Amorphous metals, a game changer to improve the efficiency of Space Cryocoolers

VULKAM, a French high-tech start-up specialized in amorphous metallic alloys (AMA), has developed a new range of materials with mechanical and thermal properties superior to those of Ti6Al4V. Vulkam is focusing on the industrialization and optimization of amorphous metals. Improving the efficiency of a cryogenic cooler is considered of great interest to space applications. Heat conduction losses in the cold finger of cryogenic coolers are one of the main causes of their lack of efficiency.Vulkam, Lynred and Thales Cryogenics have proposed to ESA a 12-month OSiP evaluation study to assess the potential of these new materials in compact space cryocoolers.Main Steps conducted during the study included:Theoretical study:Thermal analysis on current productDesign and structural analysis of PoC demonstratorApproval approach baseline proposalJoining optimisation and qualification of the brazing method on simple partsManufacturing of parts and assembling demonstrators (+ vérifications)Testing of final samplesMain Results and Achievements:Thermal Performance of Vulkalloy Zr4 ValidatedGreat expectations about thermal conductivity, losses, and general behaviour confirmedConsistency between thermal analysis and thermal loss evaluation on demonstrators: 1.8× reduction achievedMore than 50% reduction of thermal parasitic lossesSignificant increase of ‘available cooling power’ for the same input powerBrazing Behaviour InsightsFirst-time deep understanding of brazing between an amorphous metal and different crystalline alloysPreparation process and metallization improved for Vulkalloy® and each materialOptimal configuration found for each base materialManufacturing of parts for demonstrators planned based on study resultsMechanical Performance TestingNot yet conclusive, but promising clues for further investigationOne tested configuration appears promising (not far from passing)Joints are points with lowest MOS, not the AMA pipeMultiple isolated key findings may lead to compliancy if properly assembledConclusion & PerspectivesThermal analysis shows significant improvement in thermal efficiency and performance, demonstrated by boil-off measurements on samplesProcess optimizations, analysis, and qualifications necessary on final application