K. Zangeneh Madar and S. M. Monir Vaghefi,
Volume 23, Issue 2 (1-2005)
Abstract
In the present stady, thermochemical treatment in H2/NH3 atmosphere was used as a post-treatment for electroless Ni-P coatings on the AISI 4140 steel substrates. High phosphorus (9%) coatings with thicknesses of 2, 24 and 48 m were applied and the effects of the thermochemical treatment on the morphology, structural changes, roughness, hardness
and wear resistance of coatings were studied by SEM, EDS, XRD, profilometry, and microhardness tester. Wear test was used to evaluate wear characteristics of coatings. The wear behaviour of the thermochemical treated/Ni-P coated samples was assessed by comparison with thermochemical treated/uncoated (nitrided) samples. The results showed that effect of thermochemical treatment varies with the coating thickness. In addition, it was shown that a multicomponent coating containing phosphide, nitride and intermetallic phases as well as diffusion region can be developed in the thin (2 m) electroless Ni-P coated steel by thermochemical treatment. This sample showed better wear resistance than 24 m Ni-P coated steel under higher load. This behavior was ascribedto nitride phases formed at the surface as well as a nitrogen diffusion zone at the subsurface of thin Ni-P coated steel
M. Akbarzadeh, M. Zandrahimi, E. Moradpour,
Volume 37, Issue 4 (3-2019)
Abstract
Molybdenum disulfide (MoS2) is one of the most widely used solid lubricants. In this study, MoS2-Cr composite coatings were deposited onto AISI 1045 steel substrates by direct-current magnetron sputtering. The MoS2/Cr ratio in the coatings was controlled by sputtering the composite targets. The coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and nano-indentation and nano-scratch techniques. The tribological behavior of the coatings was investigated using the pin-on-disc test at room temperature. The results showed that the thickness and the hardness of the coating were 6 µmand 850-1300 HV, respectively. The degree of the crystallization of the composite coatings was enhanced with increasing the Cr contents. The incorporation of Cr into MoSx coatings resulted in the considerable improvement of coating adhesion and hardness. The optimum doping level for MoS2-Cr coatings to show the best tribological propertie was 13 atomic percent. The main wear mechanisms of the coating were delamination, tribochemical and abrasive micro cracking
