TY - JOUR

T1 - Investigation of the Hardness Development of Molybdenum Coatings under Thermal and Tribological Loading

AU - Behrens, Bernd-Arno

AU - Stockburger, Eugen

AU - Wester, Hendrik

AU - Poll, Gerhard

AU - Pape, Florian

AU - Konopka, Dennis

AU - Heimes, Norman

N1 - Funding Information: The results presented in this paper were obtained within the scope of the priority program “Fluidless Lubrication Systems with high Mechanical Load” (SPP 2074) in project 2, funded by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG))—407673224. The authors gratefully acknowledge the German Research Foundation for their financial support of this project.

PY - 2023/6/30

Y1 - 2023/6/30

N2 - The increasing global demand for innovative and environmentally friendly lubricants can be met through the use of solid lubricants. By switching from conventional lubricants such as various oils or grease to solid lubricants, new scopes of application can also be opened up. The main requirements for solid lubricants are a reduction in the coefficient of friction (CoF) and an increase in wear resistance. Due to the favourable material properties, molybdenum (Mo) coatings fulfil the tribological requirements and are therefore promising solid lubricants which can be applied via physical vapour deposition (PVD). In this work, the impact of substrate temperature on the hot hardness of deposited Mo coatings was determined. The specimen with the highest hot hardness was then tribologically examined both at the micro and nano level. Through an analysis of the wear tracks by means of nanoindentation and scanning electron microscopy (SEM), it was possible to detect the influence of the tribological load separately from that of the thermal loads. The results showed that the tribological load influenced the Mo coating by significantly increasing its hardness. This was achieved due to the work hardening of the Mo layer leading to an increase in the wear resistance of the coating.

AB - The increasing global demand for innovative and environmentally friendly lubricants can be met through the use of solid lubricants. By switching from conventional lubricants such as various oils or grease to solid lubricants, new scopes of application can also be opened up. The main requirements for solid lubricants are a reduction in the coefficient of friction (CoF) and an increase in wear resistance. Due to the favourable material properties, molybdenum (Mo) coatings fulfil the tribological requirements and are therefore promising solid lubricants which can be applied via physical vapour deposition (PVD). In this work, the impact of substrate temperature on the hot hardness of deposited Mo coatings was determined. The specimen with the highest hot hardness was then tribologically examined both at the micro and nano level. Through an analysis of the wear tracks by means of nanoindentation and scanning electron microscopy (SEM), it was possible to detect the influence of the tribological load separately from that of the thermal loads. The results showed that the tribological load influenced the Mo coating by significantly increasing its hardness. This was achieved due to the work hardening of the Mo layer leading to an increase in the wear resistance of the coating.

KW - hot hardness

KW - micro-tribology

KW - Mo coatings

KW - nano-tribology

KW - PVD

KW - SEM

KW - solid lubricants

KW - SPM

KW - work hardening

UR - http://www.scopus.com/inward/record.url?scp=85166286459&partnerID=8YFLogxK

U2 - 10.3390/lubricants11070283

DO - 10.3390/lubricants11070283

M3 - Article

VL - 11

JO - Lubricants

JF - Lubricants

SN - 2075-4442

IS - 7

M1 - 283

ER -