1. ʻO ke apo Nitriding: ʻO ka paʻakikī o ka papa nitrided ma luna o 950HV, ʻo ka brittleness ka papa 1, maikaʻi ka abrasion a me ka pale ʻana i ka corrosion, ʻoi aku ka ikaika o ka luhi, ʻoi aku ka nui o ka corrosion a me ka hana anti-seizure; liʻiliʻi ke apo piston.
2. ʻO ke apo i hoʻopaʻa ʻia ʻo Chrome: ʻO ka papa chrome-plated he mau kristal maikaʻi a maʻalahi, ʻoi aku ka paʻakikī ma luna o 850HV, ʻoi aku ka maikaʻi o ka pale ʻana i ka ʻaʻahu, a ʻo ka crisscross micro-crack network e kūpono i ka mālama ʻana i nā lubricants. Wahi a ka ʻike pili, "Ma hope o ka hoʻopaʻa ʻana i ka chrome ma ka ʻaoʻao o ke apo piston, hiki ke hoʻemi nui ʻia ka lole o ke apo. Ma nā ʻenekini me ka mahana a me ka haʻahaʻa haʻahaʻa, hiki i nā ʻano i ʻōlelo ʻia ma luna ke hoʻemi i ka ʻaʻahu o ka piston ring groove e 33 a 60".
3. Phosphating apo: Ma o ka hoʻomaʻamaʻa kemika, hana ʻia kahi papa o ka phosphating film ma ka ʻili o ke apo piston, hiki ke pale i ka huahana mai ka ʻōpala a hoʻomaikaʻi i ka holo mua o ke apo.
4. Oxidation apo: Ma lalo o ke kūlana o ka wela kiʻekiʻe a me ka oxidant ikaika, ua hoʻokumu ʻia kahi kiʻiʻoniʻoni oxide ma luna o ka ʻili o ka mea kila, nona ka corrosion resistance, anti-friction lubrication a me ka helehelena maikaʻi. Aia kekahi PVD a pēlā aku.
