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中国物理学会期刊

溅射Al对AlN的润湿与钎焊

CSTR: 32037.14.aps.65.086801

Wetting and brazing of AlN by sputtered Al

CSTR: 32037.14.aps.65.086801
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  • 由于润湿性不佳, 难以实现金属钎料对陶瓷的无过渡层直接钎焊, 本文在研究了溅射Al薄膜对AlN的润湿作用的基础上, 通过磁控溅射的方法在AlN表面沉积Al基薄膜作为钎料, 在真空条件下对AlN陶瓷进行了直接钎焊. 采用高景深光学显微镜、扫描电子显微镜和X射线能量分散谱表征了钎焊接头和剪切断口的组织及形貌. 结果表明, 高能量溅射Al粒子对AlN的撞击可以形成只有850 ℃以上高温才可获得的Al-N化学键, 实现Al对AlN的润湿, 使Al基薄膜钎料能够在较低的温度( 510 ℃)对AlN直接钎焊. 此方法获得的Al/AlN接头的剪切强度达到104 MPa, 含3.8 at.% Cu的Al合金钎料接头强度可进一步提高到165 MPa, 它们的剪切断裂都产生于钎缝金属之中; 增加钎料中的Cu含量至9.1 at.%后, Cu在钎缝与陶瓷界面的偏聚使接头的剪切强度降低为95 MPa. Al-20 at.% Ge合金可以将钎焊温度降低至510 ℃, 但Ge在钎缝与陶瓷界面的偏聚使接头在48 MPa发生断裂.

     

    The wettabilities of molten metals on ceramics are poor normally. In order to improve the wettability, all existing ceramic brazing methods introduce a compound transition layer that is formed by the reaction of active metal and ceramic. The transition layer between brazing seam and ceramic however creates negative effect on the properties of brazing joints. This paper reports our study of the wetting effect of sputtered Al particles on AlN, which enables the direct brazing of AlN using deposited Al-based films as fillers, thereby eliminating the need of a transition layer. The results show that under the bombardment of energetic sputtered Al particles, Al-N chemical bonding is formed at the interface between Al film and AlN, which typically requires temperatures above 850 ℃, much higher than the melting point of Al. The bonding remained intact even after the Al film has been melted, achieving the wetting effect on AlN. As a result, the direct brazing of AlN without the need of a transition layer becomes feasible. The shear strength of Al/AlN joint using this process reaches 104 MPa. The addition of 3.8 at.% Cu to film fillers increases the shear strength to 165 MPa. The fracture is generated in metallic brazing seam in both cases. When Cu content increases to 9.1 at.%, the segregation of Cu at the interface between the brazing seam and the ceramic reduces the shear strength of the joint to 95 MPa. With Al-20 at.% Ge, the brazing temperature can be lowered to 510 ℃, although the segregation of Ge at interface results in a low shear strength of 48 MPa. Instead of the traditional use of molten metals, utilization of the metallic vapor particles to bombard AlN achieves the wetting and the direct brazing of ceramics, with no negative effect of transition layers. This breakthrough method provides a brand new perspective to the technique of ceramic brazing.

     

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