Transition metal coatings on graphite via laser processing

Abstract

Graphite is a high temperature structural material due to its low specific gravity and high strength along with exceptional chemical and physicomechanical properties. However, graphite and other carbon materials suffer high temperature oxidation and are easily eroded by particle and gas streams. One of the ways to improve these properties is by making adherent protective coatings on carbon materials. The adherence of the coatings depends on their wettability and the difference in the values of their coefficient of thermal expansion with that of the carbon material. The transition metals have outstanding ability to combine strongly with carbon due to their partly-filled d-orbitals and ability to form strong covalent bonds. Hence, transition metals can be used to make coatings on graphite. In this paper we have deposited titanium, zirconium, and niobium coatings on graphite using a fiber laser. The coatings have been characterized using scanning electron microscope (SEM), Knoop’s hardness, X-ray diffraction, and secondary ion mass spectrometer (SIMS). A one-dimensional finite element heat transfer model of titanium coating on graphite was prepared and experimentally validated.Graphite is a high temperature structural material due to its low specific gravity and high strength along with exceptional chemical and physicomechanical properties. However, graphite and other carbon materials suffer high temperature oxidation and are easily eroded by particle and gas streams. One of the ways to improve these properties is by making adherent protective coatings on carbon materials. The adherence of the coatings depends on their wettability and the difference in the values of their coefficient of thermal expansion with that of the carbon material. The transition metals have outstanding ability to combine strongly with carbon due to their partly-filled d-orbitals and ability to form strong covalent bonds. Hence, transition metals can be used to make coatings on graphite. In this paper we have deposited titanium, zirconium, and niobium coatings on graphite using a fiber laser. The coatings have been characterized using scanning electron microscope (SEM), Knoop’s hardness, X-ray diffraction...