Wyniki wyszukiwania - BazTech

1

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

|

2021

|

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

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

|

2017

|

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.

3

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

|

2015

|

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.

4

Dynamic simulation of the movement of ceramic particles in front of growing solidification front

Borsik A., Kelemen K. K., Kaptay G.

Archiwum Technologii Maszyn i Automatyzacji

|

2001

|

Vol. 21, Nr spec

19-25

EN

The computer aided simulation of the movement of a ceramic particle in a liquid metal has been performed, while a planar solidification front is approaching the particle. Two forces (the interfacial pushing force and the drag force) acting on the particle were taken into account. It has been found that the particle gradually accelerates and reaches the steady state, i.e. moves in front of the solidification front with the same velocity, at a certain equilibrium distance. During the acceleration period the particle never approaches the interface closer than this equilibrium distance. Consequently, the "dynamic" approach introduced recently by Stefanescu et al. [7] to define the critical distance of engulfment has been proven inadequate. Therefore the critical distance of engulfment should be found from a different criterion.

PL

W artykule przedstawiono komputerową symulację ruchu ceramicznych cząstek w ciekłym metalu podczas zbliżania się do nich płaskiego frontu krzepnięcia. Wzięto pod uwagę dwie siły (siłę odpychania powierzchni rozdziału i siłę przyciągania) działające na cząstkę. Ustalono, że cząstka stopniowo przyspiesza do osiągnięcia stanu ustalonego, w którym porusza się przed frontem krzepnięcia ze stałą prędkością w określonej odległości równowagowej. W czasie przyspieszenia cząstka nigdy nie zbliża się do powierzchni rozdziału bliżej, niż wynosi jej odległość równowagowa. W efekcie udowodniono, że "dynamiczne" zbliżenie przedstawione przez Stefanescu i współautorów [7] jest niedostateczne do zdefiniowania krytycznej odległości pochłaniania. Wobec tego krytyczna odległość pochłaniania powinna być określona na podstawie innego kryterium.