| Popis: |
Sodobne tehnologije obdelave materialov se vse bolj premikajo v smeri zahtevnih pogojev odrezovanja: Ti pogoji zahtevajo, da so rezalna orodja prekrita z učinkovitimi zaščitnimi prevlekami. Taka prevleka mora prenesti visoke termomehanske obremenitve in biti obstojna proti degradaciji v zahtevnih okoljih. V ta namen se že vrsto let uporabljajo trde zaščitne prevleke na osnovi nitridov prehodnih kovin, saj nudijo visoko zaščito orodja pred velikimi obremenitvami, kot sta povišana temperatura ter tlak. Pred uporabo v proizvodnji mora vsak proces razvoja novih prevlek vključiti tudi tribološke teste pri temperaturah, ki so relevantne za dano aplikacijo. Obraba predstavlja progresivno poškodbo kontaktnih površin, ki vključuje izgubo materiala. Pojavi se na površinah, ki so izpostavljene obremenitvam in hkrati medsebojnemu relativnemu gibanju. V magistrskem delu sem za merjenje koeficienta trenja uporabil visokotemperaturni tribometer, s pomočjo katerega sem lahko preračunal obrabo prevleke TiAlN pri povišani temperaturi. Tribološka karakterizacija prevlek je sestavljena iz množice triboloških testov različnih dolžin pri različnih temperaturah. Tako sem lahko določil, kdaj v tribološkem testu pride do največje obrabe in kako se trenje ter obraba spreminjata od začetnega kontakta pa do popolne izrabe prevleke. Po vsakem opravljenem tribološkem testu sem z uporabo profilometra izmeril obrabno kaloto ter določil obrabo. Posamezne vzorce sem analiziral tudi z uporabo vrstičnega elektronskega mikroskopa ter EDS-analizo. Zanimalo me je, kakšen je vpliv temperature na tribološke lastnosti prevleke TiAlN. V prvem delu naloge so predstavljene teoretične osnove, ki jim sledi eksperimentalni del in opis ter razlaga rezultatov. Modern material processing technologies are moving towards increasingly challenging cutting conditions. These conditions require cutting tools to be covered with effective protective coatings. Such coatings must withstand high thermomechanical loads and be persistent against degradation in demanding environments. For this purpose, protective coatings based on transitional metal nitrides have been used for many years, as they offer high protection of the tool against high loads such as elevated temperature and pressure. Before being used in production, each process of developing new coatings must also include tribological tests at temperatures that are relevant for daily application of the coating. Wear represents progressive damage to the contact surface, which also involves loss of coat material. It occurs on surfaces that are exposed to stresses (forces) and, at the same time, the relative movement between them. In my master's thesis, I measured the coefficient of friction on a high temperature tribometer which was used to calculate the wear for the AlTiN coating at higher temperatures. The tribological characterization of coatings consists of a set of tribological tests of different lengths at different temperatures. This was how I was able to determine when during the tribological test maximum wear occurred and how friction and wear changed from initial contact to the failure of the coating. After each tribological test, I measured the wear route using a profilometer and determined the wear. I also analyzed individual samples using a line electron microscope and EDS-analysis. I was interested in the effect of temperature on the tribological properties of the AlTiN coating. In the first part of the assignment, the theoretical foundations are presented, followed by the experimental part, and the description and interpretation of the results. |
