Formulations for oxidation protection of composite articles

1. An article comprising:

a carbon-carbon composite structure;

an oxidation protection composition including a base layer disposed on an outer surface of the carbon-carbon composite structure and a sealing layer disposed on an outer surface of the base layer,

wherein the base layer comprises a first phosphate glass composition having a plurality of graphene nanoplatelets and a boron nitride additive dispersed throughout the base layer, and

wherein the sealing layer comprises a second phosphate glass composition and is substantially free of boron nitride.

2. The article of claim 1 , wherein the first phosphate glass composition of the base layer comprises between about 10 weight percent and about 35 weight percent of the boron nitride additive.

3. The article of claim 1 , wherein the first phosphate glass composition of the base layer is represented by the formula a(A′ 2 O) x (P 2 O 5 ) y1 b(G f O) y2 c(A″O) z :

A′ is selected from: lithium, sodium, potassium, rubidium, cesium, and mixtures thereof;

G f is selected from: boron, silicon, sulfur, germanium, arsenic, antimony, and mixtures thereof;

A″ is selected from: vanadium, aluminum, tin, titanium, chromium, manganese, iron, cobalt, nickel, copper, mercury, zinc, thulium, lead, zirconium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, actinium, thorium, uranium, yttrium, gallium, magnesium, calcium, strontium, barium, tin, bismuth, cadmium, and mixtures thereof;

a is a number in the range from 1 to about 5;

b is a number in the range from 0 to about 10;

c is a number in the range from 0 to about 30;

x is a number in the range from about 0.050 to about 0.500;

y 1 is a number in the range from about 0.040 to about 0.950;

y 2 is a number in the range from 0 to about 0.20; and

z is a number in the range from about 0.01 to about 0.5;

(x+y 1 +y 2 +z)=1; and

x<(y 1 +y 2 ).

4. The article of claim 1 , wherein the second phosphate glass composition of the sealing layer is represented by the formula a(A′ 2 O) x (P 2 O 5 ) y1 b(G f O) y2 c(A″O) z :

A′ is selected from: lithium, sodium, potassium, rubidium, cesium, and mixtures thereof;

G f is selected from: boron, silicon, sulfur, germanium, arsenic, antimony, and mixtures thereof;

A″ is selected from: vanadium, aluminum, tin, titanium, chromium, manganese, iron, cobalt, nickel, copper, mercury, zinc, thulium, lead, zirconium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, actinium, thorium, uranium, yttrium, gallium, magnesium, calcium, strontium, barium, tin, bismuth, cadmium, and mixtures thereof;

a is a number in the range from 1 to about 5;

b is a number in the range from 0 to about 10;

c is a number in the range from 0 to about 30;

x is a number in the range from about 0.050 to about 0.500;

y 1 is a number in the range from about 0.040 to about 0.950;

y 2 is a number in the range from 0 to about 0.20; and

z is a number in the range from about 0.01 to about 0.5;

(x+y 1 +y 2 +z)=1; and

x<(y 1 +y 2 ).

5. The article of claim 4 , wherein the second phosphate glass composition further comprises an aluminum phosphate.

6. The article of claim 1 , wherein the article comprises a component of an aircraft wheel braking assembly.

7. The article of claim 1 , wherein the second phosphate glass composition comprises 75.01% by weight a phosphate glass matrix.

8. The article of claim 7 , wherein the first phosphate glass composition comprises 73.22% by weight a first phosphate glass matrix and 24.54% by weight boron nitride.

9. The article of claim 7 , wherein the first phosphate glass composition comprises 80.2% by weight a first phosphate glass matrix and 17.53% by weight boron nitride.