Method for fusibly bonding a coating material to a metal article

Claim 1

A method of fusibly bonding a substantially solid powder coating material to a metal article, which comprises: Step (a) depositing the powder in the form of a band of powder onto a surface of the metal article, the band of powder being substantially uniformly levelled and of a preselected width; Step (b) melting a portion of the band of powder by focusing a laser beam thereon; Step (c) immediately thereafter melting the surface of the metal article by the heat of the laser beam on the band of powder at a heat interaction zone; and Step (d) relatively moving the focused laser beam and the heat interaction zone along the band of powder at a rate sufficient for forming a traveling melt and maintaining heat transfer into the article and cooling of a trailing portion of the melt at preselected values and subsequent hardening of the trailing portion of the melt at a relatively fixed distance from the heat interaction zone, the relative rate of laser beam movement and heat transfer being sufficient for providing a solidified surface layer having physical properties resulting essentially from heating and cooling of only the powder and a relatively thin, strong region of interstitial bond between the surface layer and the article having physical properties resulting essentially from heating and cooling of both the powder and the metal article.

Claim 2

A method of fusibly bonding a substantially solid powder coating material to a metal article, which comprises: Step (a) depositing the powder in the form of a band of powder onto a surface of the metal article, the band of powder being substantially uniformly levelled and of a preselected width; Step (b) melting a portion of the band of powder by focusing a laser beam thereon; Step (c) immediately thereafter melting the surface of the metal article by the heat of the laser beam on the band of powder at a heat interaction zone; and Step (d) relatively moving the focused laser beam and the heat interaction zone along the band of powder at a rate sufficient for forming a traveling melt and maintaining heat transfer into the article and cooling of a trailing portion of the melt at preselected values and subsequent hardening of the trailing portion of the melt at a relatively fixed distance from the heat interaction zone, the relative rate of laser beam movement and heat transfer being sufficient for providing a solidified surface layer having physical properties resulting essentially from heating and cooling of only the powder and a relatively thin, strong region of interstitial bond between the surface layer and the article having physical properties resulting essentially from heating and cooling of both the powder and the metal article.