SURFACE TREATED ADDITIVE MANUFACTURING PRINTHEAD NOZZLES AND METHODS FOR THE SAME

Abstract

Nozzles for additive manufacturing and methods for improving wettability of the nozzles are disclosed. The nozzle may include a body having an inner surface and an outer surface. The inner surface may define an inner volume of the nozzle, and may have a water contact angle of greater than 1° and less than about 90°. The method may include subjecting the nozzle to a surface treatment. The surface treatment may include plasma treating a surface of the nozzle such that free radicals, polar functional groups, or a combination thereof are formed at the surface of the nozzle.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application No. 62/898,607, filed on Sep. 11, 2019, which is incorporated herein by reference to the extent consistent with the present disclosure.

TECHNICAL FIELD

The presently disclosed embodiments or implementations are directed to nozzles, such as nozzles for additive manufacturing devices or 3D printers, and methods for improving wetting or wettability of respective surfaces of the nozzles.

BACKGROUND

Magnetohydrodynamic (MHD) liquid metal jetting processes eject liquid or molten metal drops through a nozzle. To effectively facilitate the ejection of the liquid metal drops through the nozzle, it is necessary that the liquid metal sufficiently wets an inside surface of the nozzle. Conventional materials that may be used to fabricate the nozzles for MHD printheads, however, are not naturally wettable by liquid metal. Further, the materials utilized for the nozzles must be tolerable of relatively high temperatures, not very conductive, non-magnetic, and machinable. As such, ceramics or graphite are often utilized to fabricate the printhead housing and nozzles of MHD printheads. Ceramics and graphite, however, do not exhibit sufficient liquid metal wetting.

In view of the foregoing, conventional nozzles may often include a coating, such as a metallic wetting enhancement coating disposed along an inner surface thereof. For example, conventional nozzles may often include a nickel coating applied to the inner surface thereof via a vapor deposition or plating process. While the coating enhances liquid metal wetting along the inner surface of the nozzle, the coating also presents additional problems and challenges. For example, the coating may often interact with the liquid metal. In another example, the coating may introduce contamination that may eventually clog the nozzle.

What is needed, then, are improved nozzles and methods for improving wetting or wettability of the nozzles.

SUMMARY

The following presents a simplified summary in order to provide a basic understanding of some aspects of one or more embodiments of the present teachings. This summary is not an extensive overview, nor is it intended to identify key or critical elements of the present teachings, nor to delineate the scope of the disclosure. Rather, its primary purpose is merely to present one or more concepts in simplified form as a prelude to the detailed description presented later.

The present disclosure may provide a method for improving wettability of a nozzle for an additive manufacturing device. The method may include subjecting the nozzle to a surface treatment. The surface treatment may include plasma treating a surface of the nozzle. The plasma treatment may at least partially forms free radicals, polar functional groups, or combinations thereof at the surface of the nozzle.

In some examples, the surface treatment may include plasma treating an inner surface of the nozzle.

In some examples, plasma treating the inner surface of the nozzle may include orienting the nozzle at an off-axis orientation relative to a plasma of the plasma treatment.

In some examples, orienting the nozzle at the off-axis orientation may include disposing the nozzle on a fixture configured to maintain the nozzle at the off-axis orientation.

In some examples, plasma treating the inner surface of the nozzle further may include rotating the nozzle about a vertical axis thereof.

In some examples, the fixture may protect an end surface of the nozzle from the plasma treatment.

In some examples, the method may further include masking an end surface of the nozzle before subjecting the nozzle to the surface treatment.

In some examples, the surface treatment may include plasma treating the nozzle in a plasma oven.

In some examples, the surface treatment may include plasma treating an inner surface of the nozzle and an end surface of the nozzle.

In some examples, the method may further include removing a portion of the nozzle disposed adjacent the end surface of the nozzle.

In some examples, removing the portion of the nozzle disposed adjacent the end surface of the nozzle may include one or more of milling, filing, sanding, abrading, or combinations thereof.

In some examples, the surface treatment may include plasma treating the surface of the nozzle for a period of time of from about 1 min to about 60 min.

In some examples, the nozzle may be fabricated from graphite.

In some examples, the method may further include subjecting the nozzle to a post-treatment process to preserve the surface treatment of the nozzle. The post-treatment process may include contacting the surface of the nozzle with an intermediate sacrificial material.

In some examples, the post-treatment process may further include cooling the nozzle with the intermediate sacrificial material contacting the surface of the nozzle.

In some examples, the method may not include depositing a coating on the surface of the nozzle.

The present disclosure may provide a nozzle for additive manufacturing. The nozzle may include a body having an inner surface and an outer surface. The inner surface may define an inner volume of the nozzle, and the inner surface of the nozzle may have a water contact angle of greater than 1° and less than about 90°.

The present disclosure may provide a nozzle for additive manufacturing. The nozzle may include a body having an inner surface and an outer surface. The inner surface may define an inner volume of the nozzle. The inner surface of the nozzle may be subjected to a surface treatment such that the inner surface includes increased free radicals and/or polar functional groups as compared to an untreated surface of the nozzle.

In some examples, a coating is not disposed on the inner surface and the outer surface of the nozzle.

In some examples, the nozzle may further include an intermediate sacrificial material disposed in the inner volume of the nozzle.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present teachings. These and/or other aspects and advantages in the embodiments of the disclosure will become apparent and more readily appreciated from the following description of the various embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1A illustrates a schematic cross-sectional view of an exemplary 3D printer, according to one or more embodiments disclosed.

FIG. 1B illustrates an enlarged view of the nozzle of the 3D printer indicated by the box labeled “1B” of FIG. 1A, according to one or more embodiments disclosed.

FIG. 2 is a plot illustrating the growth of occlusions in the control nozzle of Example 1.

FIG. 3 is a plot illustrating the growth of occlusions in the test nozzle of Example 1.

DETAILED DESCRIPTION

The following description of various typical aspect(s) is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses.

As used throughout, ranges are used as shorthand for describing each and every value that is within the range. Any value within the range may be selected as the terminus of the range. In addition, all references cited herein are hereby incorporated by reference in their entireties. In the event of a conflict in a definition in the present disclosure and that of a cited reference, the present disclosure controls.

Additionally, all numerical values are “about” or “approximately” the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art. It should be appreciated that all numerical values and ranges disclosed herein are approximate values and ranges, whether “about” is used in conjunction therewith. It should also be appreciated that the term “about,” as used herein, in conjunction with a numeral refers to a value that may be ±0.01% (inclusive), ±0.1% (inclusive), ±0.5% (inclusive), ±1% (inclusive) of that numeral, ±2% (inclusive) of that numeral, ±3% (inclusive) of that numeral, ±5% (inclusive) of that numeral, ±10% (inclusive) of that numeral, or ±15% (inclusive) of that numeral. It should further be appreciated that when a numerical range is disclosed herein, any numerical value falling within the range is also specifically disclosed.

As used herein, the term “or” is an inclusive operator, and is equivalent to the term “and/or,” unless the context clearly dictates otherwise. The term “based on” is not exclusive and allows for being based on additional factors not described, unless the context clearly dictates otherwise. In the specification, the recitation of “at least one of A, B, and C,” includes embodiments containing A, B, or C, multiple examples of A, B, or C, or combinations of A/B, A/C, B/C, A/B/B/ BB/C, AB/C, etc. In addition, throughout the specification, the meaning of “a,” “an,” and “the” include plural references. The meaning of “in” includes “in” and “on.”

Reference will now be made in detail to exemplary embodiments of the present teachings, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same, similar, or like parts.

The present disclosure is directed to nozzles, such as nozzles for additive manufacturing devices or 3D printers, and methods for improving wetting or wettability of respective surfaces (e.g., inner and/or outer surfaces) of the nozzles. As used herein, the term “wettability” or the like may refer to the ability of a liquid to maintain contact with a solid surface, resulting from intermolecular interactions when the liquid and the solid are brought together or contacted with one another. A degree of wetting or wettability may be determined by a force balance between adhesive and cohesive forces. Adhesive forces between the liquid and the solid may cause a liquid drop to spread across the surface. Cohesive forces within the liquid may cause the drop to “ball up” and avoid contact with the surface. A relatively higher wettability of a surface towards a specific liquid implies that the specific liquid will spread to a higher degree across the solid surface. As further described herein, the methods may include exposing or subjecting respective surfaces of the nozzles to one or more surface treatments to thereby modify (e.g., chemically modify) the respective surfaces of the nozzles. The surface treatments may directly modify the respective surfaces of the nozzles, and thereby improve wettability of the respective surfaces without a coating.

FIG. 1A illustrates a schematic cross-sectional view of an exemplary additive manufacturing layering device or 3D printer 100 that may utilize the nozzles disclosed herein, according to one or more embodiments. The 3D printer 100 may be a magnetohydrodynamic (MHD) printer. It should be appreciated, however, that any additive manufacturing device may utilize the nozzles and methods disclosed herein. The 3D printer 100 may include a body 102, which may also be referred to herein as a pump chamber, one or more heating elements (one is shown 104), one or more metallic coils 106, a stage 108, a substrate 110, a computing system 112, or any combination thereof, operably coupled with one another. As illustrated in FIG. 1A, the heating elements 104 may be at least partially disposed about the body 102, and the metallic coils 106 may be at least partially disposed about the body 102 and/or the heating elements 104. As further illustrated in FIG. 1A, the substrate 110 may be disposed on the stage 108 and below the body 102. The body 102 may include an inner surface 114 defining an inner volume 116 thereof. The body 102 may define a nozzle 118 disposed at a first end portion 120 thereof. FIG. 1B illustrates an enlarged view of the nozzle 118 of the 3D printer 100, indicated by the box labeled “1B” of FIG. 1A, according to one or more embodiments.

In an exemplary operation of the 3D printer 100 with continued reference to FIGS. 1A and 1B, a build material (e.g., metal) from a source 122 may be directed to the inner volume 116 of the body 102. The heating elements 104 may at least partially melt the build material contained in the inner volume 116 of the body 102. For example, the build material may be a solid, such as a solid metal, and the heating elements 104 may heat the body 102 and thereby heat the build material from a solid to a liquid (e.g., molten metal). The metallic coils 106 may be coupled with a power source (not shown) capable of or configured to facilitate the deposition of the build material on the substrate 110. For example, the metallic coils 106 and the power source coupled therewith may be capable of or configured to generate a magnetic field, which may generate an electromotive force within the body 102, thereby generating an induced electrical current in the molten metal disposed in the body 102. The magnetic field and the induced electrical current in the molten metal may create a radially inward force on the liquid metal, known as a Lorenz force, which creates a pressure at the nozzle 118. The pressure at the nozzle 118 may expel the molten metal out of the nozzle 118 toward the substrate 110 and/or the stage 108 in the form of one or more drops.

Referring back to FIG. 1B, the nozzle 118 may include or be fabricated from one or more ceramic and/or graphitic materials. Illustrative ceramic and/or graphitic materials may be or include, but are not limited to, graphite, boron nitride, silicon nitride, aluminum nitride, aluminum oxide, composites thereof, or combinations thereof.

In at least one embodiment, a portion 126 of the inner surface 114, a portion 128 of an outer surface 124, and/or a portion 132 of an end surface 134 of the body 102 or the nozzle 118 thereof may be modified. For example, as further described herein, the inner, outer, and/or end surfaces 114, 124, 134 of the body 102 or the nozzle 118 thereof may be exposed or subjected to one or more surface treatments or surface treatment processes to thereby modify respective portions 126, 128, 132 of the body 102 or the nozzle 118 thereof. As used herein, the expressions “surface treatment” or “surface treatment process” may refer to a process that will modify (e.g., chemically modify) a surface to improve the direct wetting interaction or wettability between the modified surface and a build material (e.g., molten metal). Accordingly, in at least one embodiment, the respective portions 126, 128, 132 of the inner, outer, and/or end surfaces 114, 124, 134 may be chemically different than remaining portions 130 of the nozzle 118 not exposed to the one or more surface treatments.

In at least one embodiment, the one or more surface treatments may include plasma treating the inner, outer, and/or end surfaces 114, 124, 134 of the nozzle 118 with a device capable of or configured to generate a plasma. As used herein, the term or expression “plasma treatment” or the like may refer to a process in which a gas is ionized to form plasma and alter a surface of a material. Plasma treatment may include introducing one or more gases (e.g., mixture of gases) and energizing the gases with a source of power (e.g., radio frequency). Illustrative gases that may be utilized in the plasma treatment may be or include, but are not limited to, oxygen, nitrogen, argon, hydrogen, carbon tetrafluoride, or combinations thereof. In at least one embodiment, the plasma treatment may be conducted in a sealed chamber, such as a sealed vacuum chamber. The chamber may be maintained at a negative pressure (e.g., low pressure vacuum). In another embodiment, the plasma treatment may be conducted in open air/atmosphere outside of a chamber. In at least one embodiment, the one or more gases may not need to be introduced. For example, the device capable of or configured to generate the plasma may not need a source of the one or more gases and/or may be conducted in atmospheric conditions. Illustrative devices may be or include PLASMA WAND, which is commercially available from Plasma Etch, Inc. of Carson City, NV.

In at least one embodiment, the device capable of or configured to generate the plasma may be a plasma oven maintained at a low pressure. It should be appreciated that in some plasma ovens, the plasma uses ions that may be directionally accelerated in a radio frequency (RF) field. For example, in some plasma ovens, the plasma uses ions that are accelerated downward in the RF field, thereby providing the plasma in the downward direction. In such plasma ovens, it may be difficult to subject some surfaces, such as the inner surface 114 of the nozzle 118 to the plasma. As such, in at least one embodiment, the plasma treatment may include orienting or maintaining the nozzle 118 at a slightly off-axis orientation to facilitate contact between the directional plasma and the target surfaces 114, 124, 134 of the nozzle 118. For example, FIG. 2 illustrates the nozzle 118 maintained at an off-axis orientation to facilitate contact between the directional plasma 200 and the inner surface 114 of the nozzle 118. In an exemplary embodiment, illustrated in FIG. 2, a fixture or support 202 may be utilized to maintain the off-axis orientation of the nozzle 118. As illustrated in FIG. 2, the fixture 202 may orient the nozzle 118 such that a vertical axis 204 of the nozzle 118 may be angled or may form an angle (θ) with respect to a vertical axis 206 of the fixture 202. The angle (θ) may be any angle to allow contact between the directional plasma 200 and the inner surface 114 of the nozzle 118. In at least one embodiment, the nozzle 118 may be rotated to facilitate complete radial contact between the directional plasma 200 and the radial inner surface 114 of the nozzle 118. For example, the nozzle 118 may be rotated about the vertical axis 204 to thereby facilitate contact between the directional plasma 200 and the radial inner surface 114 thereof. It should be appreciated that the fixture 202 may also protect or prevent the end surface 134 of the nozzle 118 from being subjected to the surface treatment, thereby maintaining the end surface 134 in a native, untreated state.

In at least one embodiment, all of the inner, outer, and/or end surfaces 114, 124, 134 of the nozzle 118 may be subjected to the one or more surface treatments. In another embodiment, only one of the inner, outer, and/or end surfaces 114, 124, 134 of the nozzle 118 may be subjected to the one or more surface treatments. For example, only the inner surface 114 of the nozzle 118 is subjected to the one or more surface treatments. In another example, only the outer surface 124 of the nozzle 118 is subjected to the one or more surface treatments. In yet another example, only the end surface 134 of the nozzle 118 is subjected to the one or more surface treatments.

In a preferred implementation, the end surface 134 of the nozzle 118 is not subjected to the one or more surface treatments or the end surface 134 is subjected to the one or more surface treatments, but portions 132 of the nozzle 118 that are modified are subsequently removed from the nozzle 118. For example, in at least one embodiment, the surface treatment may include subjecting the end surface 134 to the plasma treatment to modify the portion 134 or the end surface 134, and subsequently removing the modified portion 134 or end surface 134 via a subsequent process. The subsequent process to remove the modified portion 134 and/or the end surface 134 may include any physical process sufficient to remove material (e.g., graphite) from the nozzle 118. For example, the subsequent process to remove the modified portion 134 and/or the end surface 134 may include milling, filing, sanding, abrading, or the like, or combinations thereof. In at least one embodiment, the surface treatment may include masking, protecting, or otherwise covering the end surface 134 of the nozzle 118 prior to the plasma treatment to thereby prevent modification of the end surface 134 and the portion 132.

The inner, outer, and/or end surfaces 114, 124, 134 of the nozzle 118 may be subjected to the one or more surface treatments for an amount of time sufficient to substantially or completely modify the respective surfaces 114, 124, 134 or the respective portions 126, 128, 132 of the nozzle 118. In at least one embodiment, the inner, outer, and/or end surfaces 114, 124, 134 of the nozzle 118 may be subjected to the one or more surface treatments for a period of from about 1 min to about 60 min. For example, the inner, outer, and/or end surfaces 114, 124, 134 of the nozzle 118 may be subjected to the one or more surface treatments for a period of from about 1 min, about 5 min, about 10 min, about 15 min, about 20 min, about 30 min, about 40 min, about 50 min, or about 55 min to about 60 min. In another example, the inner, outer, and/or end surfaces 114, 124, 134 of the nozzle 118 may be subjected to the one or more surface treatments for a period of from about 1 min to about 5 min, about 10 min, about 15 min, about 20 min, about 30 min, about 40 min, about 50 min, about 55 min, or about 60 min. In yet another example, the inner, outer, and/or end surfaces 114, 124, 134 of the nozzle 118 may be subjected to the one or more surface treatments for a period of from about 1 min, about 5 min, about 10 min, about 15 min, about 20 min, or about 30 min to about 40 min, about 50 min, about 55 min, or about 60 min.

In an exemplary embodiment, the nozzle 118 may be fabricated from graphite. Without being bound by theory, it is believed that the surface treatment with the plasma may at least partially clean the respective surfaces 114, 124, 134 of the nozzle 118. It is also believed that the plasma may at least partially form or produce free radicals, thereby making the respective surfaces 114, 124, 134 relatively more reactive. It is further believed that the plasma may at least partially form polar functional groups at the respective surfaces 114, 124, 134. Illustrative polar functional groups are known in the art and may at least partially depend on the material used to fabricate the nozzle 118, one or more parameters of the plasma treatment, or combinations thereof. As further discussed herein, the wettability may be measured with a goniometer. As such, the degree of the plasma treatment may be measured with the goniometer as well.

The respective portions 126, 128, 132 of the nozzle 118 that are modified with the surface treatment may have a thickness of from about 1 Angstrom (Å) to about 500 Å. For example, the respective portions 126, 128, 132 of the nozzle 118 that are modified with the surface treatment may have a thickness of from about 1 Å, about 5 Å, about 10 Å, about 50 Å, about 100 Å, or about 150 Å to about 200 Å, about 250 Å, about 300 Å, about 350 Å, about 400 Å, or about 500 Å. In another example, the respective portions 126, 128, 132 of the nozzle 118 that are modified with the surface treatment may have a thickness of greater than 1 Å and less than or equal to 500 Å, less than or equal to 400 Å, less than or equal to 300 Å, less than or equal to 200 Å, less than or equal to 100 Å, less than or equal to 50 Å, or less than or equal to 10 Å. In yet another example, the respective portions 126, 128, 132 of the nozzle 118 that are modified with the surface treatment may have a thickness of from about 1 Å to about 500 Å, about 100 Å to about 400 Å, or about 200 Å to about 300 Å. It should be appreciated that the thickness of the respective portions 126, 128 are significantly thinner than a coating, such as a coating prepared from electroless plating (e.g., nickel coating), which may have a thickness of from about 1 μm to about 100 μm, more typically from about 10 μm to about 25 μm.

As used herein, the expression “water contact angle” may refer to the angle that deionized water or a test liquid contacts a surface. The water contact angle may be measured with any suitable goniometer. The inner, outer, and/or end surfaces 114, 124, 134 of the nozzles 118 that are modified via the surface treatment may have a water contact angle of greater than 1° and less than about 90°, less than about 50°, less than about 40°, less than about 30°, less than about 25°, less than about 20°, less than about 15°, or less than about 10°. In another example, the inner, outer, and/or end surfaces 114, 124, 134 of the nozzles 118 that are modified via the surface treatment may have a water contact angle of from about 1° to about 90°, about 5° to about 80°, about 10° to about 70°, about 15° to about 60°, about 20° to about 50°, or about 20° to about 40°. Illustrative test liquids may be or include, but are not limited to, water, ethylene glycol, diiodomethane, or the like, or combinations thereof.

In at least one embodiment, the inner, outer, and/or end surfaces 114, 124, 134 of the nozzles 118 that are modified via the surface treatment may have a relatively smoother surface (e.g., less roughness) as compared to an untreated surface.

In at least one embodiment, the surface treated inner, outer, and/or end surfaces 114, 124, 134 and/or the modified portions 126, 128, 132 of the nozzle 118 may be exposed or subjected to a subsequent or post-treatment process capable of or configured to at least partially protect or maintain the surface treated properties of the modified inner, outer, and/or end surfaces 114, 124, 134 and/or the modified portions 126, 128, 132 of the nozzle 118. For example, the surface treated inner, outer, and/or end surfaces 114, 124, 134 and/or the modified portions 126, 128, 132 may exhibit gradual losses of the functionality when exposed to atmospheric conditions. As such, the inner, outer, and/or end surfaces 114, 124, 134 and/or the modified portions 126, 128, 132 may be subjected to a subsequent process that may at least partially halt, reduce, or otherwise slow the loss of functionality, thereby at least partially preserving the functionality.

In at least one embodiment, the post-treatment process may include storing and/or sealing the treated nozzles 118 in vacuum-packed, hermetically sealed bags. In another embodiment, the post-treatment process may include contacting the inner, outer, and/or end surfaces 114, 124, 134 and/or the modified portions 126, 128, 132 with an intermediate sacrificial material. The inner, outer, and/or end surfaces 114, 124, 134 and/or the modified portions 126, 128, 132 of the nozzle 118 may be contacted with the intermediate sacrificial material immediately after the surface treatment, or shortly thereafter. For example, the respective surfaces 114, 124 and/or the modified portions 126, 128 may be contacted with the intermediate sacrificial material within about 2 hours of the surface treatment (e.g., about 0 hours to about 2 hours). In at least one embodiment, the post-treatment process may also include draining the intermediate sacrificial material from the nozzle 118. The post-treatment process may also include subsequently cooling the nozzle 118 for storage. In some examples, the intermediate sacrificial material may not be drained from the nozzle 118 prior to cooling. As such, the nozzle 118 may be cooled with the intermediate sacrificial material disposed in the inner volume 116 and/or with the intermediate sacrificial material contacting the inner, outer, and/or end surfaces 114, 124, 134.

The intermediate sacrificial material may have thermal expansion properties similar or substantially similar to the nozzle 118 to thereby maintain structural integrity (e.g., reduce cracking) of the nozzle 118 while cooling the nozzle 118. For example, the intermediate sacrificial material may have similar thermal expansion properties to the nozzle 118 at a temperature of from about room temperature to a melting point of the intermediate sacrificial material.

The intermediate sacrificial material may have a relatively low melting point to thereby introduce less thermal stress, and enable displacement by a molten build material or a primary jetting metal during printing. The melting point of the intermediate sacrificial material may be substantially equal to or less than an operating temperature or melting temperature of the build material. For example, the melting point of the intermediate sacrificial material may be from about 400° C., about 450° C., about 500° C., or about 560° C. to about 660° C., about 700° C., about 750° C., about 800° C., about 900° C., about 1000° C., about 1100° C., about 1200° C., about 1400° C., or about 1500° C.

The intermediate sacrificial material may be compatible with the build material or the primary jetting metal. For example, the intermediate sacrificial material may at least partially dissolve or combine with the molten build material during jetting, thereby replacing or removing the intermediate sacrificial material from the nozzle 118 during printing or jetting. It should be appreciated that the intermediate sacrificial material introduced into the nozzle 118 does not form a coating during normal printing operations or processes. For example, during a printing process the molten build material flowing through the nozzle 118 will displace, eject, or otherwise remove the intermediate sacrificial material from the nozzle 118.

The intermediate sacrificial material may be or include one or more metals, metal alloys, or combinations thereof. Illustrative metals and metal alloys that may be utilized for the intermediate sacrificial material may be or include, but are not limited to, the build material intended to be utilized in the 3D printer 100, aluminum, one or more soldering alloys, metals having a melting point of from about 500° C. to about 700° C., about 560° C. to about 660° C., or lower, or the like, or any combination thereof.

As used herein, the term or expression “coating” may refer to a physical barrier that separates an original or native surface of the nozzle 118 from a build material (e.g., molten metal) flowing through and/or contained in the nozzle 118. For example, a coating may refer to a material deposited (e.g., post-fabrication of the nozzle 118) on the inner, outer, and/or end surfaces 114, 124, 134 of the nozzle 118 to separate the inner, outer, and/or end surfaces 114, 124, 134 of the nozzle 118 from the molten metal flowing through and/or contained in the inner volume 116 of the nozzle 118. A coating may result in the formation of two interfaces or surface interfaces. For example, a coating may create an interface between inner, outer, and/or end surfaces 114, 124, 134 of the nozzle 118 and the coating. In another example, the coating may create an interface between the coating and the molten metal flowing through and/or contained in the nozzle 118. As noted above, coatings may generally have a thickness of from about 1 μm to about 100 μm, or more typically from about 10 μm to about 25 μm. Coatings may be deposited via various processes/techniques, such as sputtering, evaporation, electroplating, electroless plating, or the like, or any combination thereof. In at least one embodiment, the nozzle 118 disclosed herein may not include a coating. For example, the nozzle 118 and the inner, outer, and/or end surfaces 114, 124, 134 thereof may be free or substantially free of a coating. Accordingly, the inner, outer, and/or end surfaces 114, 124, 134 and/or the respective modified portions 126, 128, 132 of the nozzle 118 may directly contact the melted build material (e.g., molten metal) flowing through or contained in the nozzle 118

EXAMPLES

The examples and other implementations described herein are exemplary and not intended to be limiting in describing the full scope of compositions and methods of this disclosure. Equivalent changes, modifications and variations of specific implementations, materials, compositions and methods may be made within the scope of the present disclosure, with substantially similar results.

Example 1

A plurality of nozzles were subjected to surface treatment and evaluated for jetting stability and contamination or occlusion growth. Particularly, graphite nozzles were treated with a plasma. It was observed that plasma treating for about 15 sec to about 20 sec improved wettability of the nozzles. The treated nozzles produced straight streams of the molten metal when utilized in a liquid metal jetting process. It was also observed that the meniscus formed in treated nozzles were flush with the respective end surfaces thereof. It was further observed that plasma treating the nozzles prevented occlusion growth in the nozzles.

The present disclosure has been described with reference to exemplary implementations. Although a limited number of implementations have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these implementations without departing from the principles and spirit of the preceding detailed description. It is intended that the present disclosure be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims

1. A method for improving wettability of a nozzle for an additive manufacturing device, the method comprising subjecting the nozzle to a surface treatment, wherein the surface treatment comprises plasma treating a surface of the nozzle, wherein the plasma treatment at least partially forms free radicals, polar functional groups, or combinations thereof at the surface of the nozzle.

2. The method of claim 1, wherein the surface treatment comprises plasma treating an inner surface of the nozzle.

3. The method of claim 2, wherein plasma treating the inner surface of the nozzle comprises orienting the nozzle at an off-axis orientation relative to a plasma of the plasma treatment.

4. The method of claim 3, wherein orienting the nozzle at the off-axis orientation comprises disposing the nozzle on a fixture configured to maintain the nozzle at the off-axis orientation.

5. The method of claim 4, wherein plasma treating the inner surface of the nozzle further comprises rotating the nozzle about a vertical axis thereof.

6. The method of claim 4, wherein the fixture protects an end surface of the nozzle from the plasma treatment.

7. The method of claim 1, further comprising masking an end surface of the nozzle before subjecting the nozzle to the surface treatment.

8. The method of claim 1, wherein the surface treatment comprises plasma treating the nozzle in a plasma oven.

9. The method of claim 1, wherein the surface treatment comprises plasma treating an inner surface of the nozzle and an end surface of the nozzle.

10. The method of claim 9, further comprising removing a portion of the nozzle disposed adjacent the end surface of the nozzle.

11. The method of claim 10, wherein removing the portion of the nozzle disposed adjacent the end surface of the nozzle comprises one or more of milling, filing, sanding, abrading, or combinations thereof.

12. The method of claim 1, wherein the surface treatment comprises plasma treating the surface of the nozzle for a period of time of from about 1 min to about 60 min.

13. The method of claim 1, wherein the nozzle is fabricated from graphite.

14. The method of claim 1, further comprising subjecting the nozzle to a post-treatment process to preserve the surface treatment of the nozzle, wherein the post-treatment process comprises contacting the surface of the nozzle with an intermediate sacrificial material.

15. The method of claim 14, wherein the post-treatment process further comprises cooling the nozzle with the intermediate sacrificial material contacting the surface of the nozzle.

16. The method of claim 1, wherein the method does not comprise depositing a coating on the surface of the nozzle.

17. A nozzle for additive manufacturing, comprising a body having an inner surface and an outer surface, wherein the inner surface defines an inner volume of the nozzle, and wherein the inner surface of the nozzle comprises a water contact angle of greater than 1° and less than about 90°.

18. A nozzle for additive manufacturing, comprising a body having an inner surface and an outer surface, wherein the inner surface defines an inner volume of the nozzle, and wherein the inner surface of the nozzle is subjected to a surface treatment such that the inner surface comprises increased free radicals and/or polar functional groups as compared to an untreated surface of the nozzle.

19. The nozzle of claim 18, wherein a coating is not disposed on the inner surface and the outer surface of the nozzle.

20. The nozzle of claim 18, further comprising an intermediate sacrificial material disposed in the inner volume of the nozzle.