With further increase of the temperature (the third stage), more oxide films are broken and stripped away from the faying surface
by codominant compressive stress and shear stress.
We suppose that these compounds were released owing to erosion from the faying surface
of steel screw by dissolution of iron in tin matrix of the lead-free solder.
Weld widths were determined by predicting the temperature history at the faying surface (z = 0 m) at various y-distances from the weld center line.
It is important to note that the reported power level corresponds to the actual power at the faying surface. The points correspond to experimental data, the dashed lines correspond to weld width predictions based on peak temperature, and the solid lines correspond to the predicted weld widths based on DW, which includes the thermal history, squeeze flow, and intermolecular diffusion.
It is seen that the DW of two faying surfaces is best modeled with temperature-dependent activation energy and based on a temperature history and not a single temperature value.
All faying surfaces
must be conductive and free from nonconductive contaminants such as paints, oxides, and corrosion byproducts.
Filler metals, containing titanium or Ti coatings, were used for brazing ceramics because their properties improve the wetting of ceramics [11-13] and reduce the oxidation of faying surfaces
. Such coatings are attractive also for brazing of the cermets.
Aircraft upgrades and substitutions included more corrosion-resistant aluminum alloys in the wings and other structures, better sealants on faying surfaces
, wet installations of fasteners, and use of corrosion-resistant topcoats in critical interior areas.
When two polymer interfaces (faying surfaces) are brought together, there are asperity peaks that are brought in contact, see Fig.
Equation 2 can then be used to predict the gap height as a function of time, or more importantly, the closing of two faying surfaces as function of time.
As the faying surfaces come into intimate contact, healing of the interfaces occurs.