Copper strip corrosion testing in hydrocracked base oil in the presence of different inhibitors/Ispitivanje korozije bakarne trake u hidrokrekovanom baznom ulju u prisustvu razlicitih inhibitora

In this paper, the corrosion test of copper in hydrocracked base oil HC-6 was performed in the presence of an additive for extremely high pressures (EP additive) in different concentrations. EP additives are used to reduce wear in industrial applications, under high load conditions. Since most of these additives are sulfur-based, whose compounds can be corrosive at high temperatures, their use leads to corrosion of some materials. To prevent corrosion in the base oil with the EP additive, three commercial corrosion inhibitors are added. By chemical composition, the inhibitor RC 8210 is a derivate of dimercaptothia-diazole, RC 4220 is a synthetic neutral calcium sulfonate, and IRGAMET 39 is a derivative of tolutriazole. Efficiency of the inhibitors was monitored by standard test methods for corro-siveness to copper arising from petroleum products by the copper strip test (ASTM D-130) and the gravimetric method, while oxidation stability of the base oil was monitored by peroxide number determination. Oxidation was performed at 100[+ or -]1[degrees]C for 3 and 24 h. Results of these studies have shown that IRGAMET 39 is the most effective inhibitor in the presence of the EP additive at both examined oxidation times. Keywords: ASTM D-130; copper coupons; lubricating oil; extreme pressure additive. Available on-line at the Journal web address: (Strucni rad) U ovom radu ispitivana je korozija bakra u hidrokrekovanom baznom ulju HC-6 u prisustvu razlicitih koncentracija aditiva za ekstremno visoke pritiske (EP aditiv). EP aditivi se koriste za smanjenje habanja u industrijskim primenama, pod uslovima velikog opterecenja. Buduci da je vecina ovih aditiva na bazi sumpora cija jedinjenja mogu biti korozivna na visokim temperaturama, njihova upotreba dovodi do korozije nekih materijala. Da bi se sprecila korozija bakra u baznom ulju sa EP aditivom dodana su tri komercijalna inhibitora korozije. Po hemijskom sastavu inhibitor RC 8210 je derivat dimerkaptotiadiazola, RC 4220 sinteticki neutralan kalcijum sulfonat, a IRGAMET 39 je derivat tolutriazola. Efikasnost inhibitora pracena je u skladu sa stndardnom ASTM D-130 metodom, gravimetrijskom metodom, a oksidaciona stabilnost baznog ulja pracena je odredivanjem vrednosti peroksidnog broja. Oksidacija je trajala 3 i 24 casa na 100[degrees]C [+ or -] 1[degrees]C. Ispitivanje je pokazalo da je IRGAMET 39 najefikasniji inhibitor u prisustvu EP aditiva u oba ispitivana vremena oksidacije. Kljucne reci: ASTM D-130; bakarni ku