Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V.

Daimler Chrysler Ag

Hermann Mai

Reiner Dietsch

Steffen Beyer

Wolfgang Pompe

Klaus Schubert

A pulsed laser deposition (PLD) process is used for forming a functional metal, ceramic, or ceramic/metal layer on an inner wall of a hollow body. Simultaneously with the deposition process, a thin-film laser treatment is carried out, whereby a laser beam impinges on the coating layer as it is being formed to achieve a rapid heating followed by a rapid cooling and solidification of the deposited coating layer. In this context, the energy and material flux densities are prescribed and controlled as a function of the spacing of the condensation region from the substrate surface. Laser pulses having an energy of 1 to 2 Joules and a pulse repetition rate of 10 to 50 Hz are used. The pulse duration as well as the residual gas atmosphere in the vacuum deposition chamber are controlled so that the generated plasma flux forms the desired layered grain structure, namely a glassy amorphous structure, a columnar structure, or a polycrystalline structure. The coating or target material can be made of a conducting material and/or an insulating material. By continuously or discretely varying process parameters, it is possible to form graded layer coating systems having properties that vary through the thickness of the coating.

Method of forming metal, ceramic or ceramic/metal layers on inner

A method for depositing a thin layer on a substrate by laser pulse vapor deposition provides a substantially cylindrical target having a cylinder axis and a curved target surface. A pulsed laser beam is generated having an initial path section and an initial path section axis and is capable of producing a plasma plume from the target when the pulsed laser beam impinges on the curved target surface. A first mirror located between the target and the initial path section of the laser beam is provided having a plurality of reflective interior surfaces and a first mirror axis substantially coincident with an initial path section axis of the laser beam. The laser beam is deflected so as to impinge on the reflective interior surface of the first mirror and subsequently to be reflected and to impinge on the curved target surface by controlling a plane reflective mirror that intersects the first mirror axis and is located on a side of the first mirror opposite from the target. The plane reflective mirror is tilted at an angle to the laser beam axis and is rotatable about a rotation axis substantially coincident with the first mirror axis. The laser beam is focussed on a center of the target to produce the plasma plume on the curved target surface. The plasma plume is moved on the curved target surface over a track by moving a position where the laser beam impinges on the reflective interior surface of the first mirror step-by-step rotation of the plane reflective mirror about the rotation axis, with a thin layer being deposited with a substantially uniform thickness on the substrate by contact of the plasma plume with the substrate. The first mirror includes a plurality of plane mirrors connected in a cylindrical manner.

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Dresden, Germany

Hermann Mai