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 metal-silicon carbide-based composite material including: a composite part including a silicon carbide-based porous body constituted by a plurality of silicon carbide particles, and a metal that is infiltrated in the silicon carbide-based porous body; and first and second surface layers which contain a metal, and coat both main surfaces of the composite part. The metal contains at least one kind selected from the group consisting of aluminum and magnesium, and the amount of particles having a particle size of 300 μm or more in the plurality of silicon carbide particles is 5% by volume or less.

A metal-silicon carbide-based composite material including: a composite part including a silicon carbide-based porous body constituted by a plurality of silicon carbide particles, and a metal that is infiltrated in the silicon carbide-based porous body; and first and second surface layers which contain a metal, and coat both main surfaces of the composite part. The metal contains at least one kind selected from the group consisting of aluminum and magnesium, and the amount of particles having a particle size of 300 μm or more in the plurality of silicon carbide particles is 5% by volume or less.

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.

The method includes the steps of: a) selecting particles with particular slenderness ratios and diameters from SiC powder to serve as selected SiC material powder; b) coating a PVA coating on particles of the selected SiC material powder so that the PVA coating and the selected SiC material powder are combined into a particulate ceramic material; c) pressing the particulate ceramic material into a ceramic base body; d) sintering the ceramic base body to form a fixed shape and forming completely continuous channels from an inside to a surface thereof by cooling; and e) infiltrating the ceramic base body with molten aluminum. The ceramic composite material made by the method includes a ceramic base body having completely continuous channels from an inside to a surface thereof; an aluminum filler filled in the channels; and an aluminum coating disposed on the ceramic base body and integratedly connecting with the aluminum filler.

The method includes the steps of: a) selecting particles with particular slenderness ratios and diameters from SiC powder to serve as selected SiC material powder; b) coating a PVA coating on particles of the selected SiC material powder so that the PVA coating and the selected SiC material powder are combined into a particulate ceramic material; c) pressing the particulate ceramic material into a ceramic base body; d) sintering the ceramic base body to form a fixed shape and forming completely continuous channels from an inside to a surface thereof by cooling; and e) infiltrating the ceramic base body with molten aluminum. The ceramic composite material made by the method includes a ceramic base body having completely continuous channels from an inside to a surface thereof; an aluminum filler filled in the channels; and an aluminum coating disposed on the ceramic base body and integratedly connecting with the aluminum filler.

A ceramic material, a varistor and methods for forming a ceramic material and a varistor are disclosed. In an embodiment, a ceramic material includes ZnO as a main component and additives selected from the group consisting of an Al.sup.3+-containing solution, a Ba.sup.2+-containing solution, and at least one compound containing a metal element, wherein the metal element is selected from the group consisting of Bi, Sb, Co, Mn, Ni, Y, and Cr.

A ceramic material, a varistor and methods for forming a ceramic material and a varistor are disclosed. In an embodiment, a ceramic material includes ZnO as a main component and additives selected from the group consisting of an Al.sup.3+-containing solution, a Ba.sup.2+-containing solution, and at least one compound containing a metal element, wherein the metal element is selected from the group consisting of Bi, Sb, Co, Mn, Ni, Y, and Cr.