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Uvod: Kombinacija dveh ali več dentalnih zlitin v ustni votlini, ki so v stiku s slino lahko privede do medsebojnih interakcij in nastanka korozijskih produktov. Ti produkti so kovinski ioni, ki se sproščajo v telo in lahko povzročijo morebitne zaplete pri pacientu. (Ciszewski et al., 2007) Korozija je elektrokemijski proces, kjer pride do električnega toka med kovinami skozi elektrolit. Gonilno silo korozije predstavlja razlika potencialov med temi kovinami. (Milošev, 1994) V takšnem primeru je potrebno primarni material zamenjati z drugim. Druga rešitev je pasivacija površine primarnega materiala. Ena od tehnik pasiviranja površine je galvanska pozlatitev, kjer se na material nanese zlata plast. (Faber, n .d.) Namen: Predstaviti želimo tehnološki postopek galvanizacije s ciljem pasivacije površine. Na vzorcih pozlačene kovinske baze delne proteze iz Co-Cr zlitine smo pod mikroskopom preverili mikrostrukturo Co-Cr zlitine in zlata, njuno vezavo in debelino pozlate. Metode dela: Teoretični del diplomskega dela temelji na osnovi pregledane domače in tuje literature. Literaturo smo iskali v knjižnicah in elektronskih podatkovnih bazah. Praktični del diplomskega dela obsega izdelavo delne proteze s kovinsko bazo iz Co-Cr zlitine, njeno pozlato in metalografsko analizo vzorcev pozlačene kovinske baze. Pod mikroskopom smo raziskali mikrostrukturo pozlate, morebitne napake v mikrostrukturi in njeno debelino. Želeli smo ugotoviti, ali je zlata plast zvezna in kompaktna. Preučili smo tudi mikrostrukturo mejne površine med Co-Cr zlitino in pozlato. Rezultati: Pri metalografski analizi vzorcev smo naleteli na napako v mikrostrukturi pozlate vzorca podjezičnega loka, ki izgleda kot poroznost. Na mejni površini med Co-Cr zlitino in pozlato nismo našli napak v mikrostrukturi. Pri merjenju debeline pozlate smo prišli do ugotovitev, da je pozlata na lokalnih območjih enakomerno debela, vendar se debelina po celotni konstrukciji razlikuje. Pozlata na molarski zaponi je debelejša kot na podjezičnem loku. Razprava in zaključek: Menimo, da napaka v mikrostrukturi pozlate predstavlja poškodovan del pozlate, ki je nastal pri obdelavi površine metalografskega vzorca. Če je napaka nastala pri tehnološkem postopku pozlate, ta predstavlja neprekrito površino konstrukcije iz Co-Cr zlitine, kar posledično ne bi preprečilo nadaljnjega sproščanja kovinskih ionov. Vzrok za odstopanje v debelini pozlate po konstrukciji je premikanje konstrukcije pri mešanju elektrolita med končno pozlato kovinske baze. Introduction: The combination of two or more dental alloys in the oral cavity, which are in contact with saliva, can lead to mutual interactions and the formation of corrosion products. These products are metal ions that are released into the body and can cause potential complications for the patient. (Ciszewski at al., 2007) Corrosion is an electrochemical process where an electric current occurs between metals through an electrolyte. The driving force of corrosion is the potential difference between these metals. (Milošev, 1994) In such a case, it is necessary to replace the primary material with another. Additional solution is to passivate the surface of the primary material. One of the surface passivation techniques is galvanic gilding, where a gold layer is applied to the material. (Faber, n.d.) Purpose: We would like to present the technological process of electroplating with the aim of passivating the surface. The microstructure of the Co-Cr alloy and gold, their bonding and the thickness of the gilding were checked by stereo, light and scanning electron mictoscope on the samples of the gilded metal base of the partial prosthesis made of Co-Cr alloy. Work methods: The theoretical part of the thesis is based on the reviewed domestic and foreign literature. Literature was searched in libraries and electronic databases. The practical part of the thesis includes the production of a partial prosthesis with a metal base made of Co-Cr alloy, its gilding and metallographic analysis of samples of the gilded metal base. We investigated the microstructure of the gilding, possible defects in the microstructure and its thickness by stereo, light and scanning electron mictoscope. We wanted to find out if the gold layer is continuous and compact. We also examined the microstructure of the boundary surface between the Co-Cr alloy and gold plating. Results: During the metallographic analysis of the samples, we encountered a defect in the microstructure of the gilded sublingual arch sample, which looks like porosity. No defects in the microstructure were found on the interface between the Co-Cr alloy and the gilding. When measuring the thickness of the gilding, we came to the conclusion that the gilding is uniformly thick in local areas, but the thickness varies throughout the entire structure. The gilding on the molar clasp is thicker than on the sublingual arch. Discussion and conclusion: We believe that the defect in the microstructure of the gilding represents a damaged part of the gilding that occurred during the surface treatment of the metallographic sample. If the defect occurred during the technological process of gilding, it represents an uncovered surface of the Co-Cr alloy structure, which would not prevent the further release of metal ions. The reason for the deviation in the thickness of the gilding after the construction is in the movement of the construction during the mixing of the electrolyte during the final gilding of the metal base. |
