Metal foam body having an open-porous structure as well as a method for the production thereof
The invention relates to metal foam bodies having an open-porous structure as well as a method for producing thereof wherein according to the set task such metal foam bodies are to be provided which achieve an increased oxidation resistance and/or an increased corrosion resistance. With the metal foam bodies having an open-porous structure according to the invention, for such metal foam bodies within the webs of the open-porous structure there are channel shaped cavities formed as being determined by the production. At the same time, the webs and cavities will be provided with a metallic protective layer made of a material differing from the metallic starting material of the foam body or the channel shaped cavities will be filled with this material. For this, an adequate metal powder or an alloy component being included in the powder will be used which becomes liquid and forms a liquid phase respectively during thermal treatment below a temperature at which the metal of the base foam body is melting. Due to the capillary action wetting the surfaces of channel shaped cavities within the webs can be achieved such that after cooling down a metallic protective layer is forming or the channel shaped cavities are filled.
1. A metal foam body having an open-porous structure, said open-porous structure comprising webs forming a supporting framework of said metal foam body,
wherein channel shaped cavities are formed within the webs of said open-porous structure as being determined by a production of a base foam body,
wherein said channel shaped cavities are provided with a metallic protective layer on an inner surface of the channel shaped cavities, and the inner metallic protective layer being made of a second material being different from a metallic starting material of said base foam body,
wherein the webs of the open-porous structure have an outer metallic protective layer formed thereon, the outer metallic protective layer also being made of the second material,
wherein before the formation of said inner protective layer, the free cross sections of said channel shaped cavities within the webs are smaller than 30 percent of the average pore size of said base foam body,
wherein said base foam body is produced from nickel, iron or copper, and
wherein said inner and outer protective layers are comprised of aluminum, an aluminum base alloy, an aluminide, a tin base alloy or a copper base alloy.
2. The metal foam body of claim 1 , wherein the inner metallic protective layer only partially fills the channel shaped cavities, such that the inner metallic protective layer surrounds a hollow region within the channel shaped cavities.
3. The metal foam body of claim 1 , wherein the channel shaped cavities are further provided with a metallic coating layer on the inner metallic protective layer, the metallic coating layer being made of a third material that is different from the second material.