# US 5,350,447 A · Coating for ceramic composites

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- Number: US 5,350,447 A
- Document ID: US5350447A
- Status: Granted
- Kind: A
- Application number: 08/075,655
- Filed: 1993-06-11
- Granted: 1994-09-27
- Earliest claimed: 1991-04-12
- Assignees: Minnesota Mining and Manufacturing Company
- Inventors: Jane S. Copes
- Web page: https://patentgrep.com/patent/US5350447A

## CPC

- C04B 35/565: based on silicon carbide
- C04B 35/18: rich in aluminium oxide
- C04B 35/6309: {Aluminium phosphates}
- C04B 35/80: Fibres, filaments, whiskers, platelets, or the like
- C04B 37/005: {consisting of glass or ceramic material}
- C04B 41/009: {characterised by the material treated}
- C04B 41/5092: {Phosphate cements}
- C04B 41/85: with inorganic materials
- C04B 2235/3463: Alumino-silicates other than clay, e.g. mullite
- C04B 2235/3826: Silicon carbides
- C04B 2235/402: Aluminium
- C04B 2235/5228: Silica and alumina, including aluminosilicates, e.g. mullite
- C04B 2235/526: characterised by the length of the fibers
- C04B 2235/5264: characterised by the diameter of the fibers
- C04B 2235/5292: Flakes, platelets or plates
- C04B 2235/5436: micrometer sized, i.e. from 1 to 100 micron
- C04B 2235/661: Multi-step sintering
- C04B 2235/762: Cubic symmetry, e.g. beta-SiC
- C04B 2237/062: based on silica or silicates
- C04B 2237/083: Carbide interlayers, e.g. silicon carbide interlayers
- C04B 2237/365: Silicon carbide
- C04B 2237/38: Fiber or whisker reinforced
- C04B 2237/76: Forming laminates or joined articles comprising at least one member in the form other than a sheet or disc, e.g. two tubes or a tube and a sheet or disc
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE

## Abstract

A coating composition for use with ceramic composites to reduce gas permeability of the composites as well as provide an adhesive force to the composites. The coating composition comprises an aqueous dispersion of an aluminum phosphate precursor, silicon carbide, and aluminoborosilicate.

## Claims

### Claim 1

An unfired coating composition useful for reducing the gas permeability of a silicon carbide coated aluminoborosilicate ceramic composite, said unfired coating composition consisting essentially of:
(a) an aluminum phosphate solution prepared by dissolving aluminum metal in phosphoric acid;
(b) silicon carbide in an amount sufficient to create a fired molar ratio range of silicon carbide to aluminum phosphate of about 1:1 to 50:1; and
(c) particles of aluminoborosilicate dispersed therein in the weight range of about 0.5 to 70 weight percent of the total weight of said unfired coating composition when fired.

### Claim 2

An unfired coating composition useful for reducing the gas permeability of a silicon carbide coated aluminoborosilicate ceramic composite, said unfired coating composition comprising:
(a) an aluminum phosphate solution prepared by dissolving aluminum metal in phosphoric acid;
(b) silicon carbide in an amount sufficient to create a fired molar ratio range of silicon carbide to aluminum phosphate of about 1:1 to 50:1; and
(c) fibers of aluminoborosilicate dispersed therein in the weight range of about 0.5 to 70 weight percent of the total weight of said unfired coating composition when fired.

### Claim 3 (depends on 1)

The coating composition of claim 1 wherein said aluminoborosilicate particles are flakes.

### Claim 4 (depends on 1)

The coating composition of claim 1 wherein said fired molar ratio of silicon carbide to aluminum phosphate is about 5:1 to 30:1.

### Claim 5 (depends on 1)

The coating composition of claim 1 wherein said weight range of aluminoborosilicate particles is about 30 to 70 weight percent of the total mixture.

### Claim 6 (depends on 2)

The coating composition of claim 2 wherein said fired molar ratio range of silicon carbide to aluminum phosphate is about 5:1 to 30:1.

### Claim 7 (depends on 2)

The coating composition of claim 2 wherein said weight range of said fibers of aluminoborosilicate is about 30 to 70 weight percent of the total weight of said unfired coating composition when fired.