Wear Behavior of a Ni/Co Bilayer Coating by Physical Vapor Deposition on AISI 1045 Steel

E Pardo L,S E Rodil,B Campillo,J G González-Rodriguez,I Dominguez,H Martinez

doi:10.15415/jnp.2021.82027

Abstract

Coatings by physical vapor deposition (PVD) have become highly relevant due to their wide range of applications and the rapid rate of coating formation. In this work, AISI steel 1045 was coated with two layers, Ni and Co using the PVD technique. Each coating was deposited with a thickness of 1 μm. After applying the coatings, a post-treatment was applied in an AC plasma reactor using a boron nitride blank in an Ar atmosphere at a pressure of 3 Torr, 0.3 A, and 460 V at 4, 8, and 12h. The post-treatment was characterized by optical emission spectroscopy (OES) in a range of 200-1100 nm. The main species observed by OES were Ar+, N2, N2+, and B+. The coatings on 1045 steel and posttreatment were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Also, were subjected to tribological tests to analyze wear resistance, using the Pin-on-Disk technique. The coatings on steel 1045 present remarkably better wear properties than the uncoated 1045 steel, being the sample post-treated at 4h that showed a lower wear rate.

Highlights

One of the steels most commonly steels used in machine components such as gears, bolts, crankshafts, etc., is AISI 1045 steel due to its good mechanical properties [1,2,3]
In the 8 and 12 h coatings, according to the calculated wear factor, the wear was greater than in the 4 h coating, this behavior can be explained by the low adherence of the Boron Nitride (BN) layer and the white layer to the NiCo coatings, this can be observed in the micrographs C), D), E) and F), the material removed in powder adhered to the steel ball, leaving traces on the steel
Different treatment times with a BN target were applied to AISI steel 1045 coated with NiCocoated by magnetron sputtering, in order to evaluate the tribological behavior using the Pin on Disc technique under dry conditions

Summary

Introduction

One of the steels most commonly steels used in machine components such as gears, bolts, crankshafts, etc., is AISI 1045 steel due to its good mechanical properties [1,2,3]. To try to extend the useful life of steel parts, different processes have been developed for the application of coatings and the modification of engineering materials surfaces. The coatings assisted by Plasma, have shown that they can improve the tribological and chemical properties of materials [4,5,6,7,8] Being one of these processes assisted by plasma, the physical vapor deposition (PVD) by magnetron sputtering, by which multilayers of elements and/or compounds can be deposited over a matrix, increasing the wear resistance of the surface, compared against monolayers and their response [9,10,11,12]. BN compounds have good resistance against oxidation and chemical stability [17, 18]

Experimental

Thickness Measurements by 3D Optical Profiler and Mechanical Profiler

SEM and X-ray Diffraction

Wear Factor

Conclusions