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SiC粉末配比对CMC/高温合金钎焊接头界面组织和力学性能的影响

Effect of SiC powder ratio on interfacial microstructure and mechanical property of CMC /superalloy brazing joint

  • 摘要: 为了降低SiCf/SiC复合材料(CMC)与高温合金钎焊接头残余应力,并更进一步提升接头力学性能,采用不同配比SiC陶瓷粉末与NiCoCrWMoTiHf钎料进行混合,获得了一系列中间层,形成了热膨胀系数呈梯度过渡的钎焊接头. 接头组织分析表明,当钎料中加入不同比例的SiC粉末时,钎焊接头组成区域物相成分未发生明显变化,随着加入的陶瓷粉末增多,钎料凝固区中析出金属间化合物增多,且主要分布在钎料区两侧. 当加入的SiC陶瓷为20%(质量分数)时,钎料凝固区宽度达到最大值,且钎料凝固区与反应层区域形成冶金结合层,有利于接头力学性能的提升. 对含20%SiC陶瓷钎焊接头的剪切试验表明,其室温抗剪强度达175 MPa,1 100 ℃平均抗剪强度达到了120 MPa,证实了适当配比SiC粉末对钎焊接头力学性能提升的有效性.

     

    Abstract: To reduce the residual stress of SiCf/SiC composite material (CMC) and superalloy brazing joints, and further improve the mechanical properties of the joints, different ratios of SiC powder and NiCoCrWMoTiHf fillers were mixed to obtain a series of intermediate layers, forming brazing joints with a gradient coefficient of thermal expansion. The analysis of interfacial microstructure of joints shows that when different proportions of SiC powder are added to the filler, there is no significant change in the phase composition of the brazing seam. As the amount of ceramic powder added increases, the precipitation of intermetallic compounds in the solidification zone of the filler increases, and they are mainly distributed on both sides of the filler area. When the mass percentage of SiC ceramics added is 20%, the width of the solidification zone of the filler reaches its maximum value, and a metallurgical bonding layer is formed between the solidification zone of the filler and the reaction layer area, which is beneficial for improving the mechanical properties of the joint. The shear test of 20%SiC ceramic brazing joints shows that the room temperature shear strength reaches 175 MPa, and the average shear strength reaches 120 MPa at 1 100 ℃, confirming the effectiveness of appropriate SiC powder ratio in improving the mechanical properties of brazing joints.

     

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