Design and preparation of high-content Sc2W3O12 dispersed interlayer: alleviating the high residual stress of Cf/SiC and GH3536 joint

Abstract

Negative thermal expansion (NTE) materials were utilized to alleviate the high residual stress of brazed joints by regulating the coefficient of thermal expansion (CTE) of metal composite filler. However, the confined addition amount of NTE materials restricted their ability to control the CTE of metal composite filler. In this study, the physical properties of the brazing seam were investigated by finite element analysis to understand their influence on the stress distribution of brazed joint. Based on theoretical analysis, a new method of preparation a high-content Sc2W3O12 dispersed interlayer by cold-pressing sintering method was proposed. This method increased the optimal addition amount of Sc2W3O12 materials from 10 vol.% to 40 vol.%. When the content of Sc2W3O12 materials was 40 vol.%, the CTE of Sc2W3O12 dispersed interlayer decreased from 16.5 (the CTE of AgCuTi) to 10.9 × 10−6 K−1, achieving a gradient transition of CTE from the Cf/SiC composite material/brazing seam/GH3536. The maximum shear strength of the Cf/SiC-GH3536 joint using Sc2W3O12 dispersed interlayer is 141 MPa, which was 5.9 times higher than that of AgCuTi filler. This study highlights the potential of proposed method for preparing brazed interlayer with high-content reinforcements, which may find practical applications in other metal composites.

Keywords

• Negative thermal expansion
• Composite filler
• Residual stress
• Shear strength
• Brazing