for multilayer component fabrication and performance testing were developed. The materials and components developed showed very good ferro- and piezoelectric performance compared to literature values. Assessment of the manufacturing chain from raw material to final piezoelectric component revealed no technical bottlenecks for multilayer production. The main challenge for setting up a manufacturing line is high CAPEX. A supplier willing to do small-scale contract production was identified. In the 3D printing case, no assessment conclusions were made. An important HES concern associated with production of multilayer ceramics is the use of organic solvents in the tape casting process. Although water-based tape casting has been demonstrated, it is considered challenging for industrial production. The project has greatly contributed to increasing the competence in Norway about the fabrication and performance of lead-free piezomaterials. The partners have increased their knowledge of the theoretical basis of the materials and at the same time acquired "hands-on" experience with manufacturing and testing.

The project has greatly contributed to increasing the competence among the partners about fabrication and performance of lead-free piezomaterials. This knowledge provides a very good basis for new development projects with companies using piezomaterials for, among other things, ultrasound technology. It also provides a basis for applications for new research projects. The collaboration with CERHUM has given SINTEF useful experience with 3D printing of ceramic components and the associated challenges related to absorption and scattering effects in the fabrication of advanced functional ceramics. This experience will be valuable, not only related to piezo-components, but also in several other areas because the results from 3D-PIEZO can readily be adapted to other functional ceramic materials. Examples of relevant areas are electronics, biomaterials, sensing technologies, aerospace, catalytic and membrane reactors, and fuel cells/electrolysers.

The 3DPIEZO project will develop a manufacturing chain for lead (Pb) free piezoelectric devices for ultrasonics and other applications. 3D printing and multilayer lamination will be the principal manufacturing methods, applying high performance leadfree piezoelectric ceramics. All critical steps of the manufacturing chain will be developed and demonstrated at TRL 6. Optimised versions of at least two different materials systems will be applied: bismuth sodium titanate (BNT) and potassium sodium niobate (KNN). The consortium consists of two SMEs and one research organisation: Ceramic Powder Technology AS is a Norwegian producer of advanced ceramics powder by spray pyrolysis, CERHUM S.A. in Wallonia is a specialist in 3D printing of ceramics, and SINTEF is the largest research organisation in Norway. To guide the project and provide component designs, 3DPIEZO will have an Industrial Advisory Board (IAB) with representatives from companies that use piezoelectric components in their products or services.