Testing of substrate monolith
By applying impulse vectors in a specific direction, causing mechanical vibration of the substrate whole material and analyzing the fundamental frequency of vibration, the crack detection problem in the substrate whole material is solved, and a fast and accurate detection effect is achieved, which is suitable for large-scale applications on the production line.
Patent Information
- Application Number
- CN202380049135.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-07-29
- Filing Date
- 2023-07-17
- Publication Date
- 2025-02-18
AI Technical Summary
The prior art is difficult to detect cracks or other defects in substrate monoliths quickly and accurately, especially on production lines, where traditional visual inspection and tapping test methods are time-consuming and not reliable enough.
By applying the impact tool to cause mechanical vibration of the substrate monolith by using the impulse vector of the first axis component and the second axis component that is not zero, and by sensing and analyzing the fundamental frequency of these vibrations, comparing with the standard fundamental frequency to judge the crack state by judging the crack state by sensing and analyzing the fundamental frequency of these vibrations. .
This method can quickly and accurately detect cracks in the substrate monolith, reduce the dependence on operator experience, is suitable for large-scale inspection on production lines, and can be effectively performed in environments with high background noise.
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Figure CN119487375A_ABST
Abstract
Description
[0001] The present disclosure relates to a method of testing a substrate monolith and a testing apparatus for performing the method. Background Art
[0002] The substrate monolith is used to treat exhaust gases emitted from an internal combustion engine (e.g., a vehicle internal combustion engine). The substrate monolith can treat the exhaust gases, for example, by filtering the exhaust gases to remove particulate matter and / or by using a catalyst to oxidize and / or reduce components of the exhaust gases such as carbon monoxide, unburned hydrocarbons, and nitrogen oxides.
[0003] The substrate monolith can typically be formed of sintered metal, ceramic or metal fiber, etc. The substrate monolith is fragile due to, for example, their material composition and / or, for example, due to the presence of thin-walled structures, which define channels for gas flow within the substrate monolith. Therefore, when subjected to mechanical and / or thermal shock, the substrate monolith may be prone to breakage. The manufacture of the substrate monolith necessarily involves mechanical manipulation of the substrate monolith on the production line, which may result in mechanical loads being applied to the substrate monolith, for example, due to accidents or when transferring from one part of the production line to another. The manufacturing process also involves the application of thermal changes, such as when baking and cooling the exposed substrate monolith and during calcination of the substrate monolith after applying the carrier coating. Therefore, it is ideal to test the substrate monolith for the presence of cracks and / or other defects during or after manufacture before sending the substrate monolith to the customer.
[0004] One problem with testing substrate monoliths is that cracks or other defects may be difficult to discern visually. External cracks (i.e., cracks propagating to / from the outer surface of the substrate monolith) may be narrow, may close when standing still, and / or may be difficult to discern under lighting conditions typically present on a production line. Internal cracks within the body of the substrate monolith cannot be easily visually inspected, especially by an operator on a production line. Visual inspection is also typically time-consuming and therefore can only be applied to a small sample percentage of the produced substrate monoliths in practice.
[0005] Some operators are known to tap the substrate monolith with their fingers in an attempt to discern the presence of defects by listening to the "dull" response. However, this technique requires a certain level of experience on the part of the operator and, furthermore, the perception of the sound varies from person to person. Therefore, the conclusions from such "tap" tests are very challenging to interpret and difficult to report to the customer in an informative manner. Furthermore, like visual inspection, this method is time consuming and can only be applied to a small sample percentage of the substrate monoliths produced. Summary of the invention
[0006] In a first aspect, the present disclosure provides a method for testing a substrate monolith, the substrate monolith comprising:
[0007] i) a plurality of channels extending longitudinally along the Z-axis of the substrate monolith; and
[0008] ii) an array of walls extending along the Z-axis and forming partitions between adjacent channels;
[0009] wherein the wall array comprises a first wall oriented parallel to a first axis of the substrate monolith and a second wall oriented parallel to a second axis of the substrate monolith, the first axis and the second axis being orthogonal to the Z axis;
[0010] The method comprises the following steps:
[0011] a) applying an impulse to the base monolith with an impact tool to induce mechanical vibration in the base monolith;
[0012] b) sensing mechanical vibrations of the substrate monolith;
[0013] c) determining the fundamental frequency of the sensed mechanical vibration; and
[0014] d) comparing the fundamental frequency of the sensed mechanical vibration with the fundamental frequency obtained from testing of the second substrate monolith;
[0015] In step a), the impulse vector of the impulse has a non-zero first axis component and a non-zero second axis component.
[0016] Advantageously, a fundamental frequency obtained from the substrate monolith being tested and the second substrate monolith is used for comparison.Using a fundamental frequency can reduce or eliminate destructive interference from other frequencies.
[0017] The method can also be performed very quickly, for example under 5 seconds per substrate monolith. Advantageously, the method does not rely on operator perception and is suitable for use on a production line. In particular, it has been surprisingly found that the method can be performed despite the presence of relatively large amounts of background noise, such as is typically present in a factory production line setting.
[0018] Advantageously, the impulse vector of the impulse has a non-zero first axis component and a non-zero second axis component. Thus, the impulse vector is not directly aligned with the first wall or the second wall of the substrate monolith. It has been found that such a tilting of the impulse vector produces a lower fundamental frequency in the sensed mechanical vibrations than if the applied impulse vector were aligned with the first wall or the second wall of the substrate monolith. Furthermore, it has been found that when used with a substrate monolith, the tilting of the impulse vector produces a stronger signal amplitude for the fundamental frequency, which is more easily distinguished from other resonances and background noise (including, for example, background noise from a factory setting).
[0019] Additionally, another advantage is that the stronger resonant response of the substrate monolith when the impulse vector is not directly aligned with the first wall or the second wall means that the magnitude of the impulse can be reduced. This reduces the chance of the impact tool damaging the substrate monolith when applying the impulse.
[0020] Without being bound by theory, it is believed that the stronger and more distinguishable resonant response of the substrate monolith when the impulse vector is not directly aligned with the first wall or the second wall is due to the in-plane anisotropy of the substrate monolith. The first wall and the second wall of the substrate monolith produce a "honeycomb" network of pores in a plane orthogonal to the Z axis. Typically in the substrate monolith, the thickness of the first wall and the second wall (pore chamber wall) is less than the width of the pore chamber opening. Taking the square pore chamber as an example, the plane of the substrate monolith orthogonal to the Z axis can be similar to a checkerboard pattern with a 2D array of hollow square pore chambers, and the hollow square unit has a center aligned parallel to the first axis and the second axis. The plane is anisotropic for hardness-it has different hardnesses depending on the direction of the applied force. In particular, in the example of a square pore chamber (assuming that the wall thickness of all walls is constant), the hardness parallel to each of the first wall and the second wall will be the same. However, the hardness at 45° to the first wall and the second wall of the square channel will be lower.
[0021] In a preferred example, in step a), the impulse vector has substantially equal first and second axis components. This may be particularly suitable, for example, if the channel has substantially the same length dimension in each of the first and second axes. An example is a square bore. In the case where the channel has other shapes, it may be necessary to adjust the inclination of the impulse vector. For example, if the channel is rectangular in shape (non-square) or diamond in shape, the impulse vector may be angled, for example, to be parallel to the longest in-plane diagonal dimension of the channel.
[0022] In some examples, in step a), the impulse is applied by striking the substrate monolith in a diagonal direction relative to the first axis and the second axis. In some examples, the first axis and the second axis are orthogonal to each other and are the X axis and the Y axis of the substrate monolith, respectively. In such examples, in step a), the impulse may be applied by striking the substrate monolith in a direction 45° to the X axis and the Y axis.
[0023] In some examples, the plurality of channels include quadrilateral channels, optionally square channels.
[0024] In some examples, the substrate monolith is supported on a support system to isolate the substrate monolith from extraneous vibrations.
[0025] In some examples, the support system includes a single support member. In some other examples, the support system includes a plurality of support members. In such examples, the support member may have 3, 4 or more separate support members. The support member or each support member may include a flat support, a circular support, a blade support or a point support for contacting the surface of the substrate monolith, optionally contacting the base of the substrate monolith. In some examples, the support member or each support member may include a rigid member. However, in other preferred examples, the support member or each support member may include a soft member or an elastic member. For example, the support member or each support member may be formed by foam (e.g., polyurethane foam), an elastomer or rubber.
[0026] In some examples, the substrate monolith may be supported at one or more nodes of the substrate monolith, preferably at one or more cardinal nodes of the substrate monolith.
[0027] In some examples, in step b), sensing the mechanical vibration of the substrate monolith includes using a transducer to sense the mechanical vibration in the time domain. In some examples, the transducer may include a contact accelerometer, which may be applied to the surface of the substrate monolith. However, in other preferred examples, a non-contact transducer may be used. For example, a microphone (optionally, a unidirectional microphone) may be used to sense the mechanical vibration by sensing sound waves generated by the mechanical vibration of the substrate monolith.
[0028] In some examples, in step c), determining the fundamental frequency includes converting the sensed mechanical vibration into the frequency domain to produce a spectrum of the sensed mechanical vibration. In such examples, in step c), determining the fundamental frequency may also include applying a power spectral density (PSD) analysis to the spectrum.
[0029] Advantageously, converting the sensed mechanical vibrations into the frequency domain can produce more reliable results for a wider range of substrate monoliths than time domain analysis. For example, many substrate monoliths are highly porous and / or formed from ceramics that may contain many microcracks. This can result in such substrate monoliths not producing pure tones when impacted. Therefore, time domain analysis of mechanical vibrations has been found to be difficult. According to the present method, by converting into the frequency domain, this difficulty can be overcome.
[0030] For example, the conversion into the frequency domain may be performed by using a Fast Fourier Transform algorithm.The use of PSD analysis may advantageously reduce or eliminate ambiguity in determining the fundamental frequency from the frequency spectrum.
[0031] In some examples, the impact tool may be configured to apply a predetermined impulse. The impact tool may be automated. For example, the impact tool may be computer controlled to improve the accuracy and reproducibility of the impulse, particularly in terms of its magnitude. In some examples, the impact tool may be an automatic hammer. In some examples, the impact tool may include a metal or wooden head that contacts the substrate monolith during use. In cases where the substrate monolith is particularly fragile, a wooden head may be preferred. In cases where a greater signal strength is desired from the impact, a metal head may be preferred. As an example of a metal head, a stainless steel head may be used. Moreover, it has been found that aluminum oxide material is particularly effective for the head. It has been found that the material of the head does not change the fundamental frequency obtained, but as described above, may affect the signal strength.
[0032] The second monolith may include, for example, a reference substrate monolith, or a substrate monolith from a different substrate monolith batch compared to the substrate monolith, or may be a substrate monolith from the same substrate monolith batch as the substrate monolith.
[0033] For example, the second substrate monolith may be a reference substrate monolith, and the method may further include a step of making a judgment on a crack state of the substrate monolith based on a comparison of fundamental frequencies obtained for the substrate monolith and the reference substrate monolith.
[0034] Advantageously, the reference substrate monolith may be a substrate monolith that is known to be uncracked, eg, without any significant defects.
[0035] The comparison of the fundamental frequencies may include determining whether there is a difference in the fundamental frequencies. Optionally, it may include determining whether the difference exceeds a threshold amount. The threshold amount may be an absolute amount (e.g., a number of Hertz) or may be a relative amount (e.g., a percentage deviation of the frequency obtained for the substrate monolith compared to a reference substrate monolith).
[0036] Comparison of the fundamental frequencies may include determining the direction of a shift in the fundamental frequencies, such as whether the fundamental frequency obtained for the substrate monolith is greater or less than the fundamental frequency obtained for the reference substrate monolith.
[0037] For example, the substrate monolith and the second substrate monolith may be from a first batch and a second batch of substrate monoliths, respectively, and the method may also include a step of making a judgment about changes between batches of substrate monoliths based on a comparison of the fundamental frequencies obtained for the substrate monolith and the second substrate monolith.
[0038] When making the determination, the fundamental frequencies obtained from one or more substrate monoliths from the first batch may be compared with the fundamental frequencies obtained from one or more substrate monoliths from the second batch. For example, each batch tested may include 3 or more, 5 or more, or 10 or more substrate monoliths tested.
[0039] Comparison of the fundamental frequencies may include determining whether there is a statistically significant difference in the fundamental frequencies obtained for the first batch of substrate monoliths and the second batch of substrate monoliths.
[0040] For example, the substrate monolith and the second substrate monolith may be from a single substrate monolith batch, and the method may further include the step of making a determination regarding variations within the single substrate monolith batch based on a comparison of fundamental frequencies obtained for the substrate monolith and the second substrate monolith.
[0041] In making this determination, fundamental frequencies obtained from 3 or more, 5 or more, or 10 or more substrate monoliths from the single batch may be used.
[0042] Comparison of the fundamental frequencies may include determining whether there is a statistically significant variation in the fundamental frequencies obtained for the single batch of substrate monoliths.
[0043] In some examples, the method is performed on a production line configured to process a plurality of substrate monoliths.
[0044] The substrate monolith may be formed, for example, from sintered metals, ceramics, or metal fibers, etc. For example, the substrate monolith may be formed from cordierite, various forms of silicon carbide, or aluminum titanate.
[0045] The substrate monolith may be a "bare" substrate monolith, or alternatively may include a composition coating the porous structure of the substrate monolith (referred to as a washcoat). The washcoat may be a catalytic washcoat for producing a catalytic substrate monolith having catalytic functional capabilities (e.g., oxidation, NOx trapping, or selective catalytic reduction activity). The catalytic washcoat may include a catalyst selected from the group consisting of a hydrocarbon trap, a three-way catalyst (TWC), a NOx absorber, an oxidation catalyst such as a diesel oxidation catalyst (DOC), a selective catalytic reduction (SCR) catalyst, a lean NOx catalyst, and a combination of any two or more thereof. The catalyst (e.g., a TWC, a NOx absorber, an oxidation catalyst, a hydrocarbon trap, and a lean NOx catalyst) may contain one or more platinum group metals, particularly those selected from the group consisting of platinum, palladium, and rhodium.
[0046] In some examples, the substrate monolith being tested may be a calcined substrate monolith. In such examples, the substrate monolith and the reference substrate monolith preferably have been subjected to substantially the same calcination conditions.
[0047] The substrate monolith may include a flow-through substrate monolith or a filter substrate monolith. In a flow-through substrate monolith, a plurality of channels (also referred to as "pore chambers") extend longitudinally along the length (Z-axis) of the substrate monolith, wherein the channels are open at both ends thereof. In a filter substrate monolith (also referred to as a "wall-flow filter substrate monolith"), a plurality of channels ("pore chambers") extend longitudinally along the length (Z-axis) of the substrate monolith, wherein channels open at a first end of the substrate monolith are blocked at the opposite end, and channels open at the opposite end are blocked at the first end, such that each other adjacent channel has an open end (or blocked end) at the first end of the filter substrate monolith, and a blocked end (or open end) at its opposite end, so that when the ends of the filter substrate monolith are viewed, it resembles a chessboard of open and blocked channels. The fluid communication between the open channels at the first end of the filter substrate monolith and the open channels at its opposite end is via the porous wall structure of the filter substrate monolith.
[0048] The outer shape and size of the substrate monolith and properties such as the channel wall thickness and its porosity can vary depending on the intended application of the substrate monolith. The substrate monolith can be configured for use with an internal combustion engine (ICE) to filter exhaust gases emitted by the internal combustion engine. The internal combustion engine can be a spark ignition engine, such as a gasoline ICE, or a compression ignition engine, such as a diesel ICE.
[0049] In a second aspect, the present disclosure provides a testing device for performing the method of the first aspect, the testing device comprising:
[0050] a support system for isolating the base monolith from extraneous vibrations;
[0051] Impact tools;
[0052] a transducer for sensing mechanical vibrations of the base monolith; and
[0053] an analyzer for determining a fundamental frequency of the sensed mechanical vibration;
[0054] The impact tool includes an automatic hammer configured to apply an impulse to the substrate monolith with an impulse vector having a non-zero first axis component and a non-zero second axis component.
[0055] In some examples, the support system and the impact tool are both coupled to an alignment frame configured to ensure that an impulse vector of an impulse applied by the impact tool to a substrate monolith supported by the support system has a non-zero first axis component and a non-zero second axis component. BRIEF DESCRIPTION OF THE DRAWINGS
[0056] Aspects and embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:
[0057] Figure 1 is a schematic diagram of a substrate monolith;
[0058] Figure 2 is a schematic diagram of the test apparatus;
[0059] Figure 3 is an end view of a portion of a substrate monolith;
[0060] Figure 4 is a schematic end view of a substrate monolith subjected to an impulse;
[0061] Figure 5 showing an end view of a portion of two substrate monoliths;
[0062] Figure 6 is a frequency-amplitude graph showing the effect of impulse direction;
[0063] Figure 7 is a frequency-amplitude graph showing example test results;
[0064] Figure 8 is a frequency-amplitude graph showing example test results for cracked and uncracked substrate monoliths;
[0065] Fig. 9 is a plot of fundamental frequencies obtained for 42 substrate monolith samples;
[0066] Fig.10 is a plot of fundamental frequencies obtained for two batches, each batch comprising 10 substrate monolith samples;
[0067] Fig.11 is a frequency-amplitude graph showing example test results of substrate monoliths from four different sources; and
[0068] Fig.12 is a plot of the fundamental frequencies obtained for 10 substrate monolith samples from a single batch. DETAILED DESCRIPTION
[0069] An skilled reader will recognize that, unless the present context dictates otherwise, one or more features of one aspect or embodiment of the present disclosure may be combined with one or more features of any other aspect or embodiment of the present disclosure.
[0070] Figure 1 is a schematic diagram of a substrate monolith 1. The substrate monolith 1 comprises a plurality of channels extending longitudinally along the Z-axis of the substrate monolith 1 and an array of walls 10, 11 extending along the Z-axis, the walls 10, 11 forming partitions between adjacent channels.
[0071] The wall array includes a first wall 10 oriented parallel to a first axis of the substrate monolith 1 and a second wall 11 oriented parallel to a second axis of the substrate monolith 1, and the first axis and the second axis are both orthogonal to the Z axis. The first axis and the second axis may be orthogonal to each other. The first axis may be the X axis of the substrate monolith 1, and the second axis may be the Y axis of the substrate monolith 1.
[0072] When viewed in the XY plane of the substrate monolith 1, the first wall 10 and the second wall 11 may define a "cell" 12. In the example shown, the cell 12 is square in shape. However, the cell 12 may take other shapes. The substrate monolith 1 may have a cylindrical outer shape, but other shapes may be provided.
[0073] According to the present disclosure, the method for testing the substrate monolith 1 comprises the following steps:
[0074] a) applying an impulse J to the substrate monolith 1 with an impact tool 22 to induce mechanical vibration in the substrate monolith 1;
[0075] b) sensing mechanical vibrations of the base monolith 1;
[0076] c) determining the fundamental frequency of the sensed mechanical vibration; and
[0077] d) comparing the fundamental frequency of the sensed mechanical vibration with the fundamental frequency obtained from testing of the second substrate monolith;
[0078] In step a), the impulse vector 30 of the impulse J has a non-zero first axis component 31 and a non-zero second axis component 32 .
[0079] Figure 2 A schematic diagram of a test apparatus 20 suitable for performing tests on a substrate monolith 1 is shown. The test apparatus 20 comprises a support system 21 for isolating the substrate monolith 1 from extraneous vibrations, an impact tool 22, a transducer 23 for sensing mechanical vibrations of the substrate monolith 1, and an analyzer 24 for determining the fundamental frequency of the sensed mechanical vibrations.
[0080] Both the support system 21 and the impact tool 22 may be coupled to an alignment frame 25 configured to ensure that an impulse vector 30 of an impulse J applied by the impact tool 22 to the substrate monolith 1 supported by the support system 21 has a non-zero first axis component 31 and a non-zero second axis component 32 .
[0081] The support system 21 may include one or more support members 26. Each support member 26 may include an elastomer, foam or rubber member. In some preferred examples, 3 or 4 support members 26 may be used, which are positioned at one or more nodes of the substrate monolith 1, preferably at one or more basic nodes of the substrate monolith 1. For example, the support member 26 may contact the base of the substrate monolith 1 at a point around the pitch circle of the substrate monolith 1. In the case of a cylindrical substrate monolith, the pitch circle may be a circle with a diameter of about 68% of the average diameter of the substrate monolith. In some particularly preferred examples, 4 support members 26 arranged at equal intervals around the pitch circle, that is, arranged at an angle therebetween at 90° intervals, may be used.
[0082] The impact tool 22 may include, for example, an automatic hammer configured to apply an impulse J to the substrate monolith 1 with an impulse vector 30 having a non-zero first axis component 31 and a non-zero second axis component 32. The impact tool 22 may be configured to apply a predetermined impulse to the substrate monolith 1. The impact tool 22 may preferably be computer controlled. In some examples, the impact tool 22 may be an automatic hammer. The impact tool 22 may include a metal or wooden head 27 that contacts the substrate monolith 1 during use.
[0083] The transducer 23 may include a contact or non-contact transducer. For example, the transducer 23 may be an accelerometer that may be applied to the surface of the substrate monolith 1. In a preferred example, the transducer 23 may be a microphone, optionally a unidirectional microphone, that may be used to sense mechanical vibrations by sensing sound waves generated by the mechanical vibrations of the substrate monolith 1.
[0084] The analyzer 24 may include a controller 40. The controller 40 may include one or more processors 41, an impact tool controller 42, a signal input 43 connected to the transducer 23, and a memory 44 for storing, for example, software and data. Optionally, the analyzer 24 may also include an output, such as a display screen 45.
[0085] The one or more processors 41 may include analysis programming for analyzing the sensed mechanical vibration and converting the sensed mechanical vibration into the frequency domain to generate a spectrum of the sensed mechanical vibration. For example, the analysis programming may perform a fast Fourier transform. The one or more processors 41 may also perform a power spectral density (PSD) analysis on the spectrum.
[0086] The one or more processors 41 may be provided in a single machine housing, or in multiple housings, and / or may be provided by a distributed processing device (eg, a cloud-based processor).
[0087] Figure 3is an end view of a portion of a substrate monolith 1 showing one of the pores 12 defined by a first wall 10 (parallel to the X-axis) and a second wall 11 (parallel to the Y-axis) in the XY plane. The hardness of the substrate monolith 1 parallel to each of the first wall 10 and the second wall 11 is indicated by arrows k x and k y For the square cell substrate monolith 1, k x =k y However, the stiffness of the square channel at a diagonal angle (eg at 45°) relative to the first wall 10 and the second wall 11 will be lower and Figure 3 By arrow k d Shown.
[0088] As described above, the impulse vector 30 of the impulse J has a non-zero first axis component 31 and a non-zero second axis component 32. In a preferred example, the impulse vector 30 may have substantially equal first axis component 31 and second axis component 32. Figure 4 , where the impulse J is applied by striking the substrate monolith 1 in a diagonal direction relative to the first axis (X axis) and the second axis (Y axis). In the example shown, the impulse J is applied by striking the substrate monolith 1 in a direction 45° to the X axis and the Y axis.
[0089] Figure 5 The angles of the impulse vectors 30 for two examples of substrate monoliths 1 are shown. Figure 5 The cell 12 in the left example is a uniform square cell. Figure 5 The cells 12 of the right side example have varying sizes and shapes, having a pattern referred to as an "octagonal". In particular, the first wall 10 and the second wall 11 define a smaller square cell 12a and a larger cell 12b. The larger cell 12b may have truncated corners forming an octagonal cell. However, for the purposes of this disclosure, it will be noted that in the case of the octagonal cell 12b, the sides of the cell 12b having the longest dimension are those sides that are aligned parallel to the first axis and the second axis. Therefore, the angle of the impulse vector 30 can be considered to extend diagonally relative to the octagonal cell 12b, as shown in FIG. Figure 5 As shown by the arrow in, in the same manner as the square hole chamber 12a.
[0090] The second monolith may include, for example, a reference substrate monolith, or a substrate monolith from a different substrate monolith batch compared to substrate monolith 1 , or may be a substrate monolith from the same substrate monolith batch as substrate monolith 1 .
[0091] Example
[0092] In the following examples, substrate monoliths were tested using the methods and testing apparatus described above.
[0093] Example 1
[0094] The effect of impact direction was studied using a bare (uncoated) aluminum titanate filter substrate monolith with octagonal cells. The substrate monolith was impacted by an impact tool with two types of impacts. In the first type of impact, the impulse vector was aligned parallel to the first axis, such that it was at 0° ("parallel direction") to the first axis wall of the substrate monolith. In the second type of impact, the impulse vector was aligned diagonally to the first axis, such that it was at 45° ("diagonal direction") to the first axis wall (and also the second axis wall) of the substrate monolith.
[0095] Figure 6 The frequency spectra obtained from two types of impacts using the test setup are shown. In particular, during the test, the mechanical vibrations sensed by the microphone were converted into the frequency domain to produce a spectrum of the sensed mechanical vibrations. It can be seen that for the parallel direction impact, the spectrum does not include any single clear strongest fundamental frequency. In contrast, the diagonal direction impact produces a clearly discernible fundamental frequency at approximately 1000 Hz, which also has a larger amplitude than the parallel direction impact.
[0096] Example 2
[0097] Figure 7 Another example spectrum obtained from a flow-through substrate monolith using the testing of the present disclosure is shown. The flow-through substrate monolith is a cordierite substrate with square cells and coated with a PGM / Al2O3 catalyst. In this example, a single clearly discernible fundamental frequency at about 1300 Hz was obtained using an impact at a 45° angle to the first axis wall.
[0098] Example 3
[0099] The second substrate monolith of the method may be used as a reference substrate monolith.The method may further include the step of making a judgment on the crack state of the substrate monolith based on a comparison of fundamental frequencies obtained for the substrate monolith and the reference substrate monolith.
[0100] Figure 8The results of three spectra obtained by the present method for three filter substrate monoliths are shown. The filter substrate monolith is an aluminum titanate substrate having an octagonal pore chamber and coated with CuO / zeolite - an uncracked substrate monolith ("good part"), a first cracked substrate monolith ("cracked part 1") and a second cracked substrate monolith ("cracked part 2") serving as a reference substrate monolith. Cracked part 1 and cracked part 2 comprise a carrier coating and a calcined substrate monolith heated to 600°C in an oven. The oven door is then opened to allow cold air to pass through the hot surface of the substrate monolith. Due to the resulting thermal shock, surface cracking of the substrate monolith is observed, with the cracks extending from 3 cm to 16 cm along the Z axis and penetrating from 1 cm to 5 cm in the radial direction.
[0101] It can be seen that the fundamental frequency obtained from the good part (reference substrate monolith) is 1636 Hz, compared to 1412 Hz and 1532 Hz for cracked part 1 and cracked part 2, respectively. The change (in this example, a decrease) in the fundamental frequency can be used to determine whether the substrate monolith under test has cracked.
[0102] Example 4
[0103] As with external cracks, this method can be used to discern whether the substrate monolith has internal cracks. Such internal cracks may occur, for example, when the substrate monolith is subjected to a high cooling rate after calcination.
[0104] Fig. 9 The fundamental frequencies obtained from 42 samples of SCRF filter substrate monoliths are shown. The filter substrate monolith is an aluminum titanate substrate with octagonal cells and coated with CuO / zeolite. The samples were heated to a calcination temperature of 500°C and then subjected to cooling rates varying between 3°C / min and 9°C / min as follows:
[0105] Sample No. Cooling rate (℃ / min) 1 to 4 3 5 to 8 4 9 to 12 5 13 to 20 6 21 to 28 7 29 to 36 8 37 to 42 9
[0106] After cooling, no visible external cracks were observed on any of the samples. However, testing according to the present disclosure was able to discern that cooling rates greater than 5°C / minute resulted in internal cracking - as can be identified from the reduction in fundamental frequency obtained. It can be seen that at 6°C / minute, some samples suffered from internal cracking. A clear trend was observed that the occurrence of internal cracking increased with increasing cooling rate until, at a cooling rate of 9°C / minute, all tested samples suffered from internal cracking.
[0107] In this embodiment, the second substrate (reference substrate) may, for example, be selected to be a substrate that has been subjected to a slow cooling rate of less than or equal to 3° C. / minute, thereby obtaining a “reference” fundamental frequency of approximately 1770 Hz.
[0108] Example 5
[0109] The substrate monolith and the second substrate monolith may be from a first substrate monolith batch and a second substrate monolith batch, respectively.The method may further include the step of making a determination regarding variations between substrate monolith batches based on a comparison of fundamental frequencies obtained for the substrate monolith and the second substrate monolith.
[0110] Fig.10 The fundamental frequencies obtained from two batches of ten flow-through substrate monoliths are shown. Each flow-through substrate monolith is a cordierite substrate with square pores and is coated with a PGM / Al2O3 catalyst. Batch 1 and Batch 2 have the same slurry composition, washcoat loading, calcination temperature, etc., but are produced at different times. As can be seen from the results, the fundamental frequencies are generally consistent between batches. In addition, statistical testing using a T-test shows that for this example, the differences between batches are not statistically significant.
[0111] Therefore, this method can be used to judge between substrate monoliths manufactured at different times.
[0112] Example 6
[0113] Fig.11 The fundamental frequencies obtained from 4 different flow-through substrate monoliths are shown, which are comparable to each other in terms of their end use, but come from 4 different manufacturers. Each substrate monolith is an uncoated cordierite substrate with a square pore chamber. In this case, the second substrate monolith can be a previously selected substrate monolith. The other substrate monoliths can be potential alternative substrate monoliths for comparison with the previously selected substrate monolith. It can be seen that in this embodiment, the previously selected substrate monolith produces a fundamental frequency of approximately 415 Hz. Of the three possible alternatives, Option 1 has a similar fundamental frequency of approximately 425 Hz, while Option 2 and Option 3 have fundamental frequencies of 485 Hz and 492 Hz, respectively.
[0114] Therefore, this method can be used to judge between substrate monoliths obtained from different sources.
[0115] Example 7
[0116] The substrate monolith and the second substrate monolith may be from a single substrate monolith batch having the same configuration.The method may further include the step of making a determination regarding variations within the single substrate monolith batch based on a comparison of the fundamental frequencies obtained for the substrate monolith and the second substrate monolith.
[0117] exist Fig.12 In , 10 samples of GPF filter substrate monoliths were tested. Each filter substrate monolith was an uncoated cordierite substrate with square pores. It can be seen that the fundamental frequency obtained varies from about 2620 Hz to 2905 Hz.
[0118] Comparison of the fundamental frequencies may include determining whether there is a statistically significant variation in the fundamental frequencies obtained for the single batch of substrate monoliths.
Claims
1. A method for testing a substrate monolith, the substrate monolith comprising: i) a plurality of channels extending longitudinally along the Z-axis of the substrate monolith; as well as ii) an array of walls extending along said Z-axis and forming partitions between adjacent channels; wherein the wall array comprises a first wall oriented parallel to a first axis of the substrate monolith and a second wall oriented parallel to a second axis of the substrate monolith, the first axis and the second axis being both orthogonal to the Z axis; The method comprises the following steps: a) applying an impulse to the substrate monolith with an impact tool to induce mechanical vibration in the substrate monolith; b) sensing the mechanical vibration of the substrate monolith; c) determining the fundamental frequency of the sensed mechanical vibration; and d) comparing the fundamental frequency of the sensed mechanical vibration with a fundamental frequency obtained from testing of a second substrate monolith; In step a), the impulse vector of the impulse has a non-zero first axis component and a non-zero second axis component.
2. The method of claim 1, wherein in step a), the impulse vector has substantially equal first and second axis components.
3. A method according to claim 1 or claim 2, wherein in step a), the impulse is applied by striking the substrate monolith in a diagonal direction relative to the first axis and the second axis.
4. A method according to any preceding claim, wherein the first axis and the second axis are orthogonal to each other and are respectively the X-axis and the Y-axis of the substrate monolith. 5 . The method according to claim 4 , wherein in step a), the impulse is applied by striking the substrate monolith in a direction at 45° to the X-axis and the Y-axis.
6. A method according to any preceding claim, wherein the plurality of channels comprises quadrilateral channels, optionally square channels.
7. A method according to any preceding claim, wherein the substrate monolith is supported on a support system to isolate the substrate monolith from extraneous vibrations.
8. The method according to any preceding claim, wherein in step b), sensing the mechanical vibrations of the substrate monolith comprises sensing the mechanical vibrations in the time domain using a transducer.
9. A method according to any preceding claim, wherein in step c), determining the fundamental frequency comprises converting the sensed mechanical vibration into the frequency domain to produce a frequency spectrum of the sensed mechanical vibration.
10. The method of claim 9, wherein in step c), determining the fundamental frequency comprises applying a power spectral density (PSD) analysis to the frequency spectrum.
11. A method according to any preceding claim, wherein the second substrate monolith is a reference substrate monolith, and the method further comprises a step of making a judgment about the crack state of the substrate monolith based on a comparison of the fundamental frequencies obtained for the substrate monolith and the reference substrate monolith.
12. A method according to any one of claims 1 to 10, wherein the substrate monolith and the second substrate monolith are respectively from a first batch and a second batch of substrate monoliths, and the method further comprises a step of making a judgment about changes between batches of substrate monoliths based on a comparison of the fundamental frequencies obtained for the substrate monolith and the second substrate monolith.
13. A method according to any preceding claim, wherein the method is performed on a production line configured to process a plurality of substrate monoliths.
14. The method according to any preceding claim, wherein the substrate monolith comprises a flow-through substrate monolith or a filter substrate monolith.
15. A testing device for performing the method of any preceding claim, the testing device comprising: a support system for isolating the substrate monolith from extraneous vibrations; Impact tools; a transducer for sensing mechanical vibrations of the substrate monolith; as well as an analyzer for determining the fundamental frequency of the sensed mechanical vibration; The impact tool comprises an automatic hammer configured to apply the impulse to the substrate monolith with an impulse vector having a non-zero first axis component and a non-zero second axis component.
16. A testing device according to claim 15, wherein the support system and the impact tool are both coupled to an alignment frame, and the alignment frame is configured to ensure that the impulse vector of the impulse applied by the impact tool to the substrate monolith supported by the support system has a non-zero first axis component and a non-zero second axis component.