Research On Vacuum Brazing Process Of SiCp/6063Al Composites Used In T/R Module

In this paper, high volume(55%-75%) and low volume(15%-20%) SiCp/6063 Al composites used in the T/R module of Phased Array Radar were selected as the material for investigation. Combined with practical application of T/R module, two kinds of solders were produced and examined: brazing filler metal and soldering filler metal. The study consists the brazing technology between high and high volume, high and low volume composites which the high volume composites have nickel plating and the soldering technology between low and high volume after nickel plating, low and low volume composites after nickel plating. The study also investigated brazability of the fillers, structure property of the welding bead, and fracture morphology and air tightness of the joint. Investigation results are as follows:1. The study successfully smelted AlCuSi matrix brazing filler metal Al-24Cu-5Si-2Zn-1Ti and soldering filler metal In-48 Sn both of which are suitable for SiCp/6063 Al composites.2. Although high volume SiCp/6063 Al composites can be directly brazed with Al-24Cu-5Si-2Zn-1Ti, many pores occur in the weld seriously affecting the air tightness. The optimal welding parameter for high and low volume composites after nickel plating with Al-24Cu-5Si-2Zn-1Ti filler is 20 min under 570°C. The shear strength of brazing joint was 141 MPa. The joint had a brittle fracture and the fracture occurred in the bonding area of solder and composite material. The air tightness of the joint was 10-8Pa·m3/s. While the optimal brazing parameter for joining high volume composite after nickel plating to low volume composite with Al-24Cu-5Si-2Zn-1Ti filler is 20 min under 575°C. The shear strength of brazing joint is 98.14 MPa. The joint had a mixed fracture and the fracture occurred in low volume composite. The air tightness of joint is 10-9Pa·m3/s.3. In the case of In-48 Sn, composites were nickel plated before the soldering, whether soldering is done between low volume and high volume composites or between low volume and low volume composites. The soldering time is 20 min under 190°C for both cases. The shear strength of solder joint is 24 MPa and the fracture mainly occurred in the solder. The air tightness of joint is 10-9Pa·m3/s. Composition of the phases from the welding bead to the base material is In+Sn,In+Ni+Sn, Ni, SiCp/6063 Al.4. Brazing composites after chemical nickel plating cannot be considered the same process as brazing Ni to Ni. In process of brazing composites, Ni acts like a bridge improving wetting, spreading of the solder and participating in the diffusion reaction. However, in the lower temperature process of soldering, Ni does not participate in the diffusion reaction and therefore soldering composites can be considered as soldering of Ni.