Patent ID: 6858262
Filing Date: 2005-02-22
Classification: B23K,C23C

Abstract:
1. A method for manufacturing a cylindrical, partly cylindrical or hollow cylindrical surface-alloyed structural member made from a matrix alloy where an energy beam having a linear focus, is directed onto a workpiece surface of a workpiece being moved in front of said energy beam to form a zone of incidence on said workpiece surface wherein the workpiece surface is melted forming a liquified matrix alloy, said method comprising: a) forming a locally bounded melting bath in which the liquified matrix alloy is present in the zone of incidence of the energy beam, the melting bath having a heating front, a melting front, a solution zone and a solidification front, b) depositing the silicon powder at the side of the energy beam via a conveyor device in the direction of gravity and supplying said silicon powder in coordination with the feed movement of the workpiece in a width which corresponds to the width of the linear focus and producing thereby a layer of silicon powder having a height of 0.3-3 mm, c) heating the silicon powder supplied to the workpiece surface in the heating front of the melting bath with the energy beam at a wavelength of 780-940 nm and thereby dissolving in the melting bath the silicon powder which is in contact with the liquefied matrix alloy, d) producing convection in the solution zone with the energy beam having a specific power of at least 10 e) wherein the linear focus acts on the solution zone until the silicon powder is uniformly distributed in the melting bath, f) subjecting the uniformly distributed silicon powder in front of the energy beam, which has gone into solution metallurgically in the solution zone, to directional solidification in the solidification front at a cooling rate of 200-600 K/sec wherein the workpiece is moved at a feed rate of 500-10,000 mm/min.