Matched glass-to-Kovar seals in N₂ and Ar atmospheres

Abstract

The oxidation of Kovar alloy was investigated, the wetting and spreading behavior of hard and soft glasses on Kovar alloy were studed by using the sessile drop method, and the quality and the seal strength of glass-Kovar seals were tested. The experimental results indicated that the preoxidation of Kovar alloy for approximately 10 min at 700°C in air resulted in excellent adherence in glass-Kovar seals. The wetting and spreading behavior of glass on preoxidized Kovar alloy were superior to that on nonoxidized Kovar alloy. The wetting ability of ASF110 glass, at 950°C and 980°C in Ar and N₂ atmospheres, was significantly superior to that of ASF200R and ASF700 glasses. The seal quality of the glass-preoxidized Kovar seal was superior to that of the glass-nonoxidized Kovar seal. The shear strength of the ASF110 glass-preoxidized Kovar seal, which was prepared at 980°C for 20 min in an Ar atmosphere, was approximately 3.9 MPa.

Keywords

Kovar alloy / glass / sealing / argon / nitrogen / oxidation / wetting

References

[1] Donald IW. Preparation, properties and chemistry of glass- and glass-ceramic-to-metal seals and coatings. J. Mater. Sci., 1993, 28(11): 2841.

[2] Donald IW, Mallinson PM, Metcalfe BL, Gerrard LA, Fernie JA. Recent developments in the preparation, characterization and applications of glass- and glass-ceramic-to-metal seals and coatings. J. Mater. Sci., 2011, 46(7): 1975.

[3] Leichtfried G, Thurner G, Weirather R. Molybdenum alloys for glass-to-metal seals. Int. J. Refract. Met. Hard Mater., 1998, 16(1): 13.

[4] McCormick J, Zakraysek L. A metallographic test for glass-to-metal seal quality. 17th Annual Proceedings Reliability Physics, 1979 44

[5] Zanchetta A, Lefort P, Gabbay E. Thermal expansion and adhesion of ceramic to metal sealings: case of porcelain-Kovar junctions. J. Eur. Ceram. Soc., 1995, 15(3): 233.

[6] Zanchetta A, Lortholary P, Lefort P. Ceramic to metal sealings: interfacial reactions mechanism in a porcelain-Kovar junction. J. Alloy Compd., 1995, 228(1): 86.

[7] Chern TS, Tsai HL. Wetting and sealing of interface between 7056 Glass and Kovar alloy. Mater. Chem. Phys., 2007, 104(2–3): 472.

[8] Yext WF, Shook BJ, Katzenberger WS, Michalek RC. Improved glass-to-metal sealing through furnace atmosphere composition control. IEEE Trans. Compon. Hybrids Manuf. Technol., 1983, CHMT-6(4): 455.

[9] Thomas WB. Matched glass-to-metal seal improvements by controlled atmosphere metal oxidation. Solid State Technol., 1986, 29(9): 73

[10] Kuo DW, Leng WB, Shen ZS. Effect of Kovar alloy oxidized in simulated N₂/H₂O atmosphere on its sealing with glass. J. Univ. Sci. Technol. Beijing, 2008, 15(3): 267.

[11] Wu M, He XB, Shen ZS, Qu XH. Preparation, crystallization, and wetting of ZnO-Al₂O₃-B₂O₃-SiO₂ glass-ceramics for sealing to Kovar. Int. J. Miner. Met. Mater., 2009, 16(5): 586.

[12] Pask JA. New techniques in glass-to-metal sealing. Proceedings of the IRE: Waves and Electrons Section, 1948 286

[13] Lei DQ, Wang ZF, Li J, Li JB, Wang ZJ. Experimental study of glass to metal seals for parabolic trough receivers. Renew. Energy, 2012, 48, 85.

[14] Pask JA. From technology to the science of glass/metal and ceramic/metal sealing. Ceram. Bull., 1987, 66(11): 1587