Abstract: A method of removing material from a workpiece by directing a laser beam onto an area of the workpiece and at the same time injecting substantially continuously a stream of high speed (5-300 m/s) solid particles onto the area of the vicinity thereof. The solid particles may be aluminum oxide or zirconium oxide particles having a size in the range of 1-50 &mgr;m. The particle stream is preferably formed coaxially around the laser beam, the particles being accelerated by means such as an inert gas or electrostatic charge which does not work the material. The laser beam melts the material and the solid particles are directed into the molten material before exiting from the face of the material opposite that to which the stream is directed.

Abstract: A method of cutting or machining a material (7) by directing a laser beam (1) into a cut zone and at the same time injecting substantially continuously a stream of high speed (50-300 m/s) solid particles (4) into the cut zone or the vicinity thereof. The solid particles (4) may be aluminium oxide or zirconium oxide particles having a size in the range of 1-50 &mgr;m. The particle stream is preferably formed coaxially around the laser beam, the particles (4) being accelerated by means such as an inert gas or electrostatic charge which does not work the material. The laser beam (1) melts the material and the solid particles (4) are directed into the molten material before exiting from the face of the material opposite that to which the stream is directed.

Abstract: An energy conversion and storage device (1) which comprises a magnetic rotor (5) and a stator (7) comprising one or more electric coils whereby electrical energy may be applied to and extracted from the device (1) when the rotor (5) is rotating relative to the stator (7) and means (13, 14, 15, 17) for electromagnetically suspending the rotor (5) whilst rotating relative to the stator (7), wherein the rotor (5) comprises a tubular body portion formed of a composite of fiber reinforced material and magnetic material emnbedded within the fiber reinforced material and the stator (7) is disposed inside the rotor (5) co-axially with the rotor (5) and extends along at least a major part of the length of the said body portion of the rotor (5).

Abstract: A method of friction welding which comprises forcing together two components to be welded together and providing a relative oscillatory movement between the two components to cause rubbing together of the two components to provide friction welding thereof, said oscillatory movement being caused by means, acting on at least one of the said components, which comprises a magnetostrictive transducer.

Abstract: A wall or other surface is coated by applying a multiplicity of tiles to adhere to the surface, the edges between adjacent tiles being separtated by grouting materila comprising a vitrifiable particulate material incorporated in a binder, and applying local heat from a source of heat to the grouting material to cause vitrification of the particulate material thereby to weld the tiles together.