SUBSTRATE COATED WITH AN EROSION PROTECTION LAYER

Abstract

A substrate is coated on an outer surface with an erosion protection layer, the protective layer including a resin in which are dispersed fibers having an average length between 50 m and 500 m.

Claims

1. A substrate coated on an outer surface with an erosion protection layer, said protective layer comprising a resin in which are dispersed fibers having an average length between 50 m and 500 m.

2. The coated substrate according to claim 1, wherein the average length of the fibers is between 80 m and 150 m.

3. The coated substrate according to any one of claim 1, wherein the fibers are selected from: carbon fibers, glass fibers, silica fibers, basalt fibers, fibers of natural origin and mixtures thereof.

4. The coated substrate according to claim 3, wherein the fibers are carbon fibers.

5. The coated substrate according to any one of claim 1, wherein the fibers are present in the protective layer in a mass content between 0.1% and 30%.

6. The coated substrate according to claim 5, wherein the fibers are present in the protective layer in a mass content between 2.5% and 25%.

7. The coated substrate according to claim 1, wherein the average diameter of the fibers is 50 m or less.

8. The coated substrate according to any one of claim 1, wherein the resin is a polyurethane resin.

9. The coated substrate according to claim 1, wherein the protective layer is a paint layer in which the fibers are dispersed.

10. The coated substrate according to any one of claim 1, wherein the substrate has an aerodynamic profile.

11. The coated substrate according to claim 10, wherein the substrate is selected from: a blade, an aircraft wing or an aircraft fuselage.

12. The coated substrate according to claim 11, wherein the substrate is a wind turbine blade.

13. The coated substrate according to claim 1, wherein the substrate is of composite material comprising a fibrous reinforcement densified by a matrix, or of metallic material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Other features and advantages of the invention will be apparent from the following non-limiting description with reference to the appended drawings, wherein:

[0020] FIG. 1 is a schematic representation of a first example of a coated substrate according to the invention,

[0021] FIG. 2 is a schematic representation of a second example of a coated substrate according to the invention,

[0022] FIG. 3 is a schematic representation of a third example of a substrate coated according to the invention,

[0023] FIG. 4 is a schematic representation of a coated wind turbine blade according to the invention,

[0024] FIGS. 5A to 5D are photographs of the results of a water erosion test carried out on a coated substrate not of the invention,

[0025] FIGS. 6A to 6F are photographs of the results of a water erosion test carried out on a first example of a coated substrate according to the invention, and

[0026] FIGS. 7A to 7D are photographs of the results of a water erosion test carried out on a second example of a coated substrate according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

[0027] FIG. 1 shows a substrate 1 coated on an outer surface 6 with an erosion protection layer 3. The protective layer 3 may be in contact with the outer surface 6 of the substrate 1. When not coated with the protective layer 3, the outer surface 6 of the substrate 1 is intended to be exposed to a flow of erosion-causing particles, such as water drops or solid particles.

[0028] The substrate 1 can be made of composite material and have a fibrous reinforcement densified by a matrix. The matrix can be an organic matrix, such as an epoxy resin. The fibrous reinforcement may consist of glass or carbon reinforcing fibers, or a mixture of such reinforcing fibers. Alternatively, the substrate 1 may be metallic, for example aluminum alloy.

[0029] The protective layer 3 comprises a resin 5 in which fibers 7 having an average length between 50 m and 500 m are dispersed. Average length is the length given by the statistical distribution to half the population (size D50). The mean length of the fibers may be between 80 m and 150 m.

[0030] As indicated above, the average fiber diameter may be 50 m or less. The diameter of a fiber refers to its largest transverse dimension. Average diameter is the diameter given by the statistical distribution to half the population.

[0031] The fibers 7 can be selected from: carbon fibers, glass fibers, silica fibers, basalt fibers, fibers of natural origin, such as flax fibers, and mixtures thereof. In particular, the fibers 7 can be carbon fibers.

[0032] The resin 5 can be a polyurethane resin. Alternatively, the resin 5 can be an epoxy resin.

[0033] According to an example, the protective layer 3 can be formed by dispersing the fibers 7 in a paint composition. The protective layer 3 may consist essentially of a paint composition comprising the fibers 7. An example of a paint composition that can be used in the invention is the paint marketed by BASF as RELEST Wind HS Topcoat RAL 7035. The fibers 7 may be present in the protective layer 3 in a mass content greater than or equal to 0.1%, for example greater than or equal to 2.5%, for example greater than or equal to 5%.

[0034] The fibers 7 can for example be present in the protective layer 3 in a mass content between 0.1% and 30%, for example between 0.1% and 10%. For example, the fibers 7 may be present in the protective layer 3 in a mass content between 2.5% and 25%, for example between 2.5% and 10%, or even between 5% and 10%.

[0035] The thickness e of the protective layer 3 may be greater than or equal to 50 m, for example 100 m.

[0036] FIG. 2 shows an example embodiment in which the outer surface 6 of the substrate 1 has been coated with several protective layers 3a and 3b filled with the fibers 7. The features of the protective layer 3 described in connection with FIG. 1 apply to each of the protective layers 3a and 3b. The protective layer 3b may be in contact with the protective layer 3a. The protective layer 3b may be the same as or different from the protective layer 3a. An example embodiment with two superimposed protective layers 3a and 3b has been shown. In an alternative not shown, the coating could consist of more than two superimposed layers filled with fibers 7.

[0037] In the examples in FIGS. 1 and 2, the outer layer of the coating overlying the substrate 1 (i.e. the layer furthest from the substrate 1) is formed by a layer 3 or 3b filled with fibers 7 of average length between 50 m and 500 m. However, it is not beyond the scope of the invention when this is not the case, as will now be described in connection with FIG. 3.

[0038] In the case of FIG. 3, the outer layer 4 of the coating overlying the substrate 1 is not filled by the fibers 7. The outer layer 4 can be a paint layer. The outer layer 4 can provide an anti-erosion function or an aesthetic function. The features of the protective layer 3 described in connection with FIG. 1 apply to the protective layer 3a in the example in FIG. 3. The outer layer 4 can be in contact with the protective layer 3. In an alternative not shown, it is possible to have a plurality of superimposed layers each filled with fibers 7, and an outer layer 4 covering these superimposed layers.

[0039] FIG. 4 shows an example in which the coated substrate 10 has an aerodynamic profile and here is a blade of wind turbine 10. According to this example, the protective layer 3 covers the leading edge of the substrate 10, among other things. The thickness of the protective layer 3 has been deliberately increased in FIG. 4 to be easier to read.

[0040] In this example, the substrate 10 is a rotating part, i.e. a part intended to be rotated. The coated substrate can be a moving part such as a blade, an aircraft wing or an aircraft fuselage. Alternatively, the substrate can be a fixed part such as the surface exposed to the external environment of an industrial equipment or building.

EXAMPLES

[0041] Various tests were carried out to evaluate the improvement in erosion resistance obtained by implementing the invention. The tests were all performed according to standard ASTM G73-10 (Standard test method for liquid impingement erosion using rotating apparatus).

Example 1

Comparison

[0042] A first test not of the invention was carried out for which the results are given in FIGS. 5A to 5D.

[0043] In this test, a paint marketed by BASF as RELEST Wind HS Topcoat RAL 7035 was applied to a substrate to form a coating with a thickness of about 150 m.

[0044] FIGS. 5A, 5B, 5C and 5D show the condition of the coating at 0, 30, 60 and 90 minutes, respectively.

[0045] The coating begins to be damaged after 60 minutes (FIG. 5C). Following this damage, erosion is then rapid. The coating is found to be completely eroded after 90 minutes (FIG. 5D).

Example 2

According to the Invention

[0046] A test according to the invention was carried out for which the results are given in FIGS. 6A to 6F.

[0047] During this test, carbon fibers cut to an average length of 120 m were dispersed in the paint marketed by BASF as RELEST Wind HS Topcoat RAL 7035. The average diameter of the fibers used was 7 m. This composition was then applied to a substrate to form a coating with a thickness of about 150 m. The coating formed had a carbon fiber content of 10% by mass.

[0048] FIGS. 6A, 6B, 6C, 6D, 6E and 6F show the condition of the coating at 0, 30, 60, 90, 120 and 150 minutes, respectively.

[0049] The presence of fibers in the protective layer modifies the mode of degradation and improves erosion resistance. When fibers are present, the surface condition of the protective layer is altered rather than eroded. The appearance of a breakthrough in the protective layer is postponed over time.

[0050] Visible traces can be seen as early as 60 minutes, indicating the change in the surface condition of the protective layer (FIGS. 6C-6E).

[0051] However, the first local breakthrough of the protective layer is only obtained after 150 minutes of testing (FIG. 6F). Furthermore, even after 150 minutes of testing, the protective layer is not completely eroded but only locally pierced, unlike in the test not of the invention according to Example 1 where complete erosion was achieved as early as 90 minutes.

Example 3

According to the Invention

[0052] A further test according to the invention was carried out for which the results are given in FIGS. 7A to 7D.

[0053] This test was identical to that in Example 2 with the difference that the formed coating had a carbon fiber content of 2.5% by mass.

[0054] FIGS. 7A, 7B, 7C and 7D show the condition of the coating at 0, 30, 60 and 90 minutes, respectively.

[0055] The coating in Example 3 has better erosion resistance than the coating in Example 1. After 90 minutes of testing, a local breakthrough is simply obtained, rather than complete erosion as in the test not of the invention according to Example 1.

[0056] The phrase between . . . and . . . should be understood to include the bounds.