Space-Al-MMC

Starting point / motivation

Materials to be used in space applications must meet demanding requirements in terms of mass, stability, strength, stiffness and radiation resistance. Although the materials used are the same as in terrestrial applications, the working environment is very different, owing to high-energy particles, ionizing radiation, vacuum, large thermal variations or fast meteorites.

Especially structural applications in space require the use of materials with high specific stiffness and strength, which can withstand the harsh space conditions without relevant degradation and at the same time allow a reduction of mass, volume and cost. Currently, the average transport costs for 1kg into space are around €25,000 to €30,000.

Predecessor project SpAACe has paved the way for high-performance 0°-UD C-fibre-reinforced Aluminium metal matrix composites (Al-C fibre MMCs) with fibre volume fractions of 60%. This is achieved by technical modification of the metal-gas pressure infiltration process (P-Caster) and updating of heating and control technology.

"High-performance" stands for density-specific Youngs Modulus of currently 105 GPa/(g/cm³) and density-specific ultimate tensile strengths of 759 MPa/(g/cm³), accompanied by Coefficient of Thermal Expansion values of +1e-6mm/mm*K. Currently, only a few MMC suppliers are known on the market (MMCC (USA), Materion (USA) or TiSiC (UK) but with other, lower-performance MMC material systems). C-fibre-Al-MMCs (60%) are currently not available on the market. Only LKR is capable of production to date, however only in form of sample plates with max. dimensions of 160 x 66 x 2mm (boundaries of the P-Caster process).

Contents and goals

• Goal 1 is to increase the geometric complexity of Al-C-fibre-MMC components: from sample plates to space-relevant geometries such as L-/C-profiles or hollow rods.
• Goal 2 is the successful development of suitable joining concepts of Al-MMC parts through diffusion bonding techniques or direct, fibre-friendly integration of inserts in preforms. These facilitate the placement of metal inserts for joints, axes or through holes with minimal fibre deflection or damage. This avoids drilling of holes and damage/cutting of the continuous (“endless”) C-reinforcing fibre.
• Goal 3 is to increase the maximum dimensions of C-fibre Al-MMC to 350x350mm² by transferring the process from P-Caster to pressure die casting in squeeze casting mode.
• Goal 4 is to maintain the mechanical properties in the new geometries. Goal 5 the demonstration of 3 breadboard models by combining the developments achieved.

Goals 1-3 contribute to increasing the technical maturity of the Al-C-fibre-MMC (TRL2-> TRL4).

Expected results

With the successful upscaling of geometries it becomes possible to produce "more complex" and "larger" Al-C-fibre-MMC geometries with inserts and to produce structures such as kinematic bearings for optical instruments, sleeves for struts as well as actuators and drives for space lander vehicles.

The newly developed C-fibre-Al-MMC material in combination with unprecedented geometric possibilities of Space-Al-MMC opens the possibility to realize components with a weight of 1/3rd up to 1/5th compared to state of the art TiAlV64- and 1/2 to TiSiC-components.

Coordinator

LKR Leichtmetallkompetenzzentrum Ranshofen GmbH

Project partner

• RHP-Technology GmbH
• Aerospace & Advanced Composites GmbH

LKR Leichtmetallkompetenzzentrum Ranshofen GmbH
Braunau am Inn
A-Ranshofen
Web: www.lkr.at