Joining of thermoplastic to metal with enhanced interfacial chemical bonding

A method of attaching a thermoplastic-based workpiece and a metal workpiece, the method comprising:

• applying a metal reaction coating over a surface of a steel substrate to form a metal workpiece, the metal reaction coating being composed of chromium, nickel, titanium, aluminum, zinc, boron, manganese, silicon, or a combination of any of those materials;
• assembling the metal workpiece in overlapping fashion with a thermoplastic-based workpiece such that a faying surface of the metal workpiece overlaps and contacts a faying surface of the thermoplastic-based workpiece along a faying interface, the thermoplastic-based workpiece comprising a thermoplastic polymer matrix that includes metal-reactive carbonyl moieties, and wherein an exposed surface of the metal reaction coating constitutes the faying surface of the metal workpiece;
• and
• directing an energy source against the metal workpiece to create a concentrated zone of heat that at least warms up the metal reaction coating at the faying interface and melts a portion of the faying surface of the thermoplastic-based workpiece in contact with the metal reaction coating.

A method of attaching a thermoplastic-based workpiece and a metal workpiece, the method comprising:

• applying a metal reaction coating over a surface of a steel substrate to form a metal workpiece, the metal reaction coating being composed of chromium;
• assembling the metal workpiece in overlapping fashion with a thermoplastic composite workpiece such that a faying surface of the metal workpiece overlaps and contacts a faying surface of the thermoplastic-based workpiece along a faying interface, the thermoplastic composite workpiece comprising a thermoplastic polymer matrix that includes metal-reactive carbonyl moieties and a reinforcing phase embedded within the thermoplastic polymer matrix, and wherein an exposed surface of the metal reaction coating constitutes the faying surface of the metal workpiece;
• and
• operating a laser optic head to direct a laser beam against the metal workpiece to create a concentrated zone of heat that extends to the faying interface and at least warms up the metal reaction coating at the faying interface and melts a portion of the faying surface of the thermoplastic-based workpiece in contact with the metal reaction coating.