Superalloy component and slurry composition

1. A slurry composition for aluminising a superalloy component comprising:

an organic binder comprising at least one of chromate or phosphate, and

a solid content comprising aluminum, silicon, hafnium, and yttrium.

2. The slurry composition as claimed in claim 1 , wherein a content of the hafnium is less than or equal to 2.5% by weight of the slurry composition.

3. The slurry composition as claimed in claim 2 , wherein the hafnium content is less than or equal to 1% by weight of the slurry composition.

4. The slurry composition as claimed in claim 1 , wherein a content of the yttrium is less than or equal to 0.1% by weight of the slurry composition.

5. The slurry composition as claimed in claim 4 , wherein the yttrium content is less than or equal to 0.05% by weight of the slurry composition.

6. The slurry composition as claimed in claim 1 , wherein a content of the silicon is between 1% and 40% by weight of a total solid content.

7. The slurry composition as claimed in claim 6 , wherein the silicon content is between 1% and 20% by weight of the total solid content.

8. The slurry composition as claimed in claim 7 , wherein the silicon content is between 10% and 15% by weight of the total solid content.

9. The slurry composition as claim in claim 1 , wherein a content of the organic binder is less than or equal to 70% by weight of the slurry composition.

10. The slurry composition as claimed in claim 1 , wherein at least one of hafnium or yttrium is in the form of a member selected from the group consisting of powder, flakes, swarfs, and combinations thereof.

11. The slurry composition as claimed in claim 1 , further comprising a sulphur content which is not more than 5 ppm of the slurry composition.

12. The slurry composition as claimed in claim 1 , wherein the solid content consists of aluminum, silicon, hafnium, and yttrium.

13. The slurry composition as claimed in claim 1 , wherein the solid content consists of aluminum, silicon, hafnium, yttrium, and sulphur, wherein a content of the sulphur is not more than 5 ppm by weight of the slurry composition.

14. The slurry composition as claimed in claim 1 , wherein the organic binder comprises both chromate and phosphate.

15. A method for forming a coating on a substrate via one or more slurry compositions, the method comprising:

applying a first slurry composition to the substrate, the first slurry composition comprising an organic binder comprising at least one of chromate or phosphate, and a solid content comprising aluminum, silicon, and at least one of hafnium or yttrium; and

heating the first slurry composition to a degree effective to form a first layer comprising the aluminum, silicon, and at least one of hafnium or yttrium;

applying a second slurry composition to the substrate, the second slurry composition comprising an organic binder comprising at least one of chromate or phosphate, and a solid content comprising aluminum and silicon, but no hafnium or yttrium; and

heating the second slurry composition to a degree effective to form a second layer comprising aluminum and silicon and no hafnium or yttrium on the first layer.

16. The method of claim 15 , wherein the first slurry composition comprises both hafnium and yttrium, and wherein a content of the silicon in the first slurry composition is between 1% and 40% by weight of a total solid content.

17. The method of claim 15 , wherein the heating the first slurry composition comprises:

heating the first slurry composition to a temperature of at least about 300° C. to cure the first slurry composition; and

heating the first slurry composition to a temperature of from 700°-1100° C. to diffuse aluminum, silicon, and at least one of hafnium or yttrium into a surface layer of the substrate.