Joining of Cf/SiC composite with AuNi(Cu)-Cr brazing fillers and interfacial reactions
Carbon fiber reinforced SiC (Cf/SiC) ceramic matrix composites (CMS), which exhibit an excellent resistance to wear and oxidation at high temperatures, have been considered as a desirable high temperature structural material in aeronautical turbines and advanced rocket propulsion thrust chambers.In many applications,the joining of Cf/SiC to itself or to metals is necessary to fabricate complex structural components and the joints must retain their properties at high temperatures.In the present paper, six AuNi(Cu)-Cr brazing fillers were designed for joining of Cf/SiC composite.The alloys were fabricated into brazing foils with a thickness of 0.1 mm by the rapidly-solidifying technique.The alloys” wettability on the Cf/SiC composite was studied with the sessile drop method.After heating at 1120℃ for 20 min the contact angle of AuNi(Cu)-Cr brazing fillers reduced with the increase of the content of active element Cr.The microstructures of the Cf/SiC joints were examined with SEM, XEDS and EPMA.It was found that element Cr participated in the interfacial reactions and a thin Cr3C2 diffusion layer was formed between the composite and the brazing fillers.Element Ni strongly diffused into the Cf/SiC matrix and reacted with SiC and Ni2Si compound was formed.The average three-point bend strengths of the Cf/SiC joints using Au-Ni20-Cr10 (wt, %) and Au70-Ni10-Cu10-Cr10 (wt, %) are 154.5 Mpa and 171.6 Mpa,respectively at room temperature.However, there is a remarkable difference for the bend strength of the two joints at 600℃, that is, the former is 75.2 Mpa, while the later decreased to 28.6 Mpa.Element Cu in AuNi-Cr system alloys can increase the room temperature strength of Cf/SiC joints, but it weakened the joint strength at elevated temperature.When the test temperature reached 700℃, the bend strengths of the two joints decreased to 17.7 Mpa and 9.8 Mpa, respectively.
Ceramic matrix composites (CMC) Wettability Joining Interfaces Reaction
Bo Chen Hua-ping Xiong Xin Wu Yao-yong Cheng Wei Mao
Lab. of Welding and Forging, Beijing Institute of Aeronautical Materials, Beijing 100095, China
国内会议
西安
英文
181-187
2016-10-10（万方平台首次上网日期，不代表论文的发表时间）