Journal Published Online: 25 August 2016
Volume 5, Issue 4

Properties of CrC+(Ni-W) Duplex Layers Produced in Vacuum Chromizing Process Combined With Galvanic Treatment



Diffusion chromizing was applied to increase the durability of tools, which operate under wear conditions. Vacuum chromizing, as opposed to other known methods, i.e., powder pack, gas, and molten salt baths, is ecological on account of non-toxic substrates, as well as absence of harmful wastes. Vacuum chromizing of tool steel results in hard and wear resistant chromium carbide coatings. However, the obtained carbide layers exhibited rather poor corrosion resistance in chloride media. To improve their corrosion resistance, Ni-W alloy was deposited electrolytically on the steel surface before the chromizing process. This resulted in the formation of CrC+(Ni-W) type duplex layers with modified characteristics. The objective of this paper was to determine the structure of these duplex layers on tool steel surface, their tribological properties and corrosion resistance in chloride solutions. Investigations of layers’ thickness, their morphology, phase composition, hardness, and depth profiles of elements in the layer diffusion zone have been carried out. The chemical composition and distribution of the phases formed in the surface region of the samples were examined by a SEM microscope, equipped with a BSE detector and an EDS spectrometer. Wear resistance tests were carried out by the three-cylinder-cone method. Electrochemical corrosion measurements of obtained layers were performed in a 0.5 M NaCl solution. The tests proved that the wear resistance of duplex layers of the CrC+(Ni-W) type, produced by vacuum chromizing of electrolytically coated steel, is as good as that of carbide layers of the CrC type, produced on bare steel surface, but their corrosion resistance is higher.

Author Information

Kasprzycka, E.
Faculty of Civil Engineering, Mechanics and Petrochemistry, Warsaw Univ. of Technology, Warszawa, PL
Bogdanski, B.
Inst. of Precision Mechanics, Warsaw, PL
Pages: 14
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Stock #: MPC20150074
ISSN: 2165-3992
DOI: 10.1520/MPC20150074