Ceramic-metallic composites are disclosed along with the processes for their manufacture. The present invention improves high temperature strength of Al.sub.2O.sub.3—Al composites by displacing aluminum in the finished product with other substances that enhance the high temperature strength. Each process commences with a preform initially composed of at least 5% by weight silicon dioxide, and the finished product includes Al.sub.2O.sub.3, aluminum and another substance.

Ceramic-metallic composites are disclosed along with the processes for their manufacture. The present invention improves high temperature strength of Al.sub.2O.sub.3—Al composites by displacing aluminum in the finished product with other substances that enhance the high temperature strength. Each process commences with a preform initially composed of at least 5% by weight silicon dioxide, and the finished product includes Al.sub.2O.sub.3, aluminum and another substance.

A silicon carbide-graphite composite is described, including (i) interior bulk graphite material and (ii) exterior silicon carbide matrix material, wherein the interior bulk graphite material and exterior silicon carbide matrix material inter-penetrate one another at an interfacial region therebetween, and wherein graphite is present in inclusions in the exterior silicon carbide matrix material. Such material may be formed by contacting a precursor graphite article with silicon monoxide (SiO) gas under chemical reaction conditions that are effective to convert an exterior portion of the precursor graphite article to a silicon carbide matrix material in which graphite is present in inclusions therein, and wherein the silicon carbide matrix material and interior bulk graphite material interpenetrate one another at an interfacial region therebetween. Such silicon carbide-graphite composite is usefully employed in applications such as implant hard masks in manufacturing solar cells or other optical, optoelectronic, photonic, semiconductor and microelectronic products, as well as in ion implantation system materials, components, and assemblies, such as beam line assemblies, beam steering lenses, ionization chamber liners, beam stops, and ion source chambers.

A silicon carbide-graphite composite is described, including (i) interior bulk graphite material and (ii) exterior silicon carbide matrix material, wherein the interior bulk graphite material and exterior silicon carbide matrix material inter-penetrate one another at an interfacial region therebetween, and wherein graphite is present in inclusions in the exterior silicon carbide matrix material. Such material may be formed by contacting a precursor graphite article with silicon monoxide (SiO) gas under chemical reaction conditions that are effective to convert an exterior portion of the precursor graphite article to a silicon carbide matrix material in which graphite is present in inclusions therein, and wherein the silicon carbide matrix material and interior bulk graphite material interpenetrate one another at an interfacial region therebetween. Such silicon carbide-graphite composite is usefully employed in applications such as implant hard masks in manufacturing solar cells or other optical, optoelectronic, photonic, semiconductor and microelectronic products, as well as in ion implantation system materials, components, and assemblies, such as beam line assemblies, beam steering lenses, ionization chamber liners, beam stops, and ion source chambers.

Ceramic-metallic composites are disclosed along with the processes for their manufacture. The present invention improves high temperature strength of Al.sub.2O.sub.3—Al composites by displacing aluminum in the finished product with other substances that enhance the high temperature strength. Each process commences with a preform initially composed of at least 5% by weight silicon dioxide, and the finished product includes Al.sub.2O.sub.3, aluminum and another substance.

Ceramic-metallic composites are disclosed along with the processes for their manufacture. The present invention improves high temperature strength of Al.sub.2O.sub.3—Al composites by displacing aluminum in the finished product with other substances that enhance the high temperature strength. Each process commences with a preform initially composed of at least 5% by weight silicon dioxide, and the finished product includes Al.sub.2O.sub.3, aluminum and another substance.

An inorganic circuit board article including: a porous inorganic sheet having a low dielectric loss of from 1×10.sup.−5 to 3×10.sup.−3 at a high frequency of from 10 to 30 GHz and the porous inorganic sheet has a percent porosity of from 30 to 50 vol %; a dielectric polymer having a low dielectric loss of from 10.sup.−4 to 10.sup.−3 at a high frequency of from 10 to 20 GHz, wherein the dielectric polymer occupies the pores of the porous inorganic sheet, and the inorganic circuit board article has a dielectric loss of from 1×10.sup.−4 to 9×10.sup.−4. The disclosure also includes methods of making and using the inorganic circuit board article.

An article including carbon-carbon composite substrate may be treated with an antioxidant coating prior to use in an oxidizing environment. The antioxidant coating may be configured to reduce oxidation at an external surface of the C-C composition and reduce ingress of oxidants into pores or other open passages defined by the C-C composite substrate to avoid internal oxidation. An example article includes a C-C composite substrate, a bond coat, and an antioxidant coating. The C-C composite substrate defines a friction surface and a non-friction surface. The bond coat is disposed on the non-friction surface. The antioxidant coating may be disposed on at least a portion of the bond coat. The antioxidant coating may include ytterbium disilicate and a sintering aid.

An article including carbon-carbon composite substrate may be treated with an antioxidant coating prior to use in an oxidizing environment. The antioxidant coating may be configured to reduce oxidation at an external surface of the C-C composition and reduce ingress of oxidants into pores or other open passages defined by the C-C composite substrate to avoid internal oxidation. An example article includes a C-C composite substrate, a bond coat, and an antioxidant coating. The C-C composite substrate defines a friction surface and a non-friction surface. The bond coat is disposed on the non-friction surface. The antioxidant coating may be disposed on at least a portion of the bond coat. The antioxidant coating may include ytterbium disilicate and a sintering aid.

A solid state heater and methods of manufacturing the heater is disclosed. The heater comprises a unitary component that includes portions that are graphite and other portions that are silicon carbide. Current is conducted through the graphite portion of the unitary structure between two or more terminals. The silicon carbide does not conduct electricity, but is effective at conducting the heat throughout the unitary component. In certain embodiments, chemical vapor conversion (CVC) is used to create the solid state heater. If desired, a coating may be applied to the unitary component to protect it from a harsh environment.