| 摘要 |
A cast iron piston ring is provided with a friction reducing packing of bonded iron oxide nd carbon powder in a groove of its outer circumferential face, and with a hard chromium electrodeposit on all other surfaces by first applying a packing composition including a heat curing bonding agent, thereafter coating the packing with an aqueous polytetrafluoroethylene dispersion, drying and sintering the resin into a continuous film while simultaneously curing the packing, and thereafter electrodepositing chromium, the cured packing being protected against attack by the chromium plating bath by the resin film.
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