CORROSION OF BIOCOMPATIBLE METALS AND ALLOYS IN ARTIFICIAL SALIVA

V diplomskem delu smo raziskovali korozijo biokompatibilnih kovin in zlitin v umetni slini. Pri tem smo preučevali super nerjavno jeklo AISI 316L ter titanovo zlitino Ti90Al6V4. Korozijo smo merili z gravimetrično metodo. Vzorce smo pri konstantni temperaturi 37˚C potopljene v umetno slino pasivirali 24, 48 in 72 ur. Meritve smo ponovili tudi ob dodatku kislin, ki se zelo pogosto uporabljajo v prehrani in pijačah. Uporabili smo jabolčno kslino, vinsko kislino, mlečno kislino in ortofosforno kislino. Na podlagi pridobljenih meritev smo določili hitrost korozije. Ugotovili smo, da so bile izgube mase vzorcev zelo majhne v nekaterih primerih celo nične, kar doakzuje izredno dobro korozijsko odpornost uporabljenih materialov. Opazili smo tudi, da se korozijska hitrost materiala v danem mediju po določenem času prične zniževati, kar je posledica nastanka zaščitne oksidne plasti na površini vzorcev, le- ta jih ščiti pred nadaljno korozijo.In this diploma thesis we researched the corrosion of biocompatible metals and alloys in artificial saliva. In the research we used austenitic stainless steel AISI 316L and titanium alloy Ti90Al6V4. The corrosion rates were measured by gravimetric method. The samples were immersed in artificial saliva at a constant temperature of 37˚ C and passivated for 24, 48 and 72 hours. The measurements were also repeated with the addition of acids often used as additives in food and beverages. Malic acid, tartaric acid, lactic acid and ortho-phosphoric acid were used for the measurements. On the basis of the acquired results we were able to determine the corrosion rate. The research showed that the mass loss rates on the samples were very low, in some cases even zero. These results suggest an exceptional corrosion resistance of the materials used. Additionally, we noticed, that the corrosion rates get lower after a specific time, which is a consequence of a protective oxide layer emerging on the surface of the samples, which protects them from further corrosion