Boride layer growth kinetics during boriding of molybdenum by the Spark Plasma Sintering (SPS) technology.
Yu, L. G.
Khor, Khiam Aik
Date of Issue2006
School of Mechanical and Aerospace Engineering
Molybdenum borides have potential industrial applications as abrasive, corrosion-resistant and electrode materials due to their high hardness values, chemical inertness, and electronic conductivity. In this work, boride layers are formed on the surface of Mo samples using a pack boriding method with the assistant of the spark plasma sintering (SPS) technique. The process was performed in the temperature range 1000–1400 °C and with a holding time of 30 min at the preset temperature. The microstructure, microhardness, and fracture toughness of the molybdenum boride layer are investigated by optical microscopy, X-ray diffraction and microhardness indentations. Results showed that the boride layer, mainly composed of MoB, have thickness in the range ∼ 6–155 μm. The boriding kinetics is studied by linking the boride layer thickness with the boriding temperature. The activation energy and pre-exponential constant are estimated from the experimental results, and are found to be 218.8 J/mol and 1.41 cm2/s respectively. The MoB layers have a preferred orientation in the (002) direction, which is reflected by a distinct columnar growth observed in the optical micrographs of polished cross-sections of SPS samples.
Surface and coatings technology
© 2006 Elsevier. This is the author created version of a work that has been peer reviewed and accepted for publication by Surface and Coatings Technology, Elsevier. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at DOI: [http://dx.doi.org/10.1016/j.surfcoat.2006.05.042]