A two-fluid nozzle for atomizing a liquid with a gas in which at least two conduits, a central and annular conduit, converge in an internal mixing zone for the liquid and gas, in which the nozzle has a central discharge orifice having a shoulder at its upstream end, and a two-piece, thermally resistant metal alloy heat shield for the central discharge orifice which the heat shield includes a retaining ring and an outwardly flaring liner for the outlet connected so that the retaining ring bears against the central outlet shoulder and is held in place by the flared construction at its downstream end, preferably the liner has heat conductive flexible packing disposed between its outside surface and the discharge orifice. The central discharge orifice may open into a protective cap which is cylindrical at one end and rounds out to an elliptical end surface.