Controlled Atmosphere Brazing of 3003 Aluminum Alloy Using Low-Melting-Point Filler Metal Fabricated by Melt-Spinning Technology

Abstract

3003 aluminum alloy was widely used for the manufacturing of heat exchangers in the automotive industry by employing controlled atmosphere brazing (CAB) with NOCOLOK flux brazing technology. However, commercially available filler metals for NOCOLOK flux brazing technology are usually required to be carried out at a relatively high temperature, causing the assembled heat exchanger to be partially molten or easily deformed. A new low-melting-point brazing filler metal Al-5.0Si-20.5Cu-2.0Ni was prepared by using melt-spinning technology and then applied to CAB of 3003 aluminum alloy in this research. The solidus and liquidus of brazing filler metal was 513.21 °C and 532.48 °C. All elements were evenly distributed and free from elemental segregation. The microstructure of brazing filler metal was uniform, and the grain size was less than 500 nm. As the brazing temperature reached 575 °C, the void in the joint disappeared completely. The morphology of CuAl2 was sensitive to the brazing temperature and dwell time. The appearance of net-like CuAl2 brazed at 575 °C for 20 min was more beneficial to improve joint mechanical properties. The leakage rate of the joint was qualified to be 10−10 Pa·m3/s when the brazing temperature was 570 °C or higher. The maximum shear strength of 76.1 MPa can be obtained when the joint was brazed at 575 °C for 20 min. More dwell time induced growth of the interfacial layer and reduced joint shear strength. The open circuit potential and corrosion current density test indicated that the brazing filler metal Al-5.0Si-20.5Cu-2.0Ni had better corrosion resistance than that of 3003 aluminum alloy.

Quality, Microstructure, and Properties of Metal Alloys

“…The work presented in this Special Issue [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] demonstrates the possibilities of further improving the microstructure quality and mechanical properties of metal alloys.…”

“…A new low-melting-point brazing filler metal Al-5.0Si-20.5Cu-2.0Ni was prepared by using melt-spinning technology, then applied to CAB of 3003 aluminum alloy in [17]. The microstructure of brazing filler metal was uniform, and the grain size was less than 500 nm.…”

Investigation on the Corrosion Resistance of 3003 Aluminum Alloy in Acidic Salt Spray under Different Processing States

“…Mn can also form an Al 6 Mn phase with Al, and impurity Fe can dissolve in Al 6 Mn to form Al 6 (MnFe) compounds [6,7]. 3003 aluminum alloy is one of the most common aluminum manganese alloys, which is widely used in building construction, food packaging, automotive parts, and air conditioning radiators due to its good formability, corrosion resistance, and welding performance [8][9][10].…”

Measurement Methods for Flux Residue Quantity after Controlled Atmosphere Brazing of Aluminum Coolers

“…The aim of these studies is to minimize flux residue while ensuring the integrity of the air cooler. The CAB process is the most commonly used brazing technology in the automotive industry, especially for complex geometry connections (Gao et al, 2022). It enables continuous production with relatively low costs.…”

“…In the automotive industry, NOCOLOK flux is the most commonly used flux (Gao et al, 2022). It is a non-hygroscopic, white powder, with a defined particle size distribution, based on the eutectic mixture of potassium fluoroaluminate KAlF 4 -K 3 AlF 6 .…”