Fluxinsluitsels

Fluxinsluitsels is a term found in some Dutch-language discussions of metalworking fluxes to denote small inclusions embedded within a flux paste or slurry used for soldering, brazing, or welding. These inclusions are particulate matter that remains in the flux after preparation or forms during flux–metal interactions. The concept highlights how inhomogeneities within flux can influence flow, cleaning action, and oxide removal. Etymology: The word combines flux with insluitsels (inclusions) in Dutch, signaling particulate constituents that are not part of the ideal homogeneous flux.

Formation and composition: Inclusions may originate from impurities in the flux base, from corrosion products of container materials, or from reaction products formed with the metal oxide layer. They can be oxides, chlorides, fluorides, or sulfides, depending on the flux chemistry and processing temperature. Size typically ranges from sub-micron to tens of microns.

Impact and handling: Fluxinsluitsels can alter viscosity and surface tension, affecting wetting and flow. They may improve or impair cleaning action depending on their chemistry and distribution. Excess or large inclusions often lead to residues or incomplete oxide removal and are usually minimized in industrial flux formulations.

Detection: Characterization relies on microscopy, scanning electron microscopy with energy-dispersive spectroscopy, or sedimentation analysis to assess portioning and composition.

See also: Flux, Inclusions, Soldering, Welding, Brazing.