We don't have synonyms for petong yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are betong, patong and petone.
(n) :
Obsolete form of paktong. [An alloy of zinc, copper and nickel, closely resembling silver, of Chinese origin; any of a number of similar alloys developed in imitation of the Chinese product.]
(n) :
Obsolete form of paktong. [An alloy of zinc, copper and nickel, closely resembling silver, of Chinese origin; any of a number of similar alloys developed in imitation of the Chinese product.]