Float Glass To4J50Fe-Ni Alloy Seal

Abstract:Sealing glass have high airtightness, widely used in the field under high vacuum requirements, such vacuum glass. Vacuum glass has excellent thermal and sound insulation function.Currently, the mainstream sealing technology of the vacuum is rigid glass seal. The temperature difference between the inner and outer of the vacuum glass would have a greater stress which reduced the life of the vacuum glass. The use of flexible metal frame sealing could be a good solution to the stress problem.This paper studied the float glass to Fe-Ni alloy seal in order to provide technical support for metal sealing vacuum glass with deformable structure. Sealing Fe-Ni alloy and float glass by coating low-melting glass paste between float glass and pre-oxidized Fe-Ni alloy. The low melting sealing glass was SnO-ZnO-P2O5glass (referred SZP glass) and PbO-ZnO-B2O3glass(referred Pb glass). In this paper, the properties and structure of4J50Fe-Ni alloy oxidation in the atmosphere were studied by XRD, SEM and other testing methods.The sealing feasibility of the sealing glass to float glass and Fe-Ni alloys was studied by the thermal expansion coefficient and wettability testing and other testing methods. The sealing performance,sealing mechanism and failure mechanism of float glass to Fe-Ni alloy were studied by mechanical testing, SEM and other detection methods. The results showed that:1)Oxidation of4J50Fe-Ni alloy under an air atmosphere condition in different temperature (500～520℃) and different relative humidity (22%-60%) were studied. A discontinuous oxide film generates on the surface of4J50Fe-Ni alloy in the initial stage of oxidation. The main phase composition of the oxide film is Fe2O3. After10～15minutes oxidation, an uniform and continuous oxide film generates on the surface. The main phase composition of the oxide film is Fe2O3and Fe3O4. With increasing the oxidation temperature and relative humidity, the oxidation process of4J50Fe-Ni alloy accelerates.2) Good wettability could obtain when SZP glass incubated on float glass and Fe-Ni alloy substrate for30min in430～440℃, or Pb glass incubated on float glass and Fe-Ni alloy substrate for1h in360～380℃. The desired wetting temperature would increase when the filler was added. Good wettability could obtain when Pb glass adding8wt.%α-Al2O3glass incubated for1h in400～410℃.3)Pb Glass was more in line with the principle of matching seal and higher strength than SZP glass, so it was better sealing. In the sealing stage, Pb glass and oxide film would miscible.At the same time, iron ions of the oxide film would diffusion to the Pb glass side, Pb glass would diffusion to the Fe-Ni alloy side.when the oxide film reaches a certain thickness, Pb glass can not penetrate the oxide film, an oxide film to Pb glass miscible layer which has a composition gradient would form between Pb glass and Fe-Ni alloy. Failure of the sealing glass was oxide film to Pb glass miscible layer and the interface of Pb glass substrate and miscible layer.The strength of the interface of Pb glass substrate and miscible layer would improve by adding8wt.%α-Al2O3in the Pb glass. Using Pb glass which adding8wt.%α-Al2O3as sealing glass, Fe-Ni alloy pre-oxidation process for the oxidation time15min,60%relative humidity, sealing process was400℃for1h, the strength of float glass to Fe-Ni alloys was3.53MPa.