Abstract:
The invention comprises a method of making self-supporting composite ceramic structures by the oxidation reaction of a body of molten parent metal precursor with a vapor-phase oxidant to form an oxidation reaction product. This reaction or growth is continued to form a thick, self-supporting ceramic body. The composite is recovered and in a separate subsequent operation, the surface is coated with one or more materials in order to effect desired changes in the properties of the surface, e.g., hardness, corrosion resistance.
Abstract:
A method for producing an alumina of high purity, which comprises forming an oxidation reaction product of an aluminum parent metal and an oxygen-containing vapor-phase oxidant, comminuting the resultiang ceramic body, and leaching any non-alumina materials therefrom, and recovering said substantially pure alumina material.
Abstract:
A method is provided of producing a self-supporting ceramic composite structure having one or more encasement members (14), such as an encasing stell sleeve, joined to it by growth of the ceramic material to engagement surface(s) of the encasement member(s) (14). A parent metal is contacted with a body of filler (38) which is encased by the encasement mmber(s) (14). The resulting assembly is heated to melt and oxidize the parent metal, e.g., aluminum, to form a polycrystalline material comprising an oxidation reaction product which grows through the body of filler (38) and stops at the engagement surface(s) of the encasement member(s) (14) which thereby determines the surface geometry of the grown ceramic matrix. Upon cooling, the encasement member(s) (14) is shrinkfitted about the ceramic composite body. The invention also provides the resultant articles, for example, a ceramic composite body having a stainless steel member affixed thereto.
Abstract:
The invention comprises a method of making self-supporting composite ceramic structures by the oxidation reaction of a body of molten parent metal precursor with a vapor-phase oxidant to form an oxidation reaction product. This reaction or growth is continued to form a thick, self-supporting ceramic body. The composite is recovered and in a separate subsequent operation, the surface is coated with one or more materials in order to effect desired changes in the properties of the surface, e.g., hardness, corrosion resistance.
Abstract:
In the present invention, there is provided a method for producing a self-supporting ceramic body by the oxidation of a parent metal to form a polycrystalline ceramic material consisting essentially of the oxidation reaction product of said parent metal with an oxidant, including a vapor-phase oxidant, and optionally one or more metallic constituents. The method comprises the steps of providing at least a portion of said parent metal with a barrier means at least partially spaced from said parent metal for establishing at least one surface of the ceramic body, and heating said parent metal to a temperature above its melting point but below the melting point of the oxidation reaction product to form a body of molten metal. At that temperature, the molten metal is reacted with the oxidant, thus forming the oxidation reaction product. At least a portion of the oxidation reaction product is maintained in contact with and between the molten metal and oxidant to transport the molten metal through the oxidation reaction product toward the barrier means and into contact with the oxidant so that the oxidation reaction product continues to form at the interface between the oxidant and previously formed oxidation reaction product optionally leaving metal dispersed through the polycrystalline material. The reaction is continued to the barrier means to produce a ceramic body having the surface established by the barrier means. A composite is formed by superimposing a barrier onto a filler material, such as a preform, and infiltrating the filler with the polycrystalline ceramic matrix grown to the barrier means.