Patent Application
20210205927
The present disclosure relates generally to surface coatings and, more particularly, to surface coatings having a nanoparticle modification of a feedstock powder applied to a metallic component via a laser cladding process.
Numerous aerospace products or systems include components that are exposed to harsh operating conditions (e.g., high temperature or salt or sulfur-based environments) that result in corrosion or oxidation to the surfaces of the components. Protective coatings are thus critical to ensure durability. While several coating options exist, many use deposition methods (e.g., electrochemical deposition or plating or chemical vapor deposition) that are expensive because of a need to dispose of process byproducts as hazardous waste. Deposition methods also tend to debit or detract from the thermal and electrical properties of the component (e.g., the process or coating reduces thermal conductivity for a heat exchanger) or rely upon compositions having constituents (e.g., Cr) that may soon be banned due to environmental regulations. To address these issues a protective coating methodology that produces minimal waste, limits property debits to the part, and avoids reliance on systems with regulatory restrictions is desirable.
A system for forming a coating having a plurality of nanosized particles on a work surface is disclosed. In various embodiments, the system includes a laser configured to direct a laser beam at a focal region on the work surface; and an applicator configured to direct a nanoparticle coated feedstock powder at the focal region of the work surface.
In various embodiments, the nanoparticle coated feedstock powder comprises a metallic powder. In various embodiments, the nanoparticle coated feedstock powder comprises a plurality of nanosized oxide particles. In various embodiments, the nanoparticle coated feedstock powder is prepared via an acoustic mixing apparatus. In various embodiments, the plurality of nanosized oxide particles is attached to the metallic powder via an electrostatic attraction. In various embodiments, the plurality of nanosized oxide particles comprises a rare earth oxide.
In various embodiments, the laser beam is configured to create a melt pool on the work surface and the applicator is configured to direct the nanoparticle coated feedstock powder at the melt pool. In various embodiments, the melt pool comprises molten material from both the work surface and the nanoparticle coated feedstock powder.
In various embodiments, the system further includes an acoustic mixing apparatus configured to prepare the nanoparticle coated feedstock powder via a resonant acoustic mixing process. In various embodiments, the system also includes a particle feed system configured to transport the nanoparticle coated feedstock powder from the acoustic mixing apparatus to the applicator.
A method of forming a coating containing a plurality of nanosized particles on a work surface is disclosed. In various embodiments, the method includes directing a laser beam at a focal region on the work surface; directing a nanoparticle coated feedstock powder comprising the plurality of nanosized particles toward the focal region of the work surface; and forming a melt pool at the focal region, the melt pool comprising molten material from both the work surface and the nanoparticle coated feedstock powder.
In various embodiments, the method further includes forming a uniform distribution of the plurality of nanosized particles throughout the melt pool. In various embodiments, the method further includes solidifying the melt pool to lock in place the uniform distribution of the plurality of nanosized particles throughout the melt pool.
In various embodiments, the nanoparticle coated feedstock powder comprises a metallic powder and a plurality of nanosized oxide particles. In various embodiments, the nanoparticle coated feedstock powder is prepared via an acoustic mixing apparatus. In various embodiments, the plurality of nanosized oxide particles is attached to the metallic powder via an electrostatic attraction.
In various embodiments, the laser beam is configured to form the melt pool on the work surface and an applicator is configured to direct the nanoparticle coated feedstock powder at the melt pool. In various embodiments, the nanoparticle coated feedstock powder comprises metallic particles that are generally spherical in shape. In various embodiments, the metallic particles comprise an alloy. In various embodiments, the plurality of nanosized oxide particles comprise a rare earth metal.
The forgoing features and elements may be combined in any combination, without exclusivity, unless expressly indicated herein otherwise. These features and elements as well as the operation of the disclosed embodiments will become more apparent in light of the following description and accompanying drawings.
The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the following detailed description and claims in connection with the following drawings. While the drawings illustrate various embodiments employing the principles described herein, the drawings do not limit the scope of the claims.
The following detailed description of various embodiments herein makes reference to the accompanying drawings, which show various embodiments by way of illustration. While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that changes may be made without departing from the scope of the disclosure. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected, or the like may include permanent, removable, temporary, partial, full or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. It should also be understood that unless specifically stated otherwise, references to “a,” “an” or “the” may include one or more than one and that reference to an item in the singular may also include the item in the plural. Further, all ranges may include upper and lower values and all ranges and ratio limits disclosed herein may be combined.
The following disclosure provides a method of coupling a feedstock powder coated with nanosized particles (or nanoparticles) with a laser cladding process to deposit dispersion strengthened coatings onto metallic parts for enhanced corrosion resistance. Resonant acoustic mixing is employed to attach the nanoparticles to the feedstock powder via an electrostatic attraction. The rapid melting from the laser cladding process disperses the nanoparticles in a melt pool and a high solidification rate locks the nanoparticles in place to preclude agglomeration. The end result is a coating with a relatively uniform dispersion of the nanoparticles throughout. The nanoparticles of specific focus are rare earth oxides (e.g., Y2O3, CeO2, or the like), which have historically been shown to exhibit a reactive element effect that slows corrosion. For example, nanosized oxide particles dispersed in a metal matrix provide excellent creep resistance to improve retention of strength at high temperatures. In addition to rare earth oxides, in various embodiments, the nanosized particles may include non-oxides, such as, for example, carbides (e.g., tungsten carbide or titanium carbide or the like), nitrides (e.g., tungsten nitride or zirconium nitride or the like) or borides (e.g., aluminum diboride (AlB2) or titanium diboride (TiB2) or the like.
Referring now to
Still referring to
In various embodiments, the plurality of nanosized oxide particles 108 is coated onto the outer surface 102 of the particle of feedstock powder 100 via an acoustic mixing process or a resonant acoustic mixing process. Rather than mechanical agitation, via, for example, a drive mechanism or impeller, acoustic mixing induces microscale turbulence through propagating acoustic waves throughout a medium, such as, in this instance, the nanosized oxide particles and the feedstock powder. The acoustic mixing process may be carried out using an acoustic mixer, such as, for example, those sold under the tradename Resodyn™, by Resodyn Acoustic Mixers, Inc., of Butte, Mont. In various embodiments, for example, an acoustic mixer is able to coat between one to thirty-five kilograms (1 to 35 kg) of feedstock powder with nanoparticles in approximately five minutes (5 min). In various embodiments, a volume percentage of the nanoparticles to feedstock powder ranges from between one-tenth volume percent (0.1 vol %) to sixteen volume percent (16.0 vol %) or more; while in various embodiments, a volume percentage of the nanoparticles to feedstock powder ranges from between one-half volume percent (0.5 vol %) to three volume percent (3.0 vol %). The acoustic mixing process is advantageous as it provides a substantial improvement over more conventional methods of doping feedstock powders with nanosized oxides, whereby the oxides are ball-milled or attrition milled or otherwise mechanically alloyed to form the feedstock powder, which are expensive and prone to material contamination and morphology changes. Instead, the feedstock powder experiences no adverse effects on the individual metallic particles of the powder maintaining their generally spherical shape, as the nanoparticles are attached to the individual metallic particles of the feedstock powder via an electrostatic attraction.
Referring now to
As further illustrated in
Referring now to
Referring now to
Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure. The scope of the disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Different cross-hatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials.
Systems, methods and apparatus are provided herein. In the detailed description herein, references to “one embodiment,” “an embodiment,” “various embodiments,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.
Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
Finally, it should be understood that any of the above described concepts can be used alone or in combination with any or all of the other above described concepts. Although various embodiments have been disclosed and described, one of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. Accordingly, the description is not intended to be exhaustive or to limit the principles described or illustrated herein to any precise form. Many modifications and variations are possible in light of the above teaching.
