Patent Publication Number: US-2019186356-A1

Title: Segmented thermal barriers for internal combustion engines and methods of making the same

Description:
This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application Serial No. 62/379,422 filed on Aug. 25, 2016, the content of which is relied upon and incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Field 
     The present disclosure relates generally to segmented thermal barriers for internal combustion engines. 
     Technical Background 
     The efficiency of internal combustion engines may be improved by retaining heat from ignited fuel in the combustion chamber. This can be accomplished by minimizing heat loss to the surrounding engine. One solution has been to insulate parts of the combustion chamber. A problem with insulating the combustion chamber from the surrounding engine may be the development of strain within the thermal barrier during temperature cycling of the engine. 
     Accordingly, a need exists for improved thermal barriers within internal combustion engines. 
     SUMMARY 
     According to an embodiment of the present disclosure, a thermal barrier is disclosed. In embodiments, the thermal barrier comprises an array of module each comprising at least one support and a shield. In embodiments, the shield edges of at least two modules in the module array are spaced apart by a distance when at room temperature. 
     According to an embodiment of the present disclosure, a method of making a thermal barrier is disclosed. In embodiments, making the thermal barrier comprises forming at least two modules for the module array. 
     Before turning to the following Detailed Description and Figures, which illustrate exemplary embodiments in detail, it should be understood that the present inventive technology is not limited to the details or methodology set forth in the Detailed Description or illustrated in the Figures. For example, as will be understood by those of ordinary skill in the art, features and attributes associated with embodiments shown in one of the Figures or described in the text relating to one of the embodiments may well be applied to other embodiments shown in another of the Figures or described elsewhere in the text. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be better understood, and features, aspects and advantages other than those set forth above will become apparent when consideration is given to the following Detailed Description thereof. Such Detailed Description makes reference to the following Figures. 
         FIG. 1  is a cross-sectional view of a combustion chamber in an engine during an intake stroke according to an exemplary embodiment. 
         FIG. 2  is a cross-sectional view of the combustion chamber in the engine of  FIG. 1  during an exhaust stroke according to an exemplary embodiment. 
         FIG. 3  is a plot of change in brake thermal efficiency (%) of an internal combustion engine at cruise operating conditions vs. piston thermal conductivity at 400° C. (W/m·° C.). 
         FIG. 4  is a perspective view of a thermal barrier on a surface within a combustion chamber of an engine according to exemplary embodiments. 
         FIG. 5  is a perspective, cross-sectional view of the thermal barrier in  FIG. 4  on a piston surface of an engine according to exemplary embodiments. 
         FIG. 6  is a perspective view of a thermal barrier on a surface within a combustion chamber of an engine according to exemplary embodiments. 
         FIG. 7  is an overhead view of the thermal barrier in  FIG. 6  on a surface within a combustion chamber of an engine according to exemplary embodiments. 
         FIG. 8  is a circular cross-section, perspective view of an individual module with a support including a hollow portion on a surface within a combustion chamber of an engine according to exemplary embodiments. 
         FIGS. 9A-C  are perspective views of a thermal barrier according to exemplary embodiments. 
         FIG. 10  is a perspective view of two modules in the array as shown in  FIGS. 9B and 9C  according to exemplary embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure belongs. Although any methods and materials similar to or equivalent to those described herein can be used in the practice or testing of the present disclosure, the exemplary methods and materials are described below. 
     Engine fuel efficiency is affected by the thermal conductivity of the materials used to make the various components of an engine. This is particularly true for components within the combustion chamber of an engine (e.g., wall of the combustion chamber, pistons, valves, exhaust ports, manifolds, etc.). The higher the thermal conductivity of materials used in the combustion chamber, the more combustion energy lost to heat energy. By lowering the thermal conductivity of materials directly exposed to the combustion reaction, more energy of combustion is available for performing work and powering the engine (i.e., to drive the piston). That is, heat of combustion that is not lost to heat energy can be used to drive a turbocharger in the exhaust manifold and/or more effectively light off the catalytic converter during a cold-start of the engine. In addition, lowering the thermal conductivity of materials directly exposed to the combustion reaction may reduce the heat load on the engine&#39;s cooling system and thereby potentially improve aerodynamics of the vehicle with less air being diverted from outside the vehicle for the cooling system. Accordingly, the overall efficiency of the vehicle and engine (including fuel efficiency) may be improved with thermally resistant materials.  FIG. 3  provides a plot of change in brake thermal efficiency (%) of an internal combustion engine at cruise operating conditions vs. the piston material&#39;s thermal conductivity at 400° C. (W/m·° C.).  FIG. 3  illustrates the effect of piston material thermal conductivity on brake thermal efficiency of an engine at cruise operating conditions. The trend of  FIG. 3  evidences that the increase in efficiency of an engine at cruise conditions may improve exponentially or in a nonlinear fashion by reducing the thermal conductivity of materials (for the appropriate temperature range) used within the combustion chamber. 
     Conventional methods for lowering the thermal conductivity of materials within the combustion chamber have included the use of thermal barriers. Conventional thermal barriers for combustion chambers of internal combustion engines may have one or more of several problems. One major shortcoming for conventional thermal barriers may be that the thermal barrier spalls or separates from the surface within the combustion chamber when exposed to the violent combustion kinetics, high pressures (e.g., 10 bars-500 bars), and high gas temperatures (e.g., 1000° C.-3000° C.) therein. Spalling of thermal barriers including brittle ceramic materials into the combustion chamber can cause damage (e.g., gouge, plug, etc.) to other engine components and the catalytic convertor. Another shortcoming of conventional thermal barriers may be insufficient thermal resistivity properties or a different coefficient of thermal expansion (CTE) than the combustion chamber surface which may lead to separation at high temperatures. Yet another shortcoming may be non-uniform thicknesses of conventional thermal barriers on engine component surfaces. Another short coming of conventional thermal barriers may be the development of mechanical strain within surfaces of the thermal barrier exposed to temperature cycling within a combustion chamber during engine operation. In conventional thermal barriers, thermal strain is sometimes managed by using low CTE coatings or compositional gradients through the coating thickness. These measures, however, constrain the materials available for use as a thermal barrier. 
     The present application is directed to a thermal barrier  200  on any metallic surface within an internal combustion engine  100 .  FIG. 1  provides a cross-sectional view of example engine  100  during an intake stroke.  FIG. 2  provides another cross-sectional view of example engine  100  with piston  104  in a full-exhaust stroke position. Engine  100  of the present disclosure may be gasoline, diesel, natural gas, propane, or any other liquid or gas hydrocarbon powered internal combustion engine including any number (e.g., 1, 2, 3, 4, 5, 6, . . . , 12, . . . ) of combustion chambers. Engine  100  includes a number of components including a combustion chamber  102  with a piston  104  therein. Piston  104  is connected to a crankshaft  110  by a connecting rod  108  within a crankcase  112  of engine  100 . Piston  104  includes a top surface  120  adjacent combustion chamber  102 . Piston top surface may be flat, bowled, domed, or any combination thereof. Piston  104  may be made from carbon steel, aluminum, or other metals typically used in automotive applications. An intake valve  106 , an intake duct  119 , an exhaust valve  114 , an exhaust duct  118 , and a spark/glow plug  116  are also adjacent combustion chamber  102 . Of course other components and configurations of engine  100  are possible and are in accordance with the present disclosure. 
     In  FIG. 2 , intake valve  106  is closed and exhaust valve  114  is open (when piston  104  is at a full-exhaust stroke position) connecting exhaust duct  118  with combustion chamber  102  and thereby forming a chamber exhaust volume  122 . Chamber exhaust volume  122  is defined by wall surfaces and end surfaces of combustion chamber  102 , a surface of intake valve  106 , a surface of exhaust valve  114 , top surface  120  of piston  104 , and walls of exhaust duct  118  (which may include a turbocharger). In another embodiment, intake valve  106  and exhaust valve  114  are closed (when piston  104  is at a full-compression stroke position) thereby forming a chamber compression volume  121  (not shown). Chamber compression volume  121  is defined by walls and top surfaces of combustion chamber  102 , a surface of intake valve  106 , a surface of exhaust valve  114 , and top surface  120  of piston  104 . In yet another embodiment, intake valve  106  is open and exhaust valve  114  is closed (when piston  104  is at a full-intake stroke position) connecting intake duct  119  with combustion chamber  102  and thereby forming a chamber intake volume  123 . Chamber intake volume  123  is defined by wall surfaces and end surfaces of combustion chamber  102 , a surface of intake valve  106 , a surface of exhaust valve  114 , top surface  120  of piston  104 , and walls of intake duct  119 . 
     Thermal barrier  200  of the present disclosure may be on any metallic surface within engine  100 . In an exemplary embodiment, thermal barrier  200  is on a metallic surface  101  within combustion chamber  102 . Metallic surface  101  may be surfaces defining compression exhaust volume  121 , surfaces defining chamber exhaust volume  122 , or surfaces defining chamber intake volume  123 . In one embodiment, surface  101  may not be wall surfaces of combustion chamber  102  contacted by piston  104 . That is, thermal barrier  200  may be excluded from surfaces in chamber  102  subjected to mechanical friction from piston  104  or areas along the crevice quench that may wear or separate thermal barrier  200  from that surface. In another exemplary embodiment, metallic surface  101  is piston top surface  120 , wall surfaces and end surfaces of combustion chamber  102 , a surface of intake valve  106 , a surface of exhaust valve  114 , walls of exhaust duct  118 , or walls of intake duct  119 . 
     Thermal barrier  200  of the present disclosure includes an array of modules  201 . The array of modules  201  (also called “module array” herein) may include any number of modules  201  greater than  1  module. In embodiments, each module  201  in the array includes a support  202  and a shield  206 . The overall length and width of thermal barrier  200  including the array of modules  201  can have any suitable lateral dimensions (e.g., from about 0.1 mm to about 100 cm), including substantially equal dimensions. In embodiments, thermal barrier  200  includes lateral dimensions substantially equivalent to the applicable surface  101  within combustion chamber  102 . In embodiments, thermal barrier  200  conforms substantially to the 2-dimensional and/or 3-dimensional contours of metallic surface  101 . That is, the shape of thermal barrier  200  may conform to the rounded or non-uniform shapes of surface  101  to which it is connected, including a curved piston top surface  120 . 
       FIG. 4  provides an exemplary embodiment of thermal barrier  200  on surface  101 . Support  202  includes a body with a first end opposite a second end, thereby defining a thickness T 1 . In embodiments, the first end or second end of support  202  joins directly or indirectly with surface  101 . Support  202  and surface  101  may be joined by metallic bonding, metal-to-metal bonding, or direct mechanical attachment. The connection between support  202  and surface  101  is configured to resist the combustion temperatures and pressures within combustion chamber  102  during operation of engine  100 . For example, support  202  may resist spalling from surface  101  for ≥100,000 miles inside operating engine  100 . Support  202  may be applied to surface  101  via 3-D printing, metallic plating, welding (arc, laser, plasma, or friction), brazing, plasma spraying, mechanical fastening, or other conventional methods of creating metallic bonding or metal-to-metal bonds. Thickness T 1  of support  202  may be distinct from a thickness of material comprising surface  101  by the presence of a vacant volume  205 . Surface  101  within combustion chamber  102  may be identified from supports  202  by a lack of vacant volume  205 . Alternatively or additionally, an interface at the joining of support  202  and surface  101  (caused by the bonding method) may help define thickness T 1 . 
     In embodiments, the first end or second end of support  202  (opposite the end joining surface  101 ) joins with a portion of at least one shield  206 . Each support  202  has a height or thickness T 1  between its opposite ends, as well as a width (or diameter). Support  202  may have any cross-sectional shape including rectangular, annular, hexagonal, and/or any other polygon shape. Each support  202  may have a circular cross-section as shown in  FIG. 4 . Thickness T 1  of each support  202  may be from about 0.01 mm to about 10 mm, or from about 0.1 mm to about 2 mm, or from about 0.4 mm to about 2 mm, or even from about 0.5 mm to about 1 mm. In exemplary embodiments, thickness T 1  of each support  202  is substantially uniform (e.g., +/−0.5 mm) across the length and the width of thermal barrier  200  including the array of modules  201 . Thickness T 1  of support  202  may be measured from surface  101  to a termination point (or end) of support  202  away from surface  101  (e.g., where support  202  joins directly or indirectly with shield  206 ). 
     Support  202  may be substantially solid or porous across thickness T 1 . In embodiments where support  202  is porous, the porosity of support  202  may be from about 1% to about 99%, or from about 5% to about 90%. Support  202  may also include a porosity gradient across thickness T 1 . In embodiments, at least one support  202  in the module array includes a hollow portion  207  therein. In another embodiment, at least one support  202  in the module array is hollow across its thickness T 1 , defined by substantially solid side walls.  FIG. 8  provides an example cross-sectional embodiment of a single module with a hollow portion  207 . The structures of supports  202  in thermal barrier  200  are configured to retain their shape on surface  101  and around a vacant volume  205 . In embodiments, the structure of support  202  is also capable of containing insulation material  204  within a vacant volume  205 . The structure of support  202  may be sufficiently rigid and has thermo mechanical fatigue resistance so as to withstand the combustion temperatures and pressures within combustion chamber  102  during operation of engine  100 . 
     As shown in  FIG. 4 , each shield  206  in the module array includes first and second opposite edges  208 ,  210 . Each shield  206  in the module array includes an upper portion  212  opposite a lower portion  214 . Each shield  206  in the module array may be hexagonal (as shown in  FIG. 5  along plane B-B), square, triangular, heptagonal, circular, annular, and combinations thereof. Of course other polygon shapes are in accordance with the present disclosure. In embodiments, thickness T 2  of each shield  206  is defined between upper portion  212  and lower portion  214 . In embodiments, shield  206  is substantially solid between upper portion  212  and lower portion  214 . Thickness T 2  of shield  206  may be from about 0.001 mm to about 5 mm, or from about 0.1 mm to about 2 mm, or even from about 0.1 mm to about 1 mm. In addition to thickness T 2 , each shield  206  also includes a length and a width. In embodiments, thickness T 2  is substantially uniform across the length and the width of shield  206 . As shown in  FIG. 4 , thickness T 2  of shield  206  may be measured from the end of support  202  joined to lower portion  214  of shield  206 . Shield  206  may be identified from support  202  by a joining interface, or by shield  206  having a larger cross-sectional area than support  202  in module  201 . Upper portion  212  of each shield  206  may be configured for direct exposure to the combustion reaction (and associated temperatures and pressures) in combustion chamber  102 . In embodiments, upper portion  212  of each shield  206  may have a variation tolerance along its surface in compliance with tolerances required for engine  100 , such as ≤1 mm, or ≤0.01 mm. In embodiments, lower portion  214  of each shield  206  is spaced apart from and substantially parallel to surface  101 . 
     Conventional thermal barriers may create a nonlinear temperature gradient between the combustion chamber surface on which the thermal barrier is attached and other adjacent surfaces which may be cooled by engine coolant. In one example, when a supported shield (or skin) is fixed to a surface of an internal combustion chamber, thermal expansion and contraction of the thermal barrier causes strain within the shield in areas between the supports. That is, in conventional thermal barriers, discrete portions of the skin are fixed to the combustion chamber surface by supports and areas of the shield (or skin) between the supports experience thermomechanical fatigue from expansion and contraction of the thermal barrier during temperature cycling in the combustion chamber. During heating, the continuous shield experiences compression in areas between the supports. During cooling, the continuous shield experiences tension in areas between the supports. This repeated process via temperature cycling in the combustion chamber can cause thermomechanical fatigue and failure. 
     Thermal barrier  200  of the present disclosure reduces thermal strains and thermomechanical fatigue in areas between supports  202  by providing breaks or segmentation between adjacent supports. That is, the shield  206  edges  208  or  210  of at least two modules in the array are spaced apart (either overlapping or non-overlapping) by a distance D 1  when at room temperature. That is, edges  208  or  210  of at least two shields  206  in the module array are spaced apart by a distance D 1  when at room temperature (e.g., 25° C.). Distance D 1  as a non-overlap distance between adjacent shields  206  in the module array is shown in  FIG. 4 . That is, in the  FIGS. 4 and 5  embodiment, the edges of adjacent shields in the module array do not overlap. In embodiments, distance D 1  is substantially parallel to surface  101 . The shields  206  of the module array in the  FIGS. 4 and 5  embodiments can be described as non-overlapping, segmented shields or scales. 
     Distance D 1  is an overlap distance between adjacent shields  206  in the module array is shown in  FIGS. 6 and 7 . That is, in the  FIGS. 6 and 7  embodiments, the edges of adjacent shields in the module array overlap to form distance D 1  between adjacent edges. The shields  206  of the module array in the  FIGS. 6 and 7  embodiments can be described as overlapping, segmented shields or scales. Distance D 1  may be from about 0.001 micron to about 10 mm, or from about 0.001 micron to about 5 mm, or even from about 0.1 mm to about 3 mm. In embodiments, distance D 1  is measured substantially parallel to surface  101 . In embodiments, the shield edges of at least 30% modules  201  in the array are spaced apart (by distance D 1 ) from at least one adjacent module  201  shield  206  edge. In embodiments, as shown in  FIG. 4  for example, the shield edges of all the modules  201  in the array are spaced apart (by distance D 1 ) from all adjacent module shield edges in the array. Of course, thermal barrier  200  may include any combination of non-overlapping and overlapping edges spaced by distance D 1  when at room temperature (i.e., when engine  100  is not in operation). 
     In the  FIG. 4  embodiment, when edges  208 ,  210  of shields  206  in adjacent modules in the array do not overlap when at room temperature (i.e., distance D 1  is a non-overlapping distance), distance D 1  decreases to a distance D 2  (not shown) when the internal combustion engine operates. Distance D 1  is thus smaller than distance D 2 . That is, due to thermal expansion of adjacent shields  206  in the module array, distance D 1  decreases to a distance D 2  when the internal combustion engine operates (e.g., at a combustion gas temperature from about 1000° C. to about 3000° C. or more in the combustion chamber, at a piston temperature from about 100° C. to about 1000° C., when the internal temperature of the combustion chamber increases from room temperature to 100° C. or more). Distance D 2  between edges of adjacent shields  206  when engine  100  operates is less than distance D 1  between edges of adjacent shields  206  when engine  100  is not in operation (and at room temperature). In embodiments, distance D 2  is from about 0 microns to about 10 mm, or from about 0 microns to about 1 mm, or even from about 0.001 micron to about 1 mm. In embodiments, distance D 2  is configured to limit or eliminate penetration of combustion reactants or products through distance D 2 . In embodiments, distance D 2  is configured to limit or eliminate the spalling of insulation material  204  out of vacant volume  205  through distance D 2 . In embodiments, edges  208 ,  210  of adjacent modules  201  in the module array may contact (i.e., distance D 2  is 0) when engine  100  is in operation. Distance D 2  can be configured considering the material of each shield  206  (and its CTE), the reaction temperature inside combustion chamber  102 , and distance D 1 . Similarly, distance D 1  may be determined during formation and placement of adjacent modules considering the material of each shield  206  (and its CTE) and the estimated surface temperature inside engine  100  so shield  206  edges form D 2  or contact during engine operation. 
     In the  FIGS. 6 and 7  embodiment, when edges  208 ,  210  of shields  206  of adjacent modules in the array overlap when at room temperature (i.e., distance D 1  is an overlapping distance), distance D 1  increases to a distance D 3  (now shown) when the internal combustion engine operates. Distance D 3  is thus larger than distance D 1 . That is, due to thermal expansion of adjacent shields  206  in the module array, distance D 1  increases to a distance D 3  when the internal combustion engine operates (e.g., at a gas temperature from about 1000° C. to about 3000° C. or more in the combustion chamber, at a piston temperature from about 100° C. to about 1000° C. (or about 100° C. to about 600° C.), when the internal temperature of the combustion chamber increases from room temperature to 100° C. or more). Distance D 3  between edges of adjacent shields  206  when engine  100  operates is greater than distance D 1  between edges of adjacent shields  206  when engine  100  is not in operation (and at room temperature). In embodiments, distance D 3  is from about 0.001 micron to about 10 mm, or from about 0.001 micron to about 5 mm, or even from about 1 micron to about 5 mm. In embodiments, distance D 3  is configured to further limit or eliminate penetration of combustion reactants or products through distance D 3 . In embodiments, distance D 3  is configured to further limit or eliminate the spalling of insulation material  204  out of vacant volume  205  through distance D 3 . Distance D 3  can be configured considering the material of each shield  206  (and its CTE), the reaction temperature inside combustion chamber  102 , and distance D 1 . 
     In embodiments, shield  206  in each module is adjacent support  202  in said module. In embodiments, shield  206  joins directly or indirectly with support  202  in said module. Referring again to  FIG. 4 , each shield  206  may join directly to each support  202  in each module  201  at an end of support  202  spaced apart from surface  101 . Shield  206  and support  202  in each module may be joined by metallic bonding, metal-to-metal bonding, or direct mechanical attachment. The connection between support  202  and shield  206  is configured to resist the combustion temperatures and pressures within combustion chamber  102  during operation of engine  100 . For example, shield  206  may resist spalling of support  202  from surface  101  for ≥100,000 miles inside operating engine  100 . Shield  206  may be applied to support  202  via 3-D printing, metallic plating, welding (arc, laser, plasma, or friction), brazing, plasma spraying, mechanical fastening, or other conventional methods of creating metallic bonding or metal-to-metal bonds. In other embodiments, shield  206  and support  202  may be integrally formed together such that bonding of individual pieces is not necessary. 
     In embodiments, support  202  and shield  206  of module  201  may be a metal element or a metal alloy commonly used in combustion chamber  102  manufacturing. The metal or metal alloy may include carbon steel, stainless steel, aluminum alloy, aluminum, nickel plated aluminum, titanium alloy, hastelloy, nickel based super alloy, cobalt-based super alloy, and combinations thereof, for example. The metal or metal alloy encompassing support  202  and shield  206  may also be other super alloys including nickel, chromium, cobalt, and combinations thereof. The metal or metal alloy of support  202  and shield  206  may have the same or different coefficient of thermal expansion (CTE) as the material encompassing surface  101  (assuming similar operating temperature ranges) to minimize thermal expansion stresses and failures at their connection. In an exemplary embodiment, the CTE of the metal or metal alloy of support  202  and shield  206  may be within 150% of the CTE as the material encompassing surface  101  (assuming similar operating temperature ranges). In yet another embodiment, the CTE of the metal or metal alloy of support  202  may be within 150% of the CTE of the metal or metal alloy of shield  206 . In embodiments, at least one module  201  or thermal barrier  200  may have a CTE gradient from support  202  to shield  206 . 
     In embodiments, thermal barrier  200  also includes a vacant volume  205 . In embodiments, vacant volume  205  is defined at least partially between lower portion  214  of at least one shield  206  in the module array and surface  101 . Referring to  FIGS. 4 and 5 , vacant volume  205  may be defined between surface  101  and the lower portions  214  of a plurality of shields  206  in the module array. In embodiments, vacant volume  205  is a tortuous volume around a plurality of supports  202  within the module array. In embodiments, vacant volume  205  may be a singular void space or a plurality of discrete and/or interconnected voids. In embodiments, vacant volume  205  extends across at least 50% of thickness T 1 , or substantially across thickness T 1 . In embodiments, the volumetric ratio of support  202  to vacant volume  205  along a length, width, and thickness T 1  of thermal barrier  200  may be from about 3:1 to about 1:20, or from about 1:1 to about 1:5. 
     In embodiments, a cross-sectional area of all the shields  206  in the module array is greater than a cross-sectional area of all the supports  202  in the module array. As an example, shown in  FIG. 5 , the cross-sectional area of the shields  206  in the module array (shown along plane B-B substantially parallel to the combustion chamber surface) is greater than the cross-sectional area of all the supports  202  in the module array (shown along plane A-A substantially parallel to the combustion chamber surface). In embodiments, the module array includes a repeating structural pattern. As shown in  FIGS. 4-7 , thermal barrier  200  includes a repeating pattern via the plurality of modules  201  organized in a specific configuration. In embodiments, thermal barrier  200  may be non-repeating or discontinuous on surface  101  and localized to “hot spots” within the combustion chamber. 
     In embodiments, shield  206  upper portion  212  of one module is contiguous shield  206  lower portion  214  of an adjacent module.  FIGS. 6 and 7  provide an example (with overlapping edges separated by distance D 1  or distance D 3 , depending on the engine temperature) where upper portion  212  of one shield  206  in the module array is contiguous or adjacent the lower portion  214  of a second shield  206  in the module array. In embodiments, one or more shields  206  in the module array include an edge  208 ,  210  with a bevel adjacent upper portion  212  (illustrated as beveled edge  220  in  FIG. 6 ). In embodiments, one or more shields  206  in the module array include an edge  208 ,  210  with a bevel adjacent lower portion  214 . Of course, one or more modules may include a combination of beveled edges adjacent upper portion  212  and lower portion  214 . Beveled edges along the upper portion  212  and/or the lower portion  214  of adjacent modules (as shown for example in  FIGS. 6 and 7 ) may allow the increase in distance (from distance D 1  to distance D 3 ) between adjacent modules in the module array during operation of the engine. That is, opposing beveled edges between adjacent modules may substantially seal surface  101  from exposure to the combustion reaction during operation of engine  100 . In embodiments, a beveled edge may include an edge at an angle less than 90 degrees with respect to upper portion  212  or lower portion  214 . 
     In embodiments, thermal barrier  200  includes an insulation material  204 . In embodiments, insulation material  204  is contained with vacant volume  205  between shield  206  and surface  101 . That is, vacant volume  205  is at least partially filled with insulation material  204 . Thus, a portion of vacant volume  205  is occupied (or eliminated) by the presence of insulation material  204  therein. Insulation material  204  may fill from 5% to 99% of vacant volume  205 . In exemplary embodiments, insulation material  204  fills vacant volume  205 . Referring back to  FIG. 5 , insulation material  204  (shown as a cross-hatched area) is contained within vacant volume  205 . In embodiments, insulation material  204  may be configured between shield  206  and surface  101  to fortify at least one shield  206  in the module array and prevent collapsing/deforming due to the pressure of the combustion reaction. That is, insulation material  204  may mechanically support at least one shield  206  during operation of the engine. In embodiments, the volumetric ratio of support  202  to insulation material  204  along a length, width, and thickness T 1  in thermal barrier  200  may be from about 1:1 to about 1:5. In embodiments, insulation material  204  has a density gradient along thickness T 1  of support  202 . The volumetric ratio, density, and location of insulation material  204  may allow for “tuning” of thermal barrier  200  to achieve a desired thermal conductivity. 
     In an exemplary embodiment, insulation material  204  is interlocked within thickness T 1  (between shields  206  and surface  101 ) such that it does not escape, spall, or flake out from vacant volume  205  into combustion chamber  102  during operation of engine  100 . In embodiments, surface  101  and/or lower portion  214  of at least one shield  206  in the module array may be corrugated to prevent movement (via skin friction) or loss of insulation material  204  into combustion chamber  102  during operation of engine  100 . 
     Insulation material  204  may be air, a ceramic material, and/or combinations thereof. In embodiments, insulation material  204  is any material that is capable of flowing into or being contained within vacant volume  205  and with a thermal conductivity from about 0.1 W/m·K to about 12.0 W/m·K at 400° C., or from about 0.1 W/m·K to about 8.0 W/m·K at 400° C., or even from about 1.0 W/m·K to about 4.0 W/m·K at 400° C. Insulation material  204  is a composition having a thermal conductivity lower than surface  101  within vacant volume  205  to increase the thermal resistivity of thermal barrier  200  such that more energy of combustion is available for performing work and powering engine  100 . 
     In an embodiment where insulation material  204  includes ceramic material, the ceramic material may have a porosity from about 10% to about 90%, or from about 30% to about 70%. The pores of the ceramic material may include air. Example ceramic materials include, but are not limited to, yttria stabilized zirconia (YSZ), zirconium dioxide, lanthanum zirconate, gadolinium zirconate, lanthanum magnesium hexaaluminate, gadolinium magnesium hexaaluminate, lanthanum-lithium hexaaluminate, barium zirconate, strontium zirconate, calcium zirconate, sodium zirconium phosphate, mullite, aluminum oxide, cerium oxide, and combinations thereof. The ceramic material of exemplary embodiments may be ceramic foam. The ceramic material of exemplary embodiments may also be formed from aluminates, zirconates, silicates, titanates, and combinations thereof. 
     In embodiments, the total thickness of thermal barrier  200  (thickness T 1 +thickness T 2 ) is from about 0.1 mm to about 10 mm, or from about 0.1 mm to about 5 mm. In an exemplary embodiment, thermal barrier  200  has a thermal conductivity of about 0.1 W/m·K to about 12 W/m·K at 400° C., or about 1 W/m·K to about 5 W/m·K at 400° C. Various embodiments of composite thermal barrier  200  on a surface within engine  100  are provided in  FIGS. 4-9 . Of course, combinations of these embodiments and other embodiments are in accordance with this disclosure. 
     The present disclosure also includes methods of applying thermal barrier  200  to metallic surface  101  within combustion chamber  102  of engine  100 . The method includes preparing metallic surface  101  for application of at least two supports  202 . Preparing metallic surface  101  may include roughening, chemical etching, drilling, cleaning, or other processes of readying surface  101  for application of the plurality of supports  202  thereon. It is envisioned that the method of preparation of surface  101  will likely depend on the method of applying supports  202  on surface  101 . 
     Methods of making thermal barrier  200  may include forming an array of modules  201 . Methods of making thermal barrier  200  may include forming or joining a plurality of supports  202  on shield  206 . Joining the plurality of supports  202  on shield  206  includes 3-D printing, metallic plating, mechanical fastening or threading, fusion welding, brazing, resistance welding, diffusion bonding, sintering, or other conventional methods of metallically bonding supports  202  to shield  206  via metal-to-metal bonds. In embodiments, as shown in  FIG. 9A , supports  202  may be formed from a sheet metal to form thermal barrier  200 . In this embodiment, supports  202  may be formed from shield  206  by sheet metal fabrication, punch forming, superplastic forming, hydroforming, chemical etching, electrical discharge machining, mechanical milling, pressing and sintering, and other similar processes. That is, shield  206  and supports  202  may be formed in one step from a single sheet of materials disclosed herein. In embodiments, supports  202  may be joined directly or indirectly to surface  101  before supports  202  are joined directly or indirectly to at least one shield  206 . 
     Methods of making thermal barrier  200  may include removing a portion of shield  206  to create distance D 1  between at least two of the module edges in the array.  FIGS. 9B and 9C  illustrate embodiments of the module array following removal of portions of shield  206  to form distance D 1 . In embodiments,  FIGS. 9A-C  may be a sequential process of forming the array of modules  201 . 
     Methods of making thermal barrier  200  may include applying thermal barrier  200  to surface  101 . Applying thermal barrier  200  to surface  101  includes joining directly or indirectly at least two supports  202  to surface  101 . Applying thermal barrier  200  to surface  101  includes joining directly or indirectly a plurality of modules to surface  101 . A support  200  may be joined to surface  101  via 3-D printing, metallic plating, mechanical fastening or threading, fusion welding, brazing, resistance welding, diffusion bonding, sintering, or other conventional methods of metallically bonding support  202  to surface  101  via metal-to-metal bonds. Methods of applying thermal barrier  200  to surface  101  may include the formation of vacant volume  205  around supports  202 . Formation of vacant volume  205  may include etching, drilling, or any other process of metal removal. 
     Methods of making thermal barrier  200  may also include removing at least a portion of one module  201  such that the outer edge of at least two module shields  206  are spaced apart by distance D 1  when at room temperature. That is, removing at least a portion of shield  206  between two supports  202  to form distance D 1  creates two separate modules  201 . In embodiments, as shown in  FIG. 10 , a tab  218  may remain between adjacent modules to assist with applying the array of modules  201  to surface  101 . Tab  218  extends only a fraction of the length between edges of adjacent modules  201 . Methods of making thermal barrier  200  may include removing or breaking tabs  218  to form distance D 1  across the entire length between adjacent modules. In the  FIG. 10  embodiment, support  202  may be joined with surface  101  by heating methods applied through hollow portion  207  when support  202  contacts surface  101 . 
     Methods of making thermal barrier  200  may also include inserting insulation material  204  within vacant volume  205 . Methods of inserting insulation material  204  within vacant volume  205  may include pressure application, injection, pressing, impregnating, and other conventional methods of inserting a solid or gas insulator in vacant volume  205 . It is envisioned that inserting insulation material  204  within vacant volume  205  may be accomplished while applying supports  202  to surface  101 . 
     As used herein, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, examples include from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. 
     It is also noted that recitations herein refer to a component of the present invention being “configured” or “adapted to” function in a particular way. In this respect, such a component is “configured” or “adapted to” embody a particular property, or function in a particular manner, where such recitations are structural recitations as opposed to recitations of intended use. More specifically, the references herein to the manner in which a component is “configured” or “adapted to” denotes an existing physical condition of the component and, as such, is to be taken as a definite recitation of the structural characteristics of the component.