“…AISI 52100 steel is a common material tested by researchers [35,37,42,43,45,46,50,58,61,78,79,80] when experimentally assessing the friction and wear performance of refrigerants, as it a common metal used in compressors. EN1A steel has shown good adhesion properties as a substrate for depositing Nano Ni–Al 2 O 3 coatings using pulse current [74,75,76,77,81] and is also cheaper and easily available, in contrast to other specialized metals.…”