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Non-wetting to Wetting Transition Temperatures of Liquid Tin on Surfaces of Different Steel Samples Corresponding to their Spontaneous Deoxidation

Varanasi D., Aldawoudi K. E, Baumli P., Koncz-Horvath D., Kaptay G.

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 2

469--476

EN

The goal of this paper is to measure the non-wetting to wetting transition temperatures of liquid tin on surfaces of different steel samples in vacuum with residual pressure of 10-8 bar. The experiments were conducted on four steels (C45, S103, CK60 and EN1.4034) of varying compositions using pure tin (99.99%) by the sessile drop method. Non-wetting to wetting transition (contact angle decreasing below 90°) by liquid tin was observed as function of increasing temperature in the range of 820-940 K for low alloyed steels C45, S103 and CK60, while it was considerably higher (around 1130 K) for high chromium EN1.4034 steel. it is concluded that at about the same temperatures, the surfaces of the steel samples are spontaneously deoxidized due to the combined effect of high temperature, low vacuum and C-content of steels. After the oxide layer is removed, the contact angles of liquid tin on steel surfaces were found in the range of 45-80° for low alloyed C45, S103 and CK60 steels and around 20° for high chromium EN1.4034 steel. These relatively high contact angle values compared to other metal/metal couples (such as liquid Cu on steels) are due to the formation of not fully metallic intermetallic compounds (FeSn and FeSn2) at the interface (such do not form in the Cu/Fe system).

2

Increasing the Surface Hardness of Cast Iron by Electrodeposition of Borides in Molten Salts

Al-Azzawi A. H., Sytchev J., Baumli P.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 2B

1015--1018

EN

In this paper the electrodeposition of boron on the surface of cast iron as a coating is applied to increase the hardness and protect the substrate against abrasive wear. The boron containing coating was synthesized by electrodeposition process from a NaCl-KCl (1:1 mol)-10 w%NaF-10w% KBF4 molten salt. The effect of electrolysis parameters (temperature and time) on the hardness is presented; the current density varied in the range –37 – –4.5 mA/cm2, allowing perfect coverage of and respect for dimensions. The electrochemical process was carried out at different temperatures (750°C-900°C) and for different periods of time (5-10 hours). Depending on the current density and duration of electrolysis, the deposits consist of FeB or Fe2B. Microhardness measurements across the boride layer indicated very high hardness values (between 1600 and 2100 HV0.05).The structure of the boride layer is linked to its boron content and thermal history: as-deposited coatings present very small grain sizes and can be considered as nearly amorphous.

3

Effect of Wetting Agent and Carbide Volume Fraction on the Wear Response of Aluminum Matrix Composites Reinforced by WC Nanoparticles and Aluminide Particles

Lekatou A., Gkikas N., Karantzalis A. E., Kaptay G., Gacsi Z., Baumli P., Simon A.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 2B

1235--1242

EN

Aluminum matrix composites were prepared by adding submicron sized WC particles into a melt of Al 1050 under mechanical stirring, with the scope to determine: (a) the most appropriate salt flux amongst KBF4 , K2 TiF6 , K3 AlF6 and Na3 AlF6 for optimum particle wetting and distribution and (b) the maximum carbide volume fraction (CVF) for optimum response to sliding wear. The nature of the wetting agent notably affected particle incorporation, with K2 TiF6 providing the greatest particle insertion. A uniform aluminide (in-situ) and WC (ex-situ) particle distribution was attained. Two different sliding wear mechanisms were identified for low CVFs (≤1.5%), and high CVFs (2.0%), depending on the extent of particle agglomeration.

4

Microstructure And Mechanical Properties Of Al-WC Composites

Simon A., Lipusz D., Baumli P., Balint P., Kaptay G., Gergely G., Sfikas S., Lekatou A., Karantzalis A., Gacsi Z.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2B

1517--1521

EN

The scope of the research work is the production and characterization of Al matrix composites reinforced with WC ceramic nanoparticles. The synthesis process was powder metallurgy. The produced composites were examined as far as their microstructure and mechanical properties (resistance to wear, micro/macrohardness). Intermetallic phases (Al12W and Al2Cu) were identified in the microstrucutre. Al4C3 was not detected in the composites. Adding more than 5 wt% WC to the aluminum, microhardness and wear resistance exceed the values of Al alloy. Composites having weak interface bond performed the highest wear rate.