Testing of PTA automatic braze-welding technology for producing absorber joints of solar collectors

The article presents research aimed at developing a PTA braze-welding technology for producing absorber connections between tubes and copper foil with EcoBraz 38102 self-fusible brazing solder in the form of wire 1 mm in diameter. Braze-welding process was carried out by means of two techniques of braze welding of flat copper foil to a tube, while the foil had a 0 - 1.5 mm wide gap: a connection with a butt joint made by braze welding with simultaneous stamping of a semi-circular channel in the copper foil (the channel diameter equal to the tube diameter); and a connection with two braze-welded fillet joints. Metallographic tests, hardness measurement, static tensile test and thermal conduction efficiency test were performed to determine the properties of prepared connections. It was demonstrated that there exists a field of PTA braze-welding parameters which assures high quality of absorber connections between tubes and copper foil.