| abstract |
On the outer peripheral surface of both skirt portions 8 and 9 of the base material 1a of the aluminum alloy piston 1, a multi-layer solid lubricating film of the lower layer film 21 and the upper layer film 22 of this upper surface was formed. Both the lower layer coating and the upper layer coating include at least one kind of polyamideimide resin, polyimide resin, or epoxy resin, which is a binding resin, and the lower layer coating is a material containing, for example, graphite as a fixed lubricant. After the coating is applied to the outer surface of the skirt, the laser heating device is irradiated with a laser beam having a temperature rising rate of 11.3 to 23.9 ° C./sec for approximately 10 seconds to dry, and the upper layer coating is applied to the upper surface. The baking treatment was performed. This provides a film forming method capable of forming a multi-layer solid lubricating film in a time as short as possible in the entire processing time of the film forming process. |