EA037107B1 - High temperature probe - Google Patents

Abstract

High temperature probes and methods for assembling high temperature probes are disclosed. The high temperature probes may include a rod with a thermocouple embedded within the rod, and a ceramic matrix composite sheath substantially surrounding the rod. The high temperature probes may also include an outer metal tube surrounding a portion of the rod, and an inner metal tube positioned between the alumina rod and the outer metal tube, the inner metal tube being configured to prevent the rod from spatial displacement with respect to the outer metal tube.

Description

Medvedev V.N. (RU)

037107 B1 (57) High temperature probes and methods for assembling high temperature probes are disclosed. High temperature probes may include a rod with a thermocouple inserted inside the rod and a ceramic matrix composite containment shell substantially surrounding the rod. The high temperature probes may also include an outer metal tube surrounding the rod portion and an inner metal tube positioned between the alumina rod and the outer metal tube, the inner metal tube being configured to prevent spatial displacement of the rod relative to the outer metal tube.

037107 Bl

Technology area

The invention relates to temperature measurement techniques, and more particularly to temperature probes for use in harsh environments such as aircraft turbines.

State of the art

Temperature probes are essential for measuring temperature in harsh environments such as aircraft turbines. The exhaust present in aircraft turbines is intense, hot and reactive. In addition, exhaust temperatures can be expected to be even higher in future aircraft turbines. Metals such as nickel alloys are now used to protect probes used in the harsh environment of aircraft turbines. However, such probes will have a relatively short lifespan in future hotter exhaust applications.

The essence of the invention

Aspects of the present invention include temperature probes and methods for forming temperature probes. The temperature probe can include a stem, a thermocouple, an outer tube, an inner tube, and a protective jacket. The thermocouple is placed inside the stem. The outer tube surrounds at least a portion of the rod. An inner tube is positioned between the stem and the tube to prevent the stem from shifting. The ceramic matrix composite containment shell substantially surrounds the rod and the outer metal tube.

Additional aspects of the invention include methods for assembling temperature probes. A method for assembling a temperature probe may include positioning a thermocouple between a first element and a second element, mating the first element and a second element to form a stem, placing an outer tube over a portion of the stem to engage the first element and a second element, positioning an inner tube between at least a portion of the rod and at least a portion of the outer tube for securing the rod relative to the outer tube; and applying a ceramic matrix composite protective sheath to substantially cover the rod and the outer metal tube.

Additional aspects of the invention include temperature probes that include a stem, a thermocouple inserted into the stem, and a probe base extending beyond the end of the stem. Temperature probes may also include a protective sheath covering at least a portion of the stem and a portion of the base of the probe. At least one of a rod, a probe base, or a containment sheath includes a ceramic matrix composite material.

Additional aspects of the invention are directed to methods for assembling temperature probes, which include forming a rod with at least one channel, passing thermocouple wires through at least one channel, positioning the base of the probe beyond the end of the rod, wrapping ceramic fiber around the base of the probe and the rod, and converting the ceramic fiber to a ceramic matrix composite material, thereby forming a protective sheath around the probe base and stem.

Brief Description of Drawings

The invention will become clearer from the following detailed description upon examination in conjunction with the accompanying drawings, in which like elements bear the same reference numerals. When there are many like elements, a single reference designator may refer to the plurality of like elements using a lowercase letter to denote specific elements.

The drawings include the following diagrams:

fig. 1 is a cross-sectional view of a probe in accordance with aspects of the invention;

fig. 2 is a perspective view of a rod element in accordance with aspects of the invention;

fig. 3 is a perspective view of a rod in accordance with aspects of the invention;

fig. 4 is a perspective view of an outer tube surrounding a rod in accordance with aspects of the invention;

fig. 5 is a perspective view of an inner tube housed within an outer tube that surrounds a rod, in accordance with aspects of the invention;

fig. 6 is a flow diagram illustrating the steps of assembling a probe in accordance with aspects of the invention;

fig. 7 is a cross-sectional view of a probe in accordance with aspects of the invention;

fig. 8A and 8B are views of a probe rod in accordance with aspects of the invention;

fig. 9A and 9B are views of a probe base rod in accordance with aspects of the invention;

fig. 10A and 10B are views of a probe in accordance with aspects of the invention;

fig. 11 is a flow diagram illustrating the steps of assembling a probe in accordance with aspects of the invention;

fig. 12A and 12B are views of a probe in accordance with aspects of the invention;

fig. 13A and 13B are views of a probe in accordance with aspects of the invention; and

- 1 037107 fig. 14 is a flow diagram illustrating steps for assembling a probe in accordance with aspects of the invention.

Detailed description of the invention

There is a need for better performance temperature sensors. The controlled temperatures of modern turbines or newer turbines are between about 1100 and about 1200 ° C. The turbines of the future, taking into account the required sensor accuracy and the necessary control facilities, will require temperature measurements greater than 1300 ° C.

Previous standard materials for such sensors, such as nickel-based superalloys, will not withstand temperatures greater than 1200 ° C.

Taking a measurement closer to the combustion chamber means more accurate hot section control. This contributes to the planning of the service interval and the efficient use of the turbine.

The sensor will remain operational in gas turbine flow up to 1350 ° C for short periods of time and continuously above 1200 ° C. In one embodiment, the ceramic matrix composite probe contains a ceramic insulated Platinel® thermocouple that has a similar emf output to a standard Type K thermocouple output.

Without the ability to measure temperatures greater than 1300 ° C, the temperature sensor must be located farther from the hotter turbine paths. With the ability to measure a temperature of 1300 ° C, the sensor is closer and the turbine monitoring data is better.

A temperature sensor based on a ceramic matrix composite has been designed for applications in gas turbines up to a temperature of 1350 ° C. Previous high temperature turbine sensors have used nickel-based superalloys to enable operation at nearly 1200 ° C. Operation at temperatures much higher than 1200 ° C with any nickel alloy is severely limited. Suitable materials for hot section parts for new OEM turbines include ceramic matrix composites. Ceramic matrix composites have an advantage over plain ceramics only because of their creep resistance. Ceramics are already used in high performance temperature sensors, usually in the form of magnesium oxide; also used aluminum oxide. In one embodiment, an alumina ceramic matrix composite is applied to the outer region of a high performance temperature probe with both alumina fibers and alumina matrix. Ceramics of the oxide family have better resistance to the very corrosive chemical environment of the turbine combustion chamber compared to carbon composites, which require a protective coating relative to the environment, making them susceptible to erosion and subsequent failure. However, some composites based on silicon carbides or carbon have better high-temperature properties than oxide ceramics.

Alumina ceramic matrix composites operate at temperatures greater than 1200 ° C and do not require a protective coating relative to the environment, since they are resistant to the environment in the turbine.

Without the ability to measure temperatures greater than 1300 ° C, the temperature sensor must be located further from the hot paths of the turbine. Placing the sensor further from the turbine to allow for the use of nickel alloys means that it will measure a mixture of hot combustion gas and compressor cooling air, and the uncertainty in measuring the gas turbine temperature will increase, the ability to control the turbine when it degrades due to temperature will be less, which will negatively affect scheduled maintenance.

An advantage of the invention is that there is no compromise in the operating parameters of the temperature sensor due to the requirements of new turbines. The ceramic matrix composite probe can be located closer to the combustion chamber, in the normal position of the turbine sensor, and prevent degradation of performance. New turbines and turbines of the future will operate at higher temperatures. Components in the hot path of turbines must meet new, higher levels of performance, specifically temperature parameters, as temperatures increase.

Ceramic matrix composites have not yet been used in gas turbine temperature sensors. The ability to operate at higher temperatures improves the efficiency of the turbine and increases the efficiency of the turbine operator choosing the turbine over competing options. The density of ceramic matrix composites is also lower than for metals, with some weight gain, which is always desirable.

Alternative rods made of less rigid materials can be used in accordance with embodiments of the invention. Solid rods have little ductility compared to rods made from ceramic matrix composite (CMC) materials. CMC materials fail more gradually than hard ceramics like alumina. Embodiments of rods that are less brittle than ceramic rods are described below.

FIG. 1 is a cross-sectional view of one embodiment of probe 100 in accordance with aspects of the invention. The illustrated probe 100 includes a containment shell 108, a shaft 103, an inner tube 106, and an outer tube 104. Probe 100 also contains a thermocouple, described below in connection with

- 2 037107 fig. 2 inserted inside the shaft 103. Probe 100 has an axis 110 longitudinally extending through the center of probe 100.

The rod 103 can be alumina-based (e.g. alumina), silicon-based, silicon carbide-based (e.g. SiC fiber, SiC matrix, etc.), carbon-based and / or other materials / material combinations suitable for use within temperature probes. Rod 103, containment jacket 108, tubes 106 and 104, and / or other components of probe 100 may be formed from a fiber / matrix material formed into a CMC material. For example, fibers can include CH Nicalon ™, Hi-Nicalon ™, Sylramic ™, Carbon, Nextel ™ 312, Nextel ™ 610, Nextel ™ 720, nickel alloy metals, etc. The matrix can be based on silicon (for example, SiNC, SiC + Si ₃ N ₄ , SiC, SiO ₂ , etc.), based on alumina (for example, Al2O3, etc.) and / or a combination of material based on alumina and quartz-based (eg SiO ₂ + Al ₂ O ₃ , etc.).

Shown in FIG. 1, the shaft 103 is formed of a first member 102a and a second member 102b. Elements 102a and 102b may be articulated along axis 110 to form a shaft 103. In an embodiment, elements 102a and 102b are substantially symmetrical with respect to each other. Although a rod formed from two symmetrical elements is shown and described herein, it is contemplated that the rod 103 can be of a monolithic structure, can be formed from more than two elements, and the elements do not need to be symmetrical.

FIG. 2 shows the first rod member 102a of FIG. 1. The element 102a has a groove (not shown) in the mating surface 204. The mating surface 204 may be mated with a corresponding mating surface (not shown) of the element 102b. In an embodiment, a bore is present only in the first member to form a thermocouple channel 202. In other embodiments, at least one other member (eg, member 102b) has a bore that, when combined with the bore of the first member 102a, forms a thermocouple bore 202. Thermocouple 202 fits into the groove of one element 102a in front of the joint. The temperature functional portion 206 of the thermocouple is located at the end of the probe 100, which can be exposed and / or pulled out of the containment 108.

FIG. 3 shows a shaft 103 formed from an articulated first member 102a and a second member 102b. The articulation of the first element 102a and the second element 102b allows the thermocouple 202 to be embedded therebetween. In some embodiments, the rod 103 has a locking protrusion 302. The locking protrusion 302 is located in the region of the rod 103 with such a section in a plane perpendicular to the axis 110 that is larger in circumference than the section at other points. While FIG. 3 shows the stopper 302 as a uniformly enlarged circumference of the outer surface 304 of the stem 103, it is contemplated that any other structural change in the outer surface 304 that would prevent the bar from sliding axially through the surrounding tube, such as tube 104, could be used as the stopper.

FIG. 4 shows an outer tube 104 surrounding a rod 103. The placement of an outer tube 104 maintains the first member 102a and the second member 102b in an articulated position. Outer tube 104 may have an edge 114 that engages a stop lug 302 on stem 103 to prevent the stem 103 from fully passing through outer tube 104. Outer tube 104 may be made of chromium or nickel, alloys, alumina, CMC, or other material suitable for use in temperature probes.

The illustrated outer tube 104 also has a locking protrusion 402 on the outer surface 404 to prevent displacement of the containment shell 108. While FIG. 4 depicts the stopper protrusion 402 as a uniform increase in the circumference of the outer surface 404 of the outer tube 104, it is contemplated that any design modification to the outer surface 404 can be used that prevents the containment 108 from displacement along axis 110.

FIG. 5 shows a shaft 103, an outer tube 104, and an inner tube 106. The inner tube 106 may contact the inner surface of the outer tube 104 and the outer surface 304 of the shaft 103. The first end 112 of the inner tube 106 may contact the stopper protrusion 302 on the shaft 103. The inner tube 106 can be welded 502 to outer tube 104. Known welding techniques can be used. It is contemplated that the inner tube 106 and the outer tube 104 may be bonded by methods other than welding that are suitable for use in high temperature environments (eg, brazing, CMC processing, etc.). Securing the outer tube 104 to the inner tube 106 protects the rod 103 from displacement relative to the outer tube 104. In an embodiment, a locking projection 302 on the rod is positioned between the first end 112 of the inner tube 106 and the ridge 404 on the inner surface of the outer tube 104.

In an embodiment, a portion of the inner surface 504 of the inner tube 106 is not in contact with the outer surface 304 of the rod 103. This portion of the inner surface 504 may be adapted for attachment to other devices or articles. The inner surface can be adapted for attachment using threaded screws, tenons, lugs or with

- 3 037107 using other suitable attachment methods. The inner tube 106 can be made of chromium or nickel, alloys, CMC, or any material suitable for use in temperature probes.

Referring again to FIG. 1, a containment shell 108 is applied over the rod 103 and outer tube 104. The containment shell 108 may be formed from a variety of ceramic matrix composites. The ceramic matrix composite can be carbon fiber in a carbon matrix, carbon fiber in a silicon carbide matrix, silicon carbide fibers in a silicon carbide matrix, and alumina fibers in an alumina matrix, for example. The protective sheath 108 may be applied to the rod 103 in a manner that will be apparent to a person skilled in the art from the description provided herein. The outer surface 118 of the containment shell 108 may have a smoothness of about 125 or less. In one embodiment, the smoothness of the outer surface 118 of the containment shell 108 is less than 32. The containment shell 108 may have a thickness of between about 0.03 and 0.06 inches.

The containment shell 108 is attached to the outer tube 104. In one embodiment, the containment shell 108 is formed to contact a retaining lip 402 on the outer surface 404 of the outer tube 104, which prevents the containment shell 108 from dislodging.

As shown in FIG. 1-5, the temperature probe has a truncated conical shape extending downward toward the temperature function section 206, with an end that includes an outer tube 104 having a larger diameter than the diameter at the end of the temperature function section 206. The larger diameter toward the end of the outer tube 104 provides the temperature probe with voltage resistance against forces applied during operation.

FIG. 6 shows a flowchart 600 for steps in assembling an embodiment of a probe in accordance with aspects of the invention. The steps in the flowchart are described below with respect to the probe of FIG. 1-5. It should be understood that the steps can be used to assemble probes other than those shown in FIG. 1-5, and that one or more of steps 602-610 may be performed in a different order and / or may be omitted.

At block 602, a thermocouple is positioned between the first element and the second element. The thermocouple 202 may be positioned between the first element 102a and the second element 102b. In an embodiment, a thermocouple 202 is placed in a channel that is formed by a groove in at least one element. The first element and the second element can be symmetrical.

At block 604, the shaft is formed by the articulation of the first element and the second element. The rod 103 may be formed by the articulation of the first element 102a and the second element 102b. The first member 102a and the second member 102b may be articulated along the articulation surface 204 of the first member and the articulation surface of the second member (not shown). In an embodiment, the rod 103 is formed from a material that is chemically compatible with the containment shell 108 using mechanical grinding, casting, or a combination of both forming processes.

At a block 606, an outer tube is placed over at least a portion of the rod. The outer tube 104 may be placed over at least a portion of the shaft 103. The placement of the outer tube 104 engages the first member 102a and the second member 102b. The material forming the outer tube is metal or other material suitable for use in temperature probes.

At a block 608, an inner tube is placed between the outer tube portion and the rod portion. The inner tube 106 may be positioned between the outer tube portion 104 and the rod portion 103. The placement of the inner tube 106 makes it difficult for the rod 103 to move along axis 110 relative to the outer tube 104. The material forming the inner tube 106 can be metal or other material suitable for use in temperature probe at approximately 2000 ° F or higher. In some embodiments, the material forming the inner tube 106 is suitable for temperatures of about 2500 ° F or higher.

At a block 610, the inner tube and the outer tube may be welded or otherwise bonded. Inner tube 106 and outer tube 104 may be welded or otherwise bonded using known welding techniques including, but not limited to, tungsten inert gas welding or laser welding. It is also contemplated that the inner tube 106 and the outer tube 104 may be bonded using other methods suitable for bonding the probe components (eg, brazing, CMC processing, etc.).

At a block 612, a ceramic matrix composite containment shell is applied to substantially cover the rod. A ceramic matrix composite protective sheath 108 is applied to substantially cover the rod 103. The protective sheath 108 may also be applied to the outer tube. Standard methods of applying a ceramic matrix composite containment shell can be used. The containment shell 108 can increase the ductility and the amount of plastic deformation experienced by the probe 100 prior to failure.

Referring further to FIG. 7, an embodiment of a temperature probe is shown in accordance with

- 4 037107 objects of the invention. The 700 probe is designed for temperatures up to 1350 ° C. It has a ceramic matrix composite shield 702, a ceramic inner region 704, and a Platinel® wire (not shown) for the thermocouple signal. The base 708 of the probe at the turbine wall is colder than the tip 710, and the selection of a satisfactory nickel superalloy can be designed to measure temperatures up to 1150 ° C. Materials other than nickel superalloy may be selected, such as those described with respect to probe 100. Dimensions may include an insertion depth of approximately 70 mm with a tip diameter 710 of approximately 4 mm.

Referring to FIG. 8A and 8B, a rod for use in a gas turbine temperature probe is shown. Two polarities thermocouple wires 806 and 808 (eg, one positive wire and one negative wire) that connect to thermocouple junction 810 at one end of each wire are inserted into stem 800. In one embodiment, the wires are made from a high temperature thermocouple system (eg, platinum alloy, Platinel®, etc.). Other suitable CMC materials will be apparent to a person skilled in the art from the description provided herein. Ceramic fiber can be braided over each of the thermocouple wires 806 and 808 separately, such as ceramic braid 802 and ceramic braid 804. Rod 800 shown includes ceramic fiber braided cylindrically over the wires. In an embodiment, a ceramic fiber is braided over both wires 806 and 808. As seen in FIG. 8A, wires 806 and 808 are welded together at a weld point 812, thereby forming a thermocouple. The ceramic fibers over the wires can then be processed at high temperatures to form the matrix that exists from the ceramic fibers, thereby forming the 800 rod.

FIG. 9A and 9B show a stem with a base in accordance with embodiments of the invention. The base 902 can be made of a ceramic material. The base 902 has a first section 904 and a second section 906, with the first section 904 having a diameter greater than the diameter of the second section 906. The base may function like the outer tube 104 described above in connection with FIG. 1-6.

Referring to FIG. 10A and 10B, a temperature probe is shown in accordance with embodiments of the invention. The temperature probe includes a shaft 800, a base 902, and a containment shell 1002 covering the shaft 800 and base 902. The containment shell 1002 can be made of CMC material and functions like the containment jacket 108. Wires 806 and 808 exit the probe at base 902 and are accessible for welding extension wire connections. In embodiments with containment 1002, base 902 and stem 800, the entire temperature probe may be made of high temperature CMC materials with thermocouple wires 806 and 808 inside, thereby providing a less brittle sensor.

Referring further to FIG. 11, a flowchart 1100 is shown for steps in assembling a temperature probe. At 1101, a ceramic fiber is braided over two polarized wires. The two polarized wires can be high temperature thermocouple metals (eg platinum alloy, Platinel®, etc.). The ceramic fiber can be an alumina fiber such as Nextel 720 and / or other materials such as those described in connection with probe 100. In one embodiment, the ceramic fiber is cylindrically braided around each wire.

At a block 1102, the two polar wires are welded together to form a thermocouple for the temperature probe. Welding can be simple fusion welding without filler wire. At this point in the wire assembly, a thermocouple is formed.

At block 1104, two cylindrical braids are infused with a ceramic matrix precursor. The braid can be infused with liquid or steam. In one embodiment, a sol-gel process is used to infuse wires. Once the braid is infused, the wires can be held in place and exposed to elevated temperatures (eg, approximately 400 ° F) until sufficiently solidified without distortion.

At block 1106, the infused cylindrical braids are converted into two adjacent CMC cylindrical rods. In an embodiment, the braids are converted at a high temperature (eg, about 1200 ° C) to form a matrix that results from the ceramic fibers braided over the wires in block 1101. This results in a ceramic braid within the ceramic matrix over the wires.

At block 1108, the ceramic braid is wrapped over the converted wire braids (eg, a CMC subassembly). Ceramic braid can be wrapped over braided wires and thermocouple junction. Once wound, the rod is infused at block 1109, similar to infusion at block 1104, and processed at block 1110, similar to processing at block 1106, to reinforce the ceramic braid over the treated wires. CMC wires, braids, and auxiliary assemblies converted to rods assembled in accordance with blocks 1101-1110 can withstand the high temperature processing of flowchart 1100 so that they remain unchanged in the resulting rod structure.

At block 1112, the rod is inserted into the base and covered with a protective sheath. Base

5,037107 and / or the containment shell may be of a ceramic material, and each may function as an outer tube 104 or a containment shell 108, respectively, as described above in relation to FIG. 1-7.

Referring further to FIG. 12A and 12B, another embodiment of a temperature probe in accordance with aspects of the invention is shown. Temperature probe 1200 includes an insert 1218 (e.g., a stem), a probe base 1204, a thermocouple 1206, and a shroud 1202 over the probe base 1204, an insert 1218, and a thermocouple 1206. As shown, the thermocouple junction 1208 can protrude outward and extend in the direction from the protective shell 1202.

Probe base 1204 includes a first portion 1222 that is cylindrical and a second portion 1224 that is frusto-conical. The probe base 1204 also includes a cylindrical passage 1205, shaped to extend through the center of the probe base 1204, that is configured to receive the insert 1218. In an embodiment, the probe base 1204 is constructed of an alumina based material. Probe base 1204 may include an end portion 1216 that extends from containment 1202 and is not covered with containment 1202. In an embodiment, a metal base is placed over end 1216 and attached to probe 1200 by brazing described in connection with FIG. thirteen.

Insert 1218 extends through cylindrical passage 1205 of probe base 1204. In one embodiment, insert 1218 is made of an alumina-based material. In an embodiment, insert 1218 is approximately 0.125 inches in diameter. Insert 1218 includes channels 1220 formed along the entire length of insert 1218 that are configured to receive thermocouple wires 1207 1206, thereby insulating thermocouple wires 1207 from high temperatures. As shown, the insert 1218 extends partially through the cylindrical passage 1205 of the probe base 1204, although it is contemplated that the insert 1218 may extend completely through the probe base 1204, or alternatively not pass through the probe base 1204 so that only thermocouple wires 1207 are pulled through the cylindrical passage 1205.

Thermocouple 1206 is formed from thermocouple wires 1207 that extend through cylindrical passage 1205 and fit into channels 1220 with thermocouple junction 1209 formed at tip 1208 of probe 1200. In an embodiment, each of wires 1207 is approximately 0.017 inches in diameter. Thermocouple junction 1209 may function as a temperature sensing mechanism for probe 1200. As shown, thermocouple junction 1209 protrudes through a notch in tip 1208 at the distal end of probe 1200.

A shield 1202 is formed over a portion of the base 1204 of the probe and insert 1208. It is contemplated that a shield 1202 may be formed over the entire base 1204 of the probe and / or over the thermocouple junction 1209 at the tip 1208 of the probe 1202. The shield 1202 may be braided fiber ( e.g. Nextel braid, alumina fiber, alumina matrix, silicon based fibers, silicon based matrices, silicon carbide fibers and / or matrices, etc.), which can be processed to form a ceramic matrix composite (for example, by adding ceramic precursor, solidifying and sintering at high temperatures, etc.).

Probe 1200 includes portions of various shapes. The proximal end of probe 1200 has a cylindrical portion 1210 with a diameter greater than that of cylindrical portion 1214 at the distal end of probe 1200. Between portion 1210 and 1214 there is a frusto-conical portion 1212 with a diameter that decreases toward the distal end of the probe. 1200. The configuration of regions 1210, 1212, and 1214 advantageously increases the resistance of the probe 1200 to compressive forces applied to the probe 1200 during operation. In an embodiment, containment shell 1202 has an outer diameter of approximately 0.425 inches and an inner diameter of approximately 0.3 inches at section 1210. In one embodiment, containment shell 1202 has an outer diameter of approximately 0.25 inches and an inner diameter of approximately 0.125 inches at section 1214. Length probe 1200 along sections 1210, 1212, and 1214 can be approximately 2.15 inches. Section 1210 may be approximately 0.433 inches long, with segment 1212 approximately 0.539 inches long and section 1214 approximately 1.178 inches long. In an embodiment, the frusto-conical portion 1212 may decrease in diameter at an angle of approximately 9 °.

Although three regions are shown, it is contemplated that other shapes and configurations could be used to achieve the desired advantage. For example, the probe may include only two sections, with one section having a diameter larger than the other section, the probe may be completely truncated conical, the probe may include four or more sections, and so on. In an embodiment, containment 1202 is thicker near the base 1204 of the probe than at the tip 1208 of the probe to increase resistance to mechanical stress. Other shapes and configurations for the probe will be apparent to a person skilled in the art from the disclosure provided herein.

Referring further to FIG. 13A and 13B, a probe 1300 with a metal base 1301 is shown. Probe 6 037107 nickname 1300 includes a stem 1218, thermocouple wires 1207 passing through stem 1218, a probe base 1204, and a protective sheath 1202 formed over the probe shaft 1218 and base 1204. similar to the features described with respect to FIG. 12A and 12B. Probe 1300 also includes a metal base 1301 that is constructed from a thin walled inner tube 1302 and a thick walled outer tube 1304. Inner tube 1302 may be brazed to the probe base 1204. In an embodiment, the inner tube 1302 extends over a raised portion 1216 of the probe base 1204. In one embodiment, portion 1303 of inner tube 1302 extends over portion 1216 of probe base 1204 such that space 1305 remains between inner tube 1302 and containment sleeve 1202. Inner tube 1302 may be an alloy such as Nickel 201, Haynes 230, etc. Inner tube 1302 can be between about 0.010 inches to about 0.015 inches thick and can be about 0.50 inches long. In embodiments where a portion 1303 of the inner tube 1302 extends over the base 1204 of the probe, the overlapping portion 1303 may be approximately 0.10 inches long.

The inner tube 1302 may be brazed to the base 1204 of the probe or other portions of the probe 1200. In such embodiments, the portion 1303 of the inner tube 1302 that overlaps the base 1204 of the probe forms a braze seal. The inner tube 1302 is thin compared to the outer tube 1304 so that stress in the ceramic of the probe base 1204 due to brazing and junction formation is kept to a minimum. Brazing can be brazing with a high temperature active metal such as palladium alloy.

A thick walled outer tube 1304 is shown over the inner tube 1302. The outer tube 1304 may be welded to the inner tube 1302 at weld points 1308. Outer tube 1304 can be constructed from an alloy such as Haynes 230 or other alloys suitable for use in high temperature applications using temperature probes. Outer tube 1304 includes a conduit 1306 shaped to sit over containment 1202 of probe 1300. As shown, portion 1310 of outer tube 1304 extends over portion of containment 1202. In one embodiment, portion 1310 of outer tube 1304 that extends over containment 1202, close to containment 1202, but not physically attached to containment 1202. In such embodiments, weld locations 1308 attach outer tube 1304 to probe 1300, and the non-physical bond between site 1310 and containment 1202 provides probe 1300 with additional resistance to mechanical forces. voltage, for example, found in turbines. Outer tube 1304 can go (eg, by welding) to a flange and junction box for attachment to the gas turbine wall.

FIG. 14 shows a flowchart 1400 with steps for constructing a temperature probe. At a block 1402, the two wires are welded together to form a thermocouple. The wires can be made of Platinel® material. At block 1404, an insert (eg, a rod) with channels is formed. The insert can be an alumina-based material. At a block 1406, the welded wires are passed through the channels in the insert. At a block 1408, the base of the probe is positioned past the end of the insert. Once the base of the probe is positioned past the end of the insert, the insert can pass all the way through the base of the probe or partially through the base of the probe.

At a block 1410, a ceramic braid is wrapped over the insert and base of the probe. The ceramic braid can be wound over the entire insert and probe base, or partially over the insert and / or probe base. The ceramic braid can be made from an alumina based material, a silicon based material, a carbon based material, and / or other materials suitable for forming into a ceramic matrix composite material. Ceramic braid can be wound to vary thicknesses across the probe base and insert to achieve the desired shape or design.

At a block 1412, a wound ceramic fiber is infused with a ceramic matrix precursor. In an embodiment, the ceramic matrix precursor is a liquid. At a block 1414, the infused ceramic fiber is processed to form CMC material over the base of the probe and insert. The infused ceramic fiber can first be processed at a relatively low temperature before hardening. In one embodiment, the infused ceramic fiber is processed at about 400 ° F. Once the infused ceramic fiber is solidified, it is then sintered at high temperatures until the CMC material is formed. In an embodiment, the fiber is sintered at about 1200 ° C.

At a block 1414, the metal base is brazed to the base of the probe. The metal base may include an inner tube, such as a thin-walled inner tube 1302. The brazing technique is the same as used for attaching metals to ceramic materials. The brazing technique is performed at high temperatures (for example, about 1000 ° C or more). Materials used for such brazing may include palladium alloys, nikromaterials for brazing, etc. In one brew

- 7 037107 ante implementation of titanium (eg 4% constituent of the brazing alloy) can be used in metal for brazing. Brazing metal to ceramic brazed joints is performed such that molten brazing material will wet the ceramic side of the joint since ceramics are not normally wetted by molten metals. In an embodiment, the surface of the ceramic material is prepared with a molybdenum-manganese composition and with a heating treatment. In one embodiment, the CMC material is deposited between the inner tube and the base of the probe to facilitate brazing and forming a solder joint.

The shape of the solder joint is selected such that the difference in thermal expansion between the braze metal and the ceramic of the probe base is matched, thereby keeping the stress in the area of the brazed joint to a minimum during the brazing process. In an embodiment, the metal base is a thin walled inner tube (eg, inner tube 1302) to minimize mechanical stress. The overlap of the inner tube with the probe base can be of simple geometry (for example, a simple cylindrical overlap) or it can have a different geometry (for example, a square overlap, conical overlap, toroidal overlap, etc.).

Alternative configurations of probe parts and materials will be apparent from the disclosure provided herein. For example, all components, including an insert (eg, a bar), can be constructed from materials formed in CMC materials. The inner oxide CMC material can be used in combination with the outer non-oxide CMC material.

While the invention has been illustrated and described herein in connection with specific embodiments, the invention is not intended to be limiting to the details shown. In fact, various modifications may be made to the details within the scope of the claims and the range of equivalents of the claims and without departing from the invention.

Claims (23)

1. Temperature probe containing a rod with at least one channel; thermocouple wires inserted into the stem; the base of the probe enclosing the end of the rod; and a protective shell covering at least a portion of the shaft and a portion of the base of the probe; wherein the protective shell is made of a ceramic matrix composite material formed from a braided ceramic fiber by heating to a high temperature to form a ceramic matrix. 2. The probe of claim 1, wherein the thermocouple comprises a first thermocouple wire and a second thermocouple wire coupled to the first thermocouple wire to form a thermocouple. 3. The probe of claim 2, wherein the rod comprises a first ceramic matrix composite braided over the first wire and a second ceramic matrix composite braided over the second wire. 4. The probe of claim 2, wherein the first thermocouple wire and the second thermocouple wire are welded together. 5. The probe of claim 1, wherein the rod comprises an insert including at least one channel formed therein. 6. The probe of claim 5, wherein the thermocouple is mountable through said at least one channel. 7. The probe of claim 5, wherein the insert is an alumina material. 8. The probe of claim 1, wherein the base of the probe includes a cylindrical passage configured to receive an end of the rod. 9. The probe of claim 1, wherein the thermocouple comprises a thermocouple junction that extends through a notch formed at the end of the containment. 10. The probe of claim 1, wherein the base of the probe includes a cylindrical portion and a frusto-conical portion. 11. The probe of claim 10, wherein the frusto-conical portion of the base of the probe extends beyond the end of the rod. 12. The probe of claim 1, further comprising a metal base attached to the end of the probe. 13. The probe of claim 12, wherein the metal base is disposed over an end portion of the probe base. 14. The probe of claim 12, further comprising a ceramic matrix composite material, - 8 037107 located between the metal base and the end of the probe. 15. The probe of claim 12, wherein the metal base includes a thin-walled inner tube and a thick-walled outer tube. 16. The probe of claim 15, wherein the thin walled inner tube is brazed to the base of the probe. 17. A method of assembling a temperature probe according to claim 1, comprising forming a rod with at least one channel; the introduction of wires of the thermocouple through the specified at least one channel; connecting the base of the probe to the end of the rod so that the base of the probe surrounds the end of the rod; braiding a ceramic fiber over the probe base and rod to form a ceramic braid, and converting the ceramic braid to a ceramic matrix composite material to form a protective sheath covering at least a portion of the rod and a portion of the probe base, the above conversion step comprising first infusing the braided ceramic fiber by ceramic matrix precursor and then processing the infused braided ceramic fiber at a high temperature. 18. The method of claim 17, further comprising brazing the metal base to the end of the probe base. 19. The method of claim 17, wherein the brazing step further comprises applying a ceramic matrix composite material between the metal base and the probe base and heating the temperature probe to a brazing temperature. 20. The method of claim 19, wherein the heating step further includes heating the temperature probe to about 1000 ° C as the brazing temperature. 21. The method of claim 18, wherein the step of brazing further includes positioning the thin walled inner tube of the metal base over the base portion of the probe and heating the inner tube and base of the probe to a brazing temperature. 22. The method of claim 17, further comprising passing the end of the thermocouple through the end of the containment. 23. The method of claim 17, wherein the forming step further includes forming a rod-shaped alumina insert with at least one channel.