Study On The Vibration Assisted Semi Solid Brazing Of Sic_p/zl101a Composites

The removal of oxide film on the joint interface of SiCp/ZL1O1A composite using vibration assisted semi-solid brazing with different processing parameters is studied at first. Then the effect of parameters on the oxide film-removal is deeply analyzed and a physical model of this process is established. Finally, the forming process of pore in the solder joint and its effect on shear strength property is discussed.It's found that in the same vibration-frequency and vibration-times condition, with the amplitude increasing, the region of the continuous broken oxide film on the interface expands step by step to the outside. When the amplitude and vibration-times keep constant, vibration-frequency has no influence on the removal of oxide film. With the same vibration-frequency and amplitude, when vibration-times increases, the oxide film in the middle of the interface will first get broken, and afterward it transfers to the outside. And it's found that the former condition is better than the latter.The physical model of the oxide film removal is established. Before vibration, the oxide film on the base metal is continuous and complete. When the vibration begins, one solid phase gathering area appears in the middle of brazing seam. As the liquid phase is extruded, plastic strain appears on the solid particles so that they gather and grow. And the oxide films are broken here. With the vibration, the solid particles gathering areas are separated, and the oxide film on the interface is completely removed. It's due to that solid phase particles play a role in shearing the base metal. At last, the oxide film completely gets broken on the interface except that on the edge, and the solid phase particles gathering areas get smaller and smaller.The formation process of pore in the joint is described as follows. When it's in the positive half-wave vibration, the solder is pulled. The liquid phase on the edge of the solder will move inside freely, while the movement of solid phase particles is relatively slower, which supply a channel for the access of air so that pore grows up between the solid phase particles on the edge.When the pulling extent of the solder gets larger, the solder is stretched to the greatest extent, and the air channel expands to inward. In the subsequent half vibrating wave, solder will be compressed that the liquid phase in solder will move from inside to outside. As vibration progresses, more air will remain inside. After repeated vibration, the air inside will gather, grow up to form pores, and stay in the joints at last.Shear strength tests are carried out on the solder joint. It's found that the shear strength of the interface is the same with that of the base metal. The value is 120 MPa. The soldering seam has a higher shear strength and the value is 140MPa. Shearing crack happens in the base metal on the side of the interface. It could be concluded that the shear strength is much related to the base metal. And it has no direct relation with pore in the joint.