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Why Does Stainless Steel Rust?

Ka manawa: 2021-07-20 Nā Hits: 2

ʻO ke kila kila he mea ubiquitous me nā ʻano noi like ʻole-mai ka hoʻohana ʻana i nā mea lapaʻau, i nā ʻāpana kaʻa, i nā mea nani a me nā mea kuke. ʻO ka hapa nui o ka "magic" o kēia mea metala ʻo ia ka mea kuhili, ma ke kumumanaʻo, ʻaʻole ia e ʻōpala. Eia nō naʻe, inā ua loaʻa iā ʻoe a hoʻohana paha i kahi huahana kila kila, ua ʻike paha ʻoe i ka ʻōpala (corrosion) a ua nīnau paha ʻoe inā he inoa hewa ʻole kona inoa. No ke aha i kapa ʻia ai kahi mea he "stainless" rust? ʻO ka ʻōpala

Ua kamaʻāina ka hapa nui o ka poʻe i nā metala, e hoʻokomo i ke kila kuhili ʻole, e ʻino ana ke ʻike ʻia i nā kaiapuni e like me ka wai kai. ʻO ka manawa pinepine, me ka ʻike ʻole i ka ʻepekema pololei o ka mea e hana nei, ʻae ka poʻe i ka hōʻike ʻana i kahi huahana metala i ka wai kai he hopena pōʻino. ʻO ka ʻepekema ma hope o ka ʻino ʻana mai ka wai kai, ʻo ia ka wai i loko o ka chlorine, kahi mea ʻino i nā metala, me ke kila kila. Eia nō naʻe, hiki ke ʻino ʻia ke kila kila me ka ʻole o ka hana ʻana i nā huahana corrosion e kālailai (koe i ka ʻōpala), a inā ʻaʻole hiki ke ʻike ʻia kahi pōʻino kūlohelohe.

No ka hoʻomaopopo ʻana i ka mea e hana ai i ka ʻeleʻele kila he mea nui mua ka hoʻomaopopo ʻana i ka ʻepekema e pale mau ai i ka ʻōpala. Hana ʻia ke kila me ka hao a me ke kalapona, a ʻo ke kila kuhili ka hao, kalapona, a me nā wahi āpau mai 12-30% chromium. Hiki i ke kila kila ke komo i nā mea ʻē aʻe e like me ka nickel a me ka manganese, akā ʻo ka chromium ka mea nui e pale ai i ka pala. Ke ʻike ʻia ka ʻili o ke kila maʻamau i ka oxygen, hana maʻamau ia i ka ferric oxide (Fe2O3) nona ke kala ʻulaʻula kaulana. ʻAʻole hana ʻo Ferric oxide i kahi papa mau ma luna o ke kila no ka mea ʻoi aku ka nui o ka mole oxide ma mua o nā ʻātoma hao i lalo, a ma hope o ka haʻalele ʻana i ke kila hou i ʻike ʻia a laila hoʻomaka i kahi pōʻaiapili deleterious. Ke hōʻike ʻia ke kila kila i ka oxygen, hana ʻia ka chromium oxide ma ka ʻili o ke kila no ka mea he ikaika loa ka chromium no ka oxygen. ʻO ka chromium oxide kahi ʻāpana lahilahi ʻaʻole e ʻoki ʻia, a ke pale aku nei i ka hoʻoneʻe hou ʻana o ke kila kila. ʻOiai ke ʻoki ʻia ke kila kila a wehe ʻia ka ʻāpana chromium oxide, e hana ʻia kahi papa chromium oxide hou a pale i ke koena o ke kila kila ma lalo. I ka lōʻihi o ka lawa ʻana o ka chromium, e hoʻomau ka papa chromium oxide i ka pale ʻana i ke kila kuhili ʻole a pale aku i ka pala.

Ua hoʻohana paha ʻoe i ka huila uwea kila a i ʻole ka huluhulu kila no ka hoʻomaʻemaʻe ʻana i kahi mea hana kila kuhili ʻole, a laila ʻāwili ka mea hana kuhili ma kahi hoʻokahi i pulumi ʻia? A i ʻole ua ʻike paha ʻoe i kahi ipu kila kuhili ʻole a i ʻole ka pulu pulu? ʻO ka ʻino ʻino ʻole me ka loaʻa ʻole o kahi mea ʻino (e like me ka chlorine) mai nā ʻāpana kila liʻiliʻi loa e pili ana i ka ʻili kila kuhiliʻole. Hiki i ka Chromium ke pale i ke kila kila inā ʻoi aku ka nui o ka ʻike kūloko ma mua o 12%, akā inā ʻoe e uhi i ka ʻili kuhili me nā mea kila lawa, a laila hiki ke hāʻule ka ʻike kūloko o ka chromium ma lalo o ka paepae 12% a ʻaʻole hiki i ka papa chromium oxide ke pale i ka. kila kila mai ka hoʻouka ʻana o ka oxygen. Inā loaʻa kēia ʻano ʻino i ke kila kila, hiki ke hoʻoponopono ʻia e: (A) Hoʻomaʻemaʻe i ka ʻōpala a pau, a laila (B) wehe i nā ʻāpana kila liʻiliʻi ma o ka hoʻomaʻemaʻe pono ʻana i ka ʻāpana kila kila, maʻamau me ka solvent. Pono kēia mau ʻanuʻu ʻelua e ʻae i ka papa o ka chromium oxide e pale i ka mea ʻole mai ka hoʻoneʻe hou ʻana.

ʻO ke ʻano maʻamau o ka ʻōpala i loko o ke kila kila ma hope o ka ʻike ʻia ʻana o ka mea kila i nā wela kiʻekiʻe loa, pinepine i ka laulā 750-1550°F (400-850°C)1. ʻIke pinepine ʻia kēia ʻano corrosion i nā noi kuʻihao kahi i hoʻomehana ʻia ai ka stainless a laila hoʻomaha ʻia. Inā hiki mai kēia, hiki ke hana 'ia ka "sensitization" kahi i hoʻopaʻa ʻia ai ke kalapona a me ka chromium i loko o ke kila kuhiliʻole a hana i nā carbide. Aia kēia mau carbide iā lākou iho ma nā palena o ka palaoa kila, a lilo nā palena ʻai i ka chromium. Me ka haʻahaʻa haʻahaʻa o ka chromium ma nā palena o ka palaoa, hiki ke hoʻopau ʻia ka pale pale chromium oxide a hiki ke hiki ke ʻā. Hiki i ka "Sensitization" ke hoʻopōʻino i ke kila kila a mau loa; akā, hiki ke hoʻemi ʻia ka pōʻino i kekahi manawa me ka mālama wela paʻakikī.

ʻOiai ʻo ka ʻōpala kekahi mea i ʻike ʻia e ka hapa nui o mākou i kēlā me kēia lā a ʻike ʻia he mea maʻalahi hiki ke hopena mai nā kaʻina hana paʻakikī. He mea koʻikoʻi ka hoʻomaopopo ʻana i ka ʻepekema waiwai o nā metala no ka hōʻoia ʻana i ka hana pono o ka huahana a me ka hoʻoponopono ʻana i nā pilikia, e like me ka ʻōpala. He mea koʻikoʻi nō hoʻi ka hoʻomaopopo ʻana i ka ʻepekema waiwai o nā metala a me ka ʻōpala i ka wā e hana ana i kahi hoʻokolokolo hoʻokolokolo hemahema e pili ana i ka corrosion.