JP3191598B2 - How to collect samples for material survey - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sampling a material from a surface of a member made of a ceramic such as silicon nitride or the like or a brittle material such as cast iron to detect the remaining life of the member.

[0002]

2. Description of the Related Art Combustion chamber components such as pistons and cylinder heads of internal combustion engines, members used at high temperatures such as combustion chambers of gas turbines, piston rings for internal combustion engines, various seal rings, etc. For the members used, after a certain period of use, samples for material investigation are periodically collected from the members, and the microstructure, element distribution state, etc. are examined by an electron microscope, an X-ray microanalyzer, etc. Has been performed to estimate the remaining life.

[0003] Conventionally, when conducting a material survey of a member used under high-temperature and high-stress conditions as described above or a member used under a high frictional condition, a sample is directly cut out from the actual machine member in use and used for material survey. Was served as.

[0004]

However, as described above, in the method of directly cutting out a sample for material investigation from a member of an actual machine and collecting the sample, the member after sample collection is subjected to stress concentration at the sample collection portion. Continued use is difficult because of the risk of destruction.

[0005] In particular, in the case of a member made of a brittle material such as ceramics such as silicon nitride used under high-temperature high-stress or high-friction conditions or cast iron used under high-friction conditions,
Since the strength of the notch is remarkably reduced, it is impossible to use the member after sampling by an ordinary method.

SUMMARY OF THE INVENTION An object of the present invention is to obtain a sample for material investigation from a member in use in various devices, particularly a member made of a brittle material such as ceramics or cast iron. An object of the present invention is to provide a method for collecting a sample in which the member retains strength enough to withstand subsequent use, and enables the sample to be collected in a simple and low-cost manner.

The present invention is based on the observation that the size of a sample for investigating the microstructure and element distribution state of a material with an electron microscope, an X-ray microanalyzer or the like is sufficient when the size is about 100 μm or less. The gist of the invention lies in a method in which a crack is formed on the surface of a member to be measured in a shape of a small ring or other small closed locus, and a sample is collected from the crack portion.

[0008] As a specific method for generating the crack, the following three points are characterized. (1) A hollow micro-diameter indenter is pressed against the surface of a member to be measured, and microcracks are generated on the surface of the member to collect a sample.

(2) A hollow micro-diameter indenter is divided into a plurality of pieces in the circumferential direction, and each divided piece is pressed against the surface of a member to be measured to collect a sample.

(3) The surface of the member to be measured is irradiated with a laser beam in a ring shape, cracks are generated on the surface, and the sample is separated from the member to be measured at the crack portion and collected.

[0011]

According to the present invention, in the case of ceramics such as silicon nitride or brittle materials such as cast iron, the fracture criterion follows the maximum tensile principal stress theory. Therefore, if an annular pressing force is applied to the surface of the material, cracks are formed in an inverted cone shape. This is a method of collecting a sample based on the finding that the process proceeds.

That is, cracks are formed on the surface of a member to be measured for material investigation in the form of a micro ring or other small closed trajectory by a technique such as pressurization with a hollow micro-diameter indenter, irradiation with a laser beam in a circular shape, and blocking. When this occurs, it travels in an inverted conical shape inside the member, and a conical sample is separated from the member to be measured and collected.

According to such a method, it is possible to collect a material inspection sample having a small diameter in a range that does not reduce the strength of the member to be measured.

Thus, the member to be measured after sampling is
It is possible to incorporate and re-use it in the actual machine, and it is not necessary to remanufacture a substitute for the member to be measured every time a sample is collected and to incorporate it into the actual machine as in the conventional method. Samples can be collected at low cost.

In addition, a sample can be collected in a very simple manner and in a short time by causing cracks to be generated on the surface of the material to be measured by pressurization by an indenter, heating and cooling by a laser beam, and the like. Therefore, a low-cost material survey can be realized.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, and the like of the components described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples. It's just

FIG. 1 shows a method for collecting a material inspection sample from a member made of a brittle material such as ceramics or cast iron according to a first embodiment of the present invention.

In brittle materials such as ceramics such as silicon nitride and cast iron, the fracture criterion of the material often follows the principle of maximum tensile principal stress. According to this theory, if a small-diameter annular pressing force is applied to the surface of the material, the crack progresses in an inverted conical shape, and the conical fragments are separated from the material to be measured.

In the method shown in FIG. 1, since the conical sample is collected from the actual machine member, ie, the member 1 to be measured, it is made of a hard material such as diamond, sapphire, or cemented carbide, and the tip 2a is sharply finished. Hollow micro diameter (outer diameter D is 1
mm or less) is pressed against the surface 1a of the measured member 1 with a pressing force F perpendicular to the surface 1a.

Since the member to be measured 1 is made of a brittle material, a high stress concentration occurs on the pressed surface due to the pressing with the pressing force F, and a crack 3 is generated on the surface 1a in a small annular shape. It progresses in an inverted conical shape as shown.

Then, in the final stage of the crack 3, a conical fragment, that is, a sample 4, is separated from the member 1 to be measured and collected.

At this time, if a torsional moment M is applied to the indenter 2 together with the pressing force F in the vertical direction, the sample 4 can be more easily collected. Extraction of use from highly tough materials is also possible.

The sample 4 collected as described above is used for material examination such as microstructure and element distribution using an electron microscope, an X-ray microanalyzer, or the like. in this case,
If the size of the sample is about 10 to 100 μm, the required material investigation can be carried out without any trouble. Therefore, the sample 4 collected by the above method is sufficient.

After the sample 4 is collected, the member 1 to be measured can be used as a member of an actual machine without a decrease in strength because the sample 4 has a small diameter of about 10 to 100 μm.

FIGS. 2 and 3 show a second embodiment of the present invention. This embodiment relates to a method for collecting a sample applied when the surface of the member 1 to be measured is not flat. In FIG. 10, reference numeral 10 denotes an indenter made of a hard material similar to that of the first embodiment.

The indenter 10 has a hollow minute diameter (outer diameter D is 1) having a sharp end 10a as in the first embodiment.
mm or less), but is divided into a plurality of indenter pieces 101 at equal intervals in the circumferential direction as shown in FIGS. I have. Numeral 11 denotes the dividing plane.

Using the split type indenter 10, the surface 1a
When the sample 4 for material inspection is collected from the surface of the member 1 to be measured which is not a flat surface, as shown in FIG. 2, a presser having a U-shaped cross section and a leaf spring portion 15a formed in the center is provided. Jig 1
5 is used for each indenter piece 101.

The pressing portion 15c of the pressing jig 15 is brought into contact with the upper surface of each of the divided indenter pieces 101,
The support portion 15b on the opposite side is brought into contact with the base 20, and the spring portion 15a of the holding jig 15 is pressed from above by a pressing force F, and cooperates with the elasticity of the spring portion 15a to allow each indenter piece 10 to move.
1 is pressed against the surface of the member 1 to be measured.

At this time, the indenter 10 is divided into a plurality of indenter pieces 101, and a pressing jig 15 is provided for each indenter piece 101.
Therefore, even if the surface 1a of the member 1 to be measured is not a flat surface, each indenter piece 101 is pressed according to the change in the surface, an even pressing force is applied to the sampling surface, and an inverted conical crack is formed. 3 is generated, and a conical sample 4 similar to that of the first embodiment can be obtained.

FIG. 4 shows a third embodiment of the present invention. In this embodiment, the member 1 to be measured is
Is irradiated with the laser beam 21 in a small ring having a diameter D of 1 mm or less while rotating the irradiation device 22. Then, the thermal expansion of the circular portion of the member 1 to be measured which is heated by the laser beam 21 is restrained around the low temperature, and when the irradiation of the laser beam 21 is stopped and the temperature of the circular portion drops, Then, a tensile force is generated in this portion, and the crack 3 proceeds in an inverted conical shape starting from the tensile force, and the conical sample 4 is separated from the member 1 to be measured.

According to the method of irradiating and interrupting the laser beam 21 at a constant cycle when irradiating the laser beam 21, the generation of the cracks 3 is accelerated, and the sampling time of the sample 4 is shortened.

Further, as shown in FIG. 4, after irradiation with the laser beam 21, a cooling agent 24 such as low-temperature air or water is supplied from the cooling nozzle 23 to the circular portion of the member 1 to be measured which is heated by the laser beam 21. When the portion is cooled and the portion is cooled, the generation of the crack 3 is further accelerated as compared with the above-described method.

[0033]

As described above, according to the present invention, cracks are generated on the surface of a member to be measured by pressing with a hollow micro-diameter indenter, irradiating a laser beam so as to draw a micro annular trajectory or other micro-closed trajectories. At least, the crack is advanced into the member to be measured in an inverted conical shape, so that a conical sample is collected.Therefore, a material inspection sample having a small diameter in a range that does not reduce the strength of the member to be measured is used. It becomes possible to collect.

Thus, the member to be measured after sampling is
It is possible to incorporate it into the actual machine and use it again, eliminating the need to remanufacture a substitute for the member to be measured every time a sample is collected and to incorporate it into the actual machine as in the conventional method. Thus, a sample can be collected.

In addition, a sample can be collected in a very simple manner and in a short time by causing cracks to be generated on the surface of the member to be measured by pressing with an indenter, heating and cooling with a laser beam, and the like. Therefore, a low-cost material survey can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a method for collecting a sample for material investigation according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a second embodiment of the present invention.

FIG. 3 is a view taken in the direction of arrow A in FIG. 2;

FIG. 4 is a view corresponding to FIG. 1 showing a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Member to be measured 1a Surface 2, 10 Indenter 101 Indenter piece 3 Crack 4 Sample 15 Holding jig 21 Laser beam 22 Laser irradiation device 23 Cooling nozzle 24 Coolant

──────────────────────────────────────────────────続 き Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 1/00-1/34 JICST file (JOIS)

Claims (4)

(57) [Claims] 1. A material inspection method for collecting a micro sample for material investigation, wherein a crack is formed on the surface of the member to be measured in a shape of a micro ring or other small closed locus, and the sample is collected from the crack portion. Sample collection method. 2. A hollow micro-diameter indenter is pressed against the surface of a member to be measured to cause cracks on the surface of the member,
A method for collecting a sample, comprising collecting the sample. 3. A method for collecting a sample, comprising: dividing a hollow micro-diameter indenter into a plurality of pieces in a circumferential direction, and pressing a sample against a surface of a member to be measured for each divided piece. 4. A surface of a member to be measured is irradiated with a laser beam in a substantially small annular shape, a crack is generated on the surface, and a sample is separated from the member to be measured at the crack portion and collected. How to collect samples.