**Experimental Analysis of Tribological Processes in Friction Pairs with Laser Borided Elements Lubricated with Engine Oils**

**Janusz Lubas 1,\* , Wojciech Szczypi ´nski-Sala <sup>2</sup> , Paweł Wo´s <sup>1</sup> , Edyta Zieli ´nska <sup>1</sup> and Krzysztof Miernik <sup>3</sup>**


Received: 17 October 2020; Accepted: 16 December 2020; Published: 19 December 2020

**Abstract:** The present study discusses the influence of engine oils on the tribological parameters of sliding couples with laser borided surface layer. The borided layer was formed on specimens made from AISI 5045 steel by laser remelting of a surface layer coated with amorphous boron. The sliding friction and wear process was carried out on the pairs with AISI 5045 steel and SAE-48 bearing alloys which were lubricated with 5W-40 and 15W-40 engine oils. The investigation showed significant differences in the friction coefficient and temperature in the tested pairs with the laser borided surface layer. In the couples lubricated with 5W-40 engine oil, the tested parameter of friction was higher than in the couples lubricated with 15W-40 engine oil. The couples lubricated with 5W-40 engine oil showed more intensive wear of SAE-48 bearing alloy in contact with the laser borided surface layer than the pairs lubricated with 15W-40 engine oil. The laser borided surface layer used in friction pairs leads to the destruction of the lubricating properties of engine oils and reduces its resistance to scuffing.

**Keywords:** laser boriding; engine oil; wear; friction; surface layer
