Thermo‐physical and mechanical properties of the 3D‐printing materials applicable for formers of superconducting cables

Abstract This study evaluates the suitability of additively manufactured polycarbonate (PC), polyethylene terephthalate glycol (PETG), and their carbon fiber (CF) reinforced variants as spring‐shaped formers for superconducting cables, where non‐conductivity is crucial to prevent eddy current losses. The evaluation focuses on thermo‐physical and mechanical properties of the materials in as‐printed state and after annealing. All materials, except the PC+CF, exhibited sufficient heat capacity (>0.750 J/g °C) at room temperature. Contrary to expectations, the CF reinforcement did not reduce the high coefficient of thermal expansion, but this can be mitigated by former design. The tensile strength was 43 MPa for PETG and 54 MPa for PC, with only minor improvements upon adding CF and heat treatment, likely due to the insufficient fiber‐matrix adhesion. At cryogenic temperatures, tensile strength increased significantly, particularly for PETG and CF‐reinforced, thermally treated PC, with doubling the values. A similar effect was observed in the calculated Young's moduli. Compression tests in liquid nitrogen bath showed better resilience of pure PETG and PC+CF variants, with PETG‐based materials enduring 300 thermal cycles without damage. Based on their balanced properties, PETG, annealed PETG+CF and PC+CF were selected for finite element analysis, which confirmed their potential for use in superconducting cables. Highlights Polymer composites explored as insulating alternatives to Cu in cable formers. A flat spring design compensates for polymer composites' thermal expansion. Polymer composite properties measured across various temperatures. Selected materials endure thermal cycles in liquid nitrogen without damage. Finite element simulation predicts thermal deformation impact on tapes.