MATERIAL FOR THIN, SMOOTH, AND HIGH-VELOCITY FLAME SPRAYED COATINGS WITH INCREASED DEPOSITION EFFICIENCY

Abstract

A thermal spray material feedstock is provided for flash-carbide coatings. Flash carbide coatings are thin, dense, and smooth thermal spray coatings that self-activate the substrate. Flash-carbide coatings form and peen the coating to impart compressive stress for good adhesion and corrosion resistance. To achieve this combination of properties and performance, a powder that includes fine, dense, and angular particles is used; however, this powder alone results in a poor deposition efficiency of typically less than 20%. The present disclosure mitigates the poor deposition efficiency of this powder alone by providing a composition having two or more different particles at a specific ratio to improve deposition efficiency with sufficient optimized stress and corrosion properties and, in some cases, an increase in coating performance.

Claims

1. A thermal spray material feedstock, comprising: (a) a first powder comprising first particles having a dense and angular morphology and an average measurable intra-particle porosity of 0% to 15%, and (b) a second powder comprising second particles having an average measurable intra-particle porosity of 5% to 35%.

2. The thermal spray material feedstock of claim 1, wherein the second powder has a predominantly spheroidal morphology.

3. The thermal spray material feedstock of claim 1, comprising a blend ratio of 5% to 50% of the second powder and 95% to 50% of the first powder, respectively.

4. The thermal spray material feedstock of claim 3, wherein the blend ratio is 10% to 40% of the second powder and 90% to 60% of the first powder, respectively.

5. The thermal spray material feedstock of claim 3, wherein the blend ratio is 20% to 35% of the second powder and 80% to 65% of the first powder, respectively.

6. The thermal spray material feedstock of claim 3, wherein the blend ratio is 25% of the second powder and 75% of the first powder.

7. The thermal spray material feedstock of claim 1, wherein the first particles are sintered and crushed.

8. The thermal spray material feedstock of claim 7, wherein the first particles comprise WCCoCr powder, carbides, or other hard phases in a metallic matrix, wherein the other hard phases comprise all carbides of elements from the periodic system of elements in groups IV, V, and VI, all borides of elements from the periodic system of elements from the periodic system of elements in groups IV, V, and VI, or alloyed carbides or borides of at least two elements from the periodic system of elements in groups IV, V, and VI.

9. The thermal spray material feedstock of claim 8, wherein the carbides are the types of WC, TiC, Cr.sub.3C.sub.2, VC, other carbides with alloy compositions containing Co, Cr, Ni, Fe, Cu, and other alloying elements.

10. The thermal spray material feedstock of claim 1, wherein the second particles are agglomerated and sintered.

11. The thermal spray material feedstock of claim 10, wherein the second particles comprise WCCoCr powder, carbides, or other hard phases in a metallic matrix, wherein the other hard phases comprise all carbides of elements from the periodic system of elements in groups IV, V, and VI, all borides of elements from the periodic system of elements from the periodic system of elements in groups IV, V, and VI, or alloyed carbides or borides of at least two elements from the periodic system of elements in groups IV, V, and VI.

12. The thermal spray material feedstock of claim 11, wherein the carbides are types of WC, TiC, Cr.sub.3C.sub.2, VC, and others in a metallic matrix with alloy compositions containing Co, Cr, Ni, Fe, Cu, and other alloying elements.

13. The thermal spray material feedstock of claim 10, wherein the second particles comprises Al.sub.2O.sub.3.

14. The thermal spray material feedstock of claim 10, wherein the second particles comprises carbides and nitrides of Si.

15. The thermal spray material feedstock of claim 1, wherein said thermal spray material feedstock has a deposition efficiency of more than 20%.

16. The thermal spray material feedstock of claim 1, wherein said thermal spray material feedstock has a deposition efficiency of 20% to 50%.

17. The thermal spray material feedstock of claim 1, wherein said thermal spray material feedstock has a deposition efficiency of 30% to 50%.

18. A method for manufacturing a flash-carbide coating comprising: thermal spraying the material feedstock of claim 1 onto a substrate surface to form a coating.

19. The method according to claim 18, wherein the thermal spraying process is performed by high-velocity air-fuel (HVAF) or high-velocity oxy-fuel (HVOF).

20. A flash carbide coating obtained from the thermal spray material according to claim 1.

21. The thermal spray material feedstock of claim 1, wherein the first particles have an average intra-particle porosity of 0% to 15% and the second particles have an average intra-particle porosity of 10% to 35%.

22. The thermal spray material feedstock of claim 11, wherein the first particles comprise the carbides, and the carbides have a primary average carbide size greater than 1 ?m.

23. The thermal spray material feedstock of claim 10, wherein the second particles comprise the carbides, and the carbides have a primary average carbide size less than 1 ?m.

24. The thermal spray material feedstock of claim 1, wherein the first powder comprising the first particles have an average measurable intra-particle porosity of 0.01% to 15%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present disclosure is further described in the detailed description which follows, in reference to the noted plurality of drawings, by way of non-limiting examples of preferred embodiments of the present disclosure.

[0023] FIG. 1 shows abrasion and cavitation data for modified powders, according to various embodiments.

[0024] FIG. 2 shows the deposition efficiency and Almen deflection residual stress for modified powders, according to various embodiments.

[0025] FIG. 3 shows the coating hardness and roughness for modified powders, according to various embodiments.

[0026] FIG. 4(A) is a SEM image showing dense, fine, and angular particles that have been sintered and crushed.

[0027] FIG. 4(B) is a SEM image showing spheroidal particles that have been agglomerated and sintered.

[0028] FIG. 4(C) is a SEM image showing a coating structure using a blend ratio of 25% of spheroidal particles that have been agglomerated and sintered and 75% dense, fine, and angular particles that have been sintered and crushed.

[0029] FIG. 5(A) is a lower magnification SEM image of blended feedstock powder showing the conforming versus non-conforming properties of two discrete particle types.

[0030] FIG. 5(B) is a higher magnification SEM image of a thermal sprayed coating of the blended powder showing the conforming versus non-conforming properties of two particle types within the coating structure.

DETAILED DESCRIPTION

[0031] FIG. 1 illustrates abrasion and cavitation data for modified powders, including AE12368, AE12870-1, AE12870-2, AE12870-3, and XW0595. AE12368 is a material that includes 100% dense, angular particles that have been sintered and crushed. XW0595 is a material that includes particles that are 100% manufactured by agglomeration and sintering and have predominantly spheroidal morphology typical for particles achieved by this manufacturing method AE12870-1 and AE12870-2 are materials that include 50% and 75% blends of agglomerated and sintered particles, respectively. AE12870-3 is a material that includes a blend ratio of 25% spheroidal particles that have been agglomerated and sintered and 75% dense, fine, and angular particles that have been sintered and crushed. The results of FIG. 1 show that the AE12870-1, AE12870-2, and AE12870-3 materials and the resulting coatings perform unexpectedly better in abrasion and cavitation than either the agglomerated and sintered material (XW0595) alone or the sintered and crushed material (AE12368) alone.

[0032] FIG. 2 illustrates the deposition efficiency and Almen deflection residual stress for modified powders, including AE12368, AE12870-1, AE12870-2, AE12870-3, and XW0595. The results of FIG. 2 show that the AE12870-1, AE12870-2, and AE12870-3 materials achieve a significantly higher deposition efficiency and compressive stress as shown by Almen deflection as compared to the sintered and crushed material alone (AE12368).

[0033] FIG. 3 illustrates the coating hardness and roughness for modified powders, including AE12368, AE12870-1, AE12870-2, AE12870-3, and XW0595. The results of FIG. 3 show that the AE12870-1, AE12870-2, and AE12870-3 materials retain a coating hardness and a low surface roughness similar to the sintered and crushed material alone (AE12368).

[0034] FIG. 4(A) shows a SEM image of the dense, fine, and angular particles that have been sintered and crushed.

[0035] FIG. 4(B) shows a SEM image of the spheroidal particles that have been agglomerated and sintered.

[0036] FIG. 4(C) shows that the AE12870-3 material provides a coating structure in which the spheroidal particles that have been agglomerated and sintered (lighter shade) deform around the dense, fine, and angular particles that have been sintered and crushed (darker shade).

[0037] FIG. 5(A) shows a lower magnification SEM image of blended feedstock powder of the conforming versus non-conforming properties of the two particle types. In FIG. 5(A), the lower density, i.e., higher intra-particle porosity, second powder includes a spheroidal second particle 501 and the higher density, i.e., lower intra-particle porosity, first powder includes a first particle 502 having an angular and irregular morphology.

[0038] FIG. 5(B) shows a higher magnification SEM image of a thermal spray coating from the blended powder of the conforming versus non-conforming properties of the two particle types. A comparison between FIG. 5(A) and FIG. 5(B) shows that the spherical second particle 501 deforms during spray operation to a flatter non-spherical second particle 503. The outlines of the flatter non-spherical second particle 503 depicted in FIG. 5(B) indicate that the spherical second particle 501 has subsequently been deformed. In some embodiments, the spherical second particle 501 has a sphericity of 0.9 or greater prior to spray operation and a sphericity of 0.8 or lower after spray operation.

[0039] In contrast, a comparison between FIG. 5(A) and FIG. 5(B) shows that the first particle 502 retains its shape more than the second particle 502 during spray operation as evidenced by the angular and irregular morphology of the after-spray operation first particle 504 in FIG. 5(B).

[0040] Considering the data in its entirety, it can be appreciated that the blend powders using 20% to 30% spheroidal particles that have been agglomerated and sintered provide superior and unexpected results in a combination of performance criteria. For instance, the results in FIG. 2 demonstrate that the AE12870-3 material achieves an improved deposition efficiency of from 18.9% to 31.6%, which is a 67% increase. In addition, the results in FIG. 1 demonstrate that the AE12870-3 material achieves an actual increase in abrasion and cavitation resistance. Finally, the results in FIG. 3 show that the AE12870-3 material yields the lowest As-sprayed surface roughness (Ra).

[0041] Further, at least because the invention is disclosed herein in a manner that enables one to make and use it, by virtue of the disclosure of particular exemplary embodiments, such as for simplicity or efficiency, for example, the invention can be practiced in the absence of any additional element or additional structure that is not specifically disclosed herein.

[0042] It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.