Syntactic foam parts and related methods of manufacture

Abstract

A syntactic lightweight foam made of low density spheres embedded in a resin.SOLUTION: Disclosed herein are syntactic foam components and methods of making syntactic foam components. The method includes loading micro-sized low density spheres into a mold that includes a macro tolerance region and a macro restriction region. The method also includes loading macro-sized low density spheres into the mold. Thereby, the macro-sized low density spheres are surrounded by the micro-sized low density spheres and each one is spaced apart from any other one of the macro-sized low density spheres. All of the macro-sized low density spheres are completely within the macro-tolerance area of the mold. The method introduces a resin into the mold to fill the mold and embed the micro-sized low density spheres and the macro-sized low density spheres, and solidifies the resin after the resin fills the mold.SELECTED DRAWING: Figure 5A

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE

[0001] This disclosure relates generally to lightweight foams, and more particularly to syntactic lightweight foams made of low density spheres embedded in a resin. [Background technology]

[0002]

[0002] Lightweight foams are incorporated into components to facilitate their lightweight nature in higher density fluids. Some components that incorporate lightweight foams include, but are not limited to, submarines, ships, oil rigs and their components, offshore platforms, and other marine-based systems. Typical lightweight foams are compression resistant and, in some cases, water resistant, durable, and reliable. Producing lightweight foams with these properties in an efficient, cost-effective, and reliable manufacturing process can be difficult. Summary of the Invention

[0003]

[0003] The subject matter of the present application was developed in response to the current state of the art, and in particular in response to the shortcomings of conventional lightweight foams and conventional methods of making such lightweight foams. These shortcomings have not yet been fully addressed by currently available technology. Accordingly, the subject matter of the present application was developed to provide syntactic foam parts and corresponding methods of making such parts, which overcome at least some of the shortcomings of the prior art.

[0004]

[0004] Below is a non-exhaustive list of several examples of the subject matter disclosed in this specification, which may or may not be claimed.

[0005]

[0005] A method for making a syntactic foam part is disclosed herein. The method includes loading micro-sized low-density spheres into a mold, where the mold includes a macro-allowable region and a macro-restricted region. The method also includes loading the macro-sized low-density spheres into the mold, whereby the macro-sized low-density spheres are surrounded by the micro-sized low-density spheres, each macro-sized low-density sphere is spaced apart from any other macro-sized low-density sphere, some of the micro-sized low-density spheres are between adjacent macro-sized low-density spheres, and each macro-sized low-density sphere is entirely within one of the macro-allowable regions of the mold. The diameter of the macro-sized low-density spheres is at least 10 times larger than the diameter of the micro-sized low-density spheres. The method further includes introducing a resin into the mold to fill the mold and embed the micro-sized low-density spheres and the macro-sized low-density spheres in the resin. The method further includes solidifying the resin after the resin has filled the mold. The preceding subject matter of this paragraph characterizes Example 1 of the present disclosure.

[0006]

[0006] When the resin embeds the micro-sized low-density spheres, a parent foam is formed that surrounds the macro-sized low-density spheres. The entire macro-restricted area is filled with the parent foam. The preceding subject matter of this paragraph characterizes Example 2 of the present disclosure, which also includes subject matter according to Example 1 above.

[0007] Prior to loading the macro-sized low-density spheres into the mold, each of the macro-sized low-density spheres is coated with a coating material to form a coating layer that entirely surrounds each of the macro-sized low-density spheres. The coating layer has a coating thickness, and the coating layer at least partially prevents each of the macro-sized low-density spheres from entering the macro-restricted region of the mold. The preceding subject matter of this paragraph characterizes Example 3 of the present disclosure, which also includes subject matter according to Examples 1 or 2 above.

[0008] Each one of the macro-sized low-density spheres is spaced from any other one of the macro-sized low-density spheres by at least a minimum distance. The minimum distance is twice the coating thickness of the coating layer. The preceding subject matter of this paragraph characterizes Example 4 of the present disclosure, which also includes subject matter according to Example 3 above.

[0009]

[0009] The coating material of the coating layer is a syntactic foam containing micro-sized low-density spheres and a coating resin. The preceding subject matter of this paragraph characterizes Example 5 of the present disclosure, and Example 5 also includes subject matter according to Example 3 above.

[0010] Prior to loading the macro-sized low-density spheres into the mold, the method includes adding a plurality of spacing devices to each one of the macro-sized low-density spheres at various locations around the periphery of a corresponding one of the macro-sized low-density spheres. Each one of the plurality of spacing devices has a spacing length. The spacing device at least partially prevents each one of the macro-sized low-density spheres from entering the macro-restricted region of the mold. The preceding subject matter of this paragraph characterizes Example 6 of the present disclosure, which also includes subject matter according to any one of Examples 1 to 5 described above.

[0011]

[0011] Before loading the macro-sized low-density spheres and micro-sized low-density spheres into the mold, the method includes coating at least one interior wall of the mold with a boundary layer made of a boundary material. The boundary layer has a boundary thickness that defines at least a portion of the macro-restricted region of the mold. The boundary layer at least partially prevents each one of the macro-sized low-density spheres from entering at least a portion of the macro-restricted region of the mold. The preceding subject matter of this paragraph characterizes Example 7 of the present disclosure, which also includes subject matter according to any one of Examples 1 to 6 above.

[0012]

[0012] The macro-sized low-density spheres are placed in a predetermined location within the macro-permissive region of the mold using a placement tool. The preceding subject matter of this paragraph characterizes Example 8 of the present disclosure, which also includes subject matter according to any one of Examples 1 to 7 above.

[0013] The macro-sized low-density spheres further include first macro-sized low-density spheres having a first diameter and second macro-sized low-density spheres having a second diameter. The second diameter of the second macro-sized low-density spheres is at least two times larger than the first diameter of the first macro-sized low-density spheres. The preceding subject matter of this paragraph characterizes Example 9 of the present disclosure, which also includes subject matter according to any one of Examples 1 to 8 above.

[0014] The macro-sized low-density spheres are uniformly arranged in the mold, whereby the spacing between adjacent macro-sized low-density spheres is the same. The preceding subject matter of this paragraph characterizes Example 10 of the present disclosure, which also includes subject matter according to any one of Examples 1 to 9 above.

[0015] The macro-sized low-density spheres have a first density. After the resin is solidified, the resin with the embedded micro-sized low-density spheres (114) forms a parent foam having a second density. The first density is less than the second density. The preceding subject matter of this paragraph characterizes Example 11 of the present disclosure, which also includes subject matter according to any one of Examples 1 to 10 above.

[0016]

[0016] Further disclosed herein is a syntactic foam part. The syntactic foam part includes a macro-permissive region and a macro-restrictive region adjacent to the macro-permissive region. Macro-sized low-density spheres are disposed within the micro-sized low-density spheres, whereby the macro-sized low-density spheres are surrounded by the micro-sized low-density spheres, each macro-sized low-density sphere is spaced apart from any other macro-sized low-density sphere, some of the micro-sized low-density spheres are between adjacent macro-sized low-density spheres, and each macro-sized low-density sphere is entirely contained within one of the macro-permissive regions. The diameter of the macro-sized low-density spheres is at least 10 times larger than the diameter of the micro-sized low-density spheres. The syntactic foam part also includes a resin having embedded therein the macro-sized low-density spheres and the micro-sized low-density spheres. The preceding subject matter of this paragraph characterizes Example 12 of the present disclosure.

[0017]

[0017] The parent foam is formed by a resin with embedded micro-sized low density spheres, and the entire macro-restricted region is filled with a foam matrix. The preceding subject matter of this paragraph characterizes Example 13 of the present disclosure, which also includes subject matter according to Example 12 above.

[0018] Each one of the macro-sized low-density spheres is coated with a coating material to form a coating layer that entirely surrounds each one of the macro-sized low-density spheres. The coating layer has a coating thickness, and the coating layer at least partially prevents each one of the macro-sized low-density spheres from entering the macro-restricted region. Each one of the macro-sized low-density spheres is spaced from any other one of the macro-sized low-density spheres by a minimum distance of at least twice the coating thickness of the coating layer. The preceding subject matter of this paragraph characterizes Example 14 of the present disclosure, which also includes subject matter according to Examples 12 or 13 above.

[0019]

[0019] The resin having embedded therein the macro-sized low-density spheres and the micro-sized low-density spheres defines an intermediate part having a sidewall. A boundary layer is bonded to the sidewall of the intermediate part. The boundary layer is made of a boundary material and has a boundary thickness that defines at least a portion of the macro-restricted region of the mold. The boundary layer at least partially prevents each one of the macro-sized low-density spheres from entering the macro-restricted region of the mold. The preceding subject matter of this paragraph characterizes Example 15 of the present disclosure, which also includes subject matter according to any one of Examples 12 to 14 described above.

[0020]

[0020] The diameter of the micro-sized low-density spheres is less than 100 microns. The preceding subject matter of this paragraph characterizes Example 16 of the present disclosure, which also includes subject matter according to any one of Examples 12 to 15 above.

[0021]

[0021] The macro-sized low-density spheres have a diameter of 0.5 inches or more. The preceding subject matter of this paragraph characterizes Example 17 of the present disclosure, which also includes subject matter according to any one of Examples 12 to 16 above.

[0022]

[0022] Further disclosed herein is a method for making a syntactic foam part. The method includes loading micro-sized low-density spheres into a first mold. The method also includes loading macro-sized low-density spheres into the first mold, whereby the macro-sized low-density spheres are surrounded by the micro-sized low-density spheres, each macro-sized low-density sphere is spaced from any other macro-sized low-density sphere, some of the micro-sized low-density spheres are between adjacent macro-sized low-density spheres, and each macro-sized low-density sphere is completely within the macro-acceptable region of the first mold. The diameter of the macro-sized low-density spheres is at least 10 times larger than the diameter of the micro-sized low-density spheres. The method further includes introducing a resin into the first mold to fill the first mold, embedding the micro-sized low-density spheres and the macro-sized low-density spheres in the resin, and solidifying the resin after the resin fills the first mold to form an intermediate part. The method also includes removing the intermediate part from the first mold and loading the intermediate part into a second mold having a larger volume than the first mold. The intermediate part is thereby spaced from at least one inner wall of the second mold, and a peripheral region is defined between the at least one inner wall of the second mold and the intermediate part. The peripheral region defines at least a portion of the macro-restricted region of the second mold. The method further includes introducing an interface material into the peripheral region of the second mold, whereby the interface material fills the peripheral region. The method further includes solidifying the interface material after it fills the peripheral region to form a boundary layer bonded to the sidewall of the intermediate part. The preceding subject matter of this paragraph characterizes Example 18 of the present disclosure.

[0023] The interface material is at least partially formed of a parent foam comprising micro-sized low density spheres and a resin. The preceding subject matter of this paragraph characterizes Example 19 of the present disclosure, which also includes subject matter according to Example 18 above.

[0024]

[0024] Before loading the macro-sized low-density spheres into the first mold, the method includes coating each one of the macro-sized low-density spheres with a coating material to form a coating layer that entirely surrounds each one of the macro-sized low-density spheres. The coating layer has a coating thickness. Each one of the macro-sized low-density spheres is spaced from any other one of the macro-sized low-density spheres by at least a minimum distance. The minimum distance is twice the coating thickness of the coating layer. The preceding subject matter of this paragraph characterizes Example 20 of the present disclosure, which also includes subject matter according to Examples 18 or 19 above.

[0025] The described features, structures, advantages, and / or characteristics of the presently disclosed subject matter may be combined in any suitable manner in one or more examples and / or embodiments. In the following description, numerous specific details are presented to facilitate a comprehensive understanding of the embodiments of the presently disclosed subject matter. Those skilled in the art will recognize that the presently disclosed subject matter can be practiced without one or more of the specific features, details, components, materials, and / or methods of a particular example or implementation. In other cases, additional features and advantages may be recognized in particular examples and / or implementations, but may not be present in all examples or implementations. Furthermore, in some instances, well-known structures, materials, or steps have not been described or shown in detail so as not to obscure aspects of the presently disclosed subject matter. The features and advantages of the presently disclosed subject matter will become more apparent from the following description and appended claims, or may be learned by practicing the subject matter as described below.

[0026]

[0026] So that the advantages of the present subject matter may be more readily understood, a more detailed description of the subject matter outlined above will be given by reference to specific embodiments illustrated in the accompanying drawings. It will be understood that these drawings, which are not necessarily drawn to scale, depict only certain examples of the subject matter and therefore should not be considered limiting of its scope, and that the subject matter will be described with added specificity and detail using the drawings. [Brief explanation of the drawings]

[0027] [Figure 1]

[0027] FIG. 1 is a schematic front elevation view of macro-sized low-density spheres and micro-sized low-density spheres being loaded into a mold in accordance with one or more embodiments of the present disclosure. [Figure 2A]

[0028] 1A-1C are schematic cross-sectional views of hollow macro-sized low density spheres and hollow micro-sized low density spheres, in accordance with one or more embodiments of the present disclosure. [Figure 2B]

[0029] 1A-1C are schematic cross-sectional views of solid macro-sized low density spheres and solid micro-sized low density spheres, according to one or more embodiments of the present disclosure. [Figure 3]

[0030] FIG. 1 is a schematic front elevation view of a plurality of first macro-sized low-density spheres, second macro-sized low-density spheres, and micro-sized low-density spheres in a mold in accordance with one or more embodiments of the present disclosure. [Figure 4]

[0031] 1 is a schematic partial front elevation view of a macro-sized low-density sphere with a coating layer in a mold in accordance with one or more embodiments of the present disclosure. FIG. [Figure 5A]

[0032] 1 is a schematic front elevation view of micro-sized low-density spheres and macro-sized low-density spheres with a coating layer in a mold, in accordance with one or more embodiments of the present disclosure. FIG. [Figure 5B]

[0033] 1 is a schematic front elevation view of a micro-sized low-density sphere in a mold with a boundary layer and a macro-sized low-density sphere with a coating layer, in accordance with one or more embodiments of the present disclosure. FIG. [Figure 6]

[0034] 5B is a schematic front elevation view of resin being introduced into and filling the mold of FIG. 5A in accordance with one or more embodiments of the present disclosure. [Figure 7]

[0035] FIG. 5B is a schematic front elevation view of a syntactic foam part formed in the mold of FIG. 5A in accordance with one or more embodiments of the present disclosure. [Figure 8]

[0036] FIG. 1 is a schematic flow diagram of a method of making a syntactic foam part according to one or more embodiments of the present disclosure. [Figure 9]

[0037] 1 is a schematic flowchart of a method of making a syntactic foam part according to one or more embodiments of the present disclosure. [Figure 10]

[0038] 1 is a schematic flowchart of a method of making a syntactic foam part according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0028]

[0039] When reference is made herein to "one embodiment," "an embodiment," or similar phrases, it means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. The phrases "one embodiment," "an embodiment," and similar phrases appearing throughout this specification may, but do not necessarily, all refer to the same embodiment. Similarly, the term "embodiment" means an embodiment having a particular feature, structure, or characteristic described in connection with one or more embodiments of the present disclosure, but the embodiment may be associated with one or more embodiments unless there is a clear correlation suggesting otherwise.

[0029]

[0040] Some conventional methods for making syntactic foam parts involve assembling micro-sized, low-density spheres with a single size distribution into a mold and injecting resin into the spheres, embedding them to form the part. Such spheres limit the packing efficiency (i.e., volume fraction) of the mold, typically below 74 percent. The packing efficiency can be increased by introducing additional micro-sized, low-density spheres with a different size distribution. However, increasing the packing density by adding smaller spheres makes it difficult to infuse the resin into the spheres. This infusion difficulty increases the infusion time required to form the part or, in some cases, prevents the resin from being fully infused throughout the part. Ultimately, this can limit the size and complexity of parts that can be fabricated.

[0030]

[0041] Described herein are several examples of methods for making syntactic foam parts. These examples incorporate both micro-sized low-density spheres and macro-sized low-density spheres embedded in resin. The methods improve the packing efficiency of the foam while maintaining a desired level of resin permeability. Furthermore, the inclusion of macro-sized low-density spheres reduces the overall density of the syntactic foam part, thereby improving its lightweight performance. By integrating macro-sized low-density spheres within micro-sized low-density spheres, the methods efficiently reduce the part's density and improve packing efficiency without the adverse effects of overly packed micro-sized low-density spheres. The macro-sized low-density spheres are strategically placed within the syntactic foam part to minimize localized stress concentrations at the points where the macro-sized low-density spheres are closest. These stress concentrations can result in fracture of individual macro-sized low-density spheres or the parent foam between the spheres (i.e., the micro-sized low-density spheres embedded in resin), which can be detrimental to part performance. Additionally, the macro-sized low density spheres are positioned to ensure that they are not machined during subsequent processing.

[0031]

[0042] According to some embodiments, a method 200 for making a syntactic foam part, such as syntactic foam part 148 of FIG. 7, is shown in FIG. 9. Referring generally to FIG. 9 and particularly to FIG. 1, method 200 includes loading micro-sized low-density spheres 114 into a mold 102 (block 202). Method 200 also includes loading macro-sized low-density spheres 112 into macro-permissive regions 115 of the mold 102 (block 204). That is, the mold 102 includes macro-permissive regions 115 within which the macro-sized low-density spheres 112 are permitted to be placed within the mold 102. The mold 102 also includes macro-restrictive regions 117 within which the macro-sized low-density spheres 112 are not permitted to be placed within the mold 102. The macro-permissive regions 115 within the mold 102 are strategically positioned to ensure the integrity of the resulting syntactic foam part and avoid areas that may be exposed to high stress or machining in subsequent processing. In contrast, macro-restricted regions 117 are designated areas where high stresses or machining may occur and, in some cases, may include buffer zones extending beyond these regions. In other words, macro-restricted regions 117 include areas where removal of or damage to the syntactic foam could compromise the strength or function of syntactic foam part 148 if macro-sized low-density spheres 112 were present within those regions. Thus, macro-restricted regions 117 ensure that the structural design of syntactic foam part 148 accounts for the necessary clearances and buffer zones to maintain part integrity under expected operating conditions.

[0032]

[0043] In certain embodiments, the macro-restricted region 117 may include an edge of the syntactic foam part 148. Additionally or alternatively, in some embodiments, the macro-restricted region 117 may include an area designated for subsequent machining to prevent damage to the foam structure or the integrity of the macro-sized low-density spheres 112 during subsequent processing. Additionally, in other embodiments, the macro-restricted region 117 may include the space between adjacent macro-sized low-density spheres 112. Furthermore, in certain embodiments, the entire macro-restricted region 117 may be filled with micro-sized low-density spheres 114, which are subsequently embedded with resin to form a parent foam. As used herein, parent foam refers to a particular type of syntactic foam formed from the micro-sized low-density spheres 114 and resin 144 (see, e.g., FIG. 6 ). In other embodiments, at least a portion of the macro-restricted region 117 may include a material other than the micro-sized low-density spheres 114, thereby devoid of the micro-sized low-density spheres 114. For example, portions of the macro-restricted region 117 may include only resin, a resin matrix composite, or similar materials. Alternatively, and in other embodiments, the entire macro-restricted region 117 is devoid of micro-sized low-density spheres 114.

[0033]

[0044] In some embodiments, the mold 102 includes a selectively openable lid 106 that selectively covers an opening in the mold 102. Through this opening, the micro-sized low-density spheres 114 and the macro-sized low-density spheres 112 can be loaded into the mold 102. The macro-sized low-density spheres 112 are added to the mold 102 such that the macro-sized low-density spheres 112 are surrounded by the micro-sized low-density spheres 114. For simplicity, the micro-sized low-density spheres 114 are not shown in the mold 102, but the micro-sized low-density spheres 114 can fill any area of ​​the mold 102 where the macro-sized low-density spheres 112 are missing. In particular, each macro-sized low-density sphere 112 is spaced apart from every other macro-sized low-density sphere 112 such that some of the micro-sized low-density spheres 114 are between adjacent macro-sized low-density spheres 112. That is, the macro-sized low density spheres 112 are not in direct contact with each other.

[0034]

[0045] The required spacing between adjacent macro-sized low-density spheres 112 may depend on the inherent strength of the spheres themselves, with inherently stronger spheres being placed closer together than inherently weaker spheres. Proper placement of the macro-sized low-density spheres 112 is important to avoid stress concentrations in the resulting part. Because the spheres are macro-sized and significantly larger than the micro-sized low-density spheres 114, their spacing relative to the mold 102 and each other can be controlled. Thus, the minimum spacing between the macro-sized low-density spheres 112 is intentional and need not be as far apart as shown in the representation. In addition to being spaced apart from each other, each one of the macro-sized low-density spheres 112 resides entirely within one of the macro-acceptance regions 115 of the mold 102. According to some embodiments using both macro-sized low-density spheres 112 and micro-sized low-density spheres 114, the packing efficiency for all or a portion of the mold 102 is at least 76%, e.g., at least 84% packed in one embodiment, and at least 95% packed in another embodiment.

[0035]

[0046] The mold 102 forms part of the molding tool 100. The molding tool 100 further includes a resin introduction system. The resin introduction system is operable to introduce resin into the internal cavity 104 of the mold 102. In some embodiments, the resin introduction system includes a resin inlet 108 and a resin outlet 110. The resin inlet 108 is operable to introduce resin from a resin source in the resin introduction system into the internal cavity 104 (see, for example, FIG. 6 ). The resin outlet 110 is operable to release excess resin from the internal cavity 104. Each one of the resin inlets 108 and the resin outlets 110 may include a valve selectively operable to regulate the flow of resin into and out of the internal cavity 104, respectively. In the illustrated embodiment, the resin inlet 108 is located at the bottom of the mold 102, and the resin outlet 110 is located at the top of the mold 102. In other embodiments, the resin inlet 108 and the resin outlet 110 may be located at other respective locations on the mold 102.

[0036]

[0047] The size and shape of the internal cavity 104 of the mold 102 define the size and shape of the syntactic foam part 148 (see, e.g., FIG. 7 ). The syntactic foam part 148, and therefore the internal cavity 104 of the mold 102, can have any of a variety of shapes and sizes, including, without limitation, a regular shape (e.g., a rectangular-based prism, a cuboid, a cube, a pyramid, a cone, a dodecahedron, etc.) or a complex shape. Note that the macro-sized low-density spheres 112, the micro-sized low-density spheres 114, and the mold 102 are not necessarily drawn to scale. For example, in the depicted representation, the size of the macro-sized low-density spheres 112 is abnormally large relative to the size of the mold 102 to more clearly illustrate and explain the present invention. In reality, the sizes of the macro-sized low-density spheres 112 and the micro-sized low-density spheres 114 will be significantly smaller relative to the size of the mold 102 than depicted.

[0037]

[0048] The macro-sized low-density spheres 112 have a first size distribution that is larger than a second size distribution of the micro-sized low-density spheres 114. The size distributions of both the macro-sized low-density spheres 112 and the micro-sized low-density spheres 114 account for slight variations in size that may occur due to the manufacturing process of the spheres. As shown in FIGS. 2A and 2B , the diameter D1 of the macro-sized low-density spheres 112 is at least 10 times larger than the diameter D2 of the micro-sized low-density spheres 114. In some embodiments, the maximum diameter D1 of the macro-sized low-density spheres 112 is between 0.5 inches and 6 inches, inclusive, such as between 1 inch and 6 inches, inclusive, in certain embodiments, such as between 1 inch and 3 inches, inclusive, in another embodiment, and such as between 3 inches and 6 inches, inclusive, in yet other embodiments. Furthermore, in some embodiments, the maximum diameter D2 of the micro-sized low-density spheres 114 is between 20 microns and 5000 microns, inclusive, such as between 30 microns and 500 microns, inclusive, in certain embodiments, such as between 30 microns and 250 microns, inclusive, in another embodiment, etc. For example, in certain cases, the maximum diameter D2 of the micro-sized low-density spheres 114 is 100 microns or less.

[0038]

[0049] Furthermore, the size and shape of the internal cavity 104 of the mold 102 dictates the maximum diameter D1 of the macro-sized low-density spheres 112. In particular, the maximum diameter D1 is determined relative to the smallest dimension of the internal cavity 104. For example, in certain cases, the maximum diameter D1 of the macro-sized low-density spheres 112 may not exceed 75% of the smallest diameter of the internal cavity 104 in one embodiment, 50% in other embodiments, and 30% in still other embodiments. Furthermore, as the size and shape of the internal cavity 104 of the mold 102 decreases, the maximum diameter D1 of the macro-sized low-density spheres 112 decreases proportionately.

[0039]

[0050] According to some embodiments, as shown in FIGS. 1, 2A, and 3-8, each or at least one of the macro-sized low-density spheres 112 is a hollow sphere 116A. Referring to FIG. 2A, the hollow sphere 116A has a hollow interior space 120 defined by an inner surface 122 of a sidewall that also defines an outer surface 124 of the macro-sized low-density sphere 112. The hollow sphere 116A has a thin-walled structure. In other words, the thickness T1 of the sidewall is less than the radius of the macro-sized low-density sphere 112. Furthermore, in some embodiments, each or at least one of the micro-sized low-density spheres 114 is a hollow sphere 118A. Like the hollow sphere 116A, the hollow sphere 118A has a hollow interior space 126 defined by an inner surface 122 of a sidewall that also defines an outer surface 124 of the micro-sized low-density sphere 114. The hollow sphere 118A has a thin-walled structure having a thickness T2. Hollow spheres 116A and 118A may be made of any of a variety of materials, including, but not limited to, glass (e.g., borosilicate glass, quartz, and soda-lime glass), ceramic (e.g., silicon carbide, boron carbide, silicon nitride), and polymers.

[0040]

[0051] In alternative embodiments, such as those shown in FIG. 2B , each or at least one of the macro-sized low-density spheres 112 is a solid foam sphere 116B. The solid foam sphere 116B does not have a single hollow space, such as the hollow sphere 116A. Rather, the foam sphere 116B is made of a solid piece of foam having a plurality of hollow spaces in the form of open or closed cells. In some embodiments, the foam sphere 116B is made of one or more of polystyrene foam, expanded polystyrene (EPS) foam, expanded polypropylene (EPP) foam, polyethylene foam, polyurethane foam, and / or various other types of foam. In other embodiments, the foam sphere 116B is made of one or more syntactic foams formed from micro-sized low-density spheres and resin. In still other embodiments, the foam sphere 116B is made of one or more of ceramic foam or metal foam. Additionally, in some embodiments, each or at least one of the micro-sized low density spheres 114 is a solid foam sphere 118B.

[0041]

[0052] The macro-sized low-density spheres 112 have a first density. The micro-sized low-density spheres 114 have a second density when embedded in resin to form a parent foam. The first density of the macro-sized low-density spheres 112 is less than the second density of the parent foam. Thus, by including the macro-sized low-density spheres 112 in the mold 102, the resulting syntactic foam part has a lower part density compared to a syntactic foam part made entirely of the parent foam. As used herein, in certain embodiments, the micro-sized low-density spheres 114 have a density of 0.005 g / cm, inclusive. 3 and 0.6 g / cm 3 For example, in one embodiment, 0.05 g / cm 3 and 0.4 g / cm 3 and in another embodiment, 0.1 g / cm 3 and 0.3 g / cm 3and in yet another embodiment, 0.02 g / cm 3 and 0.15 g / cm 3 and in a further embodiment, 0.015 g / cm 3 and 0.03 g / cm 3 A hollow or solid sphere having a density between .

[0042]

[0053] In some embodiments, such as that shown in FIG. 1, all of the macro-sized low-density spheres 112 loaded into the mold 102 in block 204 have the same size distribution. However, in other embodiments, such as that shown in FIG. 3, the macro-sized low-density spheres 112 loaded into the mold 102 in block 204 may have different size distributions. In FIG. 3, for example, first macro-sized low-density spheres 112A having a first diameter D1 are loaded into the mold 102 along with second macro-sized low-density spheres 112B having a second diameter D3. In this case, the second macro-sized low-density spheres 112B are larger than the first macro-sized low-density spheres 112A. The mold 102 may include various quantities of the first macro-sized low-density spheres 112A and the second macro-sized low-density spheres 112B, depending on the size and shape of the mold 102.

[0043]

[0054] The second macro-sized low-density spheres 112B can be significantly larger than the first macro-sized low-density spheres 112A. In one embodiment, the second macro-sized low-density spheres 112B are between 2 and 25 times larger, inclusive, than the first macro-sized low-density spheres 112A. For example, in one embodiment, the second macro-sized low-density spheres 112B are between 3 and 15 times larger, inclusive, than the first macro-sized low-density spheres 112A. In another embodiment, the second macro-sized low-density spheres 112B are between 5 and 10 times larger, inclusive, than the first macro-sized low-density spheres 112A. Furthermore, in some embodiments, the second macro-sized low-density spheres 112B are at least two times larger than the first macro-sized low-density spheres 112A. In some embodiments, the second macro-sized low-density spheres 112B are at least seven times larger than the first macro-sized low-density spheres 112A. This allows smaller spheres to fit into the spaces between the larger spheres, optimizing packing density. Optimizing the quantity of each, as well as the spacing between the spheres, can improve packing efficiency and structural integrity of the final part. Optimization can consider the spatial distribution and placement of the spheres to maintain desired mechanical properties and prevent stress concentrations within the mold 102. Thus, in some embodiments, the sizes of the first macro-sized low-density spheres 112A and the second macro-sized low-density spheres 112B are selected in consideration of the size of the mold 102. Differently sized macro-sized low-density spheres 112 can thereby optimize space within the macro-allowable region 115. In one embodiment, the second macro-sized low-density spheres 112B are the same type of sphere (e.g., the same material) as the first macro-sized low-density spheres 112A, but are larger. However, in alternative embodiments, the second macro-sized low-density spheres 112B are a different type of sphere from the first macro-sized low-density spheres 112A. Similarly, the micro-sized low-density spheres 114 surrounding the macro-sized low-density spheres 112 can similarly have two or more size distributions.

[0044]

[0055] 4, in some embodiments, the macro-sized low-density spheres 112 are pre-coated with a coating layer 132 before being loaded into the mold 102 at block 204. The coating layer 132 has a substantially uniform (i.e., non-varying) coating thickness T c That is, the coating layer 132 is attached to the outer surface 124 of the macro-sized low-density spheres 112. The coating layer 132 may be made of any of a variety of coating materials, such as, but not limited to, a resin matrix composite, a nanoscale material, glass, water glass, colloidal silica nanoparticles, a polymer, or a ceramic. In some examples, the coating layer 132 is made of a syntactic foam that includes micro-sized low-density spheres, such as the micro-sized low-density spheres 114, and a coating resin. The coating resin may be the same resin used to embed the spheres in the mold 102 or a different resin. For example, the syntactic foam may be pre-coated onto the macro-sized low-density spheres 112 using a castable foam. Furthermore, the coating material may be porous or solid. In one example, the thickness T of the coating layer 132 relative to the diameter of the macro-sized low-density spheres 112 is c However, the diameter is between 0.05 and 1 times the diameter inclusive, for example, in one embodiment, between 0.1 and 0.75 times the diameter inclusive, and in another embodiment, between 0.2 and 0.5 times the diameter inclusive.

[0045]

[0056] The coating layer 132 can be used to space the macro-sized low-density spheres 112 from any other one of the macro-sized low-density spheres 112. Thus, the coating layer 132 maintains a uniform separation between the macro-sized low-density spheres 112 and prevents direct contact between the spheres. The uniform separation ensures that the macro-sized low-density spheres 112 are properly spaced to minimize localized stress concentrations that would otherwise lead to fracture of the matrix within or surrounding the spheres. In particular, the coating layer 132 maintains a minimum distance d between adjacent macro-sized low-density spheres 112. min In this case, the minimum distance d min is twice the coating thickness of the coating layer 132. In other words, the coating layer 132 on the first macro-sized low-density sphere combined with the coating layer 132 on the second macro-sized low-density sphere is smaller than the minimum distance d between the two spheres. min Additionally, in some cases, coating layer 132 may be used to provide strength and / or add thermal conductivity to the underlying macro-sized low-density spheres 112.

[0046]

[0057] The coating layer 132 may, in certain cases, be used to at least partially prevent the macro-sized low-density spheres 112 from entering the macro-restricted region 117 of the mold 102. For example, the coating layer 132 may prevent the macro-sized low-density spheres 112 from entering the macro-restricted region 117 of the mold 102 within a distance d side As shown in the figure, the distance d side is equal to the width of the macro-restricted region 117 along the side 134 and bottom 136. The coating layer 132 thereby prevents the macro-sized low-density spheres 112 from entering the macro-restricted region 117. In these cases, the macro-sized low-density spheres 112 can be placed within the mold 102 without further consideration of their spacing from the interior walls. When the width of the macro-restricted region 117 is equal to the width of the coating layer T cIn other embodiments where the thickness is greater than 1 / 2 mm, additional measures can be used to prevent the macro-sized low-density spheres 112 from entering the macro-restricted region 117, such as by placing the macro-sized low-density spheres 112 at specific locations within the mold 102.

[0047]

[0058] Although coating 132 is shown in some embodiments as having a single layer, in some embodiments coating layer 132 may have multiple layers of coating material, thereby increasing the thickness T of coating layer 132. c is the combined thickness of the individual layers of coating layer 132. The coating materials of the multiple layers of coating layer 132 can be the same type of coating material or different types of coating materials. For example, if coating layer 132 is of different types of coating materials, a first coating material applied over macro-sized low-density spheres 112 can be a coating material that seals the macro-sized low-density spheres 112, and the second and subsequent layers can be coating materials that are stronger than the coating material that seals the macro-sized low-density spheres 112. According to another embodiment in which the coating materials of coating layer 132 are of different types of coating materials, the first coating material applied over macro-sized low-density spheres 112 can be a solid or homogenous coating material, and the second and subsequent layers can be a composite coating material with small microspheres.

[0048]

[0059] Additionally or alternatively, the coating layer 132 may use spacing devices 113 to space the macro-sized low-density spheres 112 from any other one of the macro-sized low-density spheres 112. Spacing devices 113 are components used to maintain a predetermined distance or gap between the macro-sized spheres. As shown in FIG. 1, each one of the spacing devices 113 has a spacing length L s Thereby, the macro-sized low density spheres 112 have a spacing length of at least L sThe macro-sized low-density spheres 112 are spaced apart from one another by spacing tabs 113A. For example, referring to FIG. 1 , each of the macro-sized low-density spheres 112 may include spacing tabs 113A. The spacing tabs 113A, shown in dotted lines, are small protrusions located at various positions around the circumference of the macro-sized low-density spheres 112. The spacing tabs 113A ensure that the macro-sized low-density spheres 112 do not come into contact with each other or the side walls of the mold. The spacing tabs 113A may be made of any of a variety of materials, such as syntactic foam, plastic, rubber, or metal, which have sufficient elasticity to maintain their spacing function during the resin embedding process.

[0049]

[0060] 5A , the entire mold 102 is filled with macro-sized low-density spheres 112 and micro-sized low-density spheres 114. Each one of the macro-sized low-density spheres 112 is pre-coated with a coating layer 132, thereby spacing the macro-sized low-density spheres 112 from one another and from the interior surfaces of the mold 102, including the side surfaces 134, bottom surface 136, and top surface 138 of the mold 102. As shown, the coating layer 132 prevents the macro-sized low-density spheres 112 from entering the macro-restricted region 117 of the mold 102, and therefore the macro-sized low-density spheres 112 can be added to the mold 102 without further edge placement requirements. In some cases, the macro-sized low-density spheres 112 can be randomly placed (i.e., without intentional placement) within the mold 102, and the coating layer 132 satisfies all spacing requirements for the mold 102. This includes maintaining the proper distance between adjacent spheres and preventing spheres from entering the macro-restricted regions 117. The number of macro-sized low-density spheres 112 that can fit into the mold 102 can be maximized so that the coating layers 132 of each adjacent sphere contact each other at contact points 142. Thus, in some embodiments, the coating layer 132 of one macro-sized low-density sphere 112 can contact the coating layer 132 of another macro-sized low-density sphere 112 at contact points 142. The macro-sized low-density spheres 112 are surrounded by micro-sized low-density spheres 114. The micro-sized low-density spheres 114 fill the remaining space in the mold, including the gaps 140 between the macro-sized low-density spheres 112.

[0050]

[0061] In some embodiments, the macro-sized low-density spheres 112 are placed at predetermined locations within the macro-permissive region 115 of the mold 102 using a placement tool. Placing the macro-sized low-density spheres 112 in predetermined locations using a placement tool ensures proper spacing between the spheres and adjacent spheres, part edges, and other macro-restricted regions 117. In one embodiment, various placement tools may be employed, including a robotic pick-and-place system that properly places each macro-sized low-density sphere 112. In other embodiments, a sphere template with holes slightly larger than the spheres may be used to hold the spheres in place during loading of the micro-sized low-density spheres 114. In still other embodiments, a standoff mesh may also be utilized to prevent direct contact between the spheres. Whether using the coating layer 132 or a placement tool to place the macro-sized low-density spheres 112 in place, the spacing between adjacent macro-sized low-density spheres 112 may be maintained uniformly within the mold 102. Alternatively, the macro-sized low density spheres 112 may be distributed non-uniformly within the mold 102 to achieve specific design requirements or to optimize the structural properties of the final part.

[0051]

[0062] The total volume of the mold 102 occupied by the macro-sized low-density spheres 112 and the micro-sized low-density spheres 114 can vary. In some embodiments, the macro-sized low-density spheres 112 comprise a significant portion of the total volume, contributing to structural efficiency and reducing the overall density of the syntactic foam part. For example, the volume percentage of the macro-sized low-density spheres 112 in the mold 102 may be between 10% and 70%, inclusive; in other embodiments, between 25% and 60%, inclusive; and in still other embodiments, between 40% and 55%, inclusive. Aside from the spaces between the spheres, which will be filled with resin, the remaining volume is filled with the micro-sized low-density spheres 114. The micro-sized low-density spheres 114 occupy all voids, including the gaps 140 between the macro-sized low-density spheres 112. Ultimately, the micro-sized low-density spheres 114 fill all gaps and voids surrounding the macro-sized low-density spheres 112. In other cases, the packing density of the macro-sized low-density spheres 112 and micro-sized low-density spheres 114 within the mold 102 may be between 50% and 99% inclusive in some embodiments, between 67% and 95% inclusive in other embodiments, and between 80% and 85% inclusive in another embodiment.

[0052]

[0063] 5B , according to some embodiments, prior to loading the macro-sized low-density spheres 112 and the micro-sized low-density spheres 114 into the mold 102, the method 200 may include coating at least one interior wall of the mold 102 with a boundary layer 156. The boundary layer 156 may have a boundary thickness T 1 that defines at least a portion of the macro-confined region 117 of the mold 102. bThus, the boundary layer 156 prevents the macro-sized low density spheres 112 from extending into the boundary layer 156, and therefore prevents the macro-sized low density spheres 112 from extending into any macro-confined region 117 occupied by the boundary layer 156. The boundary layer 156 may coat all or at least one of the interior surfaces of the mold 102, including the side surface 134, bottom surface 136, and top surface 138 of the mold 102. In some embodiments, the boundary layer 156, together with the coating layer 132 of any macro-sized low density spheres 112 that contact the boundary layer 156, may define the macro-confined region 117. In other words, in some embodiments, such as that shown in FIG. 4, the thickness T c The thickness T of the combined boundary layer 156 b defines the macro-restricted region 117. In certain cases, the boundary layer 156 may provide excess material for machining during subsequent processing, protecting the macro-sized low-density spheres 112 from potential damage during subsequent processing.

[0053]

[0064] The boundary layer 156 can be made of any of a variety of boundary materials 154, such as, but not limited to, a pure resin material (e.g., epoxy resin), a resin matrix composite (i.e., a reinforcing material embedded in a matrix material), a polymer (e.g., polyurethane, silicone, etc.), a highly elastic polymer (e.g., a highly crosslinked rigid chain polymer, a nanoparticle-loaded polymer, a colloidal silica nanoparticle-loaded polymer), or a ceramic. The reinforcing material of a resin matrix composite can be any of a variety of materials, such as a fiber- or particle-reinforced composite. In some examples, the boundary layer 156 is made of a syntactic foam that includes micro-sized low-density spheres, such as the micro-sized low-density spheres 114, and a resin. This resin can be the same or a different resin used to embed the spheres in the mold 102.

[0054]

[0065] Referring generally to FIG. 9 and particularly to FIG. 6, after loading the macro-sized low-density spheres 112 in block 204, the method 200 also includes introducing resin 144 into the mold 102 (block 206), thereby causing the resin 144 to fill the mold 102. Referring to FIG. 6, in one embodiment, the resin 144 is introduced into the mold 102 through the resin inlet 108 at the bottom of the mold 102 and flows through the mold 102 in a generally bottom-to-top direction (i.e., a direction generally parallel to the directional arrow) from the bottom of the mold 102 to the top of the mold 102. In some embodiments, the resin 144 is pumped (i.e., actively pushed) through the resin inlet 108 into the mold 102 via a pump (not shown). In one embodiment, the resin 144 may also be actively drawn via negative pressure introduced at the top of the mold 102, such as via a negative pressure device (e.g., a vacuum device). After the mold 102 is filled with the resin 144 such that the macro-sized low-density spheres 112 and the micro-sized low-density spheres 114 are embedded in the resin 144, any excess resin 144 is removed from the mold 102, such as via the resin outlet 110. Although not shown, in alternative embodiments, the resin 144 may be introduced into the mold 102 from the top of the mold 102 and allowed to flow downward, generally in a top-to-bottom direction, to fill the mold 102. In still other embodiments, the resin 144 may be introduced into the mold 102 from the side of the mold 102 and allowed to flow upward and downward to fill the mold 102.

[0055]

[0066] The resin 144 can be any of a variety of resins that help embed and immobilize the macro-sized low-density spheres 112 and the micro-sized low-density spheres 114. According to some embodiments, the resin 144 can be one or more of a pure resin material (e.g., an epoxy resin), a resin matrix composite (i.e., a reinforcing material embedded within a matrix material), a high modulus polymer (e.g., a highly cross-linked rigid-chain polymer, a nanoparticle-loaded polymer, a colloidal silica nanoparticle-loaded polymer), etc. The reinforcing material of a resin matrix composite can be any of a variety of materials, such as fumed silica, nanoparticles, crushed carbon fiber, etc. According to some embodiments, the resin 144 includes a density-reducing component, such as smaller low-density spheres (e.g., hollow spheres, such as hollow glass, ceramic, or polymer spheres), which helps reduce the density of the resin 144 without compromising the strength of the resin 144.

[0056]

[0067] The introduction of resin 144 into mold 102 is such that the macro-sized low-density spheres 112 remain in the macro-allowable region 115 and do not migrate into the macro-restricted region 117. That is, any shifting of the macro-sized low-density spheres 112 and micro-sized low-density spheres 114 within mold 102 during the resin infusion process will not result in any macro-sized low-density spheres 112 entering the macro-restricted region 117. This stability is achieved by the close packing of the spheres within mold 102, the preventative function of coating layer 132 (if coated), and, in some embodiments, the strategic placement of macro-sized low-density spheres 112 at a sufficient distance from the macro-restricted region 117.

[0057]

[0068] 9 , after introducing the resin 144 into the mold 102 in block 206, the method 200 also includes solidifying the resin 144 (block 208). According to one embodiment, solidifying the resin 144 includes partially or fully curing the resin 144. Fully curing the resin 144 may include raising the temperature of the resin 144 to a curing temperature of the resin 144. To promote void-free curing of the resin 144, the interior cavity 104 of the mold 102 may be pressurized. In alternative embodiments, the resin 144 is partially or fully cured via alternative methods, such as ultraviolet or other radiation treatment of the resin 144. The curing of the resin 144 may be irreversible (e.g., the resin 144 is a thermosetting material) or reversible (e.g., the resin 144 is a thermoplastic material).

[0058]

[0069] In some examples, the interface material 154 and / or coating material is different from the resin 144. For example, the interface material 154 and / or coating material is a different type of resin than the resin 144 or is configured differently. For example, the interface material 154 and / or coating material may be stronger, denser, harder, and / or more durable than the resin 144. Because the percentage of the syntactic foam part 148 made of the interface material 154 and / or coating material is significantly lower than the percentage of the resin 144 (e.g., the coating material forms only a coating on the macro-sized low-density spheres 112), the interface material 154 and / or coating material may be denser than the resin 144 without significantly adversely affecting the overall density of the part, while still helping to improve the overall strength of the part. Thus, the coating material, which may be stronger, denser, and / or more durable than the macro-sized low-density spheres 112, protects the integrity of the macro-sized low-density spheres 112 when the resin 144 is infused and / or cured at high temperatures that could otherwise soften or damage the macro-sized low-density spheres 112.

[0059]

[0070] According to some embodiments, after the resin 144 solidifies in block 208, the macro-sized low-density spheres 112, the micro-sized low-density spheres 114, and the resin 144 form a syntactic foam part 148 (see, e.g., FIG. 7 ). As shown in FIG. 7 , the method 200 may further include removing the syntactic foam part 148 from the mold 102. After being removed from the mold 102, the syntactic foam part 148 may form a stand-alone part or may be combined with one or more other parts or components (e.g., other syntactic foam parts or blocks) to form a larger or more complex part. According to some embodiments, the syntactic foam part 148 has a viscosity of 0.05 g / cm , including both ends. 3 and 0.75 g / cm 3 Between 0.1 and 0.5 g / cm, inclusive, in one embodiment 3 In another embodiment, between 0.15 and 0.4 g / cm, inclusive. 3 The overall density is between .

[0060]

[0071] The syntactic foam part 148 includes a macro-permitted region 115 and a macro-restricted region 117 adjacent to the macro-permitted region 115. The macro-permitted region 115 ensures that the macro-sized low-density spheres are in a position that is not subject to subsequent processing or that avoids stress concentrations. As shown, the macro-restricted region 117 surrounds the exterior of the syntactic foam part 148, such that the edges of each sidewall 135 (e.g., bottom surface 137 and top surface 139) have the macro-restricted region 117. Thus, each one of the macro-sized low-density spheres 112 is entirely contained within the macro-permitted region 115 of the syntactic foam part 148. While the coating layer 132 is shown surrounding each one of the macro-sized low-density spheres 112, the coating layer 132 is considered separate from the underlying spheres and, therefore, may extend into the macro-restricted region 117. In fact, when the coating layer 132 is at least as thick as the width of the macro-restricted regions 117, the coating layer 132 can be used to prevent the macro-sized low-density spheres 112 themselves from extending into the macro-restricted regions 117. In some embodiments, the interior of the syntactic foam component 148 can also include macro-restricted regions 117 (not shown). These macro-restricted regions 117 can be used to space the spheres and minimize local stress concentrations at points where the macro-sized low-density spheres 112 are closely spaced.

[0061]

[0072] A parent foam 146, comprised of micro-sized low-density spheres 114 and resin 144, surrounds the macro-sized low-density spheres 112. In some embodiments, the entire macro-restricted region 117 may be filled with parent foam 146. In other embodiments, the macro-restricted region 117 may be partially filled with parent foam 146 and other materials (such as coating layer 132), as shown in FIG. 7. In still other embodiments, the entire macro-restricted region 117 may be devoid of micro-sized low-density spheres. The macro-permitting region 115 may include the entire macro-sized low-density spheres and a portion of parent foam 146, and may include coating layer 132 if the macro-sized low-density spheres are coated.

[0062]

[0073] 10 generally and FIG. 8 in particular, according to some embodiments, a method 300 for making a syntactic foam part 148 (see, e.g., FIG. 7) includes steps similar to blocks 202-208 of method 200. In particular, method 300 includes loading micro-sized low-density spheres 114 into a first mold 102A (block 302), loading macro-sized low-density spheres 112 into the first mold 102A (block 304) (see, e.g., FIG. 1), introducing resin 144 into the first mold 102A (block 306) (see, e.g., FIG. 6), and solidifying the resin 144 after it fills the first mold 102A to form an intermediate part 150 (block 308). However, the method 300 includes the further step of removing the intermediate part 150 from the first mold 102A (block 310) and loading the intermediate part 150 into the second mold 102B (block 312). In some embodiments, two or more intermediate parts 150 can be loaded into the second mold 102B. For example, multiple intermediate parts can be placed in the second mold 102B, stacked, or aligned laterally within the second mold 102B. Furthermore, one or more of the multiple intermediate parts can be sized differently from the others of the multiple intermediate parts. Thereby, several intermediate parts can be formed in different first molds before being loaded into the second mold 102B. The intermediate part 150 includes macro-sized low-density spheres 112 and micro-sized low-density spheres 114 embedded together by the resin 144. In some embodiments, after removing the intermediate part 150 from the first mold 102A and before loading the intermediate part 150 into the second mold 102B, the method 300 may include a secondary solidification step to further solidify the resin 144. In one embodiment, the resin 144 is only partially cured at block 308 while in the first mold 102A, and then fully cured at block 310 after the intermediate part 150 is removed from the first mold 102A.

[0063]

[0074] The second mold 102B has a larger volume than the first mold 102A. Consequently, when the intermediate part 150 is placed in the second mold 102B, the intermediate part 150 does not fill the entire volume of the second mold 102B. Accordingly, the intermediate part 150 may be placed in the second mold 102B such that at least one side wall 135 of the intermediate part 150 is spaced from at least one inner wall of the second mold 102B. In some embodiments, the intermediate part 150 is spaced from at least one of the side surfaces 134 of the second mold 102B. Furthermore, the intermediate part 150 may be positioned away from the top of the second mold 102B such that the intermediate part 150 does not contact the top surface 138 of the second mold 102B when the second mold 102B is closed. In certain embodiments, the intermediate part 150 may be spaced from the bottom of the second mold 102B using a spacing device to support the intermediate part 150 away from the bottom surface 136 of the mold 102. In this case, the spacing device maintains the position of the intermediate part 150 while still allowing resin material to flow around the intermediate part 150. The extra spacing around the intermediate part 150 in the second mold 102B thus defines a perimeter region 152 between at least one interior wall of the second mold 102B and the sidewall 135 of the intermediate part 150. The perimeter region 152 defines at least a portion of the macro-restricted region 117 of the second mold 102B. In other words, the macro-restricted region 117 of the second mold 102B may be defined by the perimeter region 152 and other regions within the second mold 102B.

[0064]

[0075] The method 300 further includes introducing an interface material 154 into the peripheral region 152 of the second mold 102B (block 314), whereby the interface material 154 fills the peripheral region 152. The interface material 154 may include any of a variety of materials capable of flowing within the peripheral region 152, including, but not limited to, a resin matrix composite (i.e., a reinforcing material embedded in a matrix material), a high modulus polymer (e.g., a highly crosslinked rigid-chain polymer, a nanoparticle-loaded polymer, a colloidal silica nanoparticle-loaded polymer), or the like. Furthermore, after the intermediate part 150 is loaded into the second mold 102B and before the interface material 154 is introduced into the second mold 102B, micro-sized low-density spheres, such as the micro-sized low-density spheres 114, are loaded into the peripheral region 152 around the intermediate part 150. In some embodiments, micro-sized low-density spheres other than the micro-sized low-density spheres 114 may be present in the interface material 154. Such spheres may be stronger or more durable than, for example, micro-sized low density spheres 114 .

[0065]

[0076] The method 300 also includes solidifying the boundary material after it fills the peripheral region 152 to form a boundary layer 156 bonded to at least one sidewall of the intermediate part 150 (block 316). The boundary layer 156 has a boundary thickness T that defines at least a portion of the macro-restricted region 117 of the mold 102. bThus, boundary layer 156 prevents macro-sized low-density spheres 112 from extending into boundary layer 156, and therefore prevents macro-sized low-density spheres 112 from extending into any macro-restricted region 117 occupied by boundary layer 156. After syntactic foam part 148 is removed from second mold 102B, syntactic foam part 148 may undergo subsequent processing, including machining. Boundary layer 156 may provide excess material to protect macro-sized low-density spheres 112 from damage during subsequent processing. Thus, in some embodiments, boundary layer 156 may be bonded to intermediate part 150, as described in method 300 using a two-mold process, or boundary layer 156 may be coated in the mold before adding the spheres, allowing syntactic foam part 148 to be made in a single mold.

[0066]

[0077] In the above description, certain terms may be used, such as "up," "down," "upper," "lower," "horizontal," "vertical," "left," "right," "over," "under," etc. These terms are used where appropriate to provide some clarity to the description when referring to interrelationships. However, these terms are not intended to imply absolute relationships, positions, and / or orientations. For example, with respect to an object, the "upper" surface may become the "lower" surface simply by turning the object upside down. It is still the same object. Furthermore, the words "including," "comprising," "having," and variations thereof mean "including, but not limited to" (unless expressly stated otherwise). Listed items do not imply that any or all of the items are mutually exclusive and / or inclusive, unless expressly stated otherwise. Terms such as "a," "an," and "the" also refer to "one or more," unless expressly stated otherwise. Additionally, the term "plurality" may be defined as "at least two." Furthermore, unless specifically stated otherwise, as defined herein, a plurality of a particular feature does not necessarily refer to every particular feature of a particular set or class.

[0067]

[0078] While in some embodiments, the terms "about" or "substantially" are defined to mean within + / - 5% of a given value, in further embodiments, any disclosure of "about" can be further narrowed and claimed to mean within + / - 4% of a given value, within + / - 3% of a given value, within + / - 2% of a given value, within + / - 1% of a given value, or the exact given value. Furthermore, when at least two values ​​of a variable are disclosed, such disclosure is specifically intended to include a range between the two values, whether or not disclosed in terms of separate embodiments or examples thereof, and is specifically intended to include a range up to and including at least the lower of the two values ​​and / or a range up to and including the higher of the two values. Furthermore, when at least three values ​​of a variable are disclosed, such disclosure is specifically intended to include ranges between any two of the values, whether or not they are disclosed with respect to separate embodiments or examples, and is specifically intended to include ranges up to and including at least value A and / or value B, where A can be any of the disclosed values ​​other than the maximum disclosed value, and B can be any of the disclosed values ​​other than the minimum disclosed value.

[0068]

[0079] Furthermore, in this specification, an instance where one element is "coupled" to another element may include direct and indirect coupling. A direct coupling may be defined as one element being connected to another element and being in some contact with the other element. An indirect coupling may be defined as a connection between two elements that are not in direct contact with each other but have one or more additional elements between the connected elements. Furthermore, in this specification, fixing one element to another element may include direct fixing and indirect fixing. In addition, in this specification, "adjacent" does not necessarily mean contact. For example, one element may be adjacent to another element without touching it.

[0069]

[0080] As used herein, the phrase "at least one of" used in conjunction with enumerated items means that various combinations of one or more of the enumerated items may be used, and that only one of each enumerated item may be required. An item may be a specific object, article, or category. In other words, "at least one of" means that any combination or number of items from the list may be used, but not all of the enumerated items may be required. For example, "at least one of item A, item B, and item C" may mean, for example, "item A," "item A and item B," "item B," "item A, item B, and item C," or "item B and item C." In some cases, "at least one of item A, item B, and item C" may mean, by way of example and not limitation, "two item A, one item B, and ten item C," "four item B, and seven item C," or other suitable combinations.

[0070]

[0081] Unless otherwise indicated, the terms "first," "second," etc. are used herein merely as designators and are not intended to impose any sequential, positional, or hierarchical requirements on the items they refer to. Furthermore, a reference to, e.g., a "second" item does not require or exclude the presence of, e.g., a "first" or lower numbered item and / or, e.g., a "third" or higher numbered item.

[0071]

[0082] As used herein, a system, device, structure, article, element, component, or hardware that is "configured to" perform a specified function does not mean that it is, in fact, capable of performing the specified function without any modification and is merely likely to perform the specified function after further modification. In other words, a system, device, structure, article, element, component, or hardware that is "configured to" perform a specified function is specifically selected, created, implemented, utilized, programmed, and / or designed for the purpose of performing the specified function. As used herein, the phrase "configured to" means that there are characteristics of the system, device, structure, article, element, component, or hardware that enable the system, device, structure, article, element, component, or hardware to perform a particular function without further modification. In this disclosure, a system, apparatus, structure, article, element, component, or hardware described as being "configured to" perform a particular function may additionally or alternatively be described as being "adapted to" and / or "operative to" perform that function.

[0072]

[0083] The schematic flow diagrams included herein are generally defined as logical flow diagrams. As such, the depicted order and labeled steps represent one embodiment of the presented method. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more steps, or portions thereof, of the depicted method. Furthermore, it is understood that the format and symbols employed are provided to illustrate the logical steps of the method and do not limit the scope of the method. While various types of arrows and lines may be used in the flow diagrams, it is understood that these do not limit the scope of the corresponding method. In fact, some arrows or other connectors may be used only to indicate the logical flow of the method. For example, arrows may indicate an indefinite amount of waiting or monitoring time between listed steps of the depicted method. Furthermore, the order in which a particular method is performed may or may not strictly follow the order of the corresponding steps depicted.

[0073]

[0084] The subject matter herein may be embodied in other specific forms without departing from its spirit and essential characteristics. The above-described embodiments are to be construed in all respects as merely illustrative and not restrictive. All changes that come within the meaning and range of equivalency of the claims are to be embraced therein.

Claims

1. A method (200) of making a syntactic foam component (148), comprising: Loading (202) micro-sized low-density spheres (114) into a mold (102), the mold (102) including a macro-allowed region (115) and a macro-restricted region (117); loading (204) macro-sized low-density spheres (112) into the mold (102), wherein the macro-sized low-density spheres (112) are surrounded by the micro-sized low-density spheres (114), each one of the macro-sized low-density spheres (112) is spaced apart from any other one of the macro-sized low-density spheres (112), some of the micro-sized low-density spheres (114) are between adjacent ones of the macro-sized low-density spheres (112), each one of the macro-sized low-density spheres (112) is entirely contained within one of the macro-acceptable regions (115) of the mold (102), and a diameter (D1) of the macro-sized low-density spheres (115) is at least ten times larger than a diameter (D2) of the micro-sized low-density spheres (114); introducing (206) a resin (114) into the mold (102) to fill the mold (102) and embed the micro-sized low-density spheres (114) and the macro-sized low-density spheres (112) within the resin (144); and The method (200) includes solidifying (208) the resin after it fills the mold (102).

2. When the resin (144) embeds the micro-sized low-density spheres (114), a parent foam is formed surrounding the macro-sized low-density spheres (112); The method (200) of claim 1, wherein the entire macro restricted area (117) is filled with the parent form.

3. further comprising, prior to loading the macro-sized low-density spheres (112) into the mold (102), coating each one of the macro-sized low-density spheres (112) with a coating material to form a coating layer (132) that entirely surrounds each one of the macro-sized low-density spheres (112); The coating layer (132) has a coating thickness (T c ) 2. The method (200) of claim 1, wherein the coating layer (132) at least partially prevents each one of the macro-sized low-density spheres (112) from entering the macro-restricted region (117) of the mold.

4. Each one of the macro-sized low density spheres (112) is spaced apart by at least a minimum distance (d min ) from any other one of said macro-sized low density spheres (112); The minimum distance (d min ) is the coating thickness (T c 4. The method (200) of claim 3, wherein the number of inputs is twice the number of inputs.

5. The method (200) of claim 3, wherein the coating material of the coating layer (132) is a syntactic foam comprising micro-sized low density spheres (114A) and a coating resin (144A).

6. adding a plurality of spacing devices (113) to each one of the macro-sized low-density spheres (112) at various locations around the periphery of a corresponding one of the macro-sized low-density spheres (112) before loading the macro-sized low-density spheres (112) into the mold (102); each one of the plurality of spacing devices has a spacing length; 2. The method (200) of claim 1, wherein the plurality of spacing devices at least partially prevent each one of the macro-sized low-density spheres (112) from entering the macro-restricted region (117) of the mold (102).

7. further comprising coating at least one interior wall of the mold (102) with a boundary layer (156) made of an interface material (154) before loading the macro-sized low-density spheres (112) and the micro-sized low-density spheres (114) into the mold (102); The boundary layer (156) has a boundary thickness (T b ) 2. The method (200) of claim 1, wherein the boundary layer (156) at least partially prevents each one of the macro-sized low-density spheres (112) from entering at least a portion of the macro-restricted region (117) of the mold (102).

8. 10. The method (200) of claim 1, wherein the macro-sized low-density spheres (112) are placed at predetermined locations within the macro-allowable region (115) of the mold (102) using a placement tool.

9. The macro-sized low-density spheres (112) further include first macro-sized low-density spheres (112A) having a first diameter (D1) and second macro-sized low-density spheres (112B) having a second diameter (D3); 2. The method (200) of claim 1, wherein the second diameter (D3) of the second macro-sized low-density spheres (112B) is at least twice as large as the first diameter (D1) of the first macro-sized low-density spheres (112A).

10. 10. The method (200) of claim 1, wherein the macro-sized low-density spheres (112) are uniformly distributed within the mold (102) such that the spacing between adjacent ones of the macro-sized low-density spheres (112) is the same.

11. the macro-sized low density spheres (112) have a first density; After the resin is solidified, the resin embedded with the micro-sized low density spheres (114) forms a parent foam having a second density; The method (200) of claim 1, wherein the first density is less than the second density.

12. A syntactic foam component (148), Macro tolerance area (115), a macro-restricted region (117) adjacent to said macro-permissive region (115); macro-sized low-density spheres (112) disposed within micro-sized low-density spheres (114), the macro-sized low-density spheres (112) being surrounded by the micro-sized low-density spheres, each one of the macro-sized low-density spheres (112) being spaced apart from any other one of the macro-sized low-density spheres (112), some of the micro-sized low-density spheres (114) being between adjacent ones of the macro-sized low-density spheres (112), each one of the macro-sized low-density spheres (112) being entirely contained within one of the macro-acceptance regions (115), and a diameter (D1) of the macro-sized low-density spheres (112) being at least ten times greater than a diameter (D2) of the micro-sized low-density spheres (114); and A syntactic foam component (148) comprising a resin (144) having embedded therein the macro-sized low-density spheres (112) and the micro-sized low-density spheres (114).

13. a parent foam is formed by the resin with the micro-sized low density spheres (114) embedded therein; 13. The syntactic foam component (148) of claim 12, wherein the entire macro-restricted region (117) is filled with the parent foam.

14. each one of the macro-sized low-density spheres (112) is coated with a coating material to form a coating layer (132) that entirely surrounds each one of the macro-sized low-density spheres (112); The coating layer (132) has a coating thickness (T c ) the coating layer (132) at least partially prevents each one of the macro-sized low density spheres (112) from entering the macro-restricted region (117); Each one of the macro-sized low density spheres (112) is a portion of the coating layer (132) that is in the coating thickness (T c ) minimum distance (d min 13. The syntactic foam component (148) of claim 12, wherein the syntactic foam component (148) is spaced apart from any other one of the macro-sized low density spheres (112) by .

15. the resin (144) having embedded therein the macro-sized low-density spheres (112) and the micro-sized low-density spheres (114) defines an intermediate part (150) having a sidewall (135); a boundary layer (156) coupled to the sidewall (135) of said intermediate piece (150); The boundary layer (156) is made of a boundary material (154); The boundary layer (156) has a boundary thickness (T b ) 13. The syntactic foam component (148) of claim 12, wherein the boundary layer (156) at least partially prevents each one of the macro-sized low density spheres (112) from entering the macro-restricted region (117).

16. 13. The syntactic foam component (148) of claim 12, wherein the diameter (D2) of the micro-sized low density spheres (114) is less than 100 microns.

17. 13. The syntactic foam component (148) of claim 12, wherein the diameter (D1) of the macro-sized low density spheres (112) is 0.5 inches or greater.

18. A method (300) of making a syntactic foam component (148), comprising: Loading (302) micro-sized low density spheres (114) into a first mold (102A); loading (304) macro-sized low-density spheres (112) into the first mold (102A), wherein the macro-sized low-density spheres (112) are surrounded by the micro-sized low-density spheres (114), each one of the macro-sized low-density spheres (112) is spaced apart from any other one of the macro-sized low-density spheres (112), some of the micro-sized low-density spheres (114) are between adjacent ones of the macro-sized low-density spheres (112), each one of the macro-sized low-density spheres (112) is entirely contained within a macro-acceptable region (115) of the first mold (102A), and a diameter (D1) of the macro-sized low-density spheres (114) is at least ten times larger than a diameter (D2) of the micro-sized low-density spheres (114); introducing (306) a resin (144) into the first mold (102A) to fill the first mold (102A) and embed the micro-sized low-density spheres (114) and the macro-sized low-density spheres (112) in the resin (144); solidifying (308) the resin (144) to form an intermediate part (150) after the resin (144) fills the first mold (102A); Removing (310) the intermediate part (150) from the first mold (102A); loading (312) the intermediate part (150) into a second mold (102B) having a volume larger than that of the first mold (102A), wherein the intermediate part (150) is spaced apart from at least one inner wall of the second mold (102B), a peripheral region (152) is defined between the at least one inner wall of the second mold (102B) and the intermediate part (150), the peripheral region (152) defining at least a portion of a macro-restricted region (117) of the second mold (102B); introducing (314) an interface material (154) into the peripheral region (152) of the second mold (102B), the interface material (154) filling the peripheral region (152); and After the interface material (154) fills the peripheral region (152), the method (300) includes solidifying (316) the interface material (154) to form a boundary layer (156) bonded to a sidewall (135) of the intermediate part (150).

19. 20. The method (300) of claim 18, wherein the interface material (154) is at least partially formed of a parent foam comprising micro-sized low density spheres (114A) and a resin.

20. further comprising, before loading the macro-sized low-density spheres (112) into the first mold (102A), coating each one of the macro-sized low-density spheres (112) with a coating material to form a coating layer (132) that entirely surrounds each one of the macro-sized low-density spheres (112); The coating layer (132) has a coating thickness (T c ) Each one of the macro-sized low density spheres (112) is spaced apart by at least a minimum distance (d min ) from any other one of said macro-sized low density spheres (112); The minimum distance (d min ) is the coating thickness (T c 20. The method (300) of claim 18, wherein the number of inputs is twice the number of inputs.

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