Patent Application
20140033908
Ballistic impact resistant components are desirable in a variety of industrial, commercial, and military applications.
Recently, armor assemblies formed of multiple materials having different material properties (i.e., high hardness and toughness) have been used.
However, these armor assemblies still have weaknesses. For example, the armor assemblies may not be stiff enough to keep from deforming or deflecting during use. Further, the armor assemblies may be relatively heavy as compared to armor assemblies using less metal.
Thus, there remains a need to develop new armor assemblies that are stiffer and lighter.
This Brief Summary is provided to introduce simplified concepts relating to techniques for manufacturing anti-ballistic components, such as armor, comprising encapsulated preformed ceramic shapes, which are further described below in the Detailed Description. This Summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining the scope of the claimed subject matter.
This disclosure relates to composites including encapsulated preformed ceramic shapes, cast in situ or otherwise encapsulated in a base metal, and techniques for manufacturing such composites. In some embodiments, such composites may be configured to protect against, withstand, or resist ballistic impacts.
In some examples a composite component may be used on its own as anti-ballistic armor. In other examples the composite component may be used along with other components (e.g., an encapsulated array) as a “backing unit” to stiffen the other components.
In some examples the preformed ceramic shapes may be encapsulated in a base metal to stiffen a composite component made from the ceramic shapes and the base metal. For example, the preformed ceramic shapes may be formed of a ceramic having a higher material hardness than the base metal, that when integrated or added to the base metal provide stiffness to the composite. Moreover, the shape of the ceramic components may be chosen to provide a lattice-like or crystalline-like structure thereby providing a highly rigid, stiff component. Moreover, the shape of the ceramic components may be chosen to provide a lattice-like or crystalline-like structure to provide for packing the preformed ceramic shapes together tightly to prevent the preformed ceramic shapes from sliding relative to each other.
In other examples the preformed ceramic shapes may be encapsulated in the base metal to lighten the composite. For example, the preformed ceramic shapes may be formed of a ceramic having a density less than a density of the base metal and the preformed ceramic shapes may displace the base metal during a metal casting process, resulting in a lighter composite component than if the same size and shape component were made of base metal alone.
In some examples the preformed ceramic shapes may be arranged in one or more layers of arrays of preformed ceramic shapes to build up additional thickness of ceramic material to reduce weight and/or increase stiffness of the composite. For example, two or more layers of arrays of preformed ceramic shapes may be arranged in an adjacent, subjacent, and/or overlapping manner. The layers of arrays of preformed ceramic shapes may be arranged such that a preformed ceramic shape in a top layer covers, minimizes, or eliminates an interstitial space between preformed ceramic shapes in a lower layer.
In some examples one or more channels may be arranged in the preformed ceramic shapes to receive the base metal to compartmentalize the preformed ceramic shapes into multiple isolated sub regions within the composite component to stiffen the composite. For example, one or more channels, void of preformed ceramic shapes and having a length greater than a width and/or a depth, may receive the base metal to form a truss structure arranged in the preformed ceramic shapes for stiffening the composite. Because the one or more channels forming a truss structure compartmentalize the preformed ceramic shapes, this may provide for an increased compression force applied to the preformed ceramic shapes contained in the isolated sub regions. For example, during solidification of the base metal, the one or more channels forming the truss structure compartmentalizing the preformed ceramic shapes may provide a compression force directed inward towards the isolated sub regions in addition to the base metal providing a compression force inward from a top and/or a bottom of the isolated sub regions. Such inward force may pack the preformed shapes.
In some examples the composite may define a backing unit that may be formed integrally with a surface of an encapsulated array to stiffen the encapsulated array.
The Detailed Description is set forth with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items.
As noted above, even though existing armor assemblies may be formed of a relatively tough metal, the armor assemblies may not be stiff enough to keep from deforming or deflecting during use. Further, because the armor assemblies may be formed of a relatively tough metal, the armor assemblies may be relatively heavy as compared to armor assemblies using less metal and/or using lighter weight alloys. This application describes anti-ballistic armor comprising preformed ceramic shapes encapsulated in an iron alloy that, together, exhibit an improved resistance to bending and a reduced weight. This application describes techniques for manufacturing such anti-ballistic armor assemblies using investment casting techniques. However, other casting techniques may also be used. By way of example and not limitation, the anti-ballistic armor herein may be used in the fields of military applications, security applications, or any other applications that may be exposed to impacts by ballistic projectiles or other high speed objects.
In general, the anti-ballistic armor includes a backing unit formed integrally with an encapsulated array. The backing unit may include a porous body encapsulated in a relatively tough iron alloy (e.g., steel alloys such as FeMnAl alloys). The porous body may be formed of a plurality of preformed ceramic shapes retained by a porous container (e.g., a metal mesh, wireframe cage, etc.). The preformed ceramic shapes may include a preformed geometry suitable to be used in the anti-ballistic armor assembly. For example, the preformed ceramic shapes may include a preformed geometry comprising a sphere. Depending on the specific application, the preformed geometry may be a cone, a jack, a half sphere, a cube, a pyramid, a bonded unit (e.g., bonded spheres, boned sphere and cone, bonded sphere and jack, bonded half spheres, etc.). For example, the preformed geometry may be chosen to provide for packing the preformed ceramic shapes together to form a lattice structure, simulating a crystalline structure that imparts stiffness to the backing unit. That is, the preformed geometry may be chosen to allow the preformed ceramic shapes to be packed together to prevent or limit an amount by which the preformed ceramic shapes can be displaced relative to one another. For example, the preformed ceramic shapes may interfere or abut with one another when the backing unit is deformed or displaced. Because the preformed ceramic shapes interfere with one another during deformation of the backing unit, and are formed of a harder material than that of the base metal of the backing unit, the preformed ceramic shapes resist being deformed or displaced, thereby increasing the stiffness of the backing unit as compared to a backing unit made of the base metal alone.
In an example where the preformed geometry is a sphere, the preformed ceramic shapes may comprise solid, substantially spherical shaped units (e.g., marbles) of ceramic that are arranged in contiguous arrays. While the preformed ceramic shapes are describes as being solid, the preformed ceramic shapes include one or more voids and/or through holes. For example, the preformed ceramic shapes may include a substantially hollow center. Further, the preformed ceramic shapes may include openings or holes arranged in the preformed ceramic shapes. For example, the preformed ceramic shapes may include one or more through holes extending through the preformed ceramic shapes. As used herein, a substantially spherical shaped unit includes a substantially round geometrical solid ceramic unit in three-dimensional space. For example, a series of silicon carbide marbles may be arranged in contact with one another to form a layer of an array of preformed ceramic shapes. In some examples, the spherical shaped unit of ceramic may have a diameter of about 0.5 inches (1.3 centimeters). In other examples, the spherical shaped unit of ceramic may have a diameter of at least about 0.25 inches (0.6 centimeters) to at most about 0.75 inches (1.9 centimeters). The diameter may vary depending on the specific application. The substantially spherical shaped unit may include flat spots, dimples, and/or bumps etc., over a portion of the surface of the substantially spherical shaped unit. For example, the substantially spherical shaped unit may include flat spots, dimples, and/or bumps etc., over less than about 20% of the surface.
Because the preformed ceramic shapes may be formed of a ceramic, the preformed ceramic shapes may have a higher material hardness than an encapsulating base metal, and a density less than the density of the encapsulating base metal which allows for stiffening and/or lightening the anti-ballistic armor. For example, the preformed ceramic shapes may displace and/or be integrated with the encapsulating base metal to provide for lightening and stiffening the anti-ballistic armor. In some embodiments, the stiffer and lighter preformed ceramic shapes may consume up to about a third of a total volume of a backing unit, thereby displacing about a third of the less stiff and heavier encapsulating base metal. As a result of the preformed ceramic shapes producing a stiffer and lighter backing unit, the anti-ballistic armor is made to be lighter and stiffer providing for lighter armored vehicles.
In some embodiments, one or more layers of arrays of preformed ceramic shapes may be arranged in an overlapping manner. For example, a top layer array of preformed ceramic shapes may be arranged above a bottom layer array of preformed ceramic shapes such that any interstitial space between contiguous preformed ceramic shapes is minimized. For instance, a preformed ceramic shape arranged in the top layer may cover an interstitial space between two preformed ceramic shapes in the bottom layer arranged below the preformed ceramic shape in the top layer.
In some embodiments, the porous body may include channels, void of preformed ceramic shapes to receive a base metal during a casting of a backing unit. For example, one or more channels may be arranged or formed in the porous container to receive the base metal during the casting of the backing unit. The base metal received by the channels may form a truss structure that compartmentalizes the preformed ceramic shapes into multiple isolated sub regions within the porous body to stiffen the backing unit. For example, the truss structure may provide for applying a compression force to the compartmentalized preformed ceramic shapes during a solidification of the base metal. The compression force applied during the solidification of the base metal may compress the preformed ceramic shapes into a tighter lattice structure than if the same porous body were made without the truss structure. The preformed ceramic shapes may provide for preventing the backing unit from deforming during pouring and/or cooling of the backing unit. For example, the preformed ceramic shapes may prevent the backing unit from warping during a pouring and/or a cooling of the backing unit. The preformed ceramic shapes may be made of alumina, zirconia, tungsten carbide, titanium carbide, boron carbide, zirconia-toughened alumina (ZTA), partially stabilized zirconia (PSZ) ceramic, silicon oxides, aluminum oxides with carbides, titanium oxide, brown fused alumina, combinations of any of these, or the like
In examples where the preformed ceramic shapes are formed of silicon carbide, the preformed ceramic shapes may be coated with one or more barrier layers or coatings to prevent interaction or reaction between the preformed ceramic shapes and the molten metal during the casting process. In one example, an interaction or reaction between the preformed ceramic shapes and the molten metal during the casting process may be characterized as a reaction between a molten metal comprising a steel alloy and the preformed ceramic shapes formed of silicon carbide. For example, during a casting process, a molten steel alloy may have a temperature of about 2732 degrees F. and may undesirably react with the ceramic element formed of silicon carbide. During the reaction, the steel alloy may react undesirably with the silicon carbide to form graphite. Further, multiple reaction layers at an interface between the solidified steel alloy and the silicon carbide may be produced during the reaction. In addition to the above, the steel alloy may penetrate the silicon carbide to some depth. All of these results compromise the integrity of the preformed ceramic shapes.
As such, casting preformed ceramic shapes formed of silicon carbide encapsulated with a steel alloy without utilizing one or more barrier layers or coatings during the casting process results in a compromised assembly. For example, casting a steel alloy onto preformed ceramic shapes formed of silicon carbide without utilizing one or more barrier layers or coatings may result in compromised preformed ceramic shapes (e.g., partially “dissolved” preformed ceramic shapes) encapsulated by a compromised steel alloy casing (e.g., cracked casing). To prevent the interaction or reaction between dissimilar materials during a casting process, a barrier layer and/or coating may be applied to the preformed ceramic shapes prior to casting the metal around the preformed ceramic shapes. The barrier layer and/or coating may provide an interface or zone that prevents the interaction or reaction between the preformed ceramic shapes and molten metal during a casting process.
In an example, where the barrier layer or coating may prevent the interaction or reaction between the preformed ceramic shapes and the molten metal, the barrier layer(s) or coating(s) may comprise, for example, a refractory layer encapsulating each preformed ceramic shape. For example, the refractory layer may comprise a metal film. The metal film may be, for example, a foil layer, a powder coat, an electroplating, a painted layer, dipped layer, etc. encapsulating the preformed ceramic shapes. In one specific example, preformed ceramic shapes may be wrapped in an aluminum foil layer.
In some embodiments, the barrier layer and/or coating may additionally or alternatively provide crush or compression protection between the preformed ceramic shapes and the base metal to allow for shrinkage of the encapsulating metal during and after solidification. For example, the preformed ceramic shapes and the base metal may have different coefficients of thermal expansion and the base metal may shrink disproportionately more relative to the preformed ceramic shapes. Specifically, the base metal may have a higher shrinkage percentage than a preformed ceramic shape. Stated otherwise, the preformed ceramic shape may shrink less than the base metal as the preformed ceramic shape and the base metal cool after solidification of the base metal. Because the preformed ceramic shape may shrink less than the base metal, the base metal may shrink down onto the preformed ceramic shape, resulting in the base metal being in tension and the preformed ceramic shape being in compression. The resulting forces may be sufficient to cause damage to either or both of the preformed ceramic shape and the base metal. For example, the resulting forces may be sufficient to crack the base metal and/or the preformed ceramic shapes. Cracking in either or both of the preformed ceramic shapes and the base metal may compromise or detract from the performance of the backing unit. The barrier layer and/or coating may provide an interface or zone that dampens the compression force during shrinkage of the solidified base metal, preventing cracking and/or voids from forming in either or both of the preformed ceramic shapes and base metal. That is the barrier layer may be crushable or compressible to allow the base metal to shrink around the ceramic elements without damaging the preformed ceramic shapes or the base metal.
In an example, where the barrier layer or coating may provide crush or compression protection (i.e., coefficient of thermal expansion mismatch protection) between the preformed ceramic shapes and the base metal during shrinkage after solidification, the barrier layer(s) or coating(s) may comprise, for example, a compressible, porous coating comprising alumina fiber, ceramic, copper, nickel, or the like. For example, porous coatings formed of fibers, granules, powders, etc. may include interstitial spaces that when crushed or compressed, reduce in size or volume.
In some embodiments, the barrier layer or coating may comprise more than one layer or coating to prevent interaction or reaction between the preformed ceramic shapes and the molten metal during the casting process, and to provide a crush or a compression protection between the preformed ceramic shapes and the molten metal during the casting process. For example, the barrier layer or coating may include a first layer (e.g., refractory layer) and a second layer (e.g., compressible layer).
In an example where the barrier layer or coating may prevent interaction or reaction and provide a crush or a compression protection between the preformed ceramic shapes and the molten metal during the casting process, the first layer may encapsulate the second layer.
Further, a wall thickness of the barrier layer or coating may vary depending on the specific application and/or on a density of the barrier layer. For example, the wall thickness may be dependent on thermal expansion coefficients of a base metal and a ceramic material to be accommodated. In a specific example, the base metal may be formed of an iron alloy (e.g., FeMnAl) that encapsulates preformed ceramic shapes formed of silicon carbide.
The encapsulating metal may comprise a relatively tough steel alloy, such as FeMnAl, stainless steel, 4140 AISI steel, or 8630 AISI steel. As used herein, the term “steel” includes alloys of iron and carbon, which may or may not include other constituents such as, for example, manganese, aluminum, chromium, nickel, molybdenum, copper, tungsten, cobalt, and/or silicon. As used herein, the term FeMnAl includes any iron based alloy including at least about 3% manganese by weight, and at least about 1% aluminum by weight. In another specific example, high-chrome iron (or white iron) may be used as a base metal for an encapsulating metal. In other examples, still other base metals (e.g., titanium, etc.) may be used to encapsulate preformed ceramic shapes according to this disclosure.
Ranges of what is considered “relatively hard” and “relatively tough” may vary depending on the application, but in one example “relatively hard” materials are those having a Vickers Hardness of at least about HV=1300 (13 GPa) or a Knoop hardness of at least about HK=800 (2.7 GPa), and “relatively tough” materials are those having a an impact toughness of at least about 10 ft-lbs at −40 degrees F. and/or a tensile strength of at least about 80,000 psi in the “as cast,” non-heat treated state. In some examples, relatively tough materials may have an impact toughness of at least about 20 ft-lbs at −40 degrees F. and/or a tensile strength of at least about 100,000 psi in the “as cast,” non-heat treated state. To be clear, however, this disclosure is not limited to using materials having the foregoing ranges of hardness or toughness.
These and other aspects of the anti-ballistic armor comprising preformed ceramic shapes will be described in greater detail below with reference to several illustrative embodiments.
This section describes an exemplary encapsulated array of solid ceramic elements comprising an encapsulated array of solid ceramic elements including a barrier layer covering solid ceramic elements.
In some implementations, the encapsulated array of solid ceramic elements may include a seam protector and/or a stiffener. These and numerous other encapsulated arrays of solid ceramic elements can be formed according to the techniques described in this section.
As shown in
The seam protected encapsulated array 102 may be installed on, in, or around, the vehicle 104 so that the first surface 112 is facing outward from the vehicle 104. Further, the seam protected encapsulated array 102 may be installed on the vehicle 104 based on a ballistic impact threat to different segments of the vehicle 104. For example, the sides of the vehicle 104 may constitute the highest threat from ballistic impact, the top of the vehicle 104 may constitute the lowest threat from ballistic impact, and the bottom may constitute a medium threat from ballistic impact. A seam protected encapsulated array 102 may be installed on the vehicle 104 to protect the vehicle 104 from ballistic threats based on various factors (e.g., weight, performance, cost). For example, a seam protected encapsulated array 102 may be installed on the sides of the vehicle 104 to protect the vehicle 104 from the highest threat from ballistic impact.
The array of ceramic elements 106 may include two or more ceramic elements 116. The geometry of a ceramic element 116 in the array of ceramic elements 106 may vary widely depending on the application, requirements, geometry, or other characteristics of the seam protected encapsulated array 102. Each of the ceramic elements 116 may be arranged to minimize space between ceramic elements 116 or to achieve overlap between ceramic elements. In one example, top view diagram 118 illustrates each ceramic element 116 comprising a hexagonal perimeter. However, in other examples, the ceramic elements 116 may have a perimeter with any number of three or more sides. A thickness of the ceramic elements 116 may vary depending on an intended application. For example, for some ballistic applications, the ceramic elements 116 may be between about 0.5 inches (1.3 centimeters) and about 2 inches (5 centimeters). However, in other embodiments, the ceramic elements 116 may be thinner or thicker.
As shown in the side view, the array of ceramic elements 106 includes two or more ceramic elements 116 arranged in an adjacent manner where each ceramic element is encapsulated by the metal alloy 108. In this specific example of the encapsulated array 110, the ceramic elements 116 are arranged in the same plane. However the ceramic elements 116 may also be arranged in an overlapping or subjacent manner. As shown in the top view 118, the ceramic elements 116, in this example, may be arranged in pentagonal configuration. In this specific example, the ceramic elements 116 are arranged to minimize seams 120 between adjacent ceramic elements 116.
The seams 120 may be defined by an interface between a ceramic element 116 arranged adjacent to another ceramic element 116 in the encapsulated array 110, where the seams 120 may be a vulnerable area of the encapsulated array 110. For example, because the seams 120 may be void of ceramic material (e.g., void of any ceramic element 116), and consist primarily of the metal alloy 108, the seams 120 may be areas of the encapsulated array 110 that are weaker than areas of the encapsulated array 110 having both the ceramic element 116 and the metal alloy 108 combined in layers.
As shown in the side view of
The encapsulated array 110 may include the array of ceramic elements 106. The array of ceramic elements 106 may include the ceramic elements 116 arranged in an adjacent manner and encapsulated in the metal alloy 108. The encapsulated array 110 may include the seams 120, which may be defined by the interfaces between adjacent ceramic elements 116.
The seam protector 122 may include one or more members 206 arranged in a lattice structure. The lattice structure of the seam protector 122 may mirror the geometric pattern of the array of ceramic elements 106. For example, the geometric pattern of the seam protector 122 may outline the geometric pattern of the array of ceramic elements 106. The lattice structure of the seam protector 122 may have the bulk of the material of the seam protector 122 arranged around the edges of the ceramic elements 116 and apertures arranged above each ceramic element 116.
Each member 206 may include a peak 208 opposite a base 210. Each base 210 may be fixed to the first surface 112 of the encapsulated array 110 and each peak 208 may be arranged in-line with a respective vulnerable seam 120.
While
Further, as illustrated in side view 212, each member 206 may be segmented via a failure zone 214. For example, the failure zone 214 may be a notch, a thin walled section, a groove, a perforation, or the like, disposed between each member 206. Each of the failure zones 214 may be weaker than a wall thickness 216 of each of the members 206. For example, each failure zone 214 may be configured to break upon a predetermined impact of a ballistic projectile on a member 206. The predetermined impact on the member 206 may break a failure zone 214 between the member 206 receiving the impact and an adjacent member 206 not receiving an impact. Because each failure zone 214 may break upon a predetermined impact, the failure zones 214 prevent propagation of breakage from one member 206 to another member 206 in the seam protector 122.
The stiffener 124 may comprise a similar or different lattice structure as the seam protector 122. For example, the stiffener 124 may also outline the geometric pattern of the array of ceramic elements 106, have the bulk of the material of the stiffener 124 arranged around the edges of the ceramic elements 116, and have apertures arranged above each ceramic element 116. The stiffener may have a similar or different geometric cross section as the seam protector. For example, the stiffener may comprise a plurality of hexagonal rings arranged adjacent to each other. Each of the hexagonal rings of the stiffener may include a planar surface opposite another planar surface. The stiffener 124 may be fixed to the second surface 114 of the encapsulated array 110 and arranged in-line with the vulnerable seams 120.
The stiffener 124 may have a thickness 406 of about 1 to 1.5 times a thickness 408 of the array 110. For example the thickness 408 of the array 110 may be about 1.4 inches (3.5 centimeters) thick, which may be substantially the same as a thickness of each ceramic element 116. Thus, the thickness 406 of the stiffener 124 may be about 1.4 inches (3.5 centimeters) to about 2.1 inches (5.3 centimeters) thick.
Each of the members 206 may include a sloped surface 504 arranged between the peak 208 and the base 210. An angle 506 of the sloped surface 504 may be any angle less than 180 degrees to provide for deflecting a projectile. For example, each of the members 206 may comprise a triangular cross-sectional shape (e.g., equilateral shaped triangle, isosceles shaped triangle, acute shaped triangle, etc.) where the angle 506 of sloped surface 504 provides for deflecting a projectile. For example, the sloped surface 504 may have an angle 506 that receives an indirect or glancing impact from a projectile rather than a direct or square impact. Further, the members 206 may compromise or break-up a projectile upon impact.
While the members 206 are illustrated as having a triangular shaped cross-section, in other embodiments, the members 206 may have a semicircle cross-sectional shape, oval shape, dome shape, etc. For example, the members 206 may have a curved sloped surface 504. For example, the members 206 may have a convex and/or concave sloped surface 504 between the peak 208 and the base 210. While the sloped surface 504 is illustrated as having a uniform or smooth surface, the sloped surface 504 may be non-uniform. For example, the sloped surfaces 504 may have one or more protruding or indenting features, such as ribs, ridges, grooves, channels, fins, quills, pyramids, mesh, nubs, dimples, or the like. The features may protrude or indent perpendicular to the respective sloped surface 504 or at an oblique angle relative to the respective sloped surface 504. The non-uniform surface may provide for enhancing each of the member's 206 ability to compromise or break-up a projectile upon impact.
The section view of the seam protected encapsulated array 204 taken along section line A-A illustrates that a barrier layer 508 may cover (e.g., wrap, coat, enclose, etc.) the solid ceramic elements 116 in the array 106 of solid ceramic elements 116. The barrier layer 508 may have a wall thickness 510 dependent on a thermal expansion coefficient of the metal alloy 108 to be accommodated, and/or on a desired seam size 512 of the encapsulated array 110. For example, the metal alloy 108 may be an iron alloy (e.g., FeMnAl) that encapsulates ceramic elements 116 formed of silicon carbide. The ceramic elements 116 may be wrapped in a barrier layer 508 having a wall thickness 510 of about 0.060 inches (0.15 centimeters), which provides a desired seam size 512 of about 0.17 inches (0.4 centimeters). The wall thickness 510 may be substantially uniform around the solid ceramic element 116.
Further, as illustrated in side view 514, the barrier layer 508 may include a first barrier layer 516 (e.g., a refractory layer) and a second barrier layer 518 (e.g., a compressible layer) to integrate or combine the solid ceramic elements 116 formed of silicon carbide with the metal alloy 108. For example, the first barrier layer 516 may be for preventing the metal alloy 108 from reacting with the solid ceramic elements 116 during a casting process, while the second barrier layer 518 may be for providing crush/compression protection during a cooling process. For example, the first barrier layer 516 may prevent a molten steel alloy from undesirably reacting with the solid ceramic elements formed of silicon carbide, while the second barrier layer 518 may prevent the steel alloy from shrinking down onto the solid ceramic elements 116 and undesirably cracking either or both of the solid ceramic elements and/or the solidified steel alloy.
While the side view 514 illustrates the barrier layer 508 including two barrier layers, (i.e., the first barrier layer 516 and second barrier layer 518), the barrier layer may include any number of layers. For example, the barrier layer 508 may comprise multiple alternating layers of the first barrier layer 516 and the second barrier layer 518.
The first barrier layer 516 may be formed of a metal film having a thickness 520 of at least about 0.001 inches (0.002 centimeters), and up to at most about 0.009 inches (0.02 centimeters). Further, the first barrier layer 516 may be an aluminum foil wrapped around both the second barrier layer 518 and the ceramic elements 116, an electroplated deposit deposited around both the second barrier layer 518 and the ceramic elements 116, a coating (e.g., a powder coating, a liquid coating, etc.) applied around both the second barrier layer 518 and the ceramic elements 116, or the like suitable for preventing a molten steel alloy from undesirably reacting with the solid ceramic elements formed of silicon carbide. For example, the first barrier layer 516 may be formed of an aluminum foil having a thickness 520 of about 0.002 inches (0.005 centimeters), and wrapped around both the second barrier layer 518 and the ceramic elements 116.
The second barrier layer 518 may be formed of an alumina fiber, a porous ceramic, a powder (e.g., a compacted powder, a powdered metallurgy), or the like suitable for preventing a steel alloy from shrinking down onto the solid ceramic elements formed of silicon carbide and undesirably cracking either or both of the solid ceramic elements and/or the solidified steel alloy. For example, the second barrier layer 518 may be formed of an alumina fiber having a thickness 522 of at least about 0.050 inches (0.13 centimeters), and up to at most about 0.060 inches (0.15 centimeters), and wrapped around the ceramic elements 116. The second barrier layer 518 may be disposed between the first barrier layer 516 and each of the ceramic elements 116.
The stiffener 124 may include voids 524 arranged in the structural lattice members 402 of the stiffener 124. For example, the voids 524 may comprise dovetail shaped walls 526 arranged in the structural lattice members 402. The dovetail shaped voids 524 may receive molten alloy via a squeeze cast process, and subsequent to solidification of the molten alloy, the dovetail shaped voids 524 may fix or lock the solidified alloy to the encapsulated solid ceramic tile array 110.
Example Methods of Forming Seam Protected Encapsulated Arrays
Process 600 includes operation 602, which represents casting a metal around an array of solid ceramic elements. For example, a molten base metal 610 may be poured into a casting shell 612 and envelops the array of ceramic elements 106. The base metal 610 may be any type of steel or metal that may be desirable for protection against ballistic impacts. In a specific example, the steel alloy may be steel alloy 4140 or 8630 under the American Iron and Steel Institute (AISI) standard. In other specific examples, the steel alloy may be a stainless steel alloy or FeMnAl.
In some embodiments, one or more of the ceramic elements 116 may be encapsulated with a barrier material. For example, the ceramic elements 116 may be covered (e.g., wrapped, coated, enclosed, etc.) with a barrier layer to integrated with the base metal 610 being poured into the casting shell. As discussed above the barrier layer may prevent the base metal 610 from reacting with the ceramic elements 116 during casting, and/or provide crush/compression protection during cooling.
Process 600 continues with operation 604, which represents cooling the encapsulated array (e.g., encapsulated array 110). For example, a metal layer 614 may solidify around the surface of the ceramic elements 116 as energy or heat 616 dissipates from the encapsulated array 110 at a relatively slow cooling rate for a predetermined period of time in a temperature controlled environment (e.g., a cooling tunnel, furnace, or the like). The casting, including the metal layer 614 and the array of ceramic elements 106 defining an encapsulated array 110. The controlled cooling may be implemented by decreasing the amount of energy being exposed to the encapsulated array 110. Alternatively, the encapsulated array 110 may be allowed to cool in a temperature controlled environment that limits the cooling rate without introducing outside energy or heat. The cooling rate and the predetermined period of time may be at a “slow rate.” As used herein, the term “slow rate” means a rate slower than a rate at which the component would air cool if placed in a location at standard temperature and pressure. The specific slow rate of cooling and the specified period of time depend on the specific combination of ceramic material and base metal, size and shape of the ceramic elements, and the desired material properties of the composite material. In some embodiments, the casting shell and encapsulated array 110 may be cooled at a continuous slow rate until it reaches a predetermined temperature (e.g., 50% of the pouring temperature, 20% of the pouring temperature, room temperature, etc.). Examples of continuous slow rates of cooling that may be used in various embodiments include rates at most about 300 degrees F. per hour, at most about 200 degrees F. per hour, at most about 150 degrees F. per hour, or at most about 100 degrees F. per hour.
Operation 604 may be followed by operation 606, which represents fixing a seam protector 122 to a first surface 112 of the encapsulated array 110. For example, another molten base metal 618 different from the base metal 610 may be poured into another casting shell 620 to cast the seam protector 122 onto the first surface of the encapsulated array 110. Here, in this embodiment, the other molten base metal 618 may be any type of steel or metal that is harder than the alloy formed around the array of ceramic elements 106. For example, the molten base metal 618 may be a high-chrome iron (or white iron) that when solidified onto the encapsulated array 110 is harder than the encapsulating metal (e.g., a steel alloy, such as FeMnAl, stainless steel, 4140 AISI steel, 8630 AISI steel, etc.) around the array of ceramic elements 106.
Process 600 may be completed at operation 608, which represents fixing a stiffener 124 to a second surface 114 opposite to the first surface 112. For example, the molten base metal 610 may be poured into another casting shell 622 to cast the stiffener 124 onto the second surface 114 of the encapsulated array 110. Here, in this embodiment, the other casting shell 622 may be a separate unit for casting the stiffener 124 onto the encapsulated array 110, or the casting shell 622 may be formed integral with the casting shell 612. In the embodiment where the casing shell 622 is a separate unit, the stiffener 124 may be cast onto the encapsulated array 110 subsequent to the cooling operation 604. In the embodiment where the casting shell 622 is formed integral with the casting shell 612, the stiffener 124 may be cast with the encapsulated array 110 during the casting operation 602. In this embodiment, the stiffener 124 and the encapsulated array 110 may be formed as a single unit.
Process 700 includes operations 602 and 604, which as discussed above with regard to
In the embodiment, where the seam protector 122 is fixed to the encapsulated array 110 via a fastener, the seam protector 122 may be pre-cast or pre-machined from the other base metal 618, that when solidified is harder than the encapsulating metal. Further, the seam protector 122 may be pre-fabricated of a ceramic and subsequently fixed to the encapsulated array 110 via a mechanical fastener.
Process 700 may be completed at operation 704, which represents fixing a stiffener 124 to a second surface 114 opposite to the first surface 112, via a mechanical fastener. For example, the device 706 may be used along with a mechanical fastener to fix a stiffener 124 to the encapsulated array 110. In addition to the mechanical fastener or as an alternative to the mechanical fastener, an adhesive may be used to fix the stiffener 124 to the encapsulated array 110.
In the embodiment, where the stiffener 124 is fixed to the encapsulated array 110 via a fastener, the stiffener 124 may be pre-cast or pre-machined from the base metal 610 used to cast the enclosure in operation 602.
Process 800 includes operation 802, which represents casting an enclosure, formed of an alloy, around an array of ceramic elements 106 and at least a portion of a seam protector 122. For example, a molten base metal 610 may be poured into a casting shell 806 and envelops the array of ceramic elements 106, and envelops at least a portion of the seam protector 122. While process 800 describes the base metal 610 enveloping a portion of the seam protector 122, the base metal 610 may envelop substantially the entire seam protector 122. For example, the base metal 610 may encapsulate both the seam protector 122 as well as the array of ceramic elements 106.
In the embodiment, where the seam protector 122 is cast in situ or otherwise partially encapsulated or entirely encapsulated in the base metal 610 cast around the array of ceramic elements 106, the seam protector 122 may be pre-cast or pre-machined from the other base metal 618, that, when solidified, is harder than the encapsulating metal. Further, the seam protector 122 may be pre-fabricated of a ceramic.
Process 800 may include operation 604, which again represents cooling the encapsulated array 110.
Process 800 may be completed at operation 804, which represents fixing a stiffener 124 to a second surface 114 opposite to the first surface 112. Operation 804 may comprise operation 804(A), which represents fixing the stiffener 124 to the second surface 114 opposite to the first surface 112, via a mechanical fastener. Further, the stiffener 124 may be welded and/or braised to the encapsulated array 110.
Alternatively, operation 804 may comprise operation 804(B), which represents casting the stiffener 124 onto the second surface 114 of the encapsulated array 110. For example, the molten base metal 610 may be poured into the other casting shell 622 to cast the stiffener 124 onto the second surface 114 of the encapsulated array 110. The other casting shell 622 may be a separate unit for casting the stiffener 124 onto the encapsulated array 110, or the casting shell 622 may be formed integral with the casting shell 806 for casting the stiffener 124 and the encapsulated array 110 as a single unit.
This section describes an exemplary encapsulated array of solid ceramic elements comprising an additive in an encapsulating metal (i.e., base metal) of the encapsulated array of solid ceramic elements.
In some examples, the encapsulating metal may be FeMnAl, high chrome iron, both FeMnAl and high chrome iron, or the like. In some implementations, the additive may be a ceramic grit formed of a metal matrix composite (MMC) (e.g., FeMnAl/alumina), a ceramic, a mixture of ceramic and metal, or the like. In some implementations, the additive may be added to the encapsulating base metal such that the additive is disposed in a portion (e.g., a first portion) of the encapsulating base metal and about the ceramic elements. In some implementations, seam protectors may be arranged above seams of the ceramic elements, and the additive may be added to the encapsulating base metal such that the additive is disposed in the portion of the encapsulating base metal below the ceramic elements. In some embodiments, the additive may be added to an encapsulating base metal such that the additive is disposed in multiple portions (e.g., first and second portions) of the encapsulating base metal. In some embodiments, the additive may be added to an encapsulating base metal formed around seam protectors. These and numerous other encapsulated arrays of solid ceramic elements comprising an additive in an encapsulating metal layer can be formed according to the techniques described in this section.
Section view 900(A) illustrates that the encapsulated array of solid ceramic elements 902(A) may include the additive 904 in a first portion 906 (e.g., a bottom or backing portion) of an encapsulating metal 908 of the encapsulated array of solid ceramic element 902(A). The additive 904 may be dispersed throughout the first portion 906, while a second portion 910 (e.g., a top portion), opposite the first portion 906, may be substantially free, or void, of the additive 904. For example, the additive 904 may be dispersed evenly (e.g., with about a same density) in the first portion 906 generally below second portion 910 and about the solid ceramic elements 116 in the array 106 of solid ceramic elements 116.
Section view 900(A) illustrates an embodiment in which the encapsulated array of solid ceramic elements 900(A) does not include a seam protector (e.g., seam protector 122). In this example, the additive 904 may be dispersed in the encapsulating metal 908 between the solid ceramic elements 116 at the seams 120. Because the seams 120 include the encapsulating metal 908 having the additive 904, the seams 120 with the additive are harder than encapsulating metal 908 without the additive 904. For example, when a projectile first encounters the seams 120 including the additive 904 below the first surface 112, the projectile may be broken up or otherwise compromised, providing protection against projectiles.
Section view 900(B) illustrates an embodiment of the encapsulated array of solid ceramic elements 902(B) which includes a seam protector 912. Similar to the seam protector 122 discussed above, the seam protector 912 may be formed of a hard material (e.g., a white iron, high chrome iron, or a ceramic). Section view 900(B) illustrates the seam protector 912 may be aligned with, and disposed over, the seams 120. The encapsulated array of solid ceramic elements 902(B) may include a second portion 914 of the encapsulating metal 908 that at least partially encapsulates the seam protector 912. While section view 900(B) illustrates the second portion 914 of the encapsulating metal 908 partially encapsulating the seam protector 912, the second portion 914 of the encapsulating metal 908 may encapsulate substantially all of the seam protector 912. For example, the encapsulating metal 908 may encapsulate the seam protector 912 such that no portion of the seam protector 912 is exposed on the first surface 112.
Section view 900(B) illustrates an embodiment of the encapsulated array of solid ceramic elements 902(B) which includes a member 916 extending distally from the seam protector 912. For example, the member 916 may extend away from the seam protector 912 down into, and be disposed in, the seams 120. The member 916 may be formed of a hard material (e.g., a white iron, high chrome iron, or a ceramic), similar to the seam protector 912. For example, the seam protector 912 and the member 916 may be formed as a single unitary unit of the hard material.
Section view 900(C) illustrates the encapsulated array of solid ceramic elements 902(C) including the additive 904 in the second portion 914 of the encapsulating metal 908. For example, the additive 904 may be dispersed throughout the first portion 906 and the second portion 914 of the encapsulating metal 908. Because the additive 904 may be dispersed in the encapsulating metal 908 of the second portion 914, the first surface 112 is harder than without the additive 904, adding protection against projectiles.
Section view 900(D) illustrates an embodiment in which the encapsulated array of solid ceramic elements 902(D) includes the additive 904 in a third portion 918 of the encapsulating metal 908. For example, the additive may be dispersed throughout the third portion 918 of the encapsulating metal 908 layered on top of the second portion 914. Because the additive 904 may be dispersed in the encapsulating metal 908 of the third portion 918 layered on top of the second portion 914 of the encapsulating metal 908 including the additive 904, the first surface 112 is harder than a single layer (e.g., second potion 914) of the encapsulating metal 908 having the additive 904, adding greater protection against projectiles.
Process 1000 includes operation 1002, which represents covering (e.g., wrap, coat, enclose, etc.) each solid ceramic element in an array of solid ceramic elements (e.g., array of ceramic elements 106) with the barrier layer. For example, a foundry casting the array of solid ceramic elements may manually cover each ceramic element, or the foundry casting the array of solid ceramic elements may be provided with the ceramic elements already covered with the barrier layer. For example an outside manufacturing facility may cover solid ceramic elements and provide the covered solid ceramic elements to the foundry casting the array of solid ceramic elements.
Process 1000 includes operation 1004, which represents preparing a casting shell 612 around the array of solid ceramic elements with the barrier layer. For example, the array of solid ceramic elements may be encapsulated in a pattern material, which is then coated or encapsulated in a casting shell. Subsequently, the casting shell may be heated to remove the pattern material creating an air gap for receiving a molten metal alloy.
Process 1000 includes operation 1006, which represents casting a metal around the array of solid ceramic elements with the barrier layer covering each solid ceramic element. For example, a molten base metal 610 may be poured into the casting shell 612 and envelops the array of solid ceramic elements. As discussed above, the base metal 610 may be any type of steel or metal that may be desirable for protection against ballistic impacts. In a specific example, the steel alloy may be FeMnAl. In the example where the steel alloy is FeMnAl, and as discussed above, the barrier layer covering each solid ceramic element prevents the base metal alloy 610 from reacting with the solid ceramic elements.
Process 1000 includes operation 1008, which represents cooling the encapsulated array. For example, a metal layer 614 may solidify around the surface of the ceramic elements covered with the barrier layer as energy or heat 616 dissipates from the encapsulated array at a relatively slow cooling rate for a predetermined period of time in a temperature controlled environment (e.g., a cooling tunnel, furnace, or the like). The casting, including the metal layer 614 and the array of solid ceramic elements with the barrier layer covering each solid ceramic element defining an encapsulated array 110. Here, and as discussed above, the barrier layer covering each solid ceramic element provides crush/compression protection during the cooling of the encapsulated array.
This section describes an exemplary anti-ballistic armor including a backing unit with preformed shapes encapsulated in a metal alloy.
In some implementations, the backing unit may be formed integral with an encapsulated array of solid ceramic elements to stiffen the encapsulated array of solid ceramic elements. In other implementations, the backing unit may include a truss structure to provide for stiffening the backing unit. These and numerous other anti-ballistic armors comprising preformed ceramic shapes can be formed according to the techniques described in this section.
The backing unit 1104 may include an encapsulated porous body 1106, cast in situ or otherwise encapsulated in a base metal (e.g., metal alloy 108). The porous body 1106 may be formed of a plurality of preformed ceramic shapes 1108. Each of the preformed ceramic shapes 1108 may comprise a uniform preformed geometry 1110. For example, an engineer, a designer, an architect, etc., may specify or require a specific profile each of the preformed ceramic shapes 1108 must comply with in order to be used in the porous body 1106. The engineer, designer, architect, etc., may explicitly describe a specific profile of the preformed ceramic shape 1108 via geometric dimensioning and tolerancing (GD&T). For example, an engineer may provide geometric dimensioning and tolerancing to a supplier, manufacturer, retailer, etc. of ceramics that explicitly describe a nominal geometry, and/or the nominal geometry's allowable variation, of the preformed geometry 1110 the preformed ceramic shapes 1108 must comply with in order to be used in the porous body 1106. The preformed ceramic shapes 1108 may be manufactured by casting, electrofusion, sintering, flame spraying, pressing, or any other process allowing the preformed ceramic shapes 1108 to be manufactured to the preformed geometry 1110.
The preformed ceramic shapes 1108 may be arranged in one or more layers 1114(A) and 1114(B) of uniform arrays of preformed ceramic shapes 1108. For example, the preformed ceramic shapes 1108 may be arranged in multiple layers of preformed ceramic shapes 1108 to build up additional thickness of ceramic material to reduce weight and/or increase stiffness of the porous body 1106. The layers 1114(A) and 1114(B) may include a series of preformed ceramic shapes arranged in contact with one another, and may be arranged in an overlapping manner. In this specific example of one or more layers 1114(A) and 1114(B), the preformed ceramic shapes 1108 are arranged in uniform arrays such that any interstitial space between the preformed ceramic shapes 1108 are minimized. For instance, a preformed ceramic shape 1108 arranged in the layer 1114(B) may cover an interstitial space between two preformed ceramic shapes 1108 in the layer 1114(A) arranged below the preformed ceramic shape 1108 in the layer 1114(B).
Further, while
The preformed ceramic shapes 1108 may employ silicon carbide, alumina, zirconia, tungsten carbide, titanium carbide, boron carbide, zirconia-toughened alumina (ZTA), partially stabilized zirconia (PSZ) ceramic, silicon oxides, aluminum oxides with carbides, titanium oxide, brown fused alumina, combinations of any of these, or the like.
With the preformed ceramic shapes 1108 employing a ceramic, the preformed ceramic shapes 1108 may have a density less than a density of the metal alloy 108 encapsulating the porous body 1106. Further, because the plurality of preformed ceramic shapes 1108 consume space in the porous body 1106, the plurality of preformed ceramic shapes 1108 displace the metal alloy 108 during a casting of the backing unit 1104. For example, the preformed ceramic shapes 1108 may consume about 36% of a total volume of the backing unit 1104, thereby displacing an amount of the metal alloy 108 needed to fill the total volume of the backing unit 1104. Because the preformed ceramic shapes 1108 may have a density less than a density of the encapsulating metal alloy 108, and displace the encapsulating metal alloy 108, the plurality of preformed ceramic shapes 1108 lighten the backing unit 1104. As a result of the backing unit 1104 being lighter, the lighter anti-ballistic armor 1102 armoring the vehicle 104 is made more efficient than a vehicle armored with heavier anti-ballistic armor.
Further, with the preformed ceramic shapes 1108 employing a ceramic, the preformed ceramic shapes 1108 may have a relatively high hardness, that may provide for increased stiffness of the backing unit 1104. For example, the preformed ceramic shapes may increase the backing unit's 1104 resistance to bending relative to the backing unit 1104 without the preformed ceramic shapes 1108. The increased stiffness provided by the preformed ceramic shapes 1108 keeps the encapsulated solid ceramic elements 116 in compression with the metal alloy 108 during use. For example, the backing unit 1104 may substantially reduce an amount the encapsulated array 110 is displaced (e.g., bent, flexed, deformed, etc.) while the anti-ballistic armor 1102 is in use on a vehicle 104.
While
The truss structure 1218 may provide for stiffening the backing unit 1104. For example, the truss structure 1218 may increase the backing unit's 1104 resistance to bending relative to the backing unit 1104 without the truss structure 1218. For example, the truss structure 1218 may compartmentalize the preformed ceramic shapes 1108 into a plurality of sub regions 1208(1), 1208(2), 1208(3), 1208(4), 1208(5), and 1208(N) to provide for applying a compression force to the preformed ceramic shapes 1108 contained in each of the sub regions 1208(1)-1208(N). For example, during solidification of the base metal received by the one or more channels 1206(A)-1206(C), the solidifying base metal received by the one or more channels 1206(A)-1206(C) may provide a compression force directed towards the sub regions 1208(1)-1208(N), packing the preformed ceramic shapes 1108 in each of the sub regions 1208(1)-1208(N) together tightly. The tightly packed sub regions 1208(1)-1208(N) of preformed ceramic shapes 1108 may prevent the preformed ceramic shapes 1108 from sliding or being displaced relative to each other, thereby stiffening the backing unit 1104. The increased stiffness provided by the truss structure 1218 keeps the encapsulated solid ceramic elements 116 in compression with the metal alloy 108 during use. For example, the truss structure 1218 may substantially reduce an amount the encapsulated array 110 is displaced (e.g., bent, flexed, deformed, etc.) while the anti-ballistic armor 1102 is in use on a vehicle 104.
While
As illustrated in side view 1302, the barrier layer 508 may cover (e.g., wrap, coat, enclose, etc.) each of the preformed ceramic shapes 1108. As discussed above, with regard to
Further, and as discussed above with regard to
Depending on the specific application, one or more of the preformed ceramic shape embodiments 1402-1408 may be used to form the porous body 1106. For example, the jack 1418 may be arranged in the one or more layers 1114(A) and 1114(B) to form the porous body 1106.
Although the disclosure uses language specific to structural features and/or methodological acts, the claims are not limited to the specific features or acts described. Rather, the specific features and acts are disclosed as illustrative forms of implementing the invention. For example, the various embodiments described herein may be rearranged, modified, and/or combined. As another example, one or more of the method acts may be performed in different orders, combined, and/or omitted entirely, depending on the preformed ceramic shapes to be produced.
