Method of manufacturing multilayer material for plain bearing
A method of manufacturing a multilayer material including a back metal and a metal plate made from a metal differing from the back metal is disclosed. The method includes heating powder of the metal formed into the metal plate in a reducing atmosphere so that an oxide on a surface of the metal powder is deoxidized, and spreading the deoxidized metal powder onto the back metal and irradiating laser beam having an energy density of 10 to 100 kW/cm 2 onto the metal powder spread on the back metal so that the metal powder is partially heated to be melted, while the laser beam is moved relative to the spread metal powder, and quenching the melted part of the metal powder at an underside of the back metal so that the melted part is rapidly solidified, whereupon the multilayer material has a dendritic structure in which the metal plate extends substantially vertically from a surface of the back metal, and the dendritic structure has a crystal grain size equal to or smaller than 0.02 mm at a cut surface thereof parallel to a surface of the back metal and/or a dendritic arm spacing equal to or smaller than 0.02 mm at a cut surface thereof vertical to the surface of the back metal.
1. A method of manufacturing a multilayer material including a back metal and a metal plate made from a metal differing from the back metal, the method comprising:
heating powder of the metal formed into the metal plate in a reducing atmosphere so that oxide on a surface of the metal powder is deoxidized and so that a hydrogen loss becomes not more than 0.05%; and
spreading the deoxidized metal powder onto the back metal and irradiating laser beam having an energy density of 10 to 100 kW/cm 2 onto the metal powder spread on the back metal so that the metal powder is partially heated to be melted, while the laser beam is moved relative to the spread metal powder, and quenching the melted part of the metal powder by water supplied toward an underside of the back metal so that the melted part is rapidly solidified at a cooling rate set at or above 100° C./sec, whereupon the multilayer material has a dendritic structure in which the metal plate extends substantially vertically from a surface of the back metal, and the dendritic structure has a crystal grain size equal to or smaller than 0.02 mm at a cut surface thereof parallel to a surface of the back metal and/or dendritic arm spacing equal to or smaller than 0.02 mm at a cut surface thereof vertical to the surface of the back metal.
2. A method according to claim 1 , wherein the deoxidizing is carried out subsequently to the spreading.
3. A method according to claim 2 , wherein the laser beam is moved at 0.2 to 5.0 m/min relative to the metal powder.
4. A method according to claim 2 , wherein the metal powder is heated at or above 800° C./sec by the laser beam.
5. A method according to claim 2 , wherein the laser beam is emitted from a semiconductor laser.
6. A method according to claim 2 , further comprising homogenizing the metal plate by annealing subsequently to the melting and solidifying the metal powder.
7. A method according to claim 1 , wherein the laser beam is moved at 0.2 to 5.0 m/min relative to the metal powder.
8. A method according to claim 1 , wherein the metal powder is heated at or above 800° C./sec by the laser beam.
9. A method according to claim 1 , wherein the laser beam is emitted from a semiconductor laser.
10. A method according to claim 1 , further comprising homogenizing the metal plate by annealing subsequently to the melting and solidifying the metal powder.