Title: Effect of number of layers on the toughness of TiN/TiC multilayer coatings

Authors: M. Azadi; A.S. Rouhaghdam; S. Ahangarani; H.H. Mofidi; M. Valiei

Addresses: Faculty of Engineering, Surface Engineering Laboratory, Materials Engineering Department, Tarbiat Modares University, P.O. Box 14115-143, Tehran ' Faculty of Engineering, Surface Engineering Laboratory, Materials Engineering Department, Tarbiat Modares University, P.O. Box 14115-143, Tehran ' Advanced Materials and Renewable Energies Department, Iranian Research Organization for Science and Technology, P.O. Box 16536-45591, Tehran, Iran ' Faculty of Engineering, Surface Engineering Laboratory, Materials Engineering Department, Tarbiat Modares University, P.O. Box 14115-143, Tehran, Iran ' Material Science and Technology, Azad University, P.O. Box 14115-143, Tehran, Iran

Abstract: The structure and mechanical properties of titanium nitride/titanium carbide multilayer coatings on H13 hot work tool steel were investigated. All coatings were deposited by the pulsed-DC plasma-assisted chemical vapour deposition. Field emission scanning electron microscopy was used to study the crystalline structure of coatings. Indentation tests were carried out by atomic force microscopy and the Vickers hardness test. The objective of this paper is to determine mechanical properties such as the hardness, the elastic modulus and the toughness of different coatings. Increasing the number of layers in multilayer coatings increased the elastic modulus, the hardness and the toughness with respect to the single-layer coatings. Superior mechanical properties such as high hardness (26.7 GPa), high elastic modulus (327.6 GPa) and high toughness (17.7 MPa.m^1/2) were related to multilayer coatings with 10 layers due to the compressive residual stress.

Keywords: toughness; multilayer coatings; hardness; elastic modulus; nanoindentation; layer numbers; titanium nitride; titanium carbide; hot work tool steel; crystalline structure; compressive residual stress.

DOI: 10.1504/IJMMP.2014.067314

International Journal of Microstructure and Materials Properties, 2014 Vol.9 No.6, pp.500 - 515

Received: 20 Jan 2014
Accepted: 10 Jun 2014
Published online: 04 Feb 2015 *

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