International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Solders are fusible metal alloys, used in industry to create permanent bond between metal surfaces. In order to achieve this, solders need to be heated above their melting point and used in liquid phase. Low melting temperature is essential from technological point of view, as well as for soldered components safety. Typical solders have Lead (Pb) аs а base component, having melting temperature of 600.6 K. Adding up to 60% of Tin (Sn) to the alloy, reduces melting temperature down to 456-461 K in average. Since 2006, RoHS regulation enforce industrial use of Lead-Free solders, typically having much higher melting temperature. However, Pb:Sn solders with up to 40% Sn still have their industrial applications, usually used for soldering Cu and Zn coated pipes while the 60% Sn containing solders are used for soldering of
electrical cables.
The achieving of these goals requires knowledge of liquid phase surface tension. Because of the difficulties, related to such measurement, the available data in literature are limited. The current report presents an equipment for measurement of the surface tension, based on the Wilhelmy plate method as well as the applied measurement procedure. The Wilhelmy method has relatively good stability. The contact angle also can be considered zero for the examined samples therefore correction coefficients are not required for the measurement. The results from measurement of Pb:Sn in ratio 40:60 and also in ratio 60:40 show that the oxidation in excess of Pb lowers the surface tension while for the case with excess of Sn, the oxidation lead to increase of the surface tension if compare with the surface tension obtained for the same solders but under non-oxidizing conditions. This could be attributed to formation in excess of PbO and SnO on the liquid surface of the corresponding solder

We present non-trivial spatio-temporal patterns observed in reactive-wetting of mercury droplets spreading on thin metal (silver or gold) films on glass at room temperature. This is the only known study of reactive-wetting at room temperature. We show that there exist two main regimes, the bulk propagation regime and the interface kinetic roughening regime. In both regimes, rich spatio-temporal patterns are observed. We study and characterize these patterns using statistical physics tools, such as the growth, roughness and persistence exponents, and show the manifestation of surface tension relaxation in these statistical measures.

The results of investigations of basic physical and chemical properties for aluminosilicate melts of different compositionsis presented. It is shown that the highest values of surface tension and adhesion was observed for the basalt melts, whereas neutral aluminosilicate glass melts without iron oxides in their composition are characterized by a high value of contact angle and the lowest values of surface forces. The insertion in the melt of ZrO₂ increases significantly wetting angles, surface tension and adhesion throughout the temperature range as compared with the same melts without zirconia. Basalt melts differ by lower viscosities and significantly less sensitivity to the effects of additives on viscosity of zirconium oxide as compared to the andesite-basalt melts.

Surface activity of water solutions, surfactants, has been calculated on the base of concentration dependence of surface tension. Compounds for deactivation, based on synthetic detergents in different concentration scales have been offered.

The object of this research paper is cation surface active substances, used for disinfection. The experiments were conducted in pure original laboratory conditions at different temperature and concentration intervals. The propounded methodology and experimental results are applicable to assess the operational qualities of disinfecting substances.