US 4,735,850 A · Refractory composite articles

Abstract

A porous substrate formed from an agglomeration of fibers preferably has a carbonaceous composition. A binder is applied to the substrate. The binder may illustratively be an acrylic or beeswax to vaporize and form pyrolized carbon during pyrolysis or may illustratively be a phenolic resin, a furfural resin or pitch to form pyrolyzed carbon on the fibers during pyrolysis. A mixture of particles having the same approximate size as the diameter of the fibers is then applied to the fibers to become mechanically locked in the substrate pores. The mixture may contain (a) a first material (preferably a compound containing boron) which oxidizes and melts at a relatively low temperature and is relatively viscous when melted, (b) a second material (preferably a compound containing silicon) which oxidizes and has an increased melting temperature and is more viscous than the first material when melted and (c) a refractory material (preferably a compound containing zirconium) having a considerably higher melting temperature oxide than the first and second materials. The first material may be obtained from group 3a of the periodic table, the second material from group 4a of the periodic table and the third material from groups 4b and 5b of the periodic table. An impermeable coating such as a carbide, oxide or a nitride is thereafter applied to the substrate. The impermeable coating tends to crack at elevated temperatures. The adjacent particles in the mixture melt and flow into the cracks to inhibit crack amplification. The ease of flow is dependent upon the proportions of the first, second and third materials in the mixture. The particles displaced in the mixture from the cracks remain mechanically locked to the substrate.

Claims18

Dependent claims

In a refractory composite material,

a substrate formed from a plurality of fibers of a carbonaceous material, the fibers being disposed in a porous non-woven relationship,
pyrolyzed carbon material disposed on the fibers of the substrate, and
particles of a mixutre of a boride, a silicon compound and a refractory material mechanically locked in the pores of the substrate.

In combination for operation at elevated temperatures,

a substrate defined by fibers disposed in a porous relationship to define a porous substrate, the fibers occupying approximately forty percent (40%) to sixty percent (60%) of the space defined by the substrate,
pyrolytic carbon disposed on the fibers and occupying to approximately twenty five percent (25%) of the space defined by the substrate, and
a mixture of particles occupying at least a portion of the remaining space defined by the substrate, the mixture of particles having approximately the same dimensions as the diameter of the fibers, the mixture of particles including a first material having properties of oxidizing and having a relatively low oxide melting temperature, a second material having properties of oxidizing and having an increased oxide melting temperature and a refractory material having properties of oxidizing and having an oxide with an oxide melting temperature considerably above the melting temperatures of the first and second oxide materials, the particles in the mixture being mechanically locked in the pores in the substrate, the oxide of the first material being non-viscous, the oxide of the second material being more viscous than the oxide of the first material and the oxide of the third material being considerably more viscous than the oxides of the first and second materials.

Dependencies are inferred from the claim text.

Refractory composite articles

Life of this patent

Refractory composite articles

Life of this patent

Abstract

Claims18