Pistons with ring groove reinforcing

A piston having therein at least one piston ring groove reinforcing member, the at least one reinforcing member being annular in form and having, in cross-section, upper and lower, generally radially extending face portions and a radially inner, generally axially extending face portion between the two generally radially extending face portions, the generally axially extending face portion initially being coated with particulate material by a physical vapour deposition technique to provide a porous adhesion assisting layer, a piston body alloy being cast around the reinforcing member in engagement with and radially extending face portions and infiltrating the porous layer;

• wherein the upper and lower, generally radially extending face portions are bonded to the cast part of the piston body by being provided, after the provision of the coating of particulate material, with a wetted layer which includes an Aluminium-Iron intermetallic compound at the interface therewith.

A method of making a piston having at least one piston ring groove reinforcing member, the at least one reinforcing member having upper and lower, generally radially extending face portions and a generally axially extending face portion between the two generally radially extending face portions and radially inwardly of the piston outer diameter, the method comprising the steps of coating with particulate material only the generally axially extending face portion by a physical vapour deposition technique to form a porous adhesion assisting layer, preheating the coated reinforcing member, placing the reinforcing member in a piston casting die, pouring molten piston body alloy around the reinforcing member including the generally axially extending face portion and the radially extending face portions, and allowing the molten alloy to solidify under an applied pressure causing the alloy to infiltrate said porous adhesion assisting layer.

A method of making a piston having at least one piston ring groove reinforcing member, the at least one reinforcing member having upper and lower, generally radially extending face portions and a generally axially extending face portion between the two generally radially extending face portions and radially inwardly of the piston outer diameter, the method comprising the steps of coating with particulate material the generally axially extending face portion by a physical vapour deposition technique to form a porous adhesion assisting layer, preheating the coated reinforcing member, placing the reinforcing member in a piston casting die, pouring molten piston body alloy around the reinforcing member, and allowing the molten alloy to solidify under an applied pressure causing the alloy to infiltrate said porous adhesion assisting layer;

• wherein, before the coated reinforcing member is placed in the piston casting die, the reinforcing member is dipped into a bath of molten Aluminium to wet the upper and lower generally radially extending face portions, so forming an Aluminium-Iron intermetallic compound at the interface therewith.