The potential for laser processing of metallic composites AILU Workshop: Laser processing of polymer, metal and ceramic composites 3 rd December 2008 Presentation by Stephen Kyle-Henney
Metal Matrix Composites There are several types of metal composite and a wide range of metals and alloys. The key systems are; Long fibre reinforcement Short fibre reinforcement Particulate reinforcement Aluminium Alloys Titanium alloys Copper Alloys (heat sinks) Details of contacts for several of these are provided at the end of the presentation This presentation concentrates on continuous fibre reinforced titanium matrix composites (TMC) The title Potential uses of laser processing is intentional, Metal composites are just reaching the aerospace market and Laser Processing is only just being considered.
SiC Fibre reinforced Titanium. TISICS Silicon carbide fibre Diameter 100µm & 140 µm UTS 3.3 & 4.0 GPa Stiffness 380 & 400 GPa Density 3.4 g/cc (35km & 18km per kg) Length tailored but up to 10km continuous. Titanium Matrix Composite Ti alloys mainly α-β and β UTS 1400 to 1850 MPa Stiffness 190 to 200 GPa Density Rule of mixture with fiber and matrix For comparison Fiber Reinforced Al-6061 UTS 1220MPa Stiffness 140GPa Density 3.0g/cc
Specific Properties Typical specific properties Specific Strength (MPa/(kg/m3)) 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 300M Ti 6-4 TMC Ti6-4/35%SiC Ti 3-2.5 TMC Ti3-2.5/35%SiC AlSiC (25%SiC) 0 0.01 0.02 0.03 0.04 0.05 Specific Modulus (Gpa/(kg/m3)) Specific strength Specific modulus
Continuous Fibre Composites What are the benefits Lighter weight than steel for similar strength Corrosion resistant Higher operating temperatures than standard alloys Near net shape manufacture Excellent compression performance Good fatigue and creep performance. Strength and stiffness tailoring within shape These attributes are attractive for aerospace, defence, marine, energy, and oil and gas exploration industries.
Some Drawbacks with TMC Current costs. Low volume manufacturing = high unit costs. Product development time. Limited industrial use needs longer development and increased testing Market acceptance. Who wants to be first? no one wants to be last! Through life costs. What are the inspection, maintenance, repair and disposal issues Supply chain. There are limited suppliers. All of these issues are being addressed. Some may be resolved through laser processing.
Laser Processing in TMC Where can laser processing be used? Basic use. Laser marking, mechanical marking may damage fibres close to the surface and create flaws. No work to date in this field but unique robust marking is essential in all markets. Component development. Complex tooling is often required which is expensive to produce for one off parts. Often billet material is machined to < 30% of its original. Laser additive techniques may provide solutions especially where thin walled tooling is required. Complex HIP cans require multiple welds with high risk of failure. Can controlled deposition reduce the risk?
Laser Processing in TMC Where can laser processing be used? Encapsulation. Preformed composite sections (tubes, plates etc) are cut and diffusion bonded into more complex parts. Laser additive routes may remove the need for secondary HIP consolidation. Cutting. Titanium composites contain silicon carbide fibre which is hard to machine. Laser cutting may speed the process and offer more complex profiles.
Laser Processing in TMC Where can laser processing be used? Component features. Often components require features such as bearing lands on shafts or mounting brackets on structures. Laser additive techniques may enable simple composite shapes to be made with cheap re-usable tooling and the features added later. Repair. There is the potential for the surface of parts or un-reinforced regions to be damaged or worn without affecting the composite. Laser additive techniques and laser cutting may enable the composite region to be salvaged or the surface repaired saving both time and cost compared to a new part.
Near net shape Manufacture Single step fabrication with matrix and fibre diffusion bonded into near net shape part.. Multi step using composite mono-sheet, panel, bar or structured preform machined to size and diffusion bonded into bulk parts. Laser techniques may help encapsulation or deposit features on components
Composite Process Options and Basic Route Powder cloth TISICS Foil- fibre Titanium foil, typically 100-150 µm thick Matrix coated fibre Titanium alloy coating Titanium powder held in an organic binder to form a flexible cloth Monofilament core Silicon carbide (tungsten or carbon) monofilaments held in a binder or woven Silicon carbide structure Wire-fibre Titanium wire typically 200-250µm Plasma sprayed Porous plasma sprayed deposit SiC fibre Spray binder Encapsulate and de-gas SiC Binder Press to MMC
Summary Laser processing offers several opportunities within the field of metal matrix composites. The UK is well placed in MMC development and could therefore provide early adoption of laser processing. More work is required to determine the best uses of laser processing. TISICS is currently a partner in the BERR Technology Strategy Board sponsored AVLAM programme. Where can you see opportunities for development and processing using Laser Techniques?
MMC contacts in the UK National Composites Network please see www.ncn-uk.co.uk select MMC working group from activities tab. For particulate based MMCs in the UK please see www.amc-mmc.co.uk For liquid metal injection MMCs in the UK please see www.cmt-ltd.com For continuous fibre reinforcement please see www.tisics.co.uk