CoorsTek, Luleå University of Technology, and CERN – AIMday collaboration breaks new ground in joining tungsten and copper

At CERN and other Big Science facilities, components must endure extreme heat loads, high radiation, and mechanical stresses. Tungsten is ideal for withstanding heat and radiation, while copper offers excellent thermal and electrical conductivity. However, their very different thermal expansion and mechanical properties make them notoriously difficult to join. Weak bonds or high residual stresses can lead to failures, limiting their combined use in critical applications.

A pre-study project

Following discussions at AIMday Big Science Technology 2024, CoorsTek Sweden and Luleå University of Technology teamed up with CERN in a pre-study project to explore new ways of joining tungsten and copper.

The team used a novel Hot Isostatic Pressing (HIP) technique, which transfers pressure to the material without a metal canister. To improve bonding, several interface engineering approaches were evaluated for joining Tungsten and Copper. In parallel, researchers developed a Finite Element Model (FEM) of the HIP process using the advanced simulation software Code-Aster. The model made it possible to study how the materials deform during heating and cooling, and how residual stresses build up in the bonded structure. Adjustments to the model, such as including the constraining effect of the material volume surrounding the pieces, brought the simulations much closer to the experimental results.

The outcome

The experiments showed that we could get the strongest and most reliable bonds, and microstructural analysis confirmed an excellent metallurgical interface. The simulations provided new insights into stress evolution and highlighted how the surrounding media must be considered when designing HIP processes.

The power of collaboration

This AIMday-inspired pre-study demonstrates the power of collaboration between Swedish industry, academia, and Big Science facilities.

“The results not only pave the way for new copper–tungsten components with improved reliability but, also deepen understanding of how to design HIP processes for dissimilar materials,” says Fredrik Engelmark, Big Science Sweden and Industrial Liaison Officer (ILO) for CERN.

Big Science for Västerbotten

Big Science Sweden is part of a project aimed at strengthening the innovation capacity of companies in Västerbotten, with a focus on the Big Science market. The project is run in collaboration with Luleå University of Technology (LTU) and LTU Business, funded by Tillväxtverket and co-funded by the European Union.

“The results also show how cutting-edge technology can be developed through regional collaborations between companies and academia,” says Adam Wikström from Big Science Sweden and LTU Business, project leader for Big Science för Västerbotten. “We’re pleased to see northern Sweden being actively represented in the Big Science arena.”