During RP2 the main progress was done on the final selection of the 2 most promising composition grades for self-fluxing nickel alloys, and the manufacturing of the tubes preforms by GC and LMD processes for sealing rings prototype machining and grinding. Finally, two sets of sealing rings were tested at Liebherr up to 20,000 cycles and the leakage measured, evaluated and compared against current solutions of sealing rings.
Other major progress was the tribology studies at room and high temperature for the NiCrSiFeB alloys obtained by the two new manufacturing routes proposed in NEMARCO (GC and LMD). High load tests were conducted to generate the debris particles for the toxicity analysis conducted in WP4. The wear kinetics study at variable contact temperature was completed. The main conclusions after tribological characterization and studies conducted in NiCrSiFeB alloys and Stellite 6 reference alloy were stated, determining the wear mechanics, wear response, and the mechanisms of the glaze layer formation in NiCrSiFeB alloys.
During the analysis of wear particles toxicity it was observed that effects were comparable between the wear particles obtained from NiCrSiFeB samples researched in the project and those from the Stellite 6 controls. The LMD process is cheaper than GC manufacturing route for sealing rings prototypes obtained at lab scale. In the best-case scenario the cost of the LMD sealing rings are 30% lower than the sealing rings obtained by GC route. The comparative CO2 emissions between the current industrial manufacturing route (with Stellite 6 and CC process) and the proposed new manufacturing routes (GC and LMD) is biased since in NEMARCO project the measured values and recorded data has been extracted in pilot lab scale processes, not fully representative of a serial industrial production environment. CO2 emissions in the best-case scenario for the LMD manufacturing route of NiCrSiFeB sealing rings are 73% higher than GC manufacturing route.
As an overview of the project results, two alloys (A and C) were selected as the best solutions. The NiCrSiFeB alloys obtained by LMD are more difficult to cut and machine than those obtained by GC, and alloy A shows better machinability than alloy C. The total wear and friction coefficient of Stellite 6 is better than any NiCrSiFeB alloy at room temperature, but alloy C obtained by both GC and LMD processes are better than Stellite 6 evaluated at 300 C, and alloy A obtained by GC and LMD and alloy C obtained by GC are better than Stellite evaluated at 650 C. Alloy C obtained by LMD is the hardest, but it has the worst wear response at both ambient and high temperature as it is unable to form a protective glaze layer, so it wears a lot compared to the other alloys evaluated at high temperature.
The endurance tests of the NiCrSiFeB sealing rings prototypes were performed by mounting two bleed air valves in parallel in the test bench and the leakage was measured after different number of test cycles. Performance curves were obtained as well as a comparison with the current solution (Stellite 6 by CC) and other materials under study by Liebherr as solutions for the sealing rings.
In terms of the exploitation and dissemination results, dissemination activities were reported in each quarterly report, acknowledgement were included in all communications and dissemination of results. All indicators in the PDER were achieved:
• Project website created in M1 and updated in M31
• Press releases and news: 4
• Social media: 12 posts
• Press notes in Partners’ websites
• Scientific and Journalistic articles: 4 (2 published, 1 submitted, 1 writing)
• Participation in workshops & congresses: 7
• Participation in fairs: 1
• Open access datasets: 2
