34 KB1211 KB30 KB200020242011Kosec, TadejaKuhar, ViljemLegat, AndražŠvara Fabjan, Erikaletnik:45številka:6str. 585-591ISSN:1580-2949COBISSID:1844583URN:URN:NBN:SI:doc-PDSSMQWOenInštitut za kovinske materiale in tehnologijeMateriali in tehnologijebronkisli dežkorozijametalografijasimulacijeCorrosion stability of different bronzes in simulsted urban rain| Korozijska stabilnost različnih bronov v umetnem kislem dežju|Copper and high copper alloys tend to passivate in humid air. In clean humid air, cuprite slowly transforms to black tenorite. If atmosphere contains aggressive species, acid rain might effect the formation of different corrosion products. The patina that forms upon exposure to urban acid rain also depends of the composition of the base alloy. In the present study three different alloys were investigated: leaded bronze, usually used for sculptures, unleaded bronze as an alloy without an impact on the environment, and new type of bronze alloy, silicon bronze. The electrochemical measurementswere performed to investigate the different bronze properties in simulated urban acid rain that contained carbonates, sulphates and nitrates, acidified to pH 5. Morphological characteristics of the three different bronzes were studied and SEM/EDX analysis of the corrosion products was performed. It was found that silicon bronze has higher corrosion resistivity than unleaded bronze, the former having higher corrosion resistivity than leaded bronze. In addition, time dependant electrochemical impedance spectroscopy measurements showed that polarization resistances for silicon bronze and unleaded increased with time, whereas it decreased for leaded bronze. The corrosion layer on silicon bronze is more compact and thinner due to homogeneous microstructureBaker ter bakrove zlitine se na vlažnem zraku pasivirajo, prihaja do nastanka t. i. patin. Najprej se tvori rdečkast kuprit, ki se nato počasi spreminja v črn tenorit. Če pa so v atmosferi agresivne zvrsti, lahko nastali kisli dež vpliva na tvorbo različnih korozijskih produktov. Patina, ki se tvori zaradi izpostavitve kislemu dežju, je odvisna tudi od sestave zlitine. V študiji smo preiskovali tri različne vrste bronastih zlitin: bron z vsebnostjo svinca, pogosto uporabljen pri ulivanju večjih bronastih spomenikov, bron brez vsebnosti svinca ter novo vrsto brona s silicijem. Elektrokemijske preiskave smo izvedli v simulirani raztopini kislega dežja, ki je vsebovala sulfate, karbonate in nitrate. Določili smo mikrostrukturne značilnosti posameznih bronov ter morfologijo korozijskih produktov. Ugotovili smo, da je najbolj korozijsko odporna zlitina bakra s silicijem, sledi recentna zlitina brez svinca, najslabše korozijske lastnosti pa ima zlitina s svincem. Nadalje smo zelektrokemijsko impedančno spektroskopijo pokazali, da se korozijske lastnosti zlitine s svincem s časom slabšajo, korozijske lastnosti zlitine brez svinca ter bron s silicijem pa se s časom izboljšujejo. Korozijski produkti na silicijevi zlitini so kompaktni predvsem zaradi homogene mikrostruktureTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije