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Synthesis and Characterization of Molybdenum Disulfide Composite Coating on Steel Using Chemical Vapor Deposition

Akbarzadeh M., Zandrahimi M., Moradpour E.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 2

555--562

EN

Molybdenum disulfide (MoS2 ) is one of the most widely used solid lubricants applied in different ways on the surfaces under friction. In this work, AISI 316 austenitic stainless steel was coated with MoS2 , using chemical vapor deposition (CVD) at four different temperatures (400, 500, 600 and 700°C). Coatings properties were investigated using SEM, EDX, XRD and FTIR, Hardness Tester and Roughness tester. The results showed that with simultaneous evaporation of sulfur and molybdenum trioxide (MoO3 ) in the CVD chamber, a uniform coating layer containing MoS2 and MoO2 phases was formed. Increase in the substrate temperature resulted in the rise in the amount of MoS2 to MoO2 phases. The thickness, grain size and the hardness of the coating were 17-29 μm, 50-120 nm and 260-480 HV respectively. Friction tests carried out using pin-on-plate method under normal loads of 10 N under ambient conditions showed values of the friction coefficient 0.25-0.40.

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Molybdenum Disulfide (MoS2) Coating on AISI 316 Stainless Steel by Thermodiffusion Method

Akbarzadeh M., Zandrahimi M., Moradpour E.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 3

1741--1748

EN

Molybdenum disulfide (MoS2) is one of the most widely used solid lubricants applied in different ways on the surfaces under friction. In this work, AISI 316 austenitic stainless steel was coated with MoS2, using thermo-diffusion method at different temperatures and times. Coatings properties were investigated using SEM, EDX, XRD and FTIR, Hardness Tester and Roughness tester. The results illustrated the formation of a uniform layer on the surface, containing MoS2 and MoO3–X phases. The thickness, grain size and the hardness of the coatings were 20-50 μm, 400-1000 nm and 350- 550 HV respectively. Friction tests carried out using ball-on-disc method under normal loads of 10 N under ambient conditions showed values of the friction coefficient 0.30-0.40. In addition, the kinetics of diffusion layers between the substrate and the coating were also investigated. It was found that there at steady temperature there is a parabolic relationship between the thickness of the diffusion layer and the treatment time. The activation energy for the process was estimated to be 143 kJ mol-1. Depending on the treatment time and temperature, the thicknesses of diffusion layer varied between 0.5 and 2.5 microns.

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Increase of reliability and tribological characteristics of gyroscopes

Kovalev E., Ignatiev M., Wisniewska-Weinert H., Leshchynsky V.

International Journal of Applied Mechanics and Engineering

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2006

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Vol. 11, no 3

501-506

EN

Now gyroscopic devices are applied in many industrial areas. Alongside with traditional mechanical gyroscopes, the increasing weight is got by systems of mechanical group realizing more perfect principles of their construction, such as gyroscopes with non-contact levitating rotor. However, complication of gyroscopic devices entails a number of problems which are not solved till now. One of the most critical problems is reliability of a rotor and stator at an emergency situation. This situation is characterized by "landing" of a rotor on stator. It leads to destruction of elements of stator because of high tangential loading (friction coefficient of ferrite is more than 0.25). Special coatings for ferrite materials have been developed to decrease friction coefficient (to 0.07) and to provide stator and rotor reliability even under emergency situation: amorphous (Al-Si)N magnetron coating and coating based on MoS2 nanoparticles with polymer binder. Tests of the developed coating was realised in vacuum [...] at loading 1-5 MPa and sliding velocity of 0.2-1.0m/s. The test results show that problem of durability of gyroscopes with non-contact levitating a rotor can be successfully solved with the help of new coatings.