A comprehensive investigation of copper tube joints made by resistance soldering

Cilj je ovoga rada bio procijeniti tehnološku lemljivost bakrenih cijevi električnim otporom. Lemljenje električnim otporom je alternativa klasičnom zagrijavanju plamenom. Vrijeme taljenja eksperimentalnih lemila određeno je DSC analizom. Ustanovljene su najčešće greške zalemljenih spojeva i otkriveni faktori koji su ih uzrokovali. Primijećene su faze Cu3Sn i Cu6Sn5 na rubovima analiziranih spojeva. Prosječna debljina IMC (intermetalnih spojeva) na uzorcima izrađenim čvrstim lemljenjem bila je 1,4 μm veća nego u slučaju lemljenja plamenom. Na kvalitetu spojeva dobivenih lemljenjem električnim otporom utječu faktori prijenosa topline između ugljičnih elektroda i zalemljenih cijevi.The aim of the study was to assess the technological solderability of copper tubes by electric resistance. Soldering by electric resistance is an alternative to classical flame heating. The melting interval of experimental solders was determined by the use of DSC analysis. The most frequently occurring defects in soldered joints were identified and the factors affecting these defects were revealed. The Cu3Sn and Cu6Sn5 phases were observed on the boundary of analysed joints. The average thickness of IMC (intermetallic compounds) on specimens fabricated by resistance soldering was 1,4 μm greater than in the case of flame soldering. The quality of soldered joints fabricated by electric resistance is affected by the factors of heat transfer between the carbon electrodes and soldered tubes