TiSiC for high-strength, lightweight components
Titanium silicon carbide (TiSiC) is a metal-matrix composite that is competitive with high-strength steel in terms of mechanical performance and has significantly lower density. TISICS, a UK SME, are developing a method for precise fibre placement, allowing highly complex and curved components to be produced from this lightweight material. TISICS is seeking partners to exploit this capability for weight reduction (typically 35 – 40%) and for development of new components.
Metal-matrix composites (MMCs) consist of a metal matrix reinforced with a fibre or particulate of a ceramic material. They provide higher specific performance (strength and stiffness vs density) than traditional materials and are compatible with conventional interfaces such as welds, seals, threads and bolts.
Depending on matrix alloy and volume fraction, titanium-matrix composites (Ti MMCs) can meet or exceed the mechanical performance of high-strength steel, providing:
- Strength: 1450 – 1800 MPa
- Stiffness: 200 – 210 GPa
- Compressive strength: >2.5 GPa (exceeding best landing gear steel)
- 40% lower density than high-strength steel
Titanium silicon carbide (TiSiC) is titanium alloy reinforced with continuous silicon carbide fibres. The silicon carbide fibre (SiC) is extremely effective in high-temperature applications and especially for Ti MMCs. Depending on titanium alloy used, SiC fibre can increase maximum operating temperature by ~200 °C, while decreasing thermal expansion to 6 x 10-6 K-1. SiC monofilaments also can be formed into curved geometries, which would be extremely difficult to achieve with conventional ceramic processing.
TISICS, a UK SME, is working with partners to develop a filament winding technique for precise fibre positioning of TiSiC that is capable of producing surfaces that bend in two axes. This allows production of increasingly complex components (including multi-axial tubular parts and spherical pressure vessels) using the TiSiC fibre. Until now, such curvature has not been achievable with standard composite production processes.
TISICS is the only commercial supplier of fibre-reinforced MMCs, including TiSiC, outside the USA. The team’s expertise covers design of components, process systems, manufacturing, fibre architecture, and fibre development. Particular strengths include tubular struts (booms, actuators, robot arms) and pressure vessels (liquid and gas). This is based on a team with experience across a range of sectors, including space, aerospace, defence and energy (generation and oil & gas exploration), dating back to the late 1980s.
Innovations & Advantages
Titanium composite TiSiC exhibits excellent mechanical and thermal properties and is a potential alternative to high-strength steel. A TiSIC filament winding system for achieving precise fibre positioning is being developed that will enable the production of tubular and spherical pressure vessels, and will provide more efficient automated production, particularly for multi-axial tubular parts.
Key advantages of TiSiC over unreinforced titanium alloys:
- High specific strength
- High specific stiffness
- High compressive strength
- Increased operating temperature (~200 °C higher)
- Improved creep performance
- High thermal stability
- Low thermal expansion (~6 x 10-6 K-1)
Hot Isostatic Pressing (HIP) is required to consolidate the fibre into the metal alloy, allowing near net shape manufacture. Benefits include:
- Reduced metal waste (typically ~90% reduction in space and aerospace)
- No sub-component assembly required
- Component optimisation for mass and space envelope
For replacement of a similar geometry part, TISICS would typically achieve 35% weight reduction but can achieve 70% weight reductions where parts can be optimised for the composite properties and near net shape manufacturing process.
Current and Potential Domains of Application
Fibre reinforced metal matrix composites can be used in the following domains and applications where TISICS has worked within these are listed. A wider range of applications exists.
Space- Primary drivers- weight reduction, reduced CTE, near net shape to reduce assembly part count- Demisable aluminium composites, reduced component size.
Pressure vessels and propellant tanks- Lighter, more compact, reduced waste and lead-time through near net shape fabrication. Demisability of aluminium tanks. Potential for structural tanks.
Robot arms and booms- reduced weight, high stiffness- high torsion tension and compression loading- integral metallic joints- good electrical and thermal conductivity
Struts and actuators- High stiffness, wide operating temperature range up to 600C, very high compression strength, integral metallic end connections for pin joints. Low CTE compact.
Structural heat pipes-
Potential for demisable upper stages with high strength and stiffness low melting point aluminium composite.
Light weight truss structure for Skylon Space plane-
Light landing gear, brakes, engine structures fuselage structures for space planes.
Civil aerospace- Driver weight reduction to reduce emissions.
Struts for engines, landing gear, flight actuators, structural components. _ lower mass high strength and stiffness, low CTE very high compression strength lower density aluminium composite exceeds titanium strength and stiffness.
Rotating Gas turbine components- Shafts, blings, disks.
Landing gear side stays, axles, main fittings, hydraulic actuators, lock links, bogie components- Low mass, near net shape manufacture, compact dimensions, corrosion resistance compared to steel.
Aircraft brakes- Torque tubes, drive keys, bolts, - potential for aluminium wheel rims.
Wing components with aluminium composite ribs and actuators or titanium composite gear beams or centre wing box.