Surface Properties of Copper-Aluminum Alloys

The polytherms of density, surface tension of the Cu-Al system melts and wetting angles of Ni-Cr, Co-Cr substrates, 25X18H9C2 stainless steel and titanium were studied by the sessile drop method. The drop contour was processed by dint of current information technologies, in particular, using the ImageJ software package [1]. The equations of density polytherms and surface tension of the Cu-Al system melts were established. It was shown that Cu-Al melts wet the substrates at 1000 K and more. We revealed the features of temperature dependences of the wetting angles.

Surface tensiometry of phase separated protein and polymer droplets by the sessile drop method

Phase separated macromolecules play essential roles in many biological and synthetic systems. We extend sessile droplet tensiometry to work with small quantities of such ultra-low surface tension droplets.

Numerical computation of wetting angles of Sn–(3−x)Ag–0.5Cu−x(Bi,In) quaternary Pb-free solder alloy systems on Cu substrate

This paper was aimed to study of the wetting angle ([Formula: see text]) of Sn–Ag–Cu, Sn–([Formula: see text])Ag–0.5Cu–([Formula: see text])Bi and Sn–([Formula: see text])Ag–0.5Cu–([Formula: see text])In ([Formula: see text], 1 and 2 in wt.%) Pb-free solder alloy systems at various temperatures (250, 280 and 310∘C) on Cu substrate in Ar atmosphere. The new Sn–([Formula: see text])Ag–0.5Cu–xBi and Sn–([Formula: see text])Ag–0.5Cu[Formula: see text]([Formula: see text]) In systems, low Ag content quaternary Pb-free solder alloys, were produced by adding 0.5%, 1% and 2% Bi and In separately to the near-eutectic Sn-3[Formula: see text]wt.%Ag–0.5[Formula: see text]wt.%Cu (SAC305) alloy. The wetting angles of new alloys, Sn[Formula: see text]2.5[Formula: see text]wt.%Ag[Formula: see text]0.5[Formula: see text]wt.%Cu[Formula: see text]0.5[Formula: see text]wt.%Bi (SAC-0.5Bi), Sn[Formula: see text]2[Formula: see text]wt.%Ag[Formula: see text]0.5[Formula: see text]wt.%Cu[Formula: see text]1[Formula: see text]wt.%Bi(SAC-1Bi), Sn[Formula: see text]1[Formula: see text]wt.%Ag[Formula: see text]0.5[Formula: see text]wt.%Cu[Formula: see text]2[Formula: see text]wt.%Bi(SAC-2Bi), Sn[Formula: see text]2.5[Formula: see text]wt.%Ag[Formula: see text]0.5[Formula: see text]wt.%Cu[Formula: see text]0.5[Formula: see text]wt.%In (SAC-0.5In), Sn[Formula: see text]2[Formula: see text]wt.%Ag[Formula: see text]0.5[Formula: see text]wt.%Cu[Formula: see text]1[Formula: see text]wt.%In (SAC-1In) and Sn[Formula: see text]1[Formula: see text]wt.%Ag[Formula: see text]0.5[Formula: see text]wt%.Cu[Formula: see text]2[Formula: see text]wt.%In (SAC-2In) were measured by sessile drop method. Experimental results showed that additions of Bi and In separately to SAC305 resulted in a continuous decrease in the [Formula: see text] up to 1[Formula: see text]wt.% above which the [Formula: see text] value was increased and it is appeared that a correlation among the [Formula: see text], alloys compositions and the test temperatures exists which recommended an empirical model to estimate the [Formula: see text] at a given Bi and In content and temperature for a given alloy systems. The numerical model estimates the [Formula: see text] understandably well with the present work.

Study on the wettability of Pannónia poplar (P.x euramericana Pannónia) from two Hungarian plantations: Győr and Solt

In Hungary, large stocks of plantation poplar reached their cutting age. The present paper is a part-time report of the OTKA project on the wettability of Pannónia poplar samples originating from two Hungarian plantations: Győr and Solt. The main question was whether the different sites of origin have a significant influence on the properties of the boards. Samples from the two plantation sites were collected from different trunks, and laboratory samples with tangential cut were prepared by planing. Wettability was measured by sessile drop method, both with distilled water and diiodomethane, using a PGX goniometer. Surface tension was calculated according to the Fowkes method.

Interfacial Reactivity of the Filled Skutterudite Smy(FexNi1−x)4Sb12 in Contact with Liquid In-Based Alloys and Sn

The study of the wettability of thermoelectric materials, as well as the search for the most proper brazing alloys, is of the maximum importance to get one step closer to the realization of a thermoelectric device. In this work, a wettability study of the filled skutterudite Smy(FexNi1−x)4Sb12 by Sn and In-based alloys is presented. Samples, having both p- and n- characters were prepared by the conventional melting-quenching-annealing technique and subsequently densified by spark plasma sintering (SPS). Afterward, wettability tests were performed by the sessile drop method at 773 K for 20 min. Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analyses performed on the cross-section of the solidified drops suggest quite a complicated scenario due to the coexistence and the interaction of a large number of different elements in each analyzed system. Indeed, the indication of a strong reaction of In-based alloys with skutterudite, accompanied by the formation of the InSb intermetallic compound, is clear; on the contrary, Sn exhibits a milder reactivity, and thus, a more promising behavior, being its appreciable wettability, whilst coupled to a limited reactivity.

Hydrophobisation of clays and nano silica for ground engineering

Altering the hydrophobicity of particles allows their use as functional construction materials in ground engineering (e.g. in barriers). This study examines the hydrophobisation of nano to micro particles by using two clays (kaolin and halloysite) and nano silica. To induce hydrophobicity, dimethyldichlorosilane (DMDCS) was used in concentrations varying from 0.25% to 20%. The sessile drop method was used to measure the contact angle (CA) of the particles. Kaolin was initially hydrophobic with a CA of 93 5◦ while the other two materials were hydrophilic. The addition of DMDCS to the materials increased CAs of all materials investigated. The maximum CAs recorded at 20% for the halloysite, kaolin and nano silica were respectively: 116 5◦, 143 3◦ and 144 6◦. The difference in CAs attained by the clays was attributed to their different structure. Scanning electron microscope-energy dispersive spectroscopy analysis showed increases in carbon content with only halloysite and nano silica after hydrophobisation. The results demonstrate that hydrophobising clays and nano silica can effectively improve their resistance to water infiltration.