Influence of the Range of Particle Sizes of the Powder Component of Saturating Medium on the Carbooxidation of Titanium
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INFLUENCE OF THE RANGE OF PARTICLE SIZES OF THE POWDER COMPONENT OF SATURATING MEDIUM ON THE CARBOOXIDATION OF TITANIUM ALLOYS I. M. Pohrelyuk,1,2 V. M. Fedirko,1 and R. V. Proskurnyak1
UDC 669.295: 621.785: 620.193: 621.78
We present the results of carbooxidation of VT1-0 and OT4 titanium alloys performed with the use of a powder carbon component of saturating medium with solid fractions whose sizes vary within the range 45–300 µm (saturation from soot, graphite, and charcoal). The results of metallographic, durometric, and profilometric investigations and the X-ray phase diffraction analysis reveal certain differences between the characteristics of the newly formed modified layers. The data of corrosion and electrochemical tests carried out in an 80% solution of sulfuric acid demonstrate that the efficiency of the carbooxidation increases as the sizes of solid fractions of the powder carbon component of the saturating medium decrease. Keywords: titanium alloys, thermochemical treatment, carbooxidation, carbon powder, range of particle sizes, corrosion.
Introduction According to their structure and properties, ternary titanium compounds with interstitial elements (carboxides and carbonitrides) are derivatives of binary titanium oxides, carbides, and nitrides. As a specific feature of these compounds, we can mention the fact that not all their characteristic features are inherited from binary compounds [1, 2]. Thus, in particular, these compounds are characterized by a higher hardness, as well as higher wear, corrosion, heat, and radiation resistances. Moreover, they also have better electric and magnetic properties, which is explained by the nonlinear changes in the parameters of their electronic structure and the type of chemical bonds that depends on the composition [3–7]. The amount of carbon required for the formation of the carboxide phase in the surface layer of titanium alloys in the course of thermodiffusion multicomponent saturation is supplied by the powder carbon component of the saturating medium [8, 9]. The aim of the present work is to estimate the efficiency of the procedure of carbooxidation of titanium alloys performed with the use of powder carbon components of saturating media with various ranges of grain sizes. Method We studied the specimens of VT1-0 (commercially pure titanium; α -alloy) and OT4 (Ti–4.2Al–1.4Mn; pseudo- α -alloy) titanium alloys. 1 2
Karpenko Physicomechanical Institute, Ukrainian National Academy of Sciences, Lviv, Ukraine. Corresponding author; e-mail: [email protected].
Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 55, No. 2, pp. 64–70, March–April, 2019. Original article submitted January 15, 2019. 1068-820X/19/5502–0205
© 2019
Springer Science+Business Media, LLC
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Fig. 1. Schematic diagram of the installation used for chemical and thermal treatment: (1) heating-and-cooling chamber, (2) sample,
(3) carbon-containing powder component, (4) heater, (5) grating for the uniform distr
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