Thermal spray coating and thermal spray power

Abstract

A thermal spray coating is made of cermet and provided on the surface of a base. The value that is gained by further dividing the value, which is gained by dividing the coefficient of thermal expansion of the thermal spray coating by the thickness of the thermal spray coating (unit: μm), by the coefficient of thermal expansion of the base is set to a value no less than 0.15×10−2. Accordingly, peeling and cracking of the thermal spray coating can be prevented from being caused by the difference in the coefficient of thermal expansion between the thermal spray coating and the base.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a thermal spray coating provided on the surface of a base according to one embodiment of the present invention; and

FIG. 2 is a cross-sectional view showing a thermal spray coating provided over a base according to another embodiment of the present invention.

Claims

1. A thermal spray coating made of cermet on a surface of a base member, wherein a value gained by dividing, by the coefficient of thermal expansion of the base member, a value that is gained by dividing the coefficient of thermal expansion of the thermal spray coating by the thickness of the thermal spray coating (unit: μm) is no less than 0.15×10−2.

2. The thermal spray coating according to claim 1, wherein the formula: t−23 e0.3 P≧0 (where, 0 <P≦10) is satisfied when the porosity of the thermal spray coating is defined as P (unit: %) and the thickness of the thermal spray coating is defined as t (unit: μm).

3. The thermal spray coating according to claim 2, wherein the porosity of the thermal spray coating is no higher than 4%.

4. The thermal spray coating according to claim 1, wherein said base member is an undercoating layer provided on a base.

5. The thermal spray coating according to claim 4, wherein the coefficient of thermal expansion of the undercoating layer is between those of the thermal spray coating and the base.

6. The thermal spray coating according to claim 1, wherein said base member is a metal base.

7. The thermal spray coating according to claim 1, wherein the thermal spray coating is formed by high velocity flame spraying.

8. The thermal spray coating according to claim 1, wherein said cermet contains boron, molybdenum, chromium, and cobalt.

9. The thermal spray coating according to claim 1, wherein said cermet contains carbon, tungsten, and cobalt.

10. A thermal spray powder used to gain the thermal spray coating according to claim 8, comprising cermet containing boron, molybdenum, chromium, and cobalt.

11. The thermal spray powder according to claim 10, wherein the cermet is a composite of molybdenum boride and a cobalt chromium alloy.

12. The thermal spray powder according to claim 11, wherein the cermet is manufactured in accordance with a granulation-sintering method.

13. The thermal spray powder according to claim 11, wherein the average particle size of the cermet is 5 μm to 50 μm.

14. A thermal spray powder used to gain the thermal spray coating according to claim 9, comprising cermet containing carbon, tungsten, and cobalt.

15. The thermal spray powder according to claim 14, wherein the cermet is a composite of tungsten carbide and cobalt.

16. The thermal spray powder according to claim 15, wherein the cermet is manufactured in accordance with a granulation-sintering method.

17. The thermal spray coating according to claim 15, wherein the average particle size of the cermet powder is 5 μm to 50 μm.