Deposition of coatings on substrates

Abstract

A process and apparatus are disclosed for the deposition of a layer of a first material onto a substrate of a second material. Powder particles of the first material are entrained into a carrier gas flow to form a powder beam directed to impinge on the substrate. This defines a powder beam footprint region at the substrate. The powder beam and the substrate are moved relative to each other to move the powder beam footprint relative to the substrate, thereby to deposit the layer of the first material. A laser is operated to cause direct, local heating of at least one of a forward substrate region and a powder beam footprint region. The laser beam direction is defined with reference to a plane coincident with or tangential to a surface of the substrate at the center of the laser beam footprint in terms of an elevation angle from the plane to the laser beam direction and in terms of an acute azimuthal angle from the movement direction to the laser beam direction. The elevation angle is 80° or less and the azimuthal angle is ±60° or less. In the apparatus, there are provided at least three laser sources arrayed around the powder beam footprint, the angular spacing between the laser sources being 120° or less.