A tungsten carbide-cubic boron nitride composite material and preparation method thereof mainly includes WC and cBN, wherein the WC powder is coated with Co nano-layer and the cBN powder is coated with SiO.sub.2 nano-layer, and hardness and toughness of the composition material can be improved by coating. The method for preparing a tungsten carbide-cubic boron nitride composite material adopts chemical vapor deposition method and high temperature sintering method. First nano-layers were coated on the surface of WC and cBN, and then the bulk materials can be obtained via high-temperature sintering.

A pre-impregnated composite tape is provided that includes: a matrix material; a plurality of fibers forming unidirectional arrays of tows encased within the matrix material; and a plurality of filler particles dispersed between adjacent fibers in the tape. The fibers have a mean fiber diameter of about 5 microns and about 40 microns, and are included within the tape at a volume fraction of about 15% and about 40%. The plurality of filler particles have a log-normal volumetric median particle size, such that the tape has a ratio of the log-normal volumetric median particle size to the mean fiber diameter that is about 0.05:1 to about 1:1. A method is also provided for forming a ceramic matrix composite.

A pliable tape is generally provided that includes: a plurality of fibers forming unidirectional arrays of tows encased within a matrix material, with four adjacent fibers in the tape define an interstitial spacing therebetween. The matrix material comprises filler particles dispersed between adjacent fibers in the tape. In one embodiment, the filler particles have a median particle size defining the interstitial spacing such that the interstitial spacing is about 0.75 to about 1.1 of the median particle size. In another embodiment, the filler particles have a median particle size that is related to the surface-to-surface spacing between adjacent fibers, with the ratio of the surface-to-surface spacing between adjacent fibers and the median particle size being about 0.3:1 to about 1:1. Methods are also provided for forming a ceramic matrix composite.

Provided is a refractory product which is not impregnated with pitch or the like, wherein it has higher corrosion-erosion resistance and thermal shock resistance as compared to a refractory product subjected to pitch or the like-impregnation treatment. The refractory product which is not impregnated with tar or pitch is characterized in that, in terms of values of physical properties of a sample of the refractory product as measured after heat-treating the sample in a non-oxidizing atmosphere at 1200 C.: an apparent porosity is 7% or less; a total void volume of pores having a pore diameter of 1 m or less is 80% or more of an integrated void volume of pores of the entire sample of the refractory product; and a gas permeability is 5010.sup.17 m.sup.2 or less.