ways to join steel and glass to geat an air tight sealing with a clean surface?

Question

i mean methods like welding or using lasers etc.

Answer 1

Here's one I found.

The fixing of the glass onto the steel begins with the application of a polyurethane-based, two-pack primer on the galvanizing. Then, a two-sided, self-adhesive strip is stuck onto the primer. The glass is subsequently pressed on or against this strip, forming the glued joint. The seam is sealed on the outside with silicon mastic. (Source A)

Answer 2

Even if it were possible to "weld" glass to steel, it's probably not a good idea because there's a large difference in the coeffficient of thermal expansion between glass and steel. Steel will roughly expand 3 or 4 times as much as glass for a given temperature rise, which means that glass would shatter with temperature changes. That's why glass is usually mounted with flexible gaskets in steel frames.

Answer 3

I've worked on a couple of chemistry lab glassware projects, where we needed to install a metal feed-through in a piece of glassware that would be expected to hold a vacuum as the temperature was raised and lowered. The problem was quite difficult.

If the glass was Pyrex, which has a very low coefficient of thermal expansion, the metal feed-through would shrink and swell with temperature change and crack the glass. We could get an initial seal, but the first time we cycled the temperature, the joint began to leak.

The problem was solved by a very experienced European glassblower. He found a glass (called "canary-glass" because of its yellow color) that had a large positive coefficient of thermal expansion, very close to that of the steel feed-throughs. Molten canary-glass was carefully wrapped around each feed-through and allowed to cool. Then each feed-through was fused into a hole through the Pyrex glassware. Because of the intervening canary-glass the seal was maintained, even as the temperature was widely varied.

I have no idea of your application but, if you intend to join glass directly to steel, I believe the coefficient of thermal expansion of both materials will be a major concern............

Answer 4

It is possible to apply a metallic coating to glass and solder, braze, or laser weld to that. Hermetic fiber optic assemblies are made by laser-welding or brazing gold-plated optical fibers. I once built a hermetically sealed optical module with a window brazed into the end of a tube. We had the edges of the windows plated; unfortunately, I don't remember the materials used. I remember we also considered using a force-fit with a soft metal sealing material.

Common light bulbs hermetically seal their leads by simply fusing the glass around them; other hermetic constructions use glass frit for sealing.

The trick in any metal-glass seal is to match the expansion coefficients as closely as possible and to design it so that any differential expansion or applied force puts the glass in pure compression.

Answer 5

You won't be able to join them directly. Primarily because their rates of thermal expansion and contraction are so different that, as they cool, the glass will crack and shatter along the joint line.

Sorry about that, but sometimes Mother Nature can be a real b|tch ☺

Doug