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ESA FLPP Awarded

S.P.A.R.K.

Alloys that survive where rockets burn hottest

Developing refractory high-entropy alloys for oxygen-rich preburners in next-generation rocket engines

January 20256 contributors
RHEARocket EnginesESA FLPP FIRST!Additive Manufacturing
S.P.A.R.K. ternary phase diagram
>3,000°C
Target melting point
300+ bar
Preburner pressure
1,240 MPa
Yield strength
ESA FLPP
Contract awarded

S.P.A.R.K.: Special Performance Alloys for Rocket Kinetics

Oxygen-rich staged combustion engines push preburner materials past 3,000°C in corrosive, oxidiser-rich gas. Existing nickel superalloys (Monel K500, Inconel 600) survive, but barely — and they limit the cycle efficiency gains that next-generation reusable engines need. SPARK develops refractory high-entropy alloys (RHEAs) engineered to operate in this regime.

The Problem

Preburners in oxygen-rich staged combustion cycles run hot, oxidising gas at pressures above 300 bar. The materials need:

  • Melting points above 2,500°C
  • Oxidation resistance at temperature in high-pO₂ environments
  • Sufficient ductility for cyclic thermal loads (reusability)
  • Compatibility with additive manufacturing (LPBF/DED) for complex cooling channel geometries

No single-element refractory metal satisfies all four. HEAs composed of W, Mo, Ta, Nb, and Cr offer a combinatorial design space where trade-offs between melting point, oxide scale stability, and room-temperature ductility can be optimised.

Approach

  1. Computational screening — CALPHAD phase predictions and DFT formation energy calculations to narrow the composition space from ~10⁶ candidates to <100 printable alloys
  2. Additive manufacturing trials — Laser Powder Bed Fusion (LPBF) to calibrate process windows (scan speed, layer thickness, preheat) and characterise defect populations
  3. Hot-gas validation — Printed coupons tested at ArianeGroup's ERBURIGK facility under representative oxygen-rich preburner conditions, benchmarked against Monel K500

Consortium

Awarded to Bimo Tech as prime contractor under ESA FLPP FIRST! programme:

  • Bimo Tech — Project lead, alloy design, computational screening, LPBF synthesis
  • ArianeGroup — End-user requirements, hot-gas testing at ERBURIGK, Monel K500 baseline data

Status

Contract awarded January 2025. The project feeds directly into P.R.I.S.M. — SPARK's alloy targets define the fitness function for PRISM's autonomous discovery pipeline.