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He pilikia koʻikoʻi ka palaho microbial (MIC) i nā ʻoihana he nui no ka mea hiki ke hoʻolilo i nā pohō waiwai nui. Ua hoʻohana ʻia ke kila kila super duplex 2707 (2707 HDSS) i nā wahi kai ma muli o kona kūpaʻa kemika maikaʻi loa. Eia nō naʻe, ʻaʻole i hōʻike ʻia kona kūpaʻa ʻana i ka MIC ma ke ʻano hoʻokolohua. Ma kēia noiʻi, ua noiʻi ʻia ke ʻano MIC o 2707 HDSS i hoʻokumu ʻia e ka bacteria aerobic kai ʻo Pseudomonas aeruginosa. Ua hōʻike ka loiloi electrochemical i ke alo o ka biofilm Pseudomonas aeruginosa i loko o ka medium 2216E, aia kahi loli maikaʻi i ka hiki ke palaho a me ka hoʻonui ʻana i ka nui o ke au o ka palaho. Ua hōʻike ka loiloi X-ray photoelectron spectroscopy (XPS) i ka emi ʻana o ka ʻike Cr ma ka ʻili o ka specimen ma lalo o ka biofilm. Ua hōʻike ka loiloi kiʻi o nā lua ua hana ka biofilm P. aeruginosa i ka hohonu o ka lua he 0.69 μm i loko o 14 mau lā o ka incubation. ʻOiai he liʻiliʻi kēia, hōʻike ia ʻaʻole i pale piha ʻo 2707 HDSS i ka MIC o nā biofilms P. aeruginosa.
Hoʻohana nui ʻia nā kila kila Duplex (DSS) i nā ʻoihana like ʻole no kā lākou hui kūpono o nā waiwai mechanical maikaʻi loa a me ke kūpaʻa ʻana i ka corrosion1,2. Eia nō naʻe, ke hana mau nei ka pitting kūloko a hoʻopilikia ia i ka pono o kēia kila3,4. ʻAʻole kūpaʻa ka DSS i ka microbial corrosion (MIC)5,6. ʻOiai ka laulā o nā noi o DSS, aia nō nā wahi kahi i lawa ʻole ai ke kūpaʻa ʻana o ka DSS no ka hoʻohana lōʻihi. ʻO ia hoʻi, pono nā mea pipiʻi me ke kūpaʻa ʻana i ka corrosion kiʻekiʻe. Ua ʻike ʻo Jeon et al7 ʻoiai nā kila kila super duplex (SDSS) he mau palena ko lākou e pili ana i ke kūpaʻa ʻana i ka corrosion. No laila, pono nā kila kila super duplex (HDSS) me ke kūpaʻa ʻana i ka corrosion kiʻekiʻe i kekahi mau noi. Ua alakaʻi kēia i ka hoʻomohala ʻana o ka HDSS alloyed kiʻekiʻe.
ʻO ke kūpaʻa ʻana o ka DSS i ka palaho e pili ana i ka lakio o nā pae alpha a me gamma a me nā wahi i hoʻopau ʻia ʻo Cr, Mo a me W 8, 9, 10 e pili ana i ka pae ʻelua. Loaʻa i ka HDSS ka nui o Cr, Mo a me N11, no laila he kūpaʻa maikaʻi loa ia a me kahi helu like ʻole o ka Pitting Resistance (PREN) kiʻekiʻe (45-50), i hoʻoholo ʻia e wt.% Cr + 3.3 (wt.% Mo + 0.5 wt% W) + 16 wt% N12. ʻO kona kūpaʻa maikaʻi loa i ka palaho e hilinaʻi ʻia ma kahi hui kaulike e loaʻa ana ma kahi o 50% ferrite (α) a me 50% austenite (γ) mau pae, ʻoi aku ka maikaʻi o nā waiwai mechanical o HDSS a ʻoi aku ke kiʻekiʻe o ke kūpaʻa ma mua o ka DSS13 maʻamau. Nā waiwai palaho Chloride. Hoʻonui ka hoʻomaikaʻi ʻana i ke kūpaʻa palaho i ka hoʻohana ʻana o HDSS i nā wahi chloride corrosive, e like me nā wahi kai.
He pilikia nui nā MIC i nā ʻoihana he nui e like me ka ʻaila a me ke kinoea a me nā pono wai14. ʻO MIC ka helu no 20% o nā pōʻino corrosion āpau15. ʻO MIC ka corrosion bioelectrochemical hiki ke ʻike ʻia ma nā wahi he nui. Hoʻololi nā Biofilms i hana ʻia ma nā ʻili metala i nā kūlana electrochemical, no laila e hoʻopilikia ana i ke kaʻina hana corrosion. Manaʻo nui ʻia ua hoʻokumu ʻia ka corrosion MIC e nā biofilms. Hoʻopili nā microorganisms electrogenic i nā metala e loaʻa ai ka ikehu hoʻomau e ola17. Ua hōʻike ʻia nā haʻawina MIC hou ʻo EET (extracellular electron transfer) ka mea e kaupalena ana i ka helu ma MIC i hoʻokumu ʻia e nā microorganisms electrogenic. Ua hōʻike ʻo Zhang et al. 18 e hoʻolalelale nā ​​​​mea hoʻopili electron i ka hoʻoili electron ma waena o nā cell Desulfovibrio sessificans a me 304 stainless steel, e alakaʻi ana i ka hoʻouka kaua MIC koʻikoʻi. Ua hōʻike ʻo Enning et al. 19 a me Venzlaff et al. 20 hiki i nā biofilms corrosive sulfate-reducing bacteria (SRB) ke omo pololei i nā electrons mai nā substrates metala, e hopena ana i ka corrosion pitting koʻikoʻi.
Ua ʻike ʻia ʻo DSS he mea hiki ke maʻalahi i ka MIC i nā wahi e loaʻa ana ka SRB, nā bacteria hoʻemi hao (IRB), a me nā mea ʻē aʻe. 21. Hoʻokumu kēia mau bacteria i ka pitting kūloko ma nā ʻili DSS ma lalo o nā biofilms22,23. ʻAʻole e like me DSS, ʻaʻole ʻike nui ʻia ka MIC o HDSS24.
ʻO Pseudomonas aeruginosa kahi bacteria motile koʻokoʻo gram-negative i hoʻolaha nui ʻia ma ke ʻano25. ʻO Pseudomonas aeruginosa kekahi hui microbial nui i loko o ke kai, e hoʻoulu ana i ka MIC i ke kila. Pili loa ʻo Pseudomonas i nā kaʻina hana corrosion a ua ʻike ʻia ʻo ia he colonizer paionia i ka wā o ka hoʻokumu ʻana o biofilm. Ua hōʻike ʻo Mahat et al. 28 a me Yuan et al. 29 he ʻano ko Pseudomonas aeruginosa e hoʻonui i ka helu corrosion o ke kila akahai a me nā alloys i nā wahi wai.
ʻO ka pahuhopu nui o kēia hana, ʻo ia ke noiʻi ʻana i nā waiwai MIC o 2707 HDSS i hoʻokumu ʻia e ka bacteria aerobic kai ʻo Pseudomonas aeruginosa me ka hoʻohana ʻana i nā ʻano electrochemical, nā ʻano hana loiloi ʻili a me ka loiloi huahana corrosion. Ua hana ʻia nā haʻawina electrochemical e pili ana i ka Open Circuit Potential (OCP), Linear Polarization Resistance (LPR), Electrochemical Impedance Spectroscopy (EIS), a me Potential Dynamic Polarization e aʻo i ke ʻano MIC o 2707 HDSS. Ua hana ʻia ka loiloi spectrometer dispersive ikehu (EDS) e ʻike i nā mea kemika ma luna o ka ʻili i ʻino ʻia. Eia kekahi, ua hoʻohana ʻia ka loiloi spectroscopy photoelectron X-ray (XPS) e hoʻoholo i ke kūpaʻa o ka passivation film oxide ma lalo o ka mana o kahi kaiapuni kai e loaʻa ana iā Pseudomonas aeruginosa. Ua ana ʻia ka hohonu o ka lua ma lalo o kahi microscope scanning laser confocal (CLSM).
Ua papa inoa ka Papa 1 i ka haku mele kemika o 2707 HDSS. Hōʻike ka Papa 2 he mau waiwai mechanical maikaʻi loa ko 2707 HDSS me ka ikaika hua o 650 MPa. Hōʻike ka Kiʻi 1 i ka microstructure optical o ka solution i mālama ʻia me ka wela 2707 HDSS. Hiki ke ʻike ʻia nā kaula elongated o nā pae austenite a me ferrite me ka ʻole o nā pae lua i loko o ka microstructure e loaʻa ana ma kahi o 50% austenite a me 50% ferrite phases.
Hōʻike ka Kiʻi 2a i ka hiki ke kaapuni hāmama (Eocp) e kūʻē i ka ʻikepili manawa hōʻike no 2707 HDSS i loko o ka abiotic 2216E medium a me ka P. aeruginosa broth no 14 mau lā ma 37 °C. Hōʻike ia ʻo ka loli nui loa a koʻikoʻi hoʻi ma Eocp e hana ʻia i loko o nā hola 24 mua. ʻO nā waiwai Eocp i nā hihia ʻelua i piʻi i ka -145 mV (vs. SCE) ma kahi o 16 h a laila hāʻule koke, hiki i ka -477 mV (vs. SCE) a me -236 mV (vs. SCE) no ka laʻana abiotic a me P, kēlā me kēia). Nā kūpona Pseudomonas aeruginosa, kēlā me kēia. Ma hope o 24 mau hola, ua paʻa ka waiwai Eocp o 2707 HDSS no P. aeruginosa ma -228 mV (vs. SCE), ʻoiai ʻo ka waiwai like no nā laʻana ʻaʻole olaola ma kahi o -442 mV (vs. SCE). Ua haʻahaʻa iki ka Eocp i ke alo o P. aeruginosa.
Ka hoʻāʻo electrochemical o 2707 mau specimens HDSS i loko o ka medium abiotic a me ka wai Pseudomonas aeruginosa ma 37 °C:
(a) ʻO Eocp ma ke ʻano he hana o ka manawa hōʻike, (b) nā piʻo polarization i ka lā 14, (c) ʻO Rp ma ke ʻano he hana o ka manawa hōʻike a me (d) ʻo icorr ma ke ʻano he hana o ka manawa hōʻike.
Ua papa inoa ka Papa 3 i nā waiwai palena electrochemical corrosion o 2707 mau laʻana HDSS i hōʻike ʻia i ka medium abiotic a me ka Pseudomonas aeruginosa i hoʻokomo ʻia i loko o ka medium no 14 mau lā. Ua hoʻonui ʻia nā tangents o nā ʻōuli anodic a me cathodic e hōʻea i nā intersections e loaʻa ai ka corrosion current density (icorr), corrosion potential (Ecorr) a me nā ʻaoʻao Tafel (βα a me βc) e like me nā ʻano maʻamau 30,31.
E like me ka mea i hōʻike ʻia ma ke Kiʻi 2b, ʻo ka neʻe ʻana o ka piʻi ʻana o ka piʻi ʻana o P. aeruginosa i hopena i ka piʻi ʻana o Ecorr i hoʻohālikelike ʻia me ka piʻi ʻana o ka abiotic. ʻO ka waiwai icorr, i kūlike me ka nui o ka palaho, ua piʻi aʻe i 0.328 μA cm-2 i loko o ka laʻana Pseudomonas aeruginosa, ʻehā manawa o ka laʻana ʻaʻole olaola (0.087 μA cm-2).
ʻO LPR kahi ʻano electrochemical maʻamau ʻaʻole luku no ka loiloi wikiwiki ʻana i ka pala. Ua hoʻohana ʻia hoʻi e aʻo iā MIC32. Hōʻike ka Kiʻi 2c i ke kū'ē polarization (Rp) ma ke ʻano he hana o ka manawa hōʻike. ʻO ka waiwai Rp kiʻekiʻe aʻe ʻo ia hoʻi ka emi ʻana o ka pala. I loko o nā hola 24 mua, ua hōʻea ka Rp o 2707 HDSS i ka waiwai kiʻekiʻe loa o 1955 kΩ cm2 no nā laʻana abiotic a me 1429 kΩ cm2 no nā laʻana Pseudomonas aeruginosa. Hōʻike pū ka Kiʻi 2c ua emi koke ka waiwai Rp ma hope o hoʻokahi lā a laila noho mau ʻaʻole i loli no nā lā 13 e hiki mai ana. ʻO ka waiwai Rp o ka laʻana Pseudomonas aeruginosa ma kahi o 40 kΩ cm2, ʻoi aku ka haʻahaʻa ma mua o ka waiwai 450 kΩ cm2 o ka laʻana non-biological.
Ua like ka waiwai icorr me ka nui o ka palaho like. Hiki ke helu ʻia kona waiwai mai ka hoʻohālikelike Stern-Geary ma lalo nei,
Ma hope o Zou et al. 33, ua manaʻo ʻia kahi waiwai maʻamau o ka pali Tafel B ma kēia hana he 26 mV/dec. Hōʻike ka Kiʻi 2d ua noho paʻa ka icorr o ka laʻana 2707 non-biological, ʻoiai ua loli nui ka laʻana P. aeruginosa ma hope o nā hola 24 mua. ʻOi aku ka kiʻekiʻe o nā waiwai icorr o nā laʻana P. aeruginosa ma mua o nā kaohi non-biological. Kūlike kēia ʻano me nā hopena kūʻē polarization.
ʻO EIS kekahi ʻano hana nondestructive i hoʻohana ʻia e wehewehe i nā hopena electrochemical ma nā interfaces corroded. ʻO nā spectra Impedance a me nā waiwai capacitance i helu ʻia o nā specimens i hōʻike ʻia i nā media abiotic a me ka hopena Pseudomonas aeruginosa, ke kū'ē Rb o ka passive film/biofilm i hoʻokumu ʻia ma luna o ka specimen, ke kū'ē hoʻoili hoʻoili Rct, Cdl electric double layer capacitance (EDL) a me nā palena QCPE Constant Phase Element (CPE). Ua kālailai hou ʻia kēia mau palena ma ke kau ʻana i ka ʻikepili me ka hoʻohana ʻana i kahi kumu hoʻohālike kaapuni like (EEC).
Hōʻike ka Kiʻi 3 i nā kiʻi Nyquist maʻamau (a a me b) a me nā kiʻi Bode (a' a me b') o 2707 mau laʻana HDSS i loko o ka medium abiotic a me ka P. aeruginosa broth no nā manawa hoʻoulu like ʻole. Hoʻemi ʻia ke anawaena o ke apo Nyquist i ke alo o Pseudomonas aeruginosa. Hōʻike ka kiʻi Bode (Kiʻi 3b') i ka hoʻonui ʻia o ka nui o ka impedance holoʻokoʻa. Hiki ke hāʻawi ʻia ka ʻike e pili ana i ka manawa hoʻomaha e ka phase maxima. Hōʻike ka Kiʻi 4 i nā ʻano kino monolayer (a) a me bilayer (b) a me kā lākou EEC e pili ana. Hoʻokomo ʻia ka CPE i loko o ke kumu hoʻohālike EEC. Hōʻike ʻia kona admittance a me ka impedance penei:
ʻElua mau kumu hoʻohālike kino a me nā kaapuni like e pili ana no ke kūpono ʻana i ka spectrum impedance o ka specimen 2707 HDSS:
kahi ʻo Y0 ka nui o ka CPE, ʻo j ka helu hoʻokalakupua a i ʻole (-1)1/2, ʻo ω ka alapine angular, a ʻo n ka helu mana CPE i emi iho ma mua o ka unity35. ʻO ka inverse o ke kū'ē hoʻoili uku (ʻo ia hoʻi 1/Rct) e pili ana i ka helu corrosion. ʻO ka Rct liʻiliʻi ʻo ia hoʻi ka wikiwiki o ka corrosion27. Ma hope o 14 mau lā o ka incubation, ua hōʻea ka Rct o nā laʻana Pseudomonas aeruginosa i 32 kΩ cm2, ʻoi aku ka liʻiliʻi ma mua o ka 489 kΩ cm2 o nā laʻana non-biological (Papa 4).
Hōʻike maopopo nā kiʻi CLSM a me nā kiʻi SEM ma ke Kiʻi 5 ua paʻa ka uhi biofilm ma ka ʻili o ka hāpana 2707 HDSS ma hope o 7 mau lā. Eia naʻe, ma hope o 14 mau lā, ua kakaikahi ka uhi biofilm a ua ʻike ʻia kekahi mau ʻāpana make. Hōʻike ka Papa 5 i ka mānoanoa o ka biofilm ma nā hāpana 2707 HDSS ma hope o ka hōʻike ʻana iā P. aeruginosa no 7 a me 14 mau lā. Ua loli ka mānoanoa biofilm kiʻekiʻe loa mai 23.4 μm ma hope o 7 mau lā a i 18.9 μm ma hope o 14 mau lā. Ua hōʻoia pū ka mānoanoa biofilm awelika i kēia ʻano. Ua emi iho ia mai 22.2 ± 0.7 μm ma hope o 7 mau lā a i 17.8 ± 1.0 μm ma hope o 14 mau lā.
(a) Kiʻi 3-D CLSM ma hope o 7 mau lā, (b) Kiʻi 3-D CLSM ma hope o 14 mau lā, (c) Kiʻi SEM ma hope o 7 mau lā a me (d) Kiʻi SEM ma hope o 14 mau lā.
Ua hōʻike ʻo EDS i nā mea kemika i loko o nā biofilms a me nā huahana pala ma nā laʻana i hōʻike ʻia iā P. aeruginosa no 14 mau lā. Hōʻike ka Kiʻi 6 ʻoi aku ka nui o ka ʻike o C, N, O, a me P i loko o nā biofilms a me nā huahana pala ma mua o nā metala ʻōlohelohe, no ka mea, pili kēia mau mea me nā biofilms a me kā lākou metabolites. Pono nā microbes i nā nui liʻiliʻi o ka chromium a me ka hao. ʻO nā pae kiʻekiʻe o Cr a me Fe i loko o ka biofilm a me nā huahana pala ma ka ʻili o nā specimens e hōʻike ana ua nalowale nā ​​​​mea o ka matrix metala ma muli o ka pala.
Ma hope o 14 mau lā, ua ʻike ʻia ka lua ʻana me ka P. aeruginosa a me ka ʻole ma ka medium 2216E. Ma mua o ka hoʻoulu ʻana, ua laumania ka ʻili o ka specimen a ʻaʻohe kīnā (Kiʻi 7a). Ma hope o ka hoʻoulu ʻana a me ka wehe ʻana i ka biofilm a me nā huahana corrosion, ua nānā ʻia nā lua hohonu loa ma ka ʻili o nā specimens ma lalo o CLSM, e like me ka mea i hōʻike ʻia ma ke Kiʻi 7b a me c. ʻAʻole i loaʻa nā lua maopopo ma ka ʻili o nā laʻana hoʻomalu ʻole biological (ka hohonu o ka lua kiʻekiʻe loa 0.02 μm). ʻO ka hohonu o ka lua kiʻekiʻe loa i hoʻokumu ʻia e Pseudomonas aeruginosa he 0.52 μm ma hope o 7 mau lā a me 0.69 μm ma hope o 14 mau lā, ma muli o ka awelika hohonu o ka lua kiʻekiʻe o 3 mau laʻana (10 mau waiwai hohonu o ka lua kiʻekiʻe i koho ʻia no kēlā me kēia laʻana) i hiki i ka 0.42 ± 0.12 μm a me 0.52 ± 0.15 μm, kēlā me kēia (Papa 5). He liʻiliʻi kēia mau waiwai hohonu o ka lua akā he mea nui.
(a) Ma mua o ka hoʻolaha ʻana, (b) 14 mau lā i loko o ka medium abiotic a me (c) 14 mau lā i loko o ka wai Pseudomonas aeruginosa.
Hōʻike ka Kiʻi 8 i nā spectra XPS o nā ʻili laʻana like ʻole, a ua hōʻuluʻulu ʻia nā ʻano kemika i kālailai ʻia no kēlā me kēia ʻili ma ka Papa 6. Ma ka Papa 6, ʻoi aku ka haʻahaʻa o nā pakeneka atomika o Fe a me Cr i ke alo o P. aeruginosa (nā laʻana A a me B) ma mua o nā laʻana hoʻomalu ʻole olaola (nā laʻana C a me D). No ka laʻana P. aeruginosa, ua hoʻopili ʻia ka piʻo spectral pae kumu Cr 2p i ʻehā mau ʻāpana piko me nā waiwai ikehu hoʻopaʻa (BE) o 574.4, 576.6, 578.3 a me 586.8 eV, hiki ke hoʻopili ʻia iā Cr, Cr2O3, CrO3 a me Cr(OH)3, kēlā me kēia (Kiʻi 9a a me b). No nā laʻana ʻole olaola, loaʻa i ka spectrum pae kumu Cr 2p ʻelua mau piko nui no Cr (573.80 eV no BE) a me Cr2O3 (575.90 eV no BE) ma ke Kiʻi. 9c a me d, kēlā me kēia. ʻO ka ʻokoʻa koʻikoʻi loa ma waena o nā laʻana abiotic a me P. aeruginosa ʻo ia ke alo o Cr6+ a me kahi hapa pili kiʻekiʻe o Cr(OH)3 (BE o 586.8 eV) ma lalo o ka biofilm.
ʻO nā spectra XPS ākea o ka ʻili o ka hāpana 2707 HDSS ma nā pāpaho ʻelua he 7 mau lā a me 14 mau lā, kēlā me kēia.
(a) 7 mau lā o ka hōʻike ʻana iā P. aeruginosa, (b) 14 mau lā o ka hōʻike ʻana iā P. aeruginosa, (c) 7 mau lā i loko o kahi ʻano abiotic a me (d) 14 mau lā i loko o kahi ʻano abiotic.
Hōʻike ʻo HDSS i nā pae kiʻekiʻe o ke kūpaʻa ʻana i ka palaho ma ka hapa nui o nā kaiapuni. Ua hōʻike ʻo Kim et al. 2 ua wehewehe ʻia ʻo UNS S32707 HDSS he DSS i hoʻohuihui nui ʻia me ka PREN oi aku ma mua o 45. ʻO ka waiwai PREN o ka specimen 2707 HDSS ma kēia hana he 49. ʻO kēia ma muli o kona ʻike chromium kiʻekiʻe a me nā pae molybdenum a me Ni kiʻekiʻe, he mea maikaʻi ia i nā kaiapuni acidic a me chloride kiʻekiʻe. Eia kekahi, he mea pono kahi ʻano kaulike maikaʻi a me ka microstructure kīnā ʻole no ke kūpaʻa o ka hoʻonohonoho a me ke kūpaʻa ʻana i ka palaho. Eia naʻe, ʻoiai kona kūpaʻa kemika maikaʻi loa, hōʻike ka ʻikepili hoʻokolohua ma kēia hana ʻaʻole i pale piha ʻo 2707 HDSS i ka MIC o nā biofilms P. aeruginosa.
Ua hōʻike ʻia nā hopena electrochemical ua hoʻonui nui ʻia ka nui o ka pala o 2707 HDSS i loko o ka P. aeruginosa broth ma hope o 14 mau lā i hoʻohālikelike ʻia me ka medium non-biological. Ma ke Kiʻi 2a, ua ʻike ʻia ka emi ʻana o Eocp ma ka medium abiotic a me ka P. aeruginosa broth i nā hola 24 mua. Ma hope mai, ua pau ka biofilm i ka uhi ʻana i ka ʻili o ka specimen a ua lilo ka Eocp i mea paʻa36. Eia naʻe, ʻoi aku ka kiʻekiʻe o ka pae o ka Eocp biological ma mua o ka Eocp non-biological. Aia ke kumu e manaʻoʻiʻo ai ʻo kēia ʻokoʻa ma muli o ka hoʻokumu ʻana o ka biofilm P. aeruginosa. Ma ke Kiʻi 2d, i ke alo o P. aeruginosa, ua hiki ka waiwai icorr o 2707 HDSS i 0.627 μA cm-2, ʻo ia ke kauoha o ka nui ma mua o ka mana abiotic (0.063 μA cm-2), i kūlike me ka waiwai Rct i ana ʻia e EIS. I nā lā mua, nā waiwai impedance ma P. Ua piʻi aʻe ka wai ʻūlū aeruginosa ma muli o ka hoʻopili ʻana o nā pūnaewele P. aeruginosa a me ke kūkulu ʻia ʻana o nā biofilms. Eia nō naʻe, ke uhi piha ka biofilm i ka ʻili o ka specimen, emi iho ka impedance. Hoʻouka mua ʻia ka papa pale ma muli o ke kūkulu ʻia ʻana o nā biofilms a me nā metabolites biofilm. No laila, ua emi ke kūpaʻa ʻana o ka corrosion i ka hala ʻana o ka manawa, a ʻo ka hoʻopili ʻana o P. aeruginosa i hoʻokumu i ka corrosion localized. Ua ʻokoʻa nā ʻano ma nā media abiotic. ʻOi aku ke kiʻekiʻe o ke kūpaʻa ʻana o ka corrosion o ka mana non-biological ma mua o ka waiwai like o nā laʻana i hōʻike ʻia i ka wai ʻūlū P. aeruginosa. Eia kekahi, no nā laʻana abiotic, ua hōʻea ka waiwai Rct o 2707 HDSS i 489 kΩ cm2 i ka lā 14, ʻo ia hoʻi he 15 mau manawa o ka waiwai Rct (32 kΩ cm2) i ke alo o P. aeruginosa. No laila, he kūpaʻa maikaʻi loa ko 2707 HDSS i ka corrosion i loko o kahi ʻano sterile, akā ʻaʻole ia e kūʻē i ka hoʻouka kaua MIC e nā biofilms P. aeruginosa.
Hiki ke ʻike ʻia kēia mau hopena mai nā piʻo polarization ma ke Kiʻi 2b. Ua hoʻopili ʻia ka lālā anodic i ka hoʻokumu ʻana o ka biofilm Pseudomonas aeruginosa a me nā hopena oxidation metala. I ka manawa like, ʻo ka hopena cathodic ka hōʻemi ʻana o ka oxygen. ʻO ke alo o P. aeruginosa i hoʻonui nui i ka nui o ke au corrosion, ma kahi o kahi kauoha o ka nui ma mua o ka mana abiotic. Hōʻike kēia e hoʻonui ka biofilm P. aeruginosa i ka corrosion localized o 2707 HDSS. Ua ʻike ʻo Yuan et al29 ua hoʻonui ʻia ka nui o ke au corrosion o 70/30 Cu-Ni alloy ma lalo o ka hoʻokūkū o ka biofilm P. aeruginosa. Hiki paha kēia ma muli o ka biocatalysis o ka hōʻemi oxygen e nā biofilms Pseudomonas aeruginosa. Hiki i kēia ʻike ke wehewehe i ka MIC o 2707 HDSS i kēia hana. Hiki i nā biofilms Aerobic ke emi iho ka oxygen ma lalo o lākou. No laila, ʻo ka hiki ʻole ke hoʻihoʻi hou i ka ʻili metala e ka oxygen he mea kōkua paha i ka MIC i kēia hana.
Ua hōʻike ʻo Dickinson et al. 38 e hiki ke hoʻopilikia pololei ʻia nā helu o nā hopena kemika a me nā electrochemical e ka hana metabolic o nā bacteria sessile ma luna o ka ʻili o ka specimen a me ke ʻano o nā huahana corrosion. E like me ka mea i hōʻike ʻia ma ke Kiʻi 5 a me ka Papa 5, ua emi ka helu o nā cell a me ka mānoanoa o ka biofilm ma hope o 14 mau lā. Hiki ke wehewehe pono ʻia kēia ma hope o 14 mau lā, ua make ka hapa nui o nā cell sessile ma luna o ka ʻili o 2707 HDSS ma muli o ka emi ʻana o nā meaʻai i loko o ka medium 2216E a i ʻole ka hoʻokuʻu ʻia ʻana o nā ion metala ʻawahia mai ka matrix 2707 HDSS. He palena kēia o nā hoʻokolohua batch.
Ma kēia hana, ua hoʻolaha ka biofilm P. aeruginosa i ka hoʻopau kūloko o Cr a me Fe ma lalo o ka biofilm ma ka ʻili 2707 HDSS (Kiʻi 6). Ma ka Papa 6, ʻo ka emi ʻana o Fe a me Cr i loko o ka laʻana D i hoʻohālikelike ʻia me ka laʻana C, e hōʻike ana ua hoʻomau ʻia ʻo Fe a me Cr i hoʻoheheʻe ʻia e ka biofilm P. aeruginosa ma mua o nā lā 7 mua. Hoʻohana ʻia ka medium 2216E e hoʻohālike i nā kaiapuni kai. Loaʻa iā ia he 17700 ppm Cl-, kahi e like me ka mea i loaʻa i loko o ka wai kai kūlohelohe. ʻO ke alo o 17700 ppm Cl- ke kumu nui no ka emi ʻana o Cr i nā laʻana abiotic 7- a me 14 lā i kālailai ʻia e XPS. Ke hoʻohālikelike ʻia me nā laʻana P. aeruginosa, ʻoi aku ka liʻiliʻi o ka hoʻoheheʻe ʻana o Cr i loko o nā laʻana abiotic ma muli o ke kūpaʻa ikaika o Cl− o 2707 HDSS i nā kaiapuni abiotic. Hōʻike ka Kiʻi 9 i ke alo o Cr6+ i loko o ka ʻili passivation. Hiki ke pili i ka wehe ʻana o Cr mai nā ʻili kila e nā biofilms P. aeruginosa, e like me ka manaʻo o Chen lāua ʻo Clayton.
Ma muli o ka ulu ʻana o ka bacteria, ʻo nā waiwai pH o ka medium ma mua a ma hope o ka mahi ʻana he 7.4 a me 8.2, kēlā me kēia. No laila, ma lalo o ka biofilm P. aeruginosa, ʻaʻole paha e lilo ka palaho waikawa organik i mea kōkua i kēia hana ma muli o ka pH kiʻekiʻe i loko o ka medium nui. ʻAʻole i loli nui ka pH o ka medium hoʻomalu ʻole biological (mai ka 7.4 mua a i ka 7.5 hope loa) i ka wā hoʻāʻo 14 lā. ʻO ka piʻi ʻana o ka pH i loko o ka medium inoculation ma hope o ka incubation ma muli o ka hana metabolic o P. aeruginosa a ua ʻike ʻia he hopena like ma ka pH i ka loaʻa ʻole o nā ʻāpana hoʻāʻo.
E like me ka mea i hōʻike ʻia ma ke Kiʻi 7, ʻo ka hohonu o ka lua i hoʻokumu ʻia e ka biofilm P. aeruginosa he 0.69 μm, ʻoi aku ka nui ma mua o ka medium abiotic (0.02 μm). He kūlike kēia me ka ʻikepili electrochemical i wehewehe ʻia ma luna. ʻOi aku ka hohonu o ka lua 0.69 μm ma mua o ka ʻumi manawa ma mua o ka waiwai 9.5 μm i hōʻike ʻia no ka 2205 DSS ma lalo o nā kūlana like. Hōʻike kēia mau ʻikepili e hōʻike ana ʻo 2707 HDSS i ka pale ʻana o MIC i ʻoi aku ka maikaʻi ma mua o 2205 DSS. ʻAʻole pono kēia e lilo i mea kupanaha, no ka mea, ʻoi aku ka nui o ka chromium o 2707 HDSS, e hāʻawi ana i ka passivation lōʻihi, ma muli o ke ʻano pae kaulike me ka ʻole o nā precipitates lua ʻino, e paʻakikī ai iā P. aeruginosa ke depassivate a hoʻomaka i nā kiko eclipse.
I ka hopena, ua loaʻa ka pitting MIC ma ka ʻili o 2707 HDSS i loko o ka hupa P. aeruginosa i hoʻohālikelike ʻia me ka pitting liʻiliʻi i loko o nā media abiotic. Hōʻike kēia hana he ʻoi aku ka maikaʻi o ke kū'ē ʻana o 2707 HDSS i ka MIC ma mua o 2205 DSS, akā ʻaʻole ia i pale piha i ka MIC ma muli o ka biofilm P. aeruginosa. Kōkua kēia mau ʻike i ke koho ʻana i nā kila kila kūpono a me ke ola lawelawe i manaʻo ʻia no ke kaiapuni kai.
Ua hāʻawi ʻia ke kūpona no 2707 HDSS e ke Kula o Metallurgy o ke Kulanui ʻo Northeastern (NEU) ma Shenyang, Kina. Ua hōʻike ʻia ka haku mele o 2707 HDSS ma ka Papa 1, kahi i kālailai ʻia e ka NEU Materials Analysis and Testing Department. Ua mālama ʻia nā laʻana āpau ma 1180 °C no 1 hola. Ma mua o ka hoʻāʻo ʻana i ka pala, ua hoʻopili ʻia ka 2707 HDSS ʻano kālā me kahi ʻili i hōʻike ʻia ma luna o 1 cm2 i 2000 grit me ka pepa silicon carbide a hoʻopili hou ʻia me ka pauka hoʻokuʻu ʻia ʻo 0.05 μm Al2O3. Pale ʻia nā ʻaoʻao a me lalo e ka pena inert. Ma hope o ka maloʻo ʻana, ua holoi ʻia nā laʻana me ka wai deionized sterile a sterilized me 75% (v/v) ethanol no 0.5 h. A laila ua hoʻomaloʻo ʻia i ka ea ma lalo o ke kukui ultraviolet (UV) no 0.5 hola ma mua o ka hoʻohana ʻana.
Ua kūʻai ʻia ke ʻano Pseudomonas aeruginosa MCCC 1A00099 mai Xiamen Marine Culture Collection Center (MCCC), Kina. Ua ulu ʻia ʻo Pseudomonas aeruginosa ma ke ʻano aerobically ma 37°C i loko o nā ʻōmole 250 ml a me nā cell aniani electrochemical 500 ml me ka hoʻohana ʻana i ka wai wai Marine 2216E (Qingdao Hope Biotechnology Co., Ltd., Qingdao, Kina). Medium (g/L): 19.45 NaCl, 5.98 MgCl2, 3.24 Na2SO4, 1.8 CaCl2, 0.55 KCl, 0.16 Na2CO3, 0.08 KBr, 0.034 SrCl2, 0.08 SrBr2, 0.022 H3BO3, 0.004 NaSiO3, 0016 NH3, 0016 NH3, 0016 NaH2PO4, 5.0 peptone, 1.0 hū hū a me 0.1 ferric citrate. Autoclave ma 121°C no 20 mau minuke ma mua o ka hoʻopili ʻana. E helu i nā pūnaewele sessile a me nā planktonic me ka hoʻohana ʻana i kahi hemocytometer ma lalo o kahi microscope māmā ma ka hoʻonui ʻana o 400X. ʻO ka nui o nā pūnaewele mua o ka planktonic Pseudomonas aeruginosa ma hope koke iho o ka hoʻopili ʻana ma kahi o 106 mau pūnaewele/ml.
Ua hana ʻia nā hoʻāʻo electrochemical i loko o kahi cell aniani ʻekolu-electrode maʻamau me ka nui waena o 500 ml. Ua hoʻopili ʻia kahi pepa platinum a me kahi electrode calomel saturated (SCE) i ka reactor ma o nā capillaries Luggin i piha i nā alahaka paʻakai, e lawelawe ana ma ke ʻano he counter a me nā electrodes kuhikuhi. No ka hana ʻana i nā electrodes hana, ua hoʻopili ʻia kahi uea keleawe i uhi ʻia i ka laholio i kēlā me kēia specimen a uhi ʻia me ka epoxy, e waiho ana ma kahi o 1 cm2 o ka ʻāpana ʻaoʻao hoʻokahi i hōʻike ʻia no ka electrode hana. I ka wā o nā ana electrochemical, ua kau ʻia nā laʻana i loko o ka medium 2216E a mālama ʻia i kahi mahana incubation mau (37 °C) i loko o kahi ʻauʻau wai. Ua ana ʻia ʻo OCP, LPR, EIS a me nā ʻikepili polarization dynamic hiki ke hoʻohana i kahi Autolab potentiostat (Reference 600TM, Gamry Instruments, Inc., USA). Ua hoʻopaʻa ʻia nā hoʻāʻo LPR ma kahi scan rate o 0.125 mV s-1 ma luna o ka laulā o -5 a me 5 mV me Eocp a me kahi alapine laʻana o 1 Hz. Ua hana ʻia ʻo EIS me kahi nalu sine i ka laulā alapine. 0.01 a i 10,000 Hz me ka hoʻohana ʻana i kahi uila i hoʻopili ʻia he 5 mV ma ke kūlana paʻa Eocp. Ma mua o ka hoʻopili ʻana o ka hiki, aia nā electrodes ma ke ʻano kaapuni ākea a hiki i ka hiki ʻana i kahi waiwai hiki ke hoʻoheheʻe ʻia me ka ʻole o ka palaho. A laila ua holo ʻia nā kiʻikuhi polarization mai -0.2 a i 1.5 V vs. Eocp ma ka helu scan o 0.166 mV/s. Ua hana hou ʻia kēlā me kēia hoʻāʻo i 3 mau manawa me a me ka ʻole o P. aeruginosa.
Ua hoʻopili ʻia nā laʻana no ka loiloi metallographic me ka pepa SiC pulu 2000 grit a laila hoʻopili hou ʻia me ka pauka hoʻokuʻu ʻia ʻana o 0.05 μm Al2O3 no ka nānā ʻana i ka ʻike maka. Ua hana ʻia ka loiloi metallographic me ka hoʻohana ʻana i kahi microscope optical. Ua kālai ʻia nā laʻana me ka 10 wt.% potassium hydroxide solution 43.
Ma hope o ka hoʻoulu ʻana, ua holoi ʻia nā laʻana i 3 mau manawa me ka hopena saline phosphate-buffered (PBS) (pH 7.4 ± 0.2) a laila hoʻopaʻa ʻia me 2.5% (v/v) glutaraldehyde no 10 mau hola e hoʻopaʻa i nā biofilms. Ma hope mai ua hoʻomaloʻo ʻia me kahi moʻo graded (50%, 60%, 70%, 80%, 90%, 95% a me 100% v/v) o ka ethanol ma mua o ka maloʻo ʻana o ka ea. ʻO ka hope loa, ua pīpī ʻia ka ʻili o ka laʻana me kahi kiʻiʻoniʻoni gula e hāʻawi i ka conductivity no ka nānā ʻana o SEM. Ua kālele ʻia nā kiʻi SEM ma nā wahi me nā pūnaewele P. aeruginosa sessile loa ma ka ʻili o kēlā me kēia specimen. Hana i ka loiloi EDS e ʻike i nā mea kemika. Ua hoʻohana ʻia kahi Zeiss Confocal Laser Scanning Microscope (CLSM) (LSM 710, Zeiss, Kelemānia) e ana i ka hohonu o ka lua. I mea e nānā ai i nā lua corrosion ma lalo o ka biofilm, ua hoʻomaʻemaʻe mua ʻia ka ʻāpana hoʻāʻo e like me ke Kina National Standard. (CNS) GB/T4334.4-2000 e wehe i nā huahana pala a me ka biofilm ma luna o ka ʻili o ka ʻāpana hoʻāʻo.
Ua hana ʻia ka loiloi X-ray photoelectron spectroscopy (XPS, ESCALAB250 surface analysis system, Thermo VG, USA) me ka hoʻohana ʻana i kahi kumu X-ray monochromatic (laina alumini Kα ma ka ikehu 1500 eV a me ka mana 150 W) ma luna o kahi laulā ikehu nakinaki ākea 0 ma lalo o nā kūlana maʻamau -1350 eV. Ua hoʻopaʻa ʻia nā spectra hoʻonā kiʻekiʻe me ka hoʻohana ʻana i ka ikehu pass 50 eV a me ka nui o ka ʻanuʻu 0.2 eV.
Ua wehe ʻia nā ʻano i hoʻomoʻa ʻia a holoi mālie ʻia me PBS (pH 7.4 ± 0.2) no 15 s45. No ka nānā ʻana i ke ola bacteria o nā biofilms ma nā laʻana, ua hoʻoluʻu ʻia nā biofilms me ka hoʻohana ʻana i ka LIVE/DEAD BacLight Bacterial Viability Kit (Invitrogen, Eugene, OR, USA). Loaʻa i ka kit ʻelua mau dyes fluorescent, kahi dye fluorescent ʻōmaʻomaʻo SYTO-9 a me kahi dye fluorescent propidium iodide (PI) ʻulaʻula. Ma lalo o CLSM, nā kiko me ka ʻōmaʻomaʻo fluorescent a me ka ʻulaʻula e hōʻike ana i nā cell ola a me nā cell make. No ka hoʻoluʻu ʻana, ua hoʻoulu ʻia kahi hui 1 ml e loaʻa ana he 3 μl SYTO-9 a me 3 μl PI solution no 20 mau minuke ma ka mahana o ka lumi (23 oC) i ka pouli. Ma hope iho, ua nānā ʻia nā laʻana i hoʻoluʻu ʻia ma ʻelua mau nalu (488 nm no nā cell ola a me 559 nm no nā cell make) me ka hoʻohana ʻana i ka mīkini Nikon CLSM (C2 Plus, Nikon, Iapana). Ua ana ʻia ka mānoanoa o Biofilm ma ke ʻano scan 3-D.
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