Protiobrabne lastnosti jekla 42CrMo₄, nitriranega v nepulzirajoči in pulzirajoči plazmi

B. Podgornik, J. Vižintin, V. Leskovšek

Kovine zlitine tehnologije 33 (1999) 51–54.

Abstract

Raziskali smo tribološke lastnosti jekla 42CrMo₄, nitriranega v nepulzirajoči in pulzirajoči plazmi, pri čemer je bilo kaljeno jeklo uporabljeno kot referenca. Z uporabo metalografije, elektronske in optične mikroskopije, merjenja mikrotrdote in topografije površine smo natančno karakterizirali kontaktno površino pred drsnim preizkusom in po njem. Ti preizkusi so bili narejeni na napravi, imenovani valjček-disk, pri suhem drsenju. Med njimi smo spreminjali koeficient trenja in količino obrabe v odvisnosti od obremenitve, drsne hitrosti in časa. Rezultati so pokazali, da se je obrabna odpornost jekla 42CrMo₄ z nitriranjem izboljšala, kar je postalo pri stopnjevanju preizkušanja vedno bolj izrazito. Ugotovljeno je bilo, da je treba spojinsko plast z nitrirane površine odstraniti, saj lahko ta plast zaradi svoje krhkosti in visoke trdote celo poslabša obrabno odpornost jekla.

The tribological properties of plasma and pulse plasma nitrided 42CrMo₄ steel were investigated and compared to hardened steel. Contact surfaces of the samples were characterized by metallographic, SEM microscopic, microhardness and profilometric techniques before and after wear testing. Wear tests were performed on a pin-on-disc wear testing machine in which nitrided pins were mated to hardened ball bearing steel discs under dry sliding conditions. The resulting wear loss as well as the coefficient of friction were monitored as a function of load, sliding speed and test time. Results show improvement of the tribological properties of 42CrMo₄ steel after plasma and pulse plasma nitriding. Improvement becomes more evident when the testing conditions become more severe. It was also found that the compound layer should be removed from the nitrided surface to avoid impairment of the tribological properties by its fracture followed by the formation of hard abrasive particles.

Keywords: nitriranje v plazmi, drsenje, obraba, plasma nitriding, dry sliding, wear

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