Some rheological properties of new and used mineral lubricant and biolubricant for tractors

ArticleIt is important to know physical characteristics of lubricating oils to ensure the highest reliability for operation of device. The use of ecological lubricants depends on their characteristics; the most important are density and viscosity, protection against wear and tear, corrosion resistance etc. The objective of this work was to find changes of the rheological properties of the synthetic oil and bio lubricant. We compared two different oils in our measurements. One sample was synthetic oil and the other was mineral oil (bio lubricant). Both oils are universal oils for tractors. Further, comparison of new and used sample after million cycles was performed. The density and the dynamic viscosity show strong exponentially decreasing dependence. With the increasing temperature, values of the both properties, decreased. It can be also observed that used samples have lower viscosity and density. The results presented in this article can be important when putting ecological lubricants into operation

Alpine regional metamorphism of Föderata Group metacarbonates (southern Veporicum, Western Carpathians, Slovakia): P–T conditions of recrystallization

P-T conditions of the Alpine regional metamorphism of carbonate successions which form the cover sequence of the southern Veporicum crystalline basement have been determined. The P-T estimates were calculated on the basis of microprobe chemical analyses of equilibrium mineral assemblages together with analyses of bulk rock chemical composition. The calibrated geothermic reactions Cal-Dol and Kfs-Phl were used. Geothermometric and geobarometric data were obtained using the SOLVCALC, TWQ and PERPLEX software programs in combination with phengite geobarometry. The metacarbonates were formed from a sedimentary-carbonate protolith in low-pressure and low-temperature conditions of greenschist facies in the kyanite stability field: TCalAb-O