Improved mechanical strength of the C/C-Mo joint by introducing polydopamine modified Ni foam to the interlayer

Abstract

For the dissimilar C/C-Mo joints, the high residual thermal stress in the joint generally leads to the low shear strength of the joint, especially when the joints are employed under the quick alternating temperature change conditions. To address this issue, three-dimensional polydopamine modified Ni foam was introduced to the C/C-Mo joints. The modification of Ni foam would avoid its complete dissolution and retain its framework after braze welding via a facile polydopamine carbonization strategy. As polydopamine modified Ni foam was introduced to the interlayer, the joint strength increased by 63%, up to 63.77 MPa. The introduction of the modified Ni foam is beneficial to improve the plastic deformation ability of the main phases in the joint, leading to the decrease of the brittleness of the braze seam. Furthermore, the residual Ni frameworks are facilitated to take full advantage of the good plastic deformation capability and energy absorption ability of the foam structure, resulting in the improved joint strength at room temperature and a high strength retention of 92.07% after 10 thermal cycles between room temperature and 1100 °C.