Interface Design for Advanced Bearing Technologies
Entitled “solutions for bearings emerging technologies”, this project aims to design novel interfaces in order to tackle premature bearing failures i.e. micropitting and Hydrogen Embrittlement (HE). Bearings as a machine element are designed to facilitate the relative motion alongside with reducing wear and friction between two rotating elements for a long period. However, in demanding applications, the rolling contact fatigue causes premature bearing failure at a shorter time than it is expected. Almost all of the rolling bearing’s fatigue failures originate from surface and subsurface cracks inducing micropitting and spalling of the surface.
Many of studies upon investigating the failed bearing surfaces reported that traces of diffused hydrogen have been detected in the steel matrix, postulating HE to be the main cause of the surface and subsurface originated fatigue. Nucleation of HE occurs at the surface of the steel substrate, where hydrogen forms and permeates through the interaction of the surface with the lubricant. Therefore, surface damage significantly gives rise to bearing failure. Micropitting as a prevailing surface fatigue in bearings facilities HE and also is induced by HE. Therefore, supressing micropitting through interface modification is of great interest to industry and greatly demanded. This project aims to address the most effective surface treatments and designing a proper lubricant/additive interaction between the rolling contact surfaces by utilising and introducing alternative additives to the lubricant. As a result of lubricant and surface modification, other properties of the bearing may encounter compromising effects such as detrimental influence on antiwear additives decomposition and effectiveness which should be taken into account. In order to mitigate micropitting two interface modification has been put forward.
The first approach is implemented through introducing a Diamine-Based Additive (DBA) which is an organic friction modifier which can interacts with the surface as well as zinc dialkyl dithiophosphate (ZDDP), which is the most well-known anti-wear additive, at the surface and generates a tribofilm as an interface layer. The interface layer, derived from interaction of DBA and ZDDP, showed that can profoundly mitigate the micropitting while protecting the surface from adhesive and abrasive wear. The second approach, which is a surface engineering strategy, is implemented through applying three kinds of Diamond-Like-Carbon (DLC) coatings on the steel substrate. One of the coatings (W doped DLC) showed that in a certain lubricant formulation (base oil + ZDDP) can successfully supress micropitting and rolling contact fatigue. The lubricant additive are supplied by the associate partner Afton chemicals and AkzoNobel and the coatings are supplied by the other associate partner Hauzer.
Sep 2009- July 2011
Sharif University of Technology, Tehran, Iran
MSc, Biomaterials Engineering (GPA: 92.5 %)
Master Project Title: Application of Ceramics and NanoHydroxyapatite in Bone and Bone Tissue Engineering.
Sep 2005- Sep 2009
Amirkabir University of Technology, Tehran, Iran
BSc, Biomaterials Engineering (GPA: 77.8 %)
Project Title: Optimization of eye orbital properties based on Hydroxyapatite-Alumina-Bioglass composite and In-vitro test of the composite. (Grade: 100 %)
Institute Functional Surfaces (iFS),
Mechanical Engineering Department
University of Leeds
For more information contact Siavash;
Supervisors: Professor Anne Neville, Professor Ardian Morina
Monthly reports are available here