JPH05133842A - Guarantee testing apparatus of ceramic moving blade part - Google Patents

Abstract

PURPOSE:To obtain a, guarantee testing apparatus of a part of a ceramic moving blade which can apply the testing load corresponding to the thermal expansion stress, and quickly remove the load, without generating the decrease of the strength after testing. CONSTITUTION:This apparatus is provided with a holding block 2 coupled to one end of a ceramic sleeve 1, a hollow annular elastic tube 3 fitted in a peripheral groove 2a at the side peripheral surface of the holding block 2, and a pressuring device 5 equipped with a function to press a pressure medium (incompressible fluid) 7 into the elastic tube 3 by means of a manually- or motor-driven pump or the like, and a function to quickly release the medium by a release valve or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a certifying test device for a ceramic rotor blade component for a gas turbine, and in particular, in order to guarantee the minimum strength of a ceramic sleeve component of a hybrid type ceramic rotor blade, a low strength component is cut off. The present invention relates to an all product assurance test (screening) device.

[0002]

2. Description of the Related Art Ceramic materials have heat resistance, corrosion resistance,
Due to its excellent wear resistance and light weight, it has come to be used in various applications as a high-value-added structural component. Typical examples thereof include a turbocharger in an automobile engine and a ceramic bearing that is expected to be used in a special environment such as an auxiliary combustion chamber.

By the way, the ceramic material has the above-mentioned excellent characteristics, but on the other hand, it has a drawback that it is brittle and its material strength varies widely. Therefore, when constructing machine parts with ceramic materials,
Quality assurance that guarantees the minimum strength of parts is an important technical issue.

In order to guarantee the quality of a metal material, it is common to confirm the presence or absence of defects by a nondestructive inspection such as an X-ray transmission test or a fluorescence penetration flaw detection test. However, in the case of ceramic materials, the size of defects that control strength is about several tens of μm at most, and it is almost impossible to find out by the nondestructive inspection method applied to the conventional metal materials. Therefore, as a means of guaranteeing the minimum strength of ceramic parts, an all-item guarantee test (screening test) is generally applied in which a predetermined load is applied to all parts before actual use and surviving parts that have not been destroyed are accepted. Has been adopted.

Therefore, in the all-product guarantee test, generally, the load test of the parts is performed in a state as close as possible to an actual use state. For example, in the case of a component in which the stress generated by the centrifugal force causes a problem in strength, a room temperature rotation test is performed as an all-product guarantee test. Further, in the case of a component in which thermal stress is a problem, a heating test, a thermal shock test, etc. are performed as an all-product guarantee test.

FIG. 5 is a cross-sectional view of a hybrid ceramic blade for a gas turbine. In this figure, the moving blade is configured by combining a metal cored bar 11 and a ceramic sleeve 12. That is, the blade effective portion exposed to the high temperature gas is constituted by the ceramic sleeve 12 having excellent heat resistance, and the implanting portion 13 and the core metal portion 11 in which a large tensile stress is generated by the centrifugal force are constituted by the metal material. The metal core 11 has a structure in which the air is cooled by the cooling air holes 14.

In the moving blade having the above structure, the ceramic sleeve 7 is subjected to centrifugal force by the centrifugal force during the operation of the turbine.
Is pressed against the ceramic sleeve 12
A compressive stress will act on. Ceramic materials have excellent heat resistance, but lack reliability in tensile stress, and metal materials have poor heat resistance but excellent tensile strength. Hybrid blades take advantage of these properties of the above two materials.

In the conventional ceramic sleeve having the above-mentioned structure, a problem in terms of strength is the thermal elongation stress generated by the difference in thermal expansion between the metal material and the contact portion of the core metal head. .. A Ni-based superalloy or the like is used as the core metal material of the hybrid ceramic blade. The coefficient of thermal expansion of this type of material is 15 to 20 × 10.
^{The temperature} is ^{−6 ° C. −1} . As a material for the ceramic sleeve, a structural ceramic material such as Si ₃ CN ₄ or SiC is used. The coefficient of thermal expansion of these ceramic materials is about 3 × 10 ^-6 ° C ^-1 .

As described above, since there is a large difference in thermal expansion coefficient between the two materials, when the temperature is raised while the cored bar head is pressed against the ceramic sleeve by centrifugal force, the difference in thermal expansion between the two causes the ceramic sleeve Is expanded and a large tensile stress is generated in the ceramic sleeve. Therefore, as a guarantee test for the ceramic sleeve component, it is necessary to guarantee the minimum strength with respect to the thermal elongation stress as described above. In the guarantee test regarding the thermal elongation stress, a test of heating a combination of a ceramic sleeve and a core metal while applying a centrifugal force, that is, a high temperature rotation test must be performed.

[0010]

In the guarantee test of all the ceramic parts, the test is carried out by applying a predetermined stress δ _p , and if the test cannot withstand the stress, it is rejected and the legs are cut. It is known that the strength of parts decreases due to the load during the unloading process of. In the worst case,
The strength of a part that has passed the guarantee test may be lower than the guarantee test stress δ _p . Such a phenomenon is
It has been confirmed experimentally by r etc., and further Ichikawa theoretically elucidated the mechanism of the strength reduction.

The mechanism of the strength reduction during the guarantee test is basically due to the delayed fracture phenomenon peculiar to ceramic materials. That is, the ceramic material exhibits delayed fracture in which the strength decreases as the crack progresses from the initial defect, and even with relatively low stress, fracture occurs even under a long-time load. The decrease in strength during the unloading process during the assurance test is also due to the crack growth as described above.
Stress δ during unloading even for non-destructive parts at _p
If the crack propagates due to (<δ _p ), the strength of the part that has passed the test may be lower than that during the test.

In order to minimize the decrease in strength after the guarantee test as described above, the load must be rapidly removed after applying the guarantee test stress δ _p . By the way, when performing a high-temperature rotation test as a guarantee test for the ceramic sleeve component of the hybrid ceramic blade, in order to unload the thermal elongation stress that occurs, lower the core metal temperature or reduce the centrifugal force. It is necessary to let However, it is difficult to rapidly reduce the once-increased rotation in the rotation test, and it is also difficult to rapidly reduce the core metal temperature. That is, in the guarantee test by the high temperature rotation test, it is extremely difficult to rapidly unload the thermal elongation stress, and it must be said that the strength is likely to be reduced.

The present invention has been made in view of the above circumstances, and provides a guarantee test device for a ceramic rotor blade component that can be loaded with a test stress equivalent to a thermal elongation stress and can be rapidly unloaded. ..

[0014]

According to the present invention, there is provided a guarantee test apparatus for a ceramic blade component, comprising: a holding block which is engaged with one end of a ceramic sleeve; and a circumferential groove provided on a side circumferential surface of the holding block. It is characterized by having a hollow annular elastic tube mounted therein and a pressurizing device capable of press-fitting an incompressible fluid into the elastic tube and rapidly releasing it.

[0015]

In the certifying device for the ceramic rotor blade component of the present invention having the above-mentioned structure, a predetermined internal pressure is applied to the ceramic sleeve by the non-compressed fluid press-fitted into the elastic tube to simulate a high temperature rotation test. be able to. When the test is completed, the pressure medium in the elastic tube can be rapidly removed by the pressurizing device, and rapid unloading can be performed after the test, so there is no risk of strength deterioration after the test. ..

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of an embodiment of the present invention, and FIG.
11 is a sectional view taken along line II-II of FIG. In these drawings, the holding block 2 that engages with the upper end of the ceramic sleeve 1, in other words, the end that is radially outside when the turbine is rotating.
Is provided with a groove 2a that goes around the side circumferential surface thereof, and a hollow annular elastic tube 3 is engaged with the groove 2a.
An opening 4 communicating with the groove 3 is provided on the upper surface of the holding block 2, and the supply cylinder 3 a of the elastic tube 3 is inserted into the opening 4. A discharge port of a pressurizing device 5 is connected to the supply cylinder 3a, and an AE sensor 6 is attached to the lower portion of the side peripheral surface of the ceramic sleeve 1.

In the figure, 7 is a pressurizing device 5 to an elastic tube 3.
Figure 3 shows a pressure medium press-fitted inside. The AE sensor 6 means an acoustic emission sensor, and in this embodiment, the output of the AE sensor 6 is input to a processing circuit (not shown) to observe the waveform of the observed sound.
It is supposed that how many sound waves with a certain amplitude or more are observed within a certain period of time.

In the embodiment having the above structure, the elastic tube 3 is made of a material that is deformable and does not cause leakage of the pressure medium,
For example, it is made of rubber or the like. Also, the holding block 2
Requires sufficient strength to transmit the internal pressure of the elastic tube 3 to the ceramic sleeve 1 against deformation of the elastic tube 3, and can be made of an appropriate metal material. Further, as the pressure medium 7, a compressible fluid, for example, a liquid such as water or oil is used. The pressurizing device 5 has a function of discharging the pressure medium by a manual or electric pump or the like to apply a predetermined internal pressure to the elastic tube 3, and a function of instantaneously releasing the internal pressure by a leak valve or the like. I shall.

The guarantee test is performed as follows according to the embodiment having the above-mentioned configuration. First, as shown in FIG. 1 and FIG.
Elastic tube 2 in groove 2a at the top of ceramic sleeve 1
The holding block that has been engaged is engaged, the pressure medium 5 is press-fitted into the elastic tube 3 by the pressurizing device 5, and the internal pressure is uniformly applied to the inner surface of the ceramic sleeve 1 via the elastic tube 3.

FIG. 3 shows the result of analyzing the stress distribution generated in the ceramic sleeve 1 to which the above-mentioned internal pressure is applied, by the finite element method. Further, FIG. 4 shows a ceramic sleeve of an actual hybrid ceramic blade,
It is a figure which shows the stress distribution state of the stress generated by a difference in thermal expansion. In these figures, the stress is divided into 6 stages as indicated by the circle numbers 1 to 6 on the stress level scale L and shown as iso-stress diagrams.

As can be seen from FIG. 3, the stress is concentrated on the inside of the blade trailing edge and the inside of the blade leading edge of the ceramic sleeve 1, and shows the maximum value inside the trailing edge. As can be seen from comparison with FIG. 4, the stress distribution state is very similar to the stress distribution state caused by the difference in thermal expansion in the actual machine.

As described above, according to the present invention, instead of performing the high temperature rotation test to actually generate the thermal elongation stress in the ceramic sleeve 1, the internal pressure is applied to the inner surface of the ceramic sleeve to test the actual machine with high accuracy. Can be simulated. That is, a component that has been destroyed by applying a predetermined internal pressure stress is determined to have a thermal elongation strength of a certain level or more and is determined as an acceptable product. Here, by rapidly removing the pressure applied to the elastic tube 3 by the pressure device 5, the internal pressure can be rapidly unloaded.

The above non-destructive judgment is made by the AE sensor 6 during the load test by the AE of the crack of the ceramic sleeve.
No signal is detected, and non-destructive inspection such as fluorescent penetrant inspection and X-ray inspection of the ceramic sleeve after the test
This is done because no crack is detected.

As described above, according to the guarantee test apparatus for ceramic blade parts of the present invention, it is possible to select a part having a thermal elongation strength of a certain level or more by performing an internal pressure load test on the ceramic part. Moreover, since the applied internal pressure can be instantly unloaded, it is possible to prevent the strength from decreasing during unloading.

[0025]

As is apparent from the above, according to the guarantee test apparatus for a ceramic rotor blade component of the present invention, pressure is applied to the elastic tube by using an incompressible fluid as a pressure medium, whereby a predetermined position of the ceramic sleeve is applied. The degree of thermal elongation stress and its distribution can be obtained in the same manner as in the high temperature rotation test by simulating the conventional high temperature rotation test in which the internal pressure is uniformly applied and the all-product guarantee test is performed. Moreover, since the unloading of the internal pressure can be performed by removing the pressure medium from the elastic tube after the end of the test, rapid unloading is possible immediately after the end of the test, and there is no fear that the strength of the ceramic sleeve will decrease after the test. Absent.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a view showing a result of analyzing a stress distribution generated in a ceramic sleeve to which an internal pressure is applied by a finite element method.

FIG. 4 is a diagram showing a stress distribution state of stress generated due to a difference in thermal expansion in a ceramic sleeve of an actual hybrid-type ceramic moving blade.

FIG. 5 is a sectional view of a hybrid ceramic blade for a gas turbine.

[Explanation of symbols]

1 ... Ceramic sleeve, 2 ... Holding block, 2a ...
Grooves, 3 ... Elastic tube, 5 ... Pressure device, 6 ... AE sensor, 7 ... Pressure medium.

Claims (1)

[Claims] 1. A holding block engaged with one end of a ceramic sleeve, a hollow annular elastic tube fitted in a circumferential groove provided on a side peripheral surface of the holding block, and an uncompressed inside the elastic tube. And a pressurizing device capable of pressurizing a fluid and rapidly releasing the fluid.