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>monocrystaline blades grown in situ within (!) a ceramic fibre reinforcing mesh. Holy hell. How in the world do they pull that off while still keeping the cry

by MertsA 8y ago

>monocrystaline blades grown in situ within (!) a ceramic fibre reinforcing mesh. Holy hell. How in the world do they pull that off while still keeping the crystal growth boundary continuous?? That sounds amazing, do you have any more information on the subject?

bushin 8y ago
Nice try, comrade.
baybal2 8y ago
>That sounds amazing, do you have any more information on the subject? No, I don't, But it is not hard to imagine. This has something to do with preventing the surface of ceramics interfering with monocrystal growth. 1. They keep the mesh temperature higher than that of melt. Knowing that both Boron and SiC fibres are grown on top of Tungsten wire, it is not that hard to imagine that you can heat them by electricity. Coreless varieties of ceramic and boron fibres are very uncommon. Very likely they used tungsten cored fibres. 2. As with anything involved with growing crystal on a crystal, one has to make sure that crystalline lattices of materials are compatible. A challenge is to marry the somewhat amorphous, and rough surface of ceramic fibres with some coating with more ordered lattice that will not disturb the monocrystal growth. Growing of crystals on top of amorphous materials is know to be doable, growing of crystals on top of another with dissimilar lattice is also known to be possible. I believe no "sci-fi" is involved there. I believe that you can even the surface of the fibre and the coating on it with repeated acid dips and recurring grow-overs of the fibre or coating material. Once you have a fine surface on the fibre, you can use something like ALD process to produce a "dissimilar lattice interface" in a very controlled, defect free fashion. 3. You have to make sure that fibres and melt do not chemically react, or react adversely to the process. The challenge there is that at temperatures of the monocrystaline alloy melt, pretty much any material will react to some extend with it. But I think the chemistry challenge is the easiest here.

by MertsA 8y ago

bushin 8y ago

Nice try, comrade.

baybal2 8y ago

>That sounds amazing, do you have any more information on the subject? No, I don't, But it is not hard to imagine. This has something to do with preventing the surface of ceramics interfering with monocrystal growth. 1. They keep the mesh temperature higher than that of melt. Knowing that both Boron and SiC fibres are grown on top of Tungsten wire, it is not that hard to imagine that you can heat them by electricity. Coreless varieties of ceramic and boron fibres are very uncommon. Very likely they used tungsten cored fibres. 2. As with anything involved with growing crystal on a crystal, one has to make sure that crystalline lattices of materials are compatible. A challenge is to marry the somewhat amorphous, and rough surface of ceramic fibres with some coating with more ordered lattice that will not disturb the monocrystal growth. Growing of crystals on top of amorphous materials is know to be doable, growing of crystals on top of another with dissimilar lattice is also known to be possible. I believe no "sci-fi" is involved there. I believe that you can even the surface of the fibre and the coating on it with repeated acid dips and recurring grow-overs of the fibre or coating material. Once you have a fine surface on the fibre, you can use something like ALD process to produce a "dissimilar lattice interface" in a very controlled, defect free fashion. 3. You have to make sure that fibres and melt do not chemically react, or react adversely to the process. The challenge there is that at temperatures of the monocrystaline alloy melt, pretty much any material will react to some extend with it. But I think the chemistry challenge is the easiest here.