Brake disk and method of making same
A brake disk or drum has at least one working surface which opposes a braking member such as a brake pad or shoe. A plurality of spaced, raised island formations are provided across the working surface, with channels extending between the island formations. Each raised island formation has an outer surface which contacts a brake pad or brake shoe during braking.
1. A brake disk, comprising: a disk body having oppositely directed surfaces; at least one of the surfaces having a plurality of spaced, raised island formations and channels extending between the island formations; and each raised island formation having an outer friction surface which contacts a brake pad during braking,
wherein at least the friction surfaces of the island formations are coated with a coating comprising at least one layer of a coating material, the coating comprises a first layer of a first coating material and at least a second layer of a second coating material, first coating layer comprises a metal, and wherein the first coating layer has a crystalline structure.
2. The brake disk as claimed in claim 1 , wherein the island formations are teardrop shaped.
3. The brake disk as claimed in claim 1 , wherein the island formations are round.
4. The brake disk as claimed in claim 1 , wherein the island formations are letter-shaped.
5. The brake disk as claimed in claim 1 , wherein the island formations are figure eight shaped.
6. The brake disk as claimed in claim 1 , wherein the island formations have peripheral edges which are at least partially rounded in shape.
7. The brake disk as claimed in claim 1 , wherein both surfaces of the disk body have a plurality of spaced, raised island formations and channels extending between the island formations.
8. The brake disk of claim 7 , wherein at least the raised island formations have a surface texture having a predetermined three dimensional pattern.
9. The brake disk as claimed in claim 1 , wherein the spaced island formations extend over the entire area of the surface.
10. The brake disk as claimed in claim 1 , wherein the disk body has a central opening and the opposite surfaces are annular surfaces, and each annular surface has a series of radially extending rows of island formations extending from the central opening to the outer periphery of the annular surface, the channels comprising radially extending spaces between the adjacent rows of island formations, and radially spaced gaps between adjacent island formations in each row.
11. The brake disk as claimed in claim 1 , wherein each surface is coated with at least one layer of a coating material extending over the entire surface area of the surface.
12. The brake disk of claim 1 , wherein the second coating material is selected from the group of coating materials consisting of metal nitride, metal oxide, metal boride and metal carbide.
13. The brake disk of claim 1 , wherein the second coating layer comprises at least one compound of the same metal as the first coating layer.
14. The brake disk of claim 1 , wherein the first coating layer has an amorphous structure.
15. The brake disk of claim 1 , wherein the metal of said first coating layer is selected from the group of metals consisting of titanium, chromium; zirconium, boron, hafnium and alloys thereof.
16. The brake disk of claim 15 , wherein the second coating layer comprises a nitride, boride, carbide or oxide of the metal used in the first coating layer.