skip to main content

SciTech ConnectSciTech Connect

Title: Impact of high energy ball milling on the nanostructure of magnetite–graphite and magnetite–graphite–molybdenum disulphide blends

Different, partly complementary and partly redundant characterization methods were applied to study the transition of magnetite, graphite and MoS{sub 2} powders to mechanically alloyed nanostructures. The applied methods were: Transmission electron microscopy (TEM), Mössbauer spectroscopy (MS), Raman spectroscopy (RS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The main objective was to prepare a model material providing the essential features of a typical tribofilm forming during automotive braking, and to assess the impact of different constituents on sliding behaviour and friction level. Irrespective of the initial grain size, the raw materials were transferred to a nanocrystalline structure and mixed on a nanoscopic scale during high energy ball milling. Whereas magnetite remained almost unchanged, graphite and molybdenum disulphide were transformed to a nanocrystalline and highly disordered structure. The observed increase of the coefficient of friction was attributed to a loss of lubricity of the latter ingredient due to this transformation and subsequent oxidation. - Highlights: • Characterization of microstructural changes induced by high energy ball milling • Assessment of the potential of different characterization methods • Impact of mechanical alloying on tribological performance revealed by tests • Preparation of an artificial third body resembling the one formed during braking.
Authors:
 [1] ; ; ;  [1] ;  [2] ;  [3] ; ; ;  [4]
  1. BAM Federal Institute for Materials Research and Testing, 12200 Berlin (Germany)
  2. Instituto de Geociências, UFRGS, P.O. Box 15001, 91501-970 Porto Alegre (Brazil)
  3. Instituto de Física, UFRGS, P.O. Box 15051, 91501-970 Porto Alegre (Brazil)
  4. Zoz Group, 57482 Wenden (Germany)
Publication Date:
OSTI Identifier:
22288686
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 86; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALLOYS; CRYSTALS; FRICTION; GRAIN SIZE; GRAPHITE; MAGNETITE; MILLING; MOLYBDENUM SULFIDES; NANOSTRUCTURES; POWDERS; RAMAN SPECTROSCOPY; RAW MATERIALS; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION; X-RAY PHOTOELECTRON SPECTROSCOPY