JPH03269251A - Measuring method for strength of ceramic component - Google Patents

Abstract

PURPOSE:To secure strength reliability and quality by measuring the amount of the diopside of a ceramic component by X-ray diffraction, estimating the strength and measuring the strength without destruction. CONSTITUTION:The X-rays are generated in an X-ray ball tube 1 in a tube shield 2. From the linear X-ray source through a shutter 3 X-rays are projected on a sample 7 provided on a sample part 6 through a solar slit 4 and diverging slit 5 at a viewing angle theta. The X-rays diffracted in the sample 7 are inputted into a counting tube 12 through a light receiving slit 8, a solar slit 9 and scattering slit 11. The viewing angle theta is rotated and scanned highly accurately, and the counted number for the number of rotation 2theta is measured. The diopside amount of the arbitrary part of a ceramic component as the sample 7 is measured by X-ray diffraction, and the strength is estimated. Then, the strength can be measured without destruction. Thus the strength can be well secured, and the quality control can be performed sufficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for measuring the strength of ceramic parts in a non-destructive manner.

(Conventional technology) Structural ceramics such as silicon nitride and silicon carbide generally have excellent heat resistance and wear resistance, so they are strongly required to have thermal properties similar to those of high performance and high output engines. Extremely useful as an engine component.

On the other hand, ceramics such as those mentioned above are brittle and highly susceptible to cracks and defects, and their strength decreases significantly depending on the size of the defect. However, the strength decrease tends to be significantly affected.

In order to put this ceramic member into practical use as an engine member, strength reliability and quality assurance are particularly important issues.

Conventionally, in order to measure the strength or detect defects in such ceramic parts, for example, defect detection by X-ray transmission, proof tests, destructive tests by sampling from each lot, strength measurements by bending tests, etc. have been carried out. ing.

(Problem to be solved by the invention) However, in measuring the strength of ceramic parts, the
Non-destructive inspection of wires, etc. is a method of detecting cracks and defects that greatly affect strength, and non-destructively eliminating parts whose strength is not satisfactory, but as mentioned above, strength However, with this inspection method, it is not easy to determine the detection limit for the size of the defect or to identify the location of the defect, and it is difficult to accurately understand the strength, especially when the shape of the part is complex in areas where strength is required. There is a difficult problem.

In addition, the proof test method is a method that applies a stress lower than the actual load condition of the component and removes low-strength products.
In this case, there is a high possibility that fine cracks will occur due to the application of load, and conducting this test will cause the problem of erroneously impairing the reliability of the strength.

Furthermore, strength measurement by bending test is a commonly used strength measurement method, and the strength is measured by cutting out parts or test items processed from the same lot, and although the measurement accuracy is excellent, Variations due to test piece shape, finishing accuracy, and test conditions increase. In addition, it is not the strength of the part itself, but the strength of a test piece of the same processed product, and it is not possible to measure the strength of specific parts such as stress concentration areas, making it difficult to decide what criteria to apply the measurement results to. have

Therefore, in view of the above circumstances, the present invention provides a method for measuring the strength of ceramic parts in which the strength of parts such as stress concentration parts of ceramic parts is non-destructively measured using X-rays to ensure strength reliability and quality. The purpose is to provide

(Means for Solving the Problems) In order to achieve the above object, the strength measuring method of the present invention measures the strength of a ceramic component whose main component is silicon nitride, Si3N4, The method is characterized in that the amount of diopside is measured in the portion by X-ray diffraction, and the intensity is estimated based on the amount of diopside.

Increasing the strength of silicon nitride ceramics can be achieved by preventing defects, making grains finer, and crystallizing grain boundary layers. When obtaining a silicon nitride ceramic that requires a high bending strength (150 MPa or more), it is important to consider the products of the grain boundary layer and the relationship between their crystallinity and strength regarding the crystallization of the grain boundary layer. This makes it possible to estimate the intensity.

The target ceramic to which the method of the present invention is applicable is a ceramic component whose main component is silicon nitride, which has been subjected to blending components such as diopside and apatite grain boundary layer materials, and which has been subjected to sintering and heat treatment.

The constituent materials and crystal structure of this silicon nitride ceramic are as follows: The base material is hexagonal crystal grains of silicon nitride β-8i3N4, and the grain boundary layer is formed between the base material crystal grains. is composed of monoclinic diopside and hexagonal apatite. The manufacturing process for crystallizing silicon nitride ceramic is to mix raw materials, shape the product into a product shape, and then sinter and crystallize it.

J, base material ■ β-8i3N4 - monoclinic system ■ 1 grain boundary layer IIa... diopside - monoclinic system ■ Ca
(Mg, Pe, AI) (SjAl) 203■ CaM
g (Sing) 2 nb...Apatite -- hexagonal system Ce4.
bt (Sin4) 30■ Y5 (Sin4)N ■ MgY4Si3013 The detection of the grain boundary layer substance is performed when diopside is monoclinic,
Since apatite is produced in a hexagonal system, this minute amount of grain boundary layer material is quantitatively detected by X-ray diffraction analysis of the crystal structure. At that time, the intensity of the X-ray source for X-ray diffraction, sample pretreatment, diffraction angle, etc. are set to the optimal conditions.
A profile of the grain boundary layer material is obtained as a diffraction result.

Then, various diopside and apatite substances as grain boundary layer substances are identified from the diffraction angle of the profile of the above-mentioned diffraction results, and each substance is quantified from the diffraction intensity. From this, the overall amount of diopside and apatite is calculated, and the diffraction intensity occupied by the amount of diopside in all grain boundary layer materials is determined. Alternatively, quantification may be performed by determining the half width from the diffraction profile.

The relationship between the amount of grain boundary layer material determined by X-ray diffraction and the strength of silicon nitride ceramic is that the bending strength increases as the ratio of diopside to the total grain boundary layer material increases. The bending strength is estimated by non-destructively measuring the amount of diopside from the X-ray diffraction of the actual ceramic component based on the characteristics whose relationship has been determined in advance, and comparing it with the above characteristics. It is.

(Function) In the above-mentioned method for measuring the strength of ceramic parts, X-rays are used to measure the strength of silicon nitride parts where diopside crystals have been formed at the grain boundaries during sintering or heat treatment. By performing diffraction, diopside and crystallinity, which are significantly related to the strength state, are measured, making it possible to accurately estimate the strength of silicon nitride ceramic parts by non-destructive measurement using X-rays.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the outline of an X-ray diffraction apparatus. , a sample 7 (ceramic component) placed in the sample section 6 is irradiated at a glancing angle θ (complementary angle of the incident angle), and the X-rays diffracted by the sample 7 are passed through a light receiving slit 8, a solar slit 9, and a scattering slit 11. The signal is input to the counter 12 (counter) through the .

Then, the glancing angle θ is rotated and scanned with high precision, and the number of counts with respect to the diffraction angle 2θ is measured.

The divergence slit 5 limits the divergence angle of the divergent X-rays in the horizontal plane, and the light receiving slit 8 restricts the divergence angle of the divergent X-rays in the horizontal plane.
Further, the scattering slit 11 prevents scattered X-rays such as air-scattered X-rays from entering the counter tube 12 from sources other than the sample.

Furthermore, in the X-ray tube 1, a high voltage is applied to the filament to irradiate a target (X-ray generation source) with an electron beam, thereby generating X-rays from the target.

The sample 7 is irradiated with the characteristic X-rays generated from this target, and the reflected X-rays (the X-rays enter about 10 μm) generated from the sample 7 are detected while changing the diffraction angle 2θ.

Then, find the diffraction angle 2θ where the X-ray diffraction intensity (count number) is strong, and calculate the lattice spacing d using Bragg's formula (2d
sinθ#nλ, λ: wavelength of incident X-ray, n: positive integer)
Substances (1) to (2) in the ceramic are identified by comparing with the unique lattice spacing d of each crystal.

Among the substances ■ to ■ in the silicon nitride ceramic, excluding the base material of ■, ■, diopside of ■, and ■, ■, ■
The apatite crystals are fine grains, and the diffraction angle 2θ at which they are detected is in the range of 15° to 40°, and conditions are set to improve the detection accuracy in this region and emphasize the peaks to perform good measurements.

The conditions for the above X-ray diffraction are such that the X-ray tube voltage and X-ray tube current are set high, and the corrosion time as a pretreatment of the sample 7 is adjusted.

Next, to explain concrete examples of strength measurement experiments, the ceramic parts to be measured include the apex seal 14 of the rotary piston engine shown in Fig. 2 made of ceramic, and the one of the diesel engine shown in Fig. 3. This is an example of the ceramic portion 15a at the tip of the glow plug 15. The tip A of the apex seal 14 has the strongest strength, and the strength of this tip A is measured. Furthermore, the strength of the glow plug 15 is also measured at a portion B surrounded by an ellipse.

Then, the apex seal 14 and the ceramic portion 15a of the glow plug 15 are prepared as experimental samples. The size of the sample is 3 x 4 mm, and the sample is subjected to corrosion for about 2 hours as a pretreatment, and the zero surface roughness of the sample surface is adjusted to about 1 μm.

In addition, as the X-ray diffraction conditions, the acceleration voltage of the X-ray tube was set to 40
KV, filament current of 80 mA, target material of Cu, and diffraction angle (2θ) variation range of 15 to 40 degrees. The lattice spacing d is 5.90 angstroms when the diffraction angle 2θ is 15 degrees, and 2.2 when the diffraction angle 2θ is 40 degrees.
It is 5 angstroms.

The measurement results of X-ray diffraction performed under the above conditions are shown in FIG. This figure 4 is the X-ray diffraction profile, and the diffraction intensity CPS (number of counts per second) with respect to the diffraction angle 2θ
It shows.

In Figure 4, the lattice spacing d corresponding to the crystal direction of the substance at which a peak occurs at each diffraction angle, that is, the crystal direction of each substance, is determined in advance, and by comparing this data, it is possible to By identifying the substance, it is possible to determine whether the constituent substance of the silicon nitride is a matrix, diopside, or apatite, and the symbols ■ to ■ shown in FIG. 4 indicate the substances. This is a substance that is produced by crystallizing an amount of the substance corresponding to its strength.

Next, from the above-mentioned X-ray diffraction profile, the total amount of the grain boundary layer of diopside and apatite is determined, and the proportion of diopside to the total grain boundary layer is determined.

This allows the strength to be estimated.

In other words, Figure 5 shows the data for determining the relationship between the ratio of diopside to the total grain boundary layer and the bending strength. It has been found that the bending strength tends to increase as the ratio decreases.

Then, the strength is estimated by applying the measured data of the ratio of diopside to the total grain boundary layer obtained from the diffraction profile of the ceramic component by the above-mentioned X-ray diffraction to the characteristics shown in Fig. 5 above. . In Figure 5, the apex seal A has a high required strength and the composition of the ceramic member, the sintering temperature conditions, etc. are set so that the amount of diopside is high, and the glow plug B Since the required strength of the ceramic part is lower than that, sufficient strength can be secured with a low amount of diopside. ing.

According to the embodiment described above, the amount of diopside at a predetermined portion of a ceramic component is measured by X-ray diffraction, and the amount of diopside is compared to the range between diopsides corresponding to the strength required for the component. It is possible to estimate the intensity and determine whether it is within the allowable range.

The strength of ceramics whose main component is silicon nitride is
As mentioned above, it is greatly influenced by the state of diopside formation in the grain boundary layer, which changes depending on the composition, sintering conditions (temperature, time), etc., and by adjusting it, it is possible to create ceramic parts with the required strength. is obtained.

(Effects of the Invention) According to the present invention as described above, the amount of diopside in any part of a ceramic component containing silicon nitride as the main two components is measured by X-ray diffraction, and the strength is determined based on the amount of diopside. By estimating , it is possible to accurately estimate the strength of the portion itself where the strength is severe by non-destructive measurement using X-rays, and the reliability of the ceramic component is improved.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of an X-ray diffraction apparatus applied to the present invention, Fig. 2 is a front view showing an example of a ceramic part, Fig. 3 is a front view of main parts showing another ceramic part, and Fig. 4 is a front view showing an example of a ceramic part. Diffraction profile diagram showing an example of measurement results by X-ray diffraction. FIG. 5 is a graph showing the relationship between measurement of X-ray diffraction and bending strength. 1...X-ray tube, 5,8.11...Slit, 7...Sample, 12...Counter tube, 14.15... ...Ceramic parts. 3 4 Japanese Unexamined Patent Publication No. 3 269251 (6)

Claims (1)

[Claims] (1) A method for measuring the strength of a ceramic component whose main component is silicon nitride, in which any part of the ceramic component is
A method for measuring the strength of ceramic parts, characterized by measuring the amount of diopside by line diffraction and estimating the strength based on the amount of diopside.