Abstract: A barrier for use in laser drilling. The barrier is placed in front of those surfaces that one wishes to protect from the laser beam. The barrier comprises a thixotropic medium, for example polyacrylamide suspension in water. The medium includes material which will disperse the laser light and material which will emit light when exposed to the laser light. The light emitter materials could be luminescent materials, phosphorescent materials, or fluorescent materials.

Abstract: A rotating or moving metal component such as a blade for a gas turbine engine is made from a composite bar of titanium alloy with the sides of the bar having a surface layer of e.g. nickel which is less likely to ignite in particle form or by frictional heating when present in oxygen or air. After the surface layer has been bonded to the titanium alloy it is then parted to provide sections which extend perpendicularly to the plane of the surface layers. Each parted section may then be machined into a blade with the nickel portion forming the tip of the blade. Alternatively, each parted section may itself form the blade tip by attachment on its titanium alloy side to a blade stem.

Abstract: A method of forming composite materials comprising reinforced fibres, such as carbon fibres 12, embedded in a metal matrix 10, 13. The method comprises forming a first metal sheet 10, laying the reinforcing fibres 12 on the first sheet 10, and explosively forming a second sheet 13 around the fibres to form an explosively joined composite.

Abstract: A method and apparatus for drilling holes through a component (16) from a first surface to a second surface. The method includes the step of applying a thixotropic water soluble medium to the second surface. The medium contains material to disperse the laser light and light emitting material (which could be fluorescent, phosphorescent or luminescent). Monitoring means and beam splitter are provided for monitoring light emitted, or reflected, by the component 16, along the length of the hole drilled by the laser and for monitoring light emitted by the medium. In this way one can detect when the laser breaks through the second surface and also produce an image indicative of the size and shape of the hole.