Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
  • G01N3/02—Details
  • G01N3/06—Special adaptations of indicating or recording means
  • G01N3/066—Special adaptations of indicating or recording means with electrical indicating or recording means

Definitions

• the invention relates to a component made of an electrically insulating material with a detection structure for mechanical damage of the component, wherein the detection structure has a permanently connected to the component electrical conductor ter and is adapted in terms of their geometry to the geometry of the component that the mechanical damage of the component is associated with a change in the electrical properties of the electrical conductor.
• a component of the type described above is described for example in DE 102 23 985 Al.
• the component is a heat shield plate which is preferably made of Kera ⁇ mik.
• a continuous thermal DEMANDS ⁇ monitoring the heat shield plate that can be installed for example in a combustion chamber of a gas turbine, there is a
• a firm connection between the electrical conductor and the component can take place either on the surface of the component, for example by introducing a ceramic conductor onto the surface or into grooves running on the surface and firing it together with the ceramic component.
• Another possibility is to provide the electrical conductor inside the component.
• an electrically conductive material may be looped housed inside a heat shield plate by the loop is inserted in the preparation of the green body in this turned ⁇ .
• Mica can be provided with an electrically conductive layer of silver and can be used in an organopolysiloxane compound. This results in a thermosetting composite material which develops after curing electrically conductive properties. Due to the crystal structure of the mica, the mica particles are particles which have strongly anisotropic mechanical properties.
• the object of the invention is to provide a component with egg ⁇ nem electrical conductor as a detection structure for damage in which the electrical conductor reacts relatively sensitive to damage.
• This object is achieved with the above-mentioned component, in which the electrical conductor is formed by mutually contacting particles having a metallic surface, he ⁇ inventively solved by the measures described in more detail below that particles with a metallic shell and one of the component properties adapted core can be used.
• a conduction of the electrical conductor is thus attributable to the fact that the particles with the metallic surface touch one another so that an exchange of electrons can take place between the particles with the metallic surface.
• the event of damage to the component specifically to ⁇ a crack growth intersecting the electrical conductor
• the line resistance of the electrical conductor is changed relatively strong.
• the electrical conductor In the production of the electrical conductor from the particles with a metallic surface, it may result due to the Her ⁇ provisioning process to a melting of the metallic surface-forming metal, so that the association of particles which form the electrical conductor, is strengthened. However, at the transition points between the now intimately connected particles, the sensitivity of the electrical conductor produced to mechanical stresses remains increased. It is also possible that the metallic surface of the particles will not be melted at ⁇ the manufacture of the component. This is the case when the melting point of the metal used is above the temperatures encountered in the manufacture of the component. For plastic components is this would be the case with the majority of metals. For ceramic components which must be subjected to an annealing treatment, suitable refractory metals such as tungsten may be used.
• the particles consist of an electrically insulating core with a metallic shell.
• a structure of the electric generated even at a melting the metal conductor is formed which is not of solid construction, but has in addition to the space formed between the particles pores also sections which filled by the electrically iso ⁇ -regulating core material of the particles are.
• the ⁇ devel- herein by resulting sponge-like structure of the conductor disgusted advantageously also has a special sensitivity to mechanical damage.
• the core is made of a material that is adapted to the behavior of the material of the component with respect to its mechanical behavior, in particular its thermal expansion behavior.
• thermally stressed components such as heat shield plates
• this has the advantage that electrical conductors laid in the interior of the component have a thermal expansion behavior adapted to the thermal expansion behavior of the surrounding component.
• stresses can be avoided, which would occur by a different thermal expansion of two different materials and could result in a mechanical overuse of the component.
• metallic materials have a higher coefficient of thermal expansion than ceramic components, which makes it difficult to use metallic conductors in ceramic heat shield plates.
• the particles are present mixed with the metallic surface in the electrical conductor with particles consisting entirely of an electrically insulating material, in particular of the material of the component.
• the metal will fill ⁇ further decreased degree in the electrical conductor.
• the pores between the particles or possibly non-metallic cores of the particles are then in electrical ter also partial areas, which are formed by the completely consisting of ei ⁇ nes electrically insulating material particles.
• an application of the detection structural ⁇ structure is particularly advantageous if the to be detected mechanical damage is the formation of cracks in the component, wherein the conductor extends in this case such that it is cut through the material to he ⁇ waiting crack growth. It is thereby advantageously achieved that the crack growth, when it has arrived at the surface of the conductor, begins to split it, preferably at right angles to its course, whereby the highest possible change in the electrical properties of the conductor is produced in relation to the progressive crack growth. It thereby becomes possible to achieve a change in electrical characteristics as soon as the crack on the conductor serving as the detection structure has arrived and then progresses further.
• the conductor runs parallel to the surface of the component. This takes into account the fact that cracks in the components usually propagate from the surface into the interior of the component and thus lead to a progressive mechanical weakening of the relevant component cross-section. The crack growth ends with a mechanical failure of the component, wherein the detection structure to prevent the component failure. If the conductors are laid parallel to the surface of the component, then it should be noted that a separation the conductor is due to a crack growth before the crack leads to a component failure.
• the electrical conductors may regard the property to check, for example, was the electrical resistance, evaluated by an electrical contact ⁇ to.
• a direct or alternating current can be sent through the electrical conductor, which allows the determination of the resistance.
• Another way to determine the properties of the electrical conductor is contactless.
• an electro ⁇ magnetic excitation is generated in the high frequency range, which leads to a response of the relevant conductor. This can be detected without contact, for example by means of an antenna.
• it is advantageous if the course of independent conductors is designed in such a way that they produce spectral signatures which can be distinguished from one another in the case of high-frequency electromagnetic excitation.
• spectral signature of one of the conductors is in connection with the invention a understood mathematical function, in which the response of the electrical conductor is determined with respect to the considered electrical property as a function of a frequency spectrum of the excitation.
• the conductor has a loop-shaped course. This can advantageously along the edge of a building ⁇ part flat expression, such. B. a heat shield plate are laid. Additionally, by using conductors having a loop-shaped course, produce particularly good charac teristic ⁇ signatures for a high frequency excitation, which is a sawn by separating the loop in the case of agreed to change crack growth in a slightly detectable manner.
• FIG. 2 shows the top view of a heat shield plate as another embodiment of the erfindungsge ⁇ MAESSING component
• Figure 5 and 6 different embodiments for e- lectric conductor, as they can be used in the fiction, ⁇ part used as partial cutouts.
• a member 11 according to Figure 1 is designed as a heat shield plate at ⁇ playing manner for the combustion chamber of a gas turbine.
• This component has a front side 12 facing the combustion chamber, which is most exposed to the thermal stress caused by the combustion process, and a rear side 13, with which it can be fastened in a manner not shown to the wall of the combustion chamber.
• the component 11 is made of Ke ⁇ ramik.
• electrical Ladder 14a laid, which may have a not visible in the illustration of Figure 1 loop-shaped course.
• These conductors 14 a have an electrical connection 15 to the rear side 13 of the component 11, which surfaces can be electrically contacted via contact surfaces 16.
• a further conductor 14 b is housed, which also forms a non-illustrated loop on the back 13. Furthermore, a raised conductor 14c is formed on the surface of the component formed by the rear side 13, which also runs loop-shaped.
• the conductors 14b and 14c also have contact surfaces 16 for contacting them. Since the contact areas on the back side 13 of the component are integrally ⁇ assigns 11 and the thermal stress on the Maisflä ⁇ chen 16 can be kept within limits, a Maisie- tion is the built-in heat shield plate also during loading ⁇ drive possible.
• Figure 2 shows a possible loop-shaped course of the conductors 14a, 14b with a constant distance from the edge of the plate-shaped member 11. It can be further seen as a progressive crack growth of the cracks 18 successively first cut the outer loop 14a and then the inner loop 14b.
• the conductors 14a, 14b according to FIG. 2 are designed as induction loops, ie they have no contact surfaces 16 and are designed to be closed.
• the electrical conductors 14 may consist of metallic particles 21 or of particles 22 consisting of a non-metallic core 23 and a metallic shell 24.
• further particles 25 of electrically insulating material may be provided in the conductors 14.
• the component 11, which is shown only as an adjoining the electrical conductor 14 portion is connected to the conductor 14 fixedly connected, wherein the respective transition between the component 11 and conductor 14 facing section according to Figure 3 to 6 all possible arrangements of the ladder 14a, 14b or 14c on the component can represent.
• the particles 21, 22, 25 used can be designed as microparticles (ie with dimensions of approximately 0.1 to 500 ⁇ m) or as nanoparticles (ie with dimensions of at most 100 nm).
• the electrical conductor 14 according to FIG. 3 is formed from metallic particles 21.
• the particles 21 are made of solid metal.
• Adjacent particles 21 berüh ⁇ ren respectively located at points of contact 26, wherein voids between the particles 27 reduce the effective conductor cross-section of the electrical conductor 14 and the sensitivity of to damage the conductor 14 raised stabili ⁇ hen for example, by a propagating crack growth in the component. 11
• the component 11 consists for example of plastic, wherein the particles 21 are poured into these. In the associated manufacturing process temperatures that are insufficient to melt the particles 21. Therefore, the contact points of the adjacent particles remain hold ER without causing a cohesive connection Zvi ⁇ rule forming the adjacent particles 21st
• the component 11 according to FIG. 4 consists of a ceramic and could, for example, form a heat shield plate.
• Metallic particles 21 are again used as the electrical conductor 14, wherein these were melted at least on their surface due to the heat treatment associated with the production of the component 11 and therefore have formed a cohesive connection 28 with respect to one another. In this case, however, cavities 27 can remain between the fused particles 21.
• metallic particles 21 Furthermore, in addition to the metallic particles 21, further particles 25 made of the same ceramic material as the component 11 have been used to form the structure of the electrical conductor 14. These may be enclosed, for example, by the metallic particles 21 or may also be joined to the material of the component 11 at the boundary to the component 11 by the heat treatment that has taken place. The edges of ceramic particles 29, which form the structure of the component 11, are also indicated.
• FIG. 4 also shows that the further particles 25 in the material of the conductor 14 can only be obtained in one of the may be given to the metallic particles 21 such concentration that the metallic particles 21 reliably form a coherent structure. Only the ⁇ se manner can prove to dash dot line indicated electrical conduction pathways train 30, the electrical conductivity of the conductor 14 provides leis ⁇ th in electrical conductors 14th
• the electrical conductor 14 according to FIG 5 for leadership of the electric current particles 22 are used which consist each ⁇ wells of a metallic shell 24 and an electrically insulating core 23rd Furthermore, further particles 25 may be provided, which consist of the material of the construction ⁇ part 11.
• the cores 23 of the particles 22 may consist of this material.
• the metallic material of the shell 24 is sufficiently temperaturbe ⁇ constantly that this is not melted by the component 11 forming heat ⁇ treatment. As a result, the particles 22 are in the unmelted state, as described for FIG. 3, so that only points of contact 26 result in the formation of the guide paths 30.
• the use of the material of the component 11 for the further particles 25 and the cores 23 has the advantage that the conductor 14 shows a behavior strongly matched to the thermal expansion behavior of the component 11 when the component 11 is subject to thermal stress.
• the stresses occurring in the electrical conductor 14 are the heating of the thermal expansions construction ⁇ part 11 therefore occurring th kept low, so that a change in the electrical properties of the conductor 14 due to a mechanical stress thereof only occurs if the component 11 example ⁇ is damaged by the formation of a crack.
• the electrical conductor 14 according to Figure 6 also consists of particles 22 having a core 23 and a shell 24.
• the envelopes 24 of the particles 22 were melted, so that at the same time forming cavities 27 a cohesive compound 28 of me - Has resulted in the formation of the electrical conductor - metallic material.
• the effective cross section of the conductor 14 in this case is reduced mainly by the cores 23, but also by the cavities 27.
• the cores 23 are not made of the same material as the component 11. However, the material of the cores 23 is adapted to the component 11 with regard to the thermal expansion behavior. This makes it possible to achieve the temperature insensitivity of the electrical conductor described with reference to FIG. 5 with respect to an undesired change in its electrical properties due to a mechanical overstress.

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• Physics & Mathematics (AREA)
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• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
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• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
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• Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
• Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)

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• 2006
  • 2006-09-13 DE DE102006043781A patent/DE102006043781A1/de not_active Ceased
• 2007
  • 2007-09-10 CN CN200780034185.6A patent/CN101523185B/zh not_active Expired - Fee Related
  • 2007-09-10 WO PCT/EP2007/059464 patent/WO2008031792A1/de active Application Filing
  • 2007-09-10 US US12/310,855 patent/US8008932B2/en not_active Expired - Fee Related
  • 2007-09-10 EP EP07803381A patent/EP2062026A1/de not_active Ceased
  • 2007-09-10 RU RU2009113566/28A patent/RU2441216C2/ru not_active IP Right Cessation

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