Abstract: A technique for joining parts of incompatible metals involves cold spraying a 150-900 micron thick layer of a metal compatible with the second part onto the first part, and friction stir joining the parts by lap welding while keeping a tool of the FSJ tool at least 300 microns away from the first part (less layer) throughout the joining, to avoid damaging the cold spray to first part interface, and formation of intermetallics. Fatigue resistance was tested, with and without a sealant.

Abstract: A technique for joining parts of incompatible metals involves cold spraying a 150-900 micron thick layer of a metal compatible with the second part onto the first part, and friction stir joining the parts by lap welding while keeping a tool of the FSJ tool at least 300 microns away from the first part (less layer) throughout the joining, to avoid damaging the cold spray to first part interface, and formation of intermetallics. Improved fatigue resistance is shown. A sealant can advantageously further improve fatigue resistance.

Abstract: In a method of monitoring in-flight particles, a mask in a is placed in a plane generally parallel to the direction of travel of the particles. The mask defines at least two slits that are generally parallel and lie in a direction having at least a component at right angles to the direction of travel. The slits have their ends offset relative to each other. The slits radiation emitted, scattered or absorbed by the particles is monitored as they traverse the slits field of view. The particles for which the radiation, emitted, scattered or absorbed which is collected through each slit as they sequentially traverse said slits bears a predetermined relationship are identified, and the size of the identified particles is determined from the amount of radiation emitted, scattered or absorbed as the identified particles traverse the slits.