Device for measuring strain and method for making and using the device

Abstract

The present invention relates to a strain gauge and methods for making and using the strain gauge to measure strain of a surface of interest. In particular, the present invention relates to a semiconductor strain gauge that is held by a metal body using a ceramic interface between the gauge and the body, the semiconductor strain gauge being capable of being attached to a surface of interest. The present invention also relates to methods for making the ceramic interface and attaching the semiconductor strain gauge to a surface of interest. The present invention, including its various embodiments, also relates to using the semiconductor strain gauge to measure strain at temperatures above 1000°F.

Description

Technical Field

[0001] The present invention, including its various embodiments, relates to a strain gage and methods for making and using the strain gage to measure strain of a surface of interest, such as a metal surface. Specifically, the present invention, including its various embodiments, relates to a semiconductor strain gage having a ceramic interface that can be attached to a surface of interest. The present invention, including its various embodiments, also relates to methods for making the ceramic interface and attaching the semiconductor strain gage and the ceramic interface to a surface of interest. The present invention, including its various embodiments, also relates to using a semiconductor strain gage to measure strain at temperatures above 1000°F, including for use in ultra-supercritical steam boilers to measure strain at temperatures above 1000°F. Background Art

[0002] The extensive load cycling of thermal power plants, especially in thick-walled components, leads to an accumulation of component damage. The ability to accurately measure component strain on high temperature components, including welds, is a currently unmet industry-wide need.

[0003] High temperature strain monitoring applications have been limited to conventional capacitive gauges or wire gauges, which have limited mechanical bandwidth, low sensitivity, and high cost. The mounting of these conventional strain gauges on the surface of the component is usually performed using welding. Unfortunately, the application of these gauges is still generally limited to relatively moderate temperatures and has limited bandwidth and low sensitivity. For example, conventional strain gauge technology uses plastic adhesives for mounting, which cannot withstand field environments above 400°F, let alone above 1000°F or 1200°F, which limits the application of online non-destructive testing by strain monitoring.

[0004] The lack of sensitivity provided by conventional strain gauges (e.g., foil-type resistive strain gauges and capacitive strain gauges) can result in late detection of events. Due to this poor performance of current strain gauge technology, critical assets in power generation facilities that contain high temperature welds or load carrying components are not monitored. The current inability to monitor dynamic strains on critical power plant components in high temperature environments becomes more problematic as power generation facilities transition to cyclic modes of operation with dramatic temperature ramp rates that can cause significant thermal strains within the components.

[0005] Therefore, there is a need for strain gauges that address these limitations of conventional strain gauges. Specifically, there is a need for strain gauges that provide strain measurements at higher temperatures, such as temperatures above 400°F, 1000°F, or 1200°F. In addition, there is a need for strain gauges that provide strain measurements for components used within power generation facilities that are exposed to these high temperatures, such as high temperature welds and load carrying elements. Summary of the invention

[0006] The present invention provides a device or apparatus for measuring strain. In one embodiment, the present invention provides an apparatus for measuring strain, comprising a body, the body comprising a ceramic portion and a semiconductor strain gauge, the semiconductor strain gauge being bonded to and packaged within a ceramic surface, wherein the body has a surface for attachment to an object to measure strain. In some embodiments, the body is a metal body and the semiconductor strain gauge packaged within the ceramic portion is within the metal body. In some embodiments, the body is a metal body and the semiconductor strain gauge packaged within the ceramic portion is on a top surface of the metal body.

[0007] The present invention also provides a method for manufacturing a device or apparatus for measuring strain. In one embodiment, the present invention provides a method for manufacturing an apparatus for measuring strain, comprising forming a ceramic part attached to a body; and bonding a semiconductor strain gauge to the ceramic part, wherein the semiconductor strain gauge is surrounded by the ceramic part.

[0008] The present invention also provides a method for measuring strain using a device or apparatus for measuring strain. In one embodiment, the present invention provides a method for measuring strain of an object, which includes attaching a body to a surface of the object, the body including a semiconductor strain gauge encapsulated in a ceramic material, wherein the semiconductor strain gauge includes one or more signal lines electrically connected to the semiconductor strain gauge and passing through the ceramic material; electrically connecting the one or more signal lines to an instrument configured to receive an electrical signal generated by the semiconductor strain gauge; and recording the electrical signal generated by the semiconductor strain gauge with the instrument.

[0009] In another embodiment, the present invention provides a method for attaching a device for measuring strain to a metal surface, comprising welding a semiconductor strain gauge encapsulated in a ceramic material to a surface of a metal component, wherein the ceramic material is disposed in an opening in a metal body having a flat surface, wherein the semiconductor strain gauge includes one or more signal lines electrically connected to the semiconductor strain gauge and passing through the ceramic material, and wherein the flat surface is disposed against the surface of the metal component.

[0010] The present invention, in its various embodiments, provides an apparatus for strain measurement with a sustained capability to measure strain both statically and dynamically at higher temperatures, such as temperatures above 1000°F. Specifically, the present invention, in its various embodiments, provides an apparatus for strain measurement of components used within power generation facilities that are exposed to these high temperatures, such as, among other components, high temperature welds and load bearing elements. The strain gauge is a high bandwidth strain gauge and can be a semiconductor strain gauge made of single crystal silicon or silicon carbide. The strain gauge is immune to hysteresis effects and frequency response that affect linear gauges and capacitive gauges to limit mechanical bandwidth. Strain gauges also have a higher gage factor than other types of gauges due to the piezoresistance effect.

[0011] Another advantage arising specifically from the use of porous metal / ceramic layers or interfaces is the ability to place the gauge on a field deployable structure (shim, rod, load cell, membrane or the like) that can be welded to a pipe, manifold, support structure, etc. This can be done in a factory environment without the need for skilled labor. Thus, the field deployable structure (e.g., metal shim) can be considered an attachable load cell that responds with surface strain within the parent structure.

[0012] Another advantage of the present invention is the ability to deploy the present invention using low energy capacitive discharge welding. The use of capacitive discharge welding is within the limits of welds permitted on boiler structures (e.g., thermocouples) for existing sensor technologies. The use of these processes prevents the need for preheating or post-heating of the structural weld. In some embodiments, the strain sensor can be attached by multiple capacitive discharge studs. It can also be deployed within the joint surface of a single stud, eliminating any need for multiple attachment points. In addition, the use of capacitive discharge stud welding allows this sensor technology to be deployed by power industry workers of the expected skill level. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a top perspective view of a metal liner and a porous sintered disk according to one embodiment of the present invention;

[0014] Figure 2 is a top view of a porous sintered disk disposed within a metal liner according to one embodiment of the present invention;

[0015] Figure 3 is a top perspective view of a metal liner according to one embodiment of the present invention, with a ceramic interface disposed on one side of a porous sintered disk and a semiconductor strain gauge bonded to the top of the ceramic interface;

[0016] Figure 4 yes Figure 3 A top view of a metal liner and a strain gauge packaged in a ceramic according to an embodiment of the present invention;

[0017] Figure 5 is attached to the surface of interest Figure 4 A top perspective view of a metal pad and a packaged strain gauge;

[0018] Fig. 6A is a top view of a semiconductor strain gauge assembly according to another embodiment of the present invention;

[0019] Figure 6B According to another embodiment of the present invention Fig. 6A Side view of a semiconductor strain gauge assembly

[0020] Figure 7 is a top perspective view of a portion of a semiconductor strain gauge assembly according to another embodiment of the present invention;

[0021] Figure 8 According to another embodiment of the present invention Figure 7 a top perspective view of an additional portion of a semiconductor strain gauge assembly; and

[0022] Fig. 9 According to another embodiment of the present invention Figure 7 A top perspective view of an additional portion of a semiconductor strain gauge assembly. DETAILED DESCRIPTION

[0023] The present invention is described more fully below with reference to the accompanying drawings. Although the present invention will be described in conjunction with specific embodiments, this should be viewed as an example and should not be viewed as limiting or as illustrating the only embodiments of the present invention. On the contrary, the present invention includes various embodiments or forms and various aspects or features, including alternatives, modifications and equivalents within the spirit and scope of the present invention and claims. In addition, the use of the terms "invention", "present invention", "embodiment" and similar terms throughout this description is used broadly and is not intended to imply that the present invention requires or is limited to any specific embodiment or aspect described or that such description is the only way in which the present invention can be made or used.

[0024] In general, the present invention is directed to a semiconductor strain gauge for measuring strain within an object of interest, such as a metal object. Specifically, the semiconductor strain gauge is attached to a ceramic interface, which is chemically, mechanically, or both chemically and mechanically attached to a metal body, such as a metal liner or other metal body, which acts as a load cell in use. The ceramic interface is formed by a liquid ceramic material that is poured into a porous portion of the metal body to create an electrically insulating base layer, on top of which one or more semiconductor strain gauges can be mounted. Thus, the porous portion serves not only as a support for the semiconductor strain gauge, but also as an interface between the semiconductor strain gauge and the metal liner through the bonding between the ceramic and the metal liner. The porous portion of the metal body or metal liner can be provided in various ways, including the use of porous sintered disks, 3D printing, foamed metals, and similar techniques. In some embodiments, the semiconductor strain gauge is surrounded by, encapsulated in, or entombed in a ceramic.

[0025] A metal body or metal pad containing a semiconductor strain gauge can be attached to the surface of an object of interest to measure the strain of the surface using the semiconductor strain gauge. The measured strain is electrically transmitted from the semiconductor strain gauge through a signal line, which is ultimately electrically connected to an instrument for recording the electrical signal or measured strain. The metal body or metal pad holding one or more semiconductor strain gauges and the associated signal lines and any associated electrical connections can be housed within a housing or protective box.

[0026] Thus, in some embodiments, the present invention provides a portable or field deployable semiconductor strain gauge sensor that can be easily attached to a surface of interest, such as a metal surface of interest, such as a pipe, manifold, support structure, etc. The semiconductor strain gauge can be used at relatively higher temperatures, including temperatures at or above 400°F, 500°F, 1000°F, and 1200°F. Thus, the semiconductor strain gauge can be used to measure strain in high temperature components, such as components having metal surfaces whose temperatures exceed those at which conventional strain gauges can be used. For example, the semiconductor strain gauge of the present invention can be used to measure strain for components used in power generation facilities that are exposed to these high temperatures, including high temperature welds, load bearing elements, control valves, relief valves, turbine cowlings, turbine high temperature components, control system hydraulic valves, spring components, reactor heads, reactor control rod structures, reactor main circulation pumps, boiler manifolds, boiler structural supports, bellows, expansion joints, main steam pipes, high energy pipes, and overheat and reheat outlet headers. Various embodiments and aspects of the invention are described below in conjunction with the accompanying drawings. Specifically, various embodiments of a strain gauge, a method for manufacturing a strain gauge, and a method for using the strain gauge are described.

[0027] Figure 1is a top perspective view of a metal pad and a porous sintered disk according to one embodiment of the present invention. As shown, the metal body 102 (which is a metal pad in this embodiment) will hold the semiconductor strain gauge and will ultimately serve as a load cell for the semiconductor strain gauge during use because it will be attached to a surface of interest where strain will be measured, such as a metal surface of a metal component of interest. The metal pad 102 can be of any size and can have any shape, including a rectangular or square shape. However, since the metal pad 102 will ultimately serve as a load cell and be attached to a surface of interest where strain is measured, the size and shape of the metal pad 102 should be selected to facilitate its attachment to the surface of interest. As noted, in use, the metal pad 102 will be attached to the surface of interest by the underside or bottom side 104 of the metal pad 102. Therefore, the underside or bottom side 104 of the metal pad 102 should be able to be attached to the surface of interest either mechanically or through a welding process. In some embodiments, the underside or bottom side 104 of the metal liner 102 can be a relatively flat or smooth surface to allow sufficient contact between the metal liner 102 and the surface of interest and easy assembly. The metal liner 102 can be made of any metal (e.g., any stainless steel, such as 316 stainless steel) or alloy. The metal liner 102 can be composed of a metal matrix composite, a binary or multinary metal system, or a 3D printed material (e.g., sintered or infused powdered metal). In some embodiments, the metal liner 102 can be made of a metal having a composition that is the same or similar to the composition of the metal surface to be measured for strain. In this case, thermal strains during use can be avoided or minimized. However, in the case where the composition of the metal liner 102 does not match the composition of the metal surface of interest, an offset can be used to calculate the correct strain measurement. In some embodiments where the semiconductor strain gauge will be used at relatively high temperatures, the metal composition of the metal liner 102 should be selected to withstand these temperatures. In some embodiments, the composition of the metal liner 102 can be selected from a mixture of metal alloys sintered or mixed in a specific ratio that is favorable for thermal expansion so that it matches the thermal expansion of the ceramic bond and the insulating layer (described further below). It should be understood that this metal liner can be manufactured using various methods known in the art. In addition, 3D printing can be used to create such a liner structure with desired properties and geometry.

[0028] The metal liner 102 is configured with an opening 106 to accommodate the porous sintered disk 108. This opening 106 can be machined into the metal liner 102. The opening 106 can take any shape, including a circular shape, in which case the opening will have a cylindrical shape. The opening 106 completely penetrates through the metal liner 102 from the top side 110 of the metal liner 102 until the bottom side 104, so that it can be accessed from either the top side 110 or the bottom side 104 of the metal liner 102. The opening 106 is sized to allow the porous sintered disk 108 to be attached within the opening 106 of the metal liner 102. Therefore, in some embodiments, the opening 106 is the same shape as the porous sintered disk 108, including a circular shape. It should be understood that the opening 106 does not need to pass completely through the liner 102, in which case the opening 106 can simply be a pocket or depression in the metal liner 102.

[0029] Figure 2 1 is a top view of a porous sintered disk disposed within a metal backing according to one embodiment of the present invention. The porous sintered disk 108 provides a structure for forming a ceramic interface or ceramic layer to which the semiconductor strain gauge will be attached and which is bonded to the metal backing 102. The porous sintered disk 108 is a metal disk that has been sintered using powdered metal and which is porous to allow liquid ceramic material to pass from one side of the porous sintered disk 108 to the other side to form and support a ceramic layer to which the semiconductor strain gauge will be attached. Because the porous sintered disk 108 will also be exposed to relatively high temperatures during use of the semiconductor strain gauge in some embodiments, the metal composition of the porous sintered disk 108 should be selected to withstand these temperatures. The sintered disk can be composed of powdered metal or foamed metal that has been formed by isostatic pressing, gasification (foaming) or other techniques. The composition of the disk depends on the physical properties desired for a given application, such as thermal expansion and oxidation resistance. In some embodiments, high nickel, chromium or other self-passivating or noble metal compositions are preferred depending on the properties required.In some embodiments, the porous sintered disk 108 can have the same composition as the metal backing 102, such as any stainless steel (eg, 316 stainless steel) or alloy.

[0030] The porous sintered disk 108 is disposed within the opening 106 within the metal backing 108 and is attached to the metal backing 102. In some embodiments, the porous sintered disk 108 is disposed within the opening 106 within the metal backing 108 and is attached by welding (e.g., using laser welding) the porous sintered disk 108 to the metal backing 102. It should be understood that the porous sintered disk 108 is placed within the opening 106 within the metal backing 102 so that it is below the surface surrounding the opening 106 on the top side 110 of the metal backing 102. In other words, a space is created that has the porous sintered disk 108 as a bottom and the walls of the opening 106 extend from the porous sintered disk 108 to the surface on the top side 110 of the metal backing 102.

[0031] Once the porous sintered disk 108 has been attached to the metal backing 102, a liquid or flowable ceramic material is used to form a ceramic layer on the top side 114 of the porous sintered disk 108, which is on the same side as the top side 110 of the metal backing 102, within the space created by the porous sintered disk 108 and the walls of the opening 106 described above. As noted, the ceramic layer 114 is used to attach to the semiconductor strain gauge and form a ceramic insulating layer. It should be understood that in some embodiments, the porous sintered disk 108 can be oxidized prior to the application of the ceramic material. In some embodiments, such oxidation can increase ionic bonding between the surface oxides of the ceramic and the porous sintered disk metal and can be used to clean and carbonize any contaminants (e.g., oils) that may be present on the surface of the porous sintered disk 108 and weaken the bond with the ceramic.

[0032] The ceramic layer is created by placing a source of liquid ceramic material against the bottom side of the porous sintered disk 108, which is on the opposite side of the top side 114 of the porous sintered disk 108. The liquid ceramic material is then drawn through the porous sintered disk 108 using a vacuum applied to the opposite side of the porous sintered disk 108, i.e., the top side 114 of the porous sintered disk 108. The porosity of the porous sintered disk 108 is such that the liquid ceramic material can pass through the porous sintered disk 108 from the bottom side of the porous sintered disk 108 to the top side 114 of the porous sintered disk 108. Thus, the liquid ceramic material forms a layer on the porous sintered disk 108 on the top side 114 of the porous sintered disk 108 and takes the shape of the space formed by the porous sintered disk 108 and the walls of the opening 106 as described above. Therefore, it should be understood that the shape of the layer of liquid ceramic material is predetermined based on the shape of the opening 106 created in the metal liner 102. In some embodiments, because the semiconductor strain gauge is a circular semiconductor wafer, a circular or cylindrical opening 106 can be used. However, the thickness of the layer of liquid ceramic material (i.e., the height of the cylindrical ceramic layer in the embodiment where the opening 106 is a cylindrical portion) can be controlled by the amount of liquid ceramic material sucked through the porous sintered disk 108. It should be understood that the thickness of the liquid ceramic material can be any desired thickness, noting that diamond planing (which can be used to produce a uniform thickness as described below) becomes more difficult when the thickness is reduced. In some embodiments, the layer of liquid ceramic material has a thickness of 0.010-0.005 inches. It should be understood that other methods known in the art can be used to deposit the liquid ceramic material on the porous sintered disk 108, such as using ultrasonic vibrations to make the liquid ceramic material flowable or flow through the medium. It should also be understood that centripetal acceleration in a centrifuge can also be used to cause penetration of the porous material using the weight of the fluid.

[0033] The ceramic material used can be any suitable flowable ceramic material so that it can be sucked through the porous sintered disk 108. In some embodiments, the ceramic material can be a non-Newtonian fluid and viscoelastically respond to shocks and vibrations that allow the use of ultrasonic or pulsed vibrations to enter the porous metal. In some embodiments, the liquid ceramic material is a polymer of one or more binders and one or more fillers, which is finally cured to form a solid ceramic layer or ceramic interface as further described below. The polymer is selected so that it will be ionically bonded to the metal oxide on the surface of the porous sintered disk 108, such as chromium, nickel and iron oxides, etc. The filler is selected to be chemically compatible with the binder and ionically bonded to the binder during the curing process. The selection of the filler component is used to adjust the mechanical modulus of the elasticity of the polymer and to provide a match with the elastic modulus of the components of the porous sintered disk 108 and the thermal expansion coefficient in some embodiments. This reduces the delta temperature strain between the ceramic material and the porous sintered disk 108 during use, for example, to avoid or minimize cracking or crazing of the semiconductor strain gauge. The concentration of the filler is selected to provide a desired degree of flowability to the fluid ceramic material to allow it to pass through the porous sintered disk 108. In addition, the filler is selected to provide an appropriate level of surface tension that helps to secure the semiconductor strain gauge to the surface of the ceramic layer. It should be understood that the relative concentrations of the binder and the filler depend on the filler in some cases. In addition, the overall particle size of the polymer achieves the binder and filler concentrations. For example, because the ceramic material remains flowable, nanoparticle size fillers are able to occupy more concentration by mass, while larger polymer sizes exhibit granular kinematic flow.

[0034] In some embodiments, the binder is a silicate and the filler is a metal oxide. In some embodiments, the binder may be a sodium-based silicate or a potassium-based silicate. In some embodiments, the filler may be zinc oxide (ZnO), magnesium oxide (MgCk) or aluminum oxide (Al2O3), noting that the latter may require a higher curing temperature. In some embodiments, the filler may be titanium oxide. In some embodiments, 20-50% or 20-30% zinc oxide by weight is used. Other materials that can be used include stainless steel powder, copper powder, nickel and nickel alloy powder, silver powder, calcium carbonate, other metal carbonates, beryllium dioxide (beryllium oxide), diamond powder, and other metal oxides. It should be understood that silver powder can form a conductive silver silicate with free ions to conduct electricity, which can allow interconnection without welding, including interconnection between dissimilar metals.

[0035] It should be appreciated that the use of porous metal technology through the use of the porous sintered disk 108 is important in applying strain gauges on top of the ceramic layer as further described below and maintaining the attachment of the ceramic layer to the porous sintered disk 108 during use (e.g., during high strain and temperature cycling). In other words, the sintered porous disk 108 not only provides mechanical support for the ceramic layer as described above, but also provides a chemical bond to the ceramic layer. The interlocking mechanical and chemical bond between the metal and ceramic layers of the porous sintered disk 108 provides the ceramic layer with immunity to thermal expansion failure and does not rely solely on shear bonding within the oxide layer or bonding to the oxide on the surface of the porous sintered disk 108. Moreover, it should be appreciated that in use, the weld used to attach the porous sintered disk 108 to the metal backing 102 will transmit the strain received by the metal backing 102 from the metal surface of interest to the porous sintered disk 108, and to the ceramic layer, which is then measured by the semiconductor strain gauge attached to the ceramic layer as further described below.

[0036] Figure 31 is a top perspective view of a metal liner according to one embodiment of the present invention, and a ceramic interface is disposed on one side of a porous sintered disk, with a semiconductor strain gauge bonded to the top of the ceramic interface. Once the desired amount of liquid ceramic material has been drawn through the porous sintered disk 108, the liquid ceramic material forms a layer of liquid ceramic material 302, which ultimately forms a ceramic insulating layer. The layer of liquid ceramic material 302 is then partially cured. It should be understood that the layer of liquid ceramic material 302 is partially cured to achieve drainage of water from the layer of liquid ceramic material 302, which in turn will facilitate bonding of the semiconductor strain gauge to the layer of partially cured liquid ceramic material 302. In some embodiments, the curing process is performed stepwise. In a first step, excess liquid water is drained from the liquid ceramic material 302 by heating at a temperature of approximately 200-220°F. In a second step, water is drained more slowly from the liquid ceramic material by heating at a temperature of approximately 350-400°F. By draining water more slowly, the retention of water vapor in the solidified material can be reduced or prevented. In some embodiments, this two-step curing process can be used using potassium silicate as a binder. In some embodiments, the layer of liquid ceramic material 302 is partially cured at a temperature of about 350-400°F. At this temperature, water will be evaporated from the binder or silicate in the polymer. It should be understood that the temperature used to partially cure the liquid ceramic material can be selected based on the activation energy level of water associated with the binder in the polymer. It should also be understood that other curing methods can also be used. For example, a desiccant or acid can be used to drain excess water from the liquid ceramic material. For example, boric acid can be used to start curing in both potassium and sodium silicates. Other organic acids (such as acetic acid) can also be used. Methanol is a desiccant that can be used to remove water from the silicate compound. In some embodiments, a desiccant or acid is used to start the curing process, but the curing is finally completed by heating the liquid ceramic material. It will be appreciated that these chemical means of curing are useful for removing water bound to the silicates and reducing the likelihood of water retention during heating.

[0037] After partially curing the layer of liquid ceramic material 302, the exposed surface of the layer of liquid ceramic material 302 is planed to provide a flat or smooth surface for placement of semiconductor strain gauges. In some embodiments, the layer of liquid ceramic material 302 is planed with diamond.

[0038] At this point, the semiconductor strain gauge is individually immersed in a source of liquid ceramic material to coat the semiconductor strain gauge, which is then placed on the surface of the partially solidified liquid ceramic material 302. It should be understood that the liquid ceramic material in which the semiconductor strain gauge is immersed can be the same as or different from the liquid ceramic material used to form the layer of liquid ceramic material 302 on the porous sintered disk 108. However, it is important that the liquid ceramic material in which the semiconductor strain gauge is immersed is capable of chemically bonding to the layer of liquid ceramic material 302 on the porous sintered disk 108 because this ceramic material is used to bond the semiconductor strain gauge to the initial ceramic insulating layer. Therefore, in one embodiment, the liquid ceramic material in which the semiconductor strain gauge is immersed is the same as the liquid ceramic material used to form the layer of liquid ceramic material 302 on the porous sintered disk 108. It should be understood that because the semiconductor strain gauge has been immersed in and covered in the liquid ceramic material, the semiconductor strain gauge itself is in Figure 3 Not visible in.

[0039] It should be understood that the liquid ceramic material on the semiconductor strain gauge or wafer due to the immersion of the semiconductor strain gauge or wafer will be substantially added to, or in contact with, the partially solidified liquid ceramic material on the porous sintered disk 108. However, the amount of this addition of liquid ceramic material associated with the semiconductor strain gauge is relatively small compared to the amount of liquid ceramic material within the layer of liquid ceramic material 302 on the porous sintered disk 108. Therefore, once the semiconductor strain gauge or wafer is placed on the surface of the layer of liquid ceramic material 302 on the porous sintered disk 108, surface tension will act to attract and hold the semiconductor strain gauge or wafer to the layer of liquid ceramic material 302 on the porous sintered disk 108.

[0040] Additionally, as noted above, due to the drainage of water during the solidification of the portion of the liquid ceramic material on the porous sintered disk 108, the addition of the liquid ceramic material associated with the semiconductor strain gauge will not re-liquefy the partially solidified liquid ceramic material on the porous sintered disk 108. In other words, by partially solidifying the liquid ceramic material on the porous sintered disk 108 and draining the water prior to placement of the semiconductor strain gauge and the associated liquid ceramic material, the contact between the liquid ceramic material on the porous sintered disk 108 and the liquid ceramic material associated with the semiconductor strain gauge during placement of the semiconductor strain gauge will avoid or minimize any re-liquefaction of the liquid ceramic material on the porous sintered disk 108. Without a reduction in the water within the liquid ceramic material on the porous sintered disk 108, the water associated with the liquid ceramic material on the semiconductor strain gauge can act to re-liquefy the liquid ceramic material on the porous sintered disk 108 when the semiconductor strain gauge is placed on that liquid ceramic layer on the porous sintered disk 108. Thus, partially curing the liquid ceramic material on the porous sintered disk 108 will allow the liquid ceramic material in which the semiconductor strain gauge has been immersed to bond to the layer of partially cured liquid ceramic material on the porous sintered disk 108. It should be understood that this portion of the curing process can be aided by using a chemical drying agent to remove free water from the uncured liquid ceramic material on the porous sintered disk 108 before reaching the activation energy temperature for water expulsion.

[0041] The use of a porous sintered disk is useful for attaching ceramics in situations where the parent gasket material must remain the same as the porous disk (e.g., a high nickel stainless alloy). In that case, the ceramic may not bond well to highly passive materials. The advantage of a porous element within the gasket is to create a mechanical interlock with the ceramic that maintains the bond to the strain gauge under a variety of mechanical and thermal conditions. The ceramic infiltrates the pores of the sintered disk where it is hardened. This creates a system where the sintered disk reinforces the ceramic and the ceramic is physically attached or locked to the metal (versus just chemically bonding to the surface). This solves the problem of ceramics not being adequately chemically bonded to some metals.

[0042] It will be appreciated that the semiconductor strain gauge will typically be the necessary circuitry within a silicon, silicon carbide or semiconductor wafer. Thus, the semiconductor wafer containing the strain gauge circuitry is what is immersed within the liquid ceramic material and placed on top of the layer of partially solidified liquid ceramic material 302. It will be appreciated that in some embodiments, the gage active length should be larger than the polymer particle size within the ceramic and in some embodiments larger than the pore size within the sintered material. Regardless, it will be appreciated that the semiconductor wafer must be sized to fit within (as described above in conjunction with Figure 2The porous sintered disk 108 is a bottom portion of the metal backing 102 and the walls of the opening 106 extend from the porous sintered disk 108 to the surface on the top side 110 of the metal backing 102.

[0043] It should also be understood that the semiconductor wafer may hold one or more semiconductor strain gauges. Figure 3 , there are four pairs of signal lines 304 that are attached to a semiconductor wafer including a plurality of strain gauges (which in this case include four semiconductor strain gauges) and that pass from the respective semiconductor strain gauges through the ceramic material. In this embodiment, four independent semiconductor strain gauges are used to make a bridge for measuring the strain of the metal surface of interest.

[0044] Each semiconductor strain gauge is attached to a signal line 304 to electrically transmit the strain measured by the corresponding semiconductor strain gauge. It should be understood that the composition of the signal line 304 may vary depending on the specific use of the semiconductor strain gauge. For example, at higher temperatures, such as temperatures above 500°F, current semiconductor wafer and signal line technology (e.g., titanium and aluminum ohmic pads or electrical contacts with gold wires for passing electrical signals into and out of semiconductor materials) may be insufficient due to the presence of a eutectic or intermetallic phase with silicon. Therefore, different metal compositions can be used for pads and signal lines. In some embodiments, the metal composition does not have a eutectic alloy with silicon below the desired operating temperature and does not form a non-conductive intermetallic compound with silicon below the desired operating temperature. These properties also contribute to ball-bonding wires after plating. In some embodiments, nickel can be used at temperatures below 1600°F; silver can be used at temperatures below 1500°F; aluminum can be used at temperatures below 1050°F; and tungsten can be used at temperatures below 1500°F. It should be understood that a "barrier layer" can be used, where a barrier layer of a safe metal (such as tungsten or nickel) can be used, followed by a layer of gold and gold guides. This keeps the gold from contacting the silicon. In some embodiments, noble metals such as platinum group metals can be used, although this is also true for more difficult ball bonding and plating procedures.

[0045] In addition, the diffusion rate of the pad and guide wire materials into the semiconductor and the corresponding equilibrium point need to be considered based on the expected operating temperature of the final sensor assembly. In some embodiments, the diffusion rate can be determined experimentally and used to select a given metal. For example, the sensor structure (e.g., semiconductor material, size and thickness, and metal for ohmic contact) should be selected so that at the equilibrium state with respect to the diffusion of the pad and guide wire materials into the semiconductor, at or above the expected operating temperature, sensor failure can be minimized or avoided.

[0046] Furthermore, it is understood that diffusion of oxygen through the pad and lead material into the semiconductor can cause a voided oxide layer and subsequent failure of the ohmic attachment. In some embodiments, a noble metal can be plated over the semiconductor to prevent oxygen from diffusing through the pad and destroying the ohmic contact.

[0047] It should be understood that the signal line can be attached to the semiconductor strain gauge or plated ohmic pad by welding, ultrasonic bonding, thermal bonding or similar attachment methods. In some embodiments, the attachment process is performed at a temperature higher than 300°F. In some embodiments, the attachment process is performed at a temperature range of more than 300-575°F. It should be understood that the specific temperature range is an addition to the thermal energy input from the selected attachment method and joins the precious transition metals from the semiconductor ohmic pad and the signal line material.

[0048] It should also be understood that in some embodiments, enamel coated nickel, aluminum or other conductive alloy wires may be used for electrical interconnection to high temperature semiconductor strain gauge components. In some embodiments, the interconnection terminates on a plated surface (e.g., a precious metal plating). In some embodiments, the interconnection terminates by welding to a post or anchor that is partially or fully plated with a precious metal or intermetallic compound that cannot oxidize below 1200°F.

[0049] Once the semiconductor strain gauge has been placed on the layer of partially cured liquid ceramic material 302, the entire ceramic material (including the layer of partially cured liquid ceramic material 302 and any liquid ceramic material added during placement of the semiconductor strain gauge on the layer of partially cured liquid ceramic material 302) is fully cured. In some embodiments, curing is performed by application of heat. In other words, the semiconductor strain gauge and the metal liner are co-fired to fully cure all of the ceramic material and ensure that the semiconductor gauge is bonded to the ceramic layer or interface.

[0050] In some embodiments, a secondary ceramic bonding process may be used in which an additional or second liquid ceramic different in composition and properties from the original base liquid ceramic material 302 is applied to partially re-liquefy the initial or base liquid ceramic material that has been partially solidified. In this case, the second liquid ceramic acts to transfer the bond to the surface of the base ceramic. In some embodiments, the second liquid ceramic erodes the base ceramic during its solidification process to activate the bond with the semiconductor strain gauge and the base ceramic. In some embodiments, the second liquid ceramic material may be able to chemically erode the semiconductor oxide layer and the base ceramic by the release of high or low pH off-gassing during the solidification cycle. For example, liquid ceramics in the phosphate family can release acidic compounds to increase the reactivity of the bonded surface during solidification.

[0051] Figure 4 yes Figure 3 A top view of a metal pad of a semiconductor strain gauge and a strain gauge packaged in a ceramic according to one embodiment of the present invention. In one embodiment, after the semiconductor strain gauge has been placed on top of the layer of partially cured liquid ceramic material 302, additional liquid ceramic material can be applied to mechanically cover or encapsulate the semiconductor strain gauge. As shown, a ceramic covering 402 can be formed to completely cover the semiconductor strain gauge. This ceramic covering 402 can be formed by placing additional liquid ceramic material on top of the semiconductor strain gauge. In some embodiments, this additional ceramic material is added after the semiconductor strain gauge and the partially cured liquid ceramic material 302 have been completely cured. In some embodiments, this additional ceramic material is cured separately. This ceramic covering 402 acts to protect the semiconductor strain gauge from direct oxygen exposure and mechanical damage during use. It also acts to tether the guide wires or signal wires from the semiconductor gauge to avoid vibration or strain of the semiconductor gauge at the signal pad. It should be understood that the liquid ceramic material used to form the ceramic cover 402 may be the same as the liquid ceramic material used to form the ceramic layer on the porous sintered disk 108, but need not be the same ceramic material used previously in the process.

[0052] Figure 5 is attached to the surface of interest Figure 41 and 1. A top perspective view of a metal pad and packaged strain gauge. As shown, the metal pad 102 is placed on a surface of interest 502, which may be a metal surface and may be attached by welding. It should be understood that the side of the metal pad 102 placed against the surface of interest 502 may be cleaned prior to placement to remove any ceramic material on its surface and to ensure a relatively flat surface for attachment to the metal 502 of interest. It should also be understood that the bottom side 116 of the porous sintered disk 108 may or may not be aligned with the surface of the metal pad 102 attached to the surface of interest 502. In any case, any strain on the surface of interest 502 is transferred through the metal pad 102 to the semiconductor strain gauge attached to the porous sintered disk 108. Because the metal pad 102 is directly attached to the surface of interest 502, in some embodiments (e.g., those embodiments in which the surface of interest 502 is a metal surface), the metal pad 102 is made of a metal that is the same or similar to the metal of the metal surface of interest 502, although this is not required because any offset between the composition of the surface of interest 502 and the metal pad 102 can be accounted for in the processing of the strain data measured by the semiconductor strain gauge.

[0053] The machined plate 506 is attached to the top side 110 of the metal backing 102. In some embodiments, the machined plate 506 can be screwed to the metal backing 102 using bolts 508 to anchor the machined plate 506 against the metal backing 102. The machined plate 506 provides an opening for a metal screw 510 that is secured to the machined plate 506 using a metal nut 512. The screw 510 passes through the machined plate 506 and is physically attached to the signal line 304 extending from the semiconductor strain gauge (i.e., at Figure 5 The four pairs of signal lines 304 in the embodiment shown in FIG. Figure 3 and Figure 4The metal nut 512 is similar to the signal line 304 of the semiconductor strain gauge) and provides an electrical connection to the signal line 304. A larger signal line 514 is attached to the metal nut 512. Thus, the electrical signal from the semiconductor gauge is transmitted to the metal screw 510 through the signal line 304 and to the larger signal line 514 through the metal nut 512. The larger signal line 514 is then electrically connected to an instrument for receiving and recording the measured strain data. It should be understood that the metal screw 510 and the corresponding metal nut 512 can be replaced with any type of suitable electrical connector that connects the signal line from the semiconductor strain gauge to the larger signal line, which passes to the corresponding instrument or records the measured strain. It should also be understood that a protective box or housing (not shown) can be placed over the entire device when attached to the metal 502 of interest to protect it from any undesirable physical contact, such as collisions.

[0054] It should be understood that the above combination Figure 1-5 The described metal sintered disk provides an embodiment of a porous portion of a metal body or metal liner that provides a structure for maintaining a ceramic interface or layer. However, it should be understood that the porous portion can be provided in other ways. In one embodiment, the porous portion of the metal body or metal liner is a material area that has been designed to have desired mechanical and chemical bonding characteristics and can have various porosities through the application of 3D printing (including direct metal laser sintering, or powder metallurgy). For example, this area can have a higher surface energy to bond to a ceramic glaze or composite oxide, while the rest of the structure is composed of a highly passivated material (such as nickel or stainless steel). This area can also be designed to have a specific thermal expansion ratio to better accommodate the expansion of the ceramic bonding and insulating layer. In this case, there is no sintered disk.

[0055] By using powder metallurgy, the transition between metal alloys can be made so that the parent metal liner is continuous (uninterrupted and without welds) with a section of metal material having desirable properties for ceramic bonding. For example, the metal body or metal liner can be designed to have a metal component that transitions from one component to another through the metal body or liner so that the metal component transitions to a component that facilitates bonding to the ceramic at the location where the ceramic contacts the metal body or liner or provides a relatively better bond with the ceramic. In addition, in embodiments where the semiconductor strain gauge is disposed within a recess or depression (compared to a through hole extending through the metal body or liner), the metal component beneath the semiconductor strain gauge can also transition to a component that similarly bonds more easily to the ceramic beneath the semiconductor strain gauge. In this embodiment, the metal component can be transitioned to a component having a thermal expansion coefficient that is similar to, approximately the same as, or matches the thermal expansion coefficient of the ceramic base layer beneath the location of the semiconductor strain gauge. More generally, in embodiments utilizing transition metal components, the components can be transitioned to have desirable material properties and fuse at an interface location such that low energy welding techniques can be applied to the structure and provide an exposed surface of the metal body or metal backing that is resistant to oxidation through the addition of chromium, nickel, and other similar passivating metals.

[0056] For example, a combination of metals (e.g., copper and stainless steel) can be used in a designed ratio. The ratio is determined by the bulk thermal expansion of the combination of these different materials. This thermal expansion can be tailored to match the (volumetric or linear) thermal expansion of the ceramic bonding layer. For example, in one embodiment, the metal can include 40% copper and 60% 400 series stainless steel. Similarly, the pad can be designed to match the thermal expansion of the structure at the point of attachment to the structure of interest. The importance of defining the coefficient of thermal expansion (CTE) of the pad is to allow the ceramic to better match the expansion and have a better response to thermal growth and shock. Designed materials or transitional materials are beneficial to the purpose of chemical bonding to various categories of ceramic materials (including glass, silicates, clays, and phosphate-based ceramics). However, it should be understood that the use of both porous sintered disks and such designed materials can be combined to provide both mechanical and chemical bonding to the ceramic bonding layer.

[0057] Fig. 6A is a top view of a semiconductor strain gauge assembly according to another embodiment of the present invention, and Figure 6B yes Fig. 6A1 is a side view of a semiconductor strain gauge assembly of FIG. In this embodiment, a porous sintered disk within a hole or depression within a metal backing is not used. Instead, the semiconductor strain gauge is disposed on the top surface of the metal backing, noting that a layer of ceramic or glass (not shown) is disposed between the top surface of the metal backing and the semiconductor strain gauge. Fig. 6A and 6B Both, a metal pad 602, which is generally depicted as a rectangular shape, is provided with a top surface 604. A semiconductor strain gauge or a plurality of semiconductor strain gauges 606 are provided on the top surface 604 of the metal pad 602. The semiconductor strain gauge 606 is buried and insulated with a ceramic layer 608. A signal line 610 extends from the semiconductor strain gauge 606 through the ceramic layer 608 and will eventually be connected to a corresponding device for recording the strain measurement performed by the semiconductor strain gauge 606. It should be understood that this semiconductor strain gauge assembly can be manufactured using assembly methods such as SOI wafers and glazing methods, which have become practical for the conventional materials described above. In addition, 3D printing of materials enables the use of glazed ceramics bonded between the metal and the semiconductor gauge. Therefore, this semiconductor strain gauge assembly provides advantages such as eliminating the need to re-liquefy the base ceramic to generate a second bond.

[0058] Figure 7 is a top perspective view of a portion of a semiconductor strain gauge assembly according to another embodiment of the present invention. As shown, a metal body or metal liner 702 holds a semiconductor strain gauge or a plurality of semiconductor strain gauges positioned at a given porous portion 704 within the metal liner 702 (e.g., within the center of the metal liner 702). It should be understood that the semiconductor strain gauge is substantially buried within the metal liner 702, but can be buried according to any of the embodiments described above. A cable connector 708 is used to connect a protective cable (not shown) within which a signal line will pass to an instrument for recording strain measurements. In use, a bottom surface 706 of the metal liner 702 will be placed on a surface of interest. Tabs 710 having eyes 712 on opposite ends can be used to attach a final assembly or load cell (such as in combination with Figure 8 712 is attached to the surface of interest. In one embodiment, the load cell can be attached to the surface of interest using capacitive discharge welded stakes, noting that the eyelets 712 can be open or closed, depending on the specific application in which the load cell is used. It should be understood that additional structure 714 integrated into the metal body or liner 702 is used to connect additional parts of the overall load cell as further described below.

[0059] Figure 8 According to another embodiment of the present invention Figure 7 A top perspective view of additional parts of the semiconductor strain gauge assembly of FIG. As shown, additional parts of the overall load cell are shown in FIG. Figure 7 . Specifically, the body 802 accommodates electrical connectors or signal introduction points 804 corresponding to the number of semiconductor strain gauges provided with the metal body or metal pad 702. In this embodiment, four electrical connectors 804 are accommodated by the body 802. It should be understood that each electrical connector 804 is insulated by an insulating cover 806. It should be understood that a signal line (not shown) will be used to connect each semiconductor strain gauge to one end of each corresponding electrical connector 804. It should also be understood that an additional set of signal lines (not shown) will be connected to the opposite ends of the electrical connectors 804 and pass from the electrical connectors 804 through a protective cable (not shown) held by the cable connector 708 to the corresponding equipment for recording strain measurements. The body 802 has a lug 808 provided on the top of the structure 714 to position the body 802 above the metal pad 702.

[0060] Fig. 9 According to another embodiment of the present invention Figure 7 A top perspective view of an additional portion of a semiconductor strain gauge assembly. As shown, Figure 7 and Figure 8 The structure is covered by a top cover 902. Bolts 904 can be used to hold the top cover 902 in place and further secure the body 802 housing the electrical connector 804 and the metal body 702 together.

[0061] It should be understood that Figure 7-9 The load cell shown is an example of a field deployable load cell in that its design and corresponding structure can be varied depending on the specific application in which the load cell will be used. In general, the overall design of the load cell is to accommodate the strain gauges and corresponding electrical connections to provide protection for these various components and to direct the mechanical strains detected by the gauges in a manner optimal for detection. For example, in some embodiments, the load cell assembly or structure can be made of a material that has a greater thermal expansion than the attachment point to the structure of interest for measurement. This provides increased interface tightness due to differential expansion during temperature increases.

[0062] It should be understood that any of the aforementioned strain gauge assemblies or load cells can be attached to a surface of interest using low energy welding techniques. For example, the load cell can be placed within the facet of a capacitive discharge welding stud so that the plasma discharge occurs substantially below the surface of the strain gauge assembly. In these cases, the energy required for assembly attachment to the structure is below 125 watt seconds and remains below the requirements for pre-weld heat treatment and post-weld heat treatment defined by ASME B31.1. In addition, a handheld capacitive discharge stud gun can be mated with a collet designed to accommodate the geometry of the strain gauge assembly. In some embodiments, the strain gauge assembly can be attached to the structure by means of a fixture designed to orient and clamp the strain gauge assembly to enable low energy welding, wherein the fixture is manufactured with a momentary or switched magnetic base for attachment to ferrous or magnetic structures. In some embodiments, the fixture can be used with a collet designed to accommodate the strain gauge assembly and transmit current for the capacitive discharge welding process. In some embodiments, the gauge assembly is driven into the welding plasma by the fixture using springs, gas pressure, hydraulic pressure, or an actuator (e.g., a solenoid). In addition, the fixture may include bearings that allow the central shaft or plunger to egress and drive the strain gauge assembly into the welding plasma in a linear motion.

[0063] In some embodiments, the load cell can be deployed and attached to the surface of interest using low-energy capacitive discharge welding. The use of capacitive discharge welding is within the limits of welding allowed on the boiler structure for existing sensor technology (e.g., thermal coupling). The use of these processes prevents the need for preheating or post-heating of structural welding. The load cell can be attached by multiple capacitive discharge piles. It can also be deployed in the combined surface of a single pile, thereby eliminating any need for multiple attachment points. The feature of placing the gauge in the base of the CD welding pile is very beneficial to field applications, where the installer is required to quickly apply the strain gauge in different environmental conditions. In addition, the use of capacitive discharge pile welding allows this sensor technology to be deployed by power industry workers of the expected technical level. However, it should be understood that in some embodiments, the load cell or strain gauge assembly can be attached to the pile or fastener without welding the assembly to the fastener and continue to measure strain at a temperature higher than the installation temperature.

[0064] It should be understood that the device can be used to measure strain in any metal surface of interest. In some embodiments, the metal surface of interest can be mild steel, low alloy steel, stainless steel (including 304, 316, 17-4PH steel) and various creep strength enhanced ferritic steel alloys (including, for example, Grade 91 and Grade 92). It should be understood that, as described above, when measuring the strain of a metal surface of interest having one of these components, the metal body or the metal liner in some embodiments can be similarly constructed using the same or similar metal as the metal of the metal surface of interest. Therefore, in some embodiments, the metal liner can be mild steel, low alloy steel, stainless steel (including 304, 316, 17-4PH steel) and various creep strength enhanced ferritic steel alloys (including, for example, Grade 90 and Grade 92). In some embodiments, the metal liner can be constructed of a high temperature alloy or iron-containing alloy having a relatively high nickel or chromium concentration or other alloy properties suitable for high temperature environments. In some embodiments, the metal liner can be constructed of a metal with a stable surface oxide, such as an oxide of chromium or nickel. In some embodiments, titanium can be used, which can be useful for measuring strain within an aircraft or spacecraft engine, frame, fuselage, heat exchanger, etc.

[0065] It should be understood that the device can also be used to measure strain in any non-metallic surface of interest. In these cases, the strain measurements can be correlated to other characteristics of the surface of interest. For example, in some embodiments, these measurements can be used to measure fluid pressure.

[0066] Various embodiments of the present invention have been described above. However, it should be understood that alternative embodiments are possible and the present invention is not limited to the specific embodiments described above. For example, semiconductor strain gauges can be made from semiconductor materials (such as doped silicon or silicon carbide) with the aid of plated ohmic contacts using transition metals or intermetallic compounds with diffusivities acceptable for the duration of use and operating temperature of the strain gauge. The plated metal must fill the vacancies within the semiconductor grid and (once occupied) become immobile at a specific concentration gradient starting from the surface of the semiconductor material. This is understood empirically and modeled as an exponential of temperature and time using methods such as the Frank-Turnbull model. In some embodiments, plated ohmic contacts using transition metals or intermetallic compounds can have an oxygen diffusion rate less than X at 1200 F. In some embodiments, plated ohmic contacts using transition metals or intermetallic compounds with silicon-containing intermetallic compounds and eutectic phases can be accomplished at temperatures above 1200 F.

Claims

1. A device for measuring strain, comprising: A metal body, the body comprising a porous portion and a ceramic portion disposed on the porous portion; as well as a semiconductor strain gauge coated in a ceramic material disposed on said ceramic portion; The body has a surface for attachment to an object to measure strain of the object.

2. The apparatus of claim 1, wherein the porous portion comprises a porous metal disk.

3. The apparatus of claim 2, wherein the porous metal disk comprises a metal sintered disk. The apparatus of claim 3 , wherein the ceramic portion is bonded to the metal sintered disk.

5. The apparatus of claim 1, wherein the ceramic portion is bonded to the metal body.

6. The apparatus of claim 5, wherein the porous portion is within the metal body, and wherein the ceramic portion is at or below an exposed surface of the metal body.

7. The apparatus of claim 1, wherein the porous portion is below the ceramic portion and the semiconductor strain gauge.

8. The apparatus of claim 1, wherein the porous portion is within the metal body, and wherein the ceramic portion is at or below an exposed surface of the metal body.

9. The apparatus of claim 1, wherein the ceramic portion includes a ceramic component that thermally expands during use along with thermal expansion of the metal body.

10. The apparatus of claim 1, wherein the metal body has a component that thermally expands during use along with thermal expansion of the ceramic portion.

11. The apparatus of claim 1 , wherein the metal body comprises a composition that transitions from a first composition at a first location within the metal body to a second composition at a second location within the metal body, wherein the second location is adjacent to the ceramic portion and the second composition bonds better to the ceramic portion than the first composition.

12. The apparatus of claim 1 , wherein the metal body comprises a composition that transitions from a first composition at a first location within the metal body to a second composition at a second location within the metal body, wherein the second location is adjacent to the ceramic portion and the second composition has approximately the same coefficient of thermal expansion as the ceramic portion.

13. A method of manufacturing an apparatus for measuring strain, comprising: forming a ceramic portion attached to the porous portion of the metal body; as well as A semiconductor strain gauge coated with a ceramic material is bonded to the ceramic part.

14. The method of claim 13, wherein the forming comprises disposing a first ceramic layer within the body, wherein the bonding comprises bonding the semiconductor strain gauge to the first ceramic layer.

15. The method of claim 13, wherein the metal body comprises a hybrid metal body having a metal component that transitions from a first component at a first location within the hybrid metal body to a second location within the hybrid metal body, and wherein forming the ceramic portion attached to the hybrid metal body comprises bonding the ceramic portion to the second component of the hybrid metal body at the second location.

16. The method of claim 13, wherein the metal body comprises a hybrid metal body having a metal component that transitions from a first component at a first location within the hybrid metal body to a second location within the hybrid metal body, and wherein the second component has approximately the same coefficient of thermal expansion as the ceramic portion.

17. The method of claim 13, wherein said forming said ceramic portion attached to said body comprises: adding a first liquefied ceramic material to a porous portion of the body; as well as partially solidifying the first liquefied ceramic material to produce a partially solidified liquefied ceramic material; and wherein said bonding said semiconductor strain gauge to said ceramic portion comprises: The semiconductor strain gauge and a second liquefied ceramic material are placed on the partially solidified liquefied ceramic material.

18. The method of claim 17, wherein the first liquefied ceramic material has the same composition as the second liquefied ceramic material.

19. The method of claim 17, further comprising: A third liquefied ceramic material is added to reliquefy the partially solidified liquefied ceramic material and provide bonding to the semiconductor strain gauge, the third liquefied ceramic material having a different composition than the first liquefied ceramic material and the second liquefied ceramic material.

20. A method for measuring strain of an object, comprising: attaching a body to a surface of an object, the body comprising a semiconductor strain gauge encapsulated within a ceramic material, wherein the semiconductor strain gauge comprises at least one signal line electrically connected to the semiconductor strain gauge and passing through the ceramic material; electrically connecting the at least one signal line to an instrument configured to receive an electrical signal generated by the semiconductor strain gauge; as well as The instrument records the electrical signal generated by the semiconductor strain gauge.

Images