空气反应钎焊ZrO2与GH3536接头组织与力学性能

Interfacial Microstructure and Properties of ZrO2 Ceramic and GH3536 Alloy Reactive Air Brazed Joints

摘要:

采用Al₂TiO₅颗粒增强的Ag-CuO-Al₂TiO₅复合钎料,在钎焊温度为1050 ℃保温30 min工艺参数下,对ZrO₂陶瓷与GH3536合金进行了空气反应钎焊(RAB),分析了钎焊接头的界面结构及其形成机制；同时研究了接头在800 ℃氧化不同时间的组织演变规律及其对连接性能的影响。结果表明,钎焊过程中Al₂TiO₅颗粒分解产生Al₂O₃和TiO₂,TiO₂与ZrO₂陶瓷反应生成ZrTiO₄相。GH3536侧金属元素发生氧化形成尖晶石层,并分别与钎缝中的Al₂O₃、CuO反应,在钎缝中生成细密分布的NiAl₂O₄相及紧邻尖晶石层的团块状NiCuO₂相。ZrO₂/GH3536接头高温氧化1000 h后,钎缝中NiAl₂O₄呈团块状分布,Cr₂O₃薄层保持稳定；尖晶石层内部元素均匀化,厚度有明显增加。接头强度随着氧化时间的延长先降低后稳定在20 MPa。

Abstract:

ZrO₂ ceramic and GH3536 alloy were successfully reactive air brazed (RAB) at 1050℃ for 30min with Ag-CuO-Al₂TiO₅ composite filler. The interface structure and formation mechanism of the brazing joint were analyzed. Meanwhile, the influence of the exposure test at 800 ℃ on the microstructure and properties of joints were systematically analyzed. The results showed that Al₂TiO₅ particles were decomposed into Al₂O₃ and TiO₂ particles, and TiO₂ reacted with ZrO₂ ceramic to form the ZrTiO₄ phase. The oxidation reaction occurred on the metal elements from GH3536, which reacted with Al₂O₃ and CuO in the brazing seam respectively to generate NiAl₂O₄ phase with fine distribution in the brazing seam and massive NiCuO₂ phase adjacent to the spinel layer. After the ZrO₂/GH3536 joint was oxidized above 1000 h at 800 ℃, NiAl₂O₄ in the brazing joint was distributed in blocks and while the thin layer of Cr₂O₃ remained stable. The elements inside the spinel layer were homogenized, the thickness of which increased significantly. The strength of the joint first decreased and then stabilized at 20 MPa with the extension of oxidation time.