Rubber Peeling Mechanism of SOFT METAL ® for CHG

SOFT METAL (SUS plate coated with rubber) is used for cylinder head gasket (CHG). Conventionally, this SUS plate is preprocessed using coating chromate. When this was changed to chrome-free agent, the rubber was peeled off from the plate. There are found that this may be due to the electrochemical reaction caused by the contact between different metals-Al of the engine block and Fe (SUS) of CHG.