Surface modification of M2 steel by combination of cathodic cage plasma deposition and magnetron sputtered MoS2-TiN multilayer coatings

• Published in: Surface & coatings technology Vol. 384; p. 125327
• Main Authors: Libório, M.S., Praxedes, G.B., Lima, L.L.F., Nascimento, I.G., Sousa, R.R.M., Naeem, M., Costa, T.H., Alves, S.M., Iqbal, Javed
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 25-02-2020; Elsevier BV
• Subjects: Adhesion; Cages; Cathodic coating (process); Coefficient of friction; Diffusion coating; Friction; Friction reduction; Frictional wear; Hard surfacing; High speed tool steels; HSS M2 steel; Indentation and hardness; Ion nitriding; Iron nitride; Lubrication; Machining; Magnetron sputtering; Martensite; Molybdenum disulfide; Molybdenum disulfide coating; Multilayers; Plasma; Plasma deposition; Pretreatment; Sliding friction; Solid lubrication; Substrates; Surface hardness; Titanium; Titanium nitride; Titanium nitride coating; Solid lubrication; HSS M2 steel; Titanium nitride coating; Molybdenum disulfide coating; Indentation and hardness
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2019.125327

Titanium nitride (TiN) is a good choice for the improvement in surface hardness of high-speed steel. Unfortunately, it has low adhesion with substrate and exhibits high friction coefficient; as a result it does not provide sufficient protection against sliding wear in metal-to-metal contact. The adhesion problem can be removed by nitriding process, whereas friction coefficient can be reduced by solid lubrication coating. In this study, an attempt is made to synthesize TiN hard coating as well as solid lubrication coating of molybdenum disulfide (MoS2) using magnetron sputtering, along with substrate pre-treatment by cathodic cage plasma deposition using titanium cathodic cage. The cathodic cage plasma nitrided sample exhibits significantly higher surface hardness, which reduced by solid lubrication coating. The nitrided sample depicts the presence of iron nitrides, TiN and nitrogen diffused martensite phases, whereas coated samples shows the presence of MoS2 and TiN phases. The friction coefficient and machining temperature are dramatically reduced by lubrication coating. This study recommends that the use of cathodic cage plasma nitriding using titanium cathodic cage is beneficial for improved surface hardness, and addition of solid lubrication coating is beneficial for reducing the coefficient of friction and machining temperature by scarifying hardness. As, both the systems are already proven to be appropriate for industrial-scale uses, thus results from this study can be applied for industrial-scale application.
•Combination of cathodic cage plasma deposition and magnetron sputtering is used for M2 tool steel.•The CCPD significantly improves the surface hardness of M2 tool steel.•The wear resistance is improved by using monolayer of MoS2 − TiN coatings.•The lubrication coating beneath the TiN coating reduces the machining temperature.