RESEARCHERS AT THE Georgia Institute of Technology in Atlanta are developing "laminated-matrix" composites, which, they believe, will be tougher, stronger and cheaper than conventional fibre-reinforced materials and which could replace metals in aircraft and engines, for reduced weight and increased efficiency.
Jack Lackey, a scientist at the Georgia Tech Research Institute (GTRI) says, that laminated-matrix composites offer the chance "of improving materials properties - particularly toughness - and lowering costs". The process combines two conventional techniques for producing mechanically tough composites: fibre-reinforcement of ceramic- or metal-matrix materials; and building up multiple-bonded layers of different materials.
Matrix materials bind the reinforcement fibres together and fill the space between them. In the new process, the matrix is created by forcing vapour through a preform, produced by stacking up layers of reinforcing cloth, to deposit a layer of material on the fibres.
By alternating the percussor gases, the matrix is built up one layer at a time. Lackey says that up to 50 layers, each 0.02-0.5mm thick, have been deposited.
Initial work, sponsored by the US Air Force, focused on infiltrating a carbonfibre preform with alternate layers of carbon- and silicon carbide matrix. The process should be applicable to other reinforcing fibres and matrix materials, says GTRI.
Lackey believes that the improved strength and toughness of the laminated matrix may allow costly reinforcing fibres to be replaced by inexpensive particles. While admitting that this is "highly speculative", he says that his team has produced samples using silicon-carbine grit instead of fibres.
Source: Flight International