method for chemical bonding of fiberglass fibers to steel surfaces to prepare the steel for bonding with carbon composite material . this fiber - bonding step greatly increases the strength of the subsequent metal - composite bond . the fiberglass fibers which are chemically bonded to the steel provide a high surface area interface to entangle with carbon fibers in the composite component , and thereby inhibit crack formation on the boundary surface between the steel and composite components when they are bonded together .