Nonreactive Spreading at High-Temperature Revisited for Metal Systems via Molecular Dynamics

Abstract

The spreading for Cu and Ag droplets on top of a rigid solid surface modeling Mo is herewith considered via molecular dynamics. The dynamics of the base radius and the contact angle are recorded and fitted using the molecular-kinetic theory. A method is described to determine for liquid metals at the microscopic level the parameters appearing in this theory. These microscopic parameters are calculated directly in the simulations and compared to the fitted values. The agreement between the fitted values and the calculated ones shows that the dissipation of energy within the drop is caused primarily by the friction of liquid atoms over the substrate. This validation supports the understanding of the mechanisms controlling the spreading of liquid metals which, up to now, were based on experimental data and fitting procedures.

Molecular dynamics simulations on dissolutive wetting of Al–Ni alloy droplets on NiAl substrate

“…Two different methods were developed by Webb et al [28] and Benhassine et al [22] to determine the time-dependent radius R ( t ) and dynamic contact angle θ ( t ) of a spreading droplet. We conducted both methods with the obtained R ( t ) and θ ( t ) data being presented for the present wetting systems.…”

“…Webb et al [21] pointed out that high-temperature wetting kinetics is very sensitive to droplet and substrate compositions, atmosphere cleanliness and crystallinity of the substrate surface. Welldefined surface is hard to achieve in experimental studies [22,23] . Distinct spreading kinetics was observed by the same wetting system with varying oxygen partial pressure, temperature, alloying technique, surface preparation, and others [24,25] .…”

“…Contemporary MD wetting studies mainly focused on spreading of pure metallic droplets on pure metallic substrates, such as Ag(l) on Cu(s) [26][27][28][29] , Al(l) on Cu(s) [30] , Pb(l) on Cu(s) [29,[31][32][33] , In(l) on Cu(s) [30] , Zn(l) on Cu(s) [30] , Sn(l) on Cu(s) [34] , Ag(l) on Ni(s) [22,[35][36][37] , Cu(l) on Ni(s) [22] , Au(l) on Ni(s) [37] , and Pb(l) on Ni(s) [38] . The solid substrates in these studies were often assumed as single crystal with orientation (100), (110), or (111).…”

“…Some wetting systems were found to be non-reactive [22,26,[30][31][32][33]35,37,38] , while the others, reactive [27][28][29][30]34,36] . For the non-reactive system, Benhassine et al [22] based on MD simulations on substrate-dropletgas contact line presented that the spreading kinetics of Ag(l) or Cu(l) on Ni(s) agree well with molecular-kinetics models. For the reactive systems, Webb et al [29] showed that dissolution reaction is responsible for accelerated wetting for Ag(l) on Cu(s); however, surface alloying reaction would lead to recessed wetting for Pb(l) on Cu(s).…”

A review of wetting versus adsorption, complexions, and related phenomena: the rosetta stone of wetting

“…Both approaches were developed for non-reactive spreading, and the last 10 years have seen numerous experiments designed to probe which approach best describes high temperature spreading of liquid metals (for a review of the subject see [117]). From meticulous experiments [115,118] and molecular dynamics simulations [119][120][121], it appears that the rate limiting mechanism for non-reactive and dissolutive spreading kinetics is friction at the triple junction, where order in the liquid at the solidliquid interface plays a key role in defining this parameter. Order in the liquid at solid-liquid interfaces has been theoretically analyzed [122][123][124][125][126][127][128][129] and experimentally observed [130][131][132][133][134][135], and will be discussed below in terms of adsorption.…”