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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

Calculation of Contact Pressures in Cylindrical Metal-Polymer Sliding Guides

Chernets Myron, Pashechko Mykhaylo, Kornienko Anatolii, Ishchenko Anatoly

Advances in Science and Technology. Research Journal

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2021

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Vol. 15, no 3

30--33

EN

Guides (linear plain bearings) of reciprocating motion are widely used in many areas of human activity. However, at present there are no reasonable methods for their calculation, in particular metal-polymer guides. The author's method of contact strength calculation of cylindrical metal-polymer sliding guides is presented in the article. The effect of load, bushing diameter and radial clearance on the maximum contact pressures and their distribution in the guide was studied on the example of epoxy-based polymer composite material Moglice of the German company DIAMANT Metallplastic GmbH, which is used to restore tribotechnical sliding systems elements. Quantitative and qualitative regularities of dependence of contact pressures on the accepted factors of influence are established: at loading increase four times the maximum contact pressures and contact angles will increase twice irrespective of change of sizes of a radial clearance and diameter of a base; increasing the base diameter leads to a directly proportional decrease in maximum contact pressures; doubling the radial clearance leads to a -fold increase in pressure, regardless of changes in the magnitude of the load and the diameter of the base. Regularities of change of contact parameters from the specified factors are given graphically.

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Effect of oxidation on the wetting of coal surfaces by water: experimental and molecular dynamics simulation studies

Li E., Lu Y., Cheng F., Wang X., Miller J. D.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 4

1039--1051

EN

The wettability of coal surfaces by water continues to be one of the key factors which determines the success of coal flotation. Consequently, oxidation of coal surfaces is a fundamental issue of interest. In this work, the effect of oxidation on the wetting of coal surfaces and the interaction between water molecules and oxygen-containing sites at the coal surface was investigated based on advancing/receding contact angle measurements and molecular dynamics simulations. For the simulation studies, a flat coal surface was constructed with the assistance of the molecular repulsion between graphite surfaces and the assembly of Wiser coal molecules. Our results indicated that the simulated advancing and receding contact angles were very similar, and both of them decreased, as expected, with an increase of hydroxyl sites at the coal surface. The good agreement between the simulated advancing/receding contact angles and the experimental receding contact angle values suggested that the configuration of the systems and the set of parameters for the simulation were appropriate. The spreading of water is mainly due to the hydrogen bonds formed between the interfacial water molecules and the hydroxyl sites at the coal surface. The hydroxyl groups show stronger hydration capacity than other oxygen-containing groups according to the calculated hydrogen bonds and interaction energies.

4

Udoskonalenie techniki obserwacji zwilżenia mączlika szklarniowego : (Trialeurodes vaporariorum Westwood)

Ratajkiewicz H., Wrocławski J.

Aparatura Badawcza i Dydaktyczna

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2015

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T. 20, nr 3

174-187

PL

Hydrofobowe właściwości powierzchni owadów zapewniają ochronę ich organizmów przed zwilżeniem przez wodę. Dzięki tym właściwościom szkodniki roślin uprawnych mogą zmniejszać zwilżenie przez krople rozpylonej cieczy. Celem pracy było udoskonalenie techniki obserwacji zwilżenia mączlika szklarniowego (Trialeurodes vaporariorum Westwood) po naniesieniu kropli poprzez opryskiwanie. Badania potwierdziły przydatność wykonanego stolika pochylanego z wbudowanym zwierciadłem płaskim w ocenie zwilżenia T. vaporariorum. Obecność obfitych wosków kutykularnych oraz mikrostruktura grzbietowej części puparium i larw mogą wyjaśniać przyczyny ich hydrofobowości. Wraz z obniżeniem napięcia powierzchniowego cieczy zwiększało się zwilżenie owada. Wyznaczenie kątów przylegania cieczy po spontanicznym osadzeniu kropli na puparium T. vaporariorum nie przyniosło jednak zadowalających rezultatów z uwagi na kształt powierzchni grzbietowej.

EN

The hydrophobic properties of insects surface protect their organisms from wetting by water. Thanks to these properties pest may reduce wetting by spray droplets. The aim of this work was to improve observation techniques of wetting the greenhouse whitefly (Trialeurodes vaporariorum Westwood) after the application of spray droplets. The study confirmed the usefulness of the tilting stage with built-in flat mirror in evaluation of wetting properties of T. vaporariorum. The presence of abundant epicuticular waxes and dorsal microstructure may explain the hydrophobicity of pupae and larvae. As the surface tension of the liquid decreased the wetting of the insect increased. Determination of the contact angles after spontaneous deposition of droplets on pupa of T. vaporariorum has not produced satisfactory results due to the shape of the dorsal surface.

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Zwilżalność w układzie ciekły stop-stały tlenek metalu

Siwiec G., Botor J.

Rudy i Metale Nieżelazne

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2004

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R. 49, nr 4

172-177

PL

Przedstawiono podstawowe informacje dotyczące zwilżalności w układzie: ciało stałe-ciecz, najważniejsze teorie zwilżalności oraz wyniki badań zwilżalności stałych tlenków metali ciekłymi metalami i stopami. W części eksperymentalnej, na wzorcowym podłożu ceramicznym z tlenku glinu, wykonano pomiary kątów zwilżania miedzią oraz stopami miedzi z antymonem, ołowiem i siarką.

EN

Fundamentals of the wettability in the solid-liquid system as well as the main theories on wettability, and the results of studies on wettability of solid metal oxides by liquid metals and alloys have been presented. In the experimental part of this work, measurements of the contact angles between Al2O3 ceramic standard substrate and copper as well as Cu-Sb, Cu-Pb and Cu-S alloys were made.

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Wyznaczanie swobodnej energii powierzchniowej napełniaczy bezpostaciowych

Rogowska R.

Problemy Eksploatacji

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2002

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nr 4

141-150

PL

W artykule przedstawiono metodę wyznaczania kąta zwilżania w zastosowaniu do dwóch materiałów bezpostaciowych - proszku brązu i proszku dwusiarczku molibdenu. Kąty zwilżania zmierzono na tensjometrze K12 produkcji KRUSS GmbH. Zastosowano dwa naczynka pomiarowe: szklane i aluminiowe. Korzystając z uzyskanych wyników obliczono swobodną energię powierzchniową metodą Owensa-Wendta-Rabela-kaelble'a. Do obliczen swobodnej energii powierzchniowej wykorzystano program K-121 KRUSS GmbH. Badane materiały zastosowano jako napełniacze kompozytów dwu- - czteroskładnikowych, w których materiałem bazowym był PTFE [1].

EN

The paper's authoress presents a method of determining contact angles of two amorphous materials - bronze powder and milybdenum disulfide powder. Contact angles were measured at the tensiometr K12 produced by KRUSS GmbH. Two measurement vessels: glass and aluminium ones were used. With the use of the obtained results the free surface energy was calculated by means of the Owens-Wedt-Rabel-Kaelble method. The K-121 KRUSS GmbH programme was applied for the surface free energy calculations. Investigated materials were used as fillers of two- and four-component composites, in which PTFE is a base material [1].