JPH0641900B2 - Measuring device for hot elastic modulus of ceramics - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hot elastic modulus measuring device for ceramics and the like, and uses a flexural flexure type non-contact displacement measuring instrument to perform accurate automatic measurement in various atmospheres. The present invention relates to a hot elastic modulus measuring device.

[Conventional technology]

When fine ceramics are used hot as high strength materials such as mechanical parts and structural materials, the elastic modulus during hot is an extremely important characteristic for estimating mechanical strength, thermal shock resistance, etc. .

As a conventional technique, the title of the invention is "a displacement measuring device for hot ceramics or the like" (Japanese Patent Laid-Open No. 61-7452).
There are a resonance method and an ultrasonic pulse method. The bending resonance method tends to be affected by the natural vibration of the vibration transmission mechanism, and the ultrasonic pulse method has a problem that the heat resistance of the vibrator is low and high temperature cannot be measured. Of these, Embodiment 4 of "Device for measuring displacement of ceramics or the like during hot" disclosed in Japanese Patent Laid-Open No. 61-7452
A conventional example of the hot elastic modulus measuring device described in 1) will be described.

FIG. 9 is a diagram schematically showing a conventional hot elastic modulus measuring device for ceramics and the like, FIG. 10 is a front sectional view of a heating furnace portion and a load applying device, and FIG. 11 is a diagram showing the conventional device. It is a figure which shows a displacement measurement position. In the figure, 1 is a sample, 2 is a heating furnace, 3 is a sample support base, 4 is a support roll, 5 is a camera with a built-in solid-state scanning light receiving element, 6 is a telephoto lens, 7 is a filter,
8 is a pressure rod, 12 is a load applying device, 20 is a personal computer, 23 is a digital thermometer, 24 is a lighting device,
25 is a camera controller, 26 is a personal computer interface, 27 is a digital plotter, 28
Is a printer, 30 is an oscilloscope, and 33 is a silicon carbide heating element.

In this hot elastic modulus measuring device, a sample 1 (width 10 mm x thickness 2.5 mm x length 60 mm) is placed on two support rolls 4 provided on an alumina sample support base 3 in a heating furnace 2. A load corresponding to 50 to 70% of the breaking strength of the sample 1 is set from the load device 12 installed outside the heating furnace 2 through the pressurizing rod 8 up to 1500 ° C. at every 100 ° C. by the three-point bending method. To load. At that time, the point A immediately below the load of the sample 1 and the point B closest to the contact point between the support roll 4 and the sample 1 are illuminated by the illuminating device 24, and the solid-state scanning light reception facing the illuminating device 24 outside the furnace. Working distance 4 with camera 5 with built-in element
60mm F number 8 telephoto lens 6 and infrared 0.8μm
Using a filter 7 that removes light having a wavelength of up to 1000 μm, a dark portion blocked by the sample 1 and a bright portion where the light directly reaches are enlarged and projected on the surface of the solid-state scanning light-receiving element by the desired salt lens 6 to form points A and B. The displacement of the point is measured and the bright portion and the dark portion are displayed on the oscilloscope 30. Then, a digital signal corresponding to the displacement is output by the output of the camera controller 25, and the output signal and the digital signal of the digital thermometer 23 are input to the personal computer 20 via the interface 26 to cause the printer 28 to perform a storage operation. The results are plotted and the digital plotter 27 is made to write a relationship curve between temperature and elastic modulus, and the hot elastic modulus is determined from the relationship between stress and the amount of deflection of the sample.

[Problems to be solved by the invention]

As described above, the conventional elastic modulus measuring method using a hot displacement measuring device such as a ceramic has a problem that a sample that is easily oxidized cannot be measured because the heating furnace is in an atmospheric atmosphere. Originally, it is desirable to be able to measure in various atmospheres such as an oxidizing atmosphere and a non-oxidizing atmosphere with this type of device, but there are restrictions due to the type of heating element, etc., and in general it is limited to either an oxidizing atmosphere or a non-oxidizing atmosphere. It is the actual situation.

As a method for preventing the oxidation of the sample, it is necessary to make the heating furnace an airtight structure and make the atmosphere of an inert gas or the like. However, in this case, since the O-ring 34 or the metal bellows 11 is used for the seal portion between the heating furnace 2 and the pressure rod 8 as shown in FIG. 12 and FIG. , The load accuracy will be significantly reduced. In order to measure the elastic modulus of a small sample such as fine ceramics by the flexural bending method, the load load accuracy must be 1 gf or less, and the conventional seal structure has a large mechanical resistance due to the movement of the pressure rod 8 and is not practical. . In addition, 1000 ℃ in some fine ceramics
Some of them are very susceptible to oxidation at the above high temperatures, and even if the heating furnace 2 is made airtight and an inert gas of 99.999% purity is flowed, it may be oxidized by a very small amount of oxygen in the inert gas. .

On the other hand, in FIG. 9, when the bending deflection of the sample 1 is measured by the camera 5 with a built-in solid-state scanning light receiving element, there is a problem that the sample image fluctuates due to the convection of the atmospheric gas at a high temperature and the measured value varies. That is, as for the deflection displacement of the sample 1, a load is applied to the center of the sample 1 set on the support roll 4, and the displacement of the sample end just below the load point at that time is measured by using the camera 5 with a built-in solid-state scanning light receiving element. A range such as C of was measured.

However, in this method, when measurement is performed by the camera 5 with a built-in solid-state scanning light-receiving element, the measurement space between the lower surface of the sample 1 and the sample support base 3 is large. As a result, the displacement measurement accuracy deteriorates.

Fine ceramics with a high elastic modulus naturally have a small amount of bending deflection. As an example, width 5mm thickness 1
The maximum bending amount of the sample is about 150 μm when a load of 60% of the breaking load is applied to the mm sample with a span of 60 mm by the three-point bending method. The displacement measurement resolution needs to be 1 μm, and if there is fluctuation, a resolution of 1 μm cannot be obtained.

The present invention is for solving the above-mentioned problems, and regardless of an oxidizing atmosphere or a non-oxidizing atmosphere, flexural displacement of a sample can be accurately measured without influence of fluctuation, and fine ceramics or the like can be measured fully automatically. An object is to provide a hot elastic modulus measuring device.

[Means for solving problems]

The apparatus for measuring the hot elastic modulus of ceramics or the like according to the present invention is a hot furnace for ceramics or the like in which a lighting device is arranged on one side of a sample heating furnace so as to face a window and a detection device is arranged on the opposite side of the lighting device. In the elastic modulus measuring device, a metal bellows that expands and contracts in conjunction with the pressure rod is installed between the sample heating furnace equipped with temperature control equipment and the pressure rod of the load applying device, and the displacement between the sample and the sample support base. It is characterized in that the measurement space is narrowed to the extent that the sample is displaced, and that the sample support base is provided with an oxidation resistant sample cover that is more active than the sample.

[Action]

The hot elastic modulus measuring apparatus for fine ceramics and the like according to the present invention includes a load applying device, a load detecting mechanism, and a displacement detecting mechanism,
A heating furnace having an airtight structure and capable of adjusting various atmospheres is installed, and a sample oxidation prevention cover that is more active than the sample is installed on the sample support table to suppress the effect of fluctuations on the flexural displacement of the sample. It is possible to measure the hot elastic modulus of fine ceramics and the like accurately without contact. Furthermore, by adding an automatic temperature control device, it becomes possible to fully automatically measure the hot elastic modulus of fine ceramics or the like.

〔Example〕

 Hereinafter, embodiments will be described with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a hot elastic modulus measuring device for ceramics or the like according to the present invention, and FIG. 2 shows a setting condition of a heating furnace of the device of the present invention, a seal portion of a pressure rod and a sample support base. FIG. 3, FIG. 3 is a plan view of the sample support base of the present invention, FIG. 4 is a view showing a displacement measurement range in the apparatus of the present invention, and FIG.
-A sectional view, FIGS. 6 and 7 are views showing an antioxidant graphite cover, and FIG. 8 is a view showing an example of measurement results by the apparatus of the present invention. In the figure, the same reference numerals as those in FIGS. 11 and 12 indicate the same contents, and 9 is a silicon rubber disc and 10
Is a fixed hardware, 11 is a metal bellows, 13 is a crosshead, 14 is a connecting rod, 15 is a load detector, 16 is an edge, 17 is a sample cover, 18 is a measurement illumination window, 19 is a ring, 21 is a load control device, 22 is a thermocouple, 29 is a vacuum device, 31 is a temperature controller, 32 is a thyristor power control device, 33 is a silicon carbide heating element, 34 is an O-ring, and 35 is a hole.

Since the load is applied to the sample 1 set in the heating furnace 2 from the outside of the furnace by the pressurizing rod 8 with an accuracy of 1 gf or less, the heating furnace 2
The metal bellows 11 is attached to the pressure rod insertion part of the above, and the silicon rubber disk 9 is fixed to the pressure rod 8 by the fixing hardware 10 so as to be airtight on the upper part thereof. Attached metal bellows 11 upper end and silicon rubber disc 9
One end of the silicone rubber disc 9 is connected to the pressure rod 8 through the fixed metal fitting 10 with the other end of the silicon rubber disc 9 being kept airtight from the outside, and the upper part of the metal bellows 11 is loaded. Four connecting rods 14 on the crosshead 13 of the device 12
Connected with the upper part of the metal bellows 11 and the crosshead 13
The metal bellows 11
The spring load required for expansion and contraction is applied to the cross head 13 connected by the rod 14, and the pressure rod 8 via the silicon rubber disk 9 is attached to the cross head 13 without being affected by the spring load. The load detector 15 has a structure that is not detected as a load. The expansion and contraction operation of the metal bellows 11 is performed during the transition of the no-load state in which the crosshead 13 and the pressure rod 8 are raised and during the transition of the loaded state in which the crosshead 13 and the pressure rod 8 are lowered. The difference in the movement of the bellows 11 is that the strain of the strain gauge portion of the load detector 15 is several microns, and therefore the silicon rubber disc 9
The strain is very small at a few microns and is not detected as a load by the load detector 15. As a result, the heating furnace 2 can have a completely airtight structure without lowering the accuracy of the load applied to the sample 1, and the measurement under various atmospheres can be performed accurately.

Further, according to the present invention, as shown in FIG. 4, it is preferable that the measurement space between the lower surface of the sample 1 and the upper end of the sample support base 3 is small, for example, the deflection amount of the sample is equal to or more to 2 m / m or less. , Suppresses convection and suppresses the occurrence of fluctuations. Further, as shown in FIG. 5, if the measurement space between the lower surface of the sample 1 and the upper end of the sample support base 3 becomes narrower by providing the displacement measuring edge 16 on the upper part of the sample support base 3,
Although the magnification of the telephoto lens 6 is increased and the displacement detection range is narrowed, the displacement measurement accuracy can be further improved.
This method can be applied not only to the displacement measurement by the fixed scanning light receiving element built-in camera 5, but also to other non-contact displacement measuring devices.

Further, as for the method of preventing the oxidation of a material which is particularly easily oxidized at a high temperature and cannot be measured in a general inert gas atmosphere, it is effective to cover the sample support stand 3 with the sample cover 17 made of graphite, which is more active than the sample. Is. Further, the sample cover 17 prevents the inflow and outflow of the inert gas, prevents the fluctuation of the inert gas in the vicinity of the sample 1 due to the flow and convection, and improves the displacement measurement accuracy.

As shown in FIG. 6, the sample cover 17 of the present invention has a hole 35 through which the pressure rod 8 passes, and a small window 18 for illumination and measurement is provided vertically on the side surface. It is preferable that the hole diameter is within a range that does not contact the pressure rod 8. Alternatively, the gap (difference in hole diameter) between the pressure rod 8 and the sample cover 17 may be increased to increase the
As shown in the figure, a ring 19 having a small hole diameter difference from the pressure rod 8
To prevent the inert gas in the heating furnace from entering and exiting the sample cover and prevent the sample 1 from being oxidized.
It is possible to eliminate a load load error due to contact between the pressure rod 7 and the pressure rod 8.

Next, the measurement of the elastic modulus by the device of the present invention will be described.

When the sample 1 is placed on the support roll 4 of the sample support base 3 arranged in the heating furnace 2 and the measurement conditions are input to the personal computer 20, the temperature controller 3 is supplied from the computer 20.
1 is sent to the silicon carbide heating element 3 from the thyristor power control device 32 in response to a signal from the temperature controller 31.
Electric power is sent to the heating furnace 3 to raise the temperature of the heating furnace 2. The sample temperature at this time is detected by the thermocouple 22 set near the sample 1,
A BCD output signal from the digital thermometer 23 is input to the personal computer 20. When the temperature of the sample 1 reaches a preset temperature, the temperature is maintained at that temperature for a certain period of time, and then a load load signal is sent from the personal computer 20 to the load load device 12 via the load control device 21, and the pressure rod is applied to the sample 1. The load is applied via 8. At this time, the gap between the bending deflection point of the sample 1 and the point D of the edge 16 provided on the sample support base 3 is measured using the camera 5 with a built-in solid-state scanning light-receiving element and the illumination device 24 arranged facing the camera 5. Sample 1
Get the displacement of. In this measurement, the light from the illumination device
This is performed by enlarging and projecting the dark portion blocked by and the bright portion to which the light directly reaches onto the surface of the solid-state scanning light receiving element by the telephoto lens 6.

The signal from the camera 5 with a built-in scanning light receiving element is output from the camera control unit 25 as a digital output signal according to the displacement. This output, the digital signal output of the digital thermometer 23, and the load signal of the load detector 15 are created by a program created by a general method through the personal computer interface 26.
0 is input, calculation is performed based on the relationship between stress and the amount of deflection, and the relationship between temperature and elastic modulus is written by the digital plotter 27 and printer 28.

In this device, if the sample support roll 4 is deformed,
Since a displacement measurement error occurs, the displacement of the contact point between the sample 1 and the sample support roll 4 may be measured and corrected by another illumination device and one fixed scanning light receiving element built-in camera (not shown). It is possible.

Further, as for a method of preventing the oxidation of a material which is particularly easily oxidized at a high temperature and which cannot be measured in a general inert gas atmosphere, it is effective to cover the sample support base 3 with the sample cover 17 made of graphite which is more active than the sample. is there.

As shown in FIG. 6, the sample cover 17 of the present invention has a hole 35 through which the pressure rod 8 passes, and a small window 18 for illumination and measurement is provided vertically on the side surface. It is preferable that the hole diameter is within a range that does not contact the pressure rod 8. Alternatively, the gap (difference in hole diameter) between the pressure rod 8 and the sample cover 17 may be increased to increase the
As shown in the figure, a ring 19 having a small hole diameter difference from the pressure rod 8
To prevent the inert gas in the heating furnace from entering and exiting the sample cover, to prevent the oxidation of the sample 1 and the fluctuation of the inert gas, and to prevent the load load error due to the contact between the sample cover 17 and the pressure rod 8. Can be eliminated.

A measurement example of the hot elastic modulus measuring apparatus for ceramics according to the present invention will be described below.

A silicon carbide sample having a width of 5.0 on the supporting roll 4 of the supporting table in the heating furnace 2 of the apparatus of the present invention shown in FIGS. 1 and 2.
mm, thickness 1.0 mm, length 75 mm with the support roll gap set to 60 mm, the support 3 is covered with the graphite cover 17, and the inside of the heating furnace is evacuated by the vacuum device 29 at room temperature to remove argon. Replace with gas. The temperature rising rate was raised at 10 ° C. per minute while flowing 200 ml of argon gas per minute, and after reaching a predetermined temperature, the temperature was maintained for 10 minutes. After the lapse of the holding time, a signal is sent from the personal computer 20 to the load applying device 12, and 500 g is added to the sample 1 in 100 g units.
The load was applied 3 times each. At this time, the deflection displacement of the sample under each load is set to a working distance of 460 mm, a telephoto lens 6 of F number 8, a filter 7 for removing light of a wavelength of 0.8 μm to 1000 μm in the infrared region, and a camera 5 with a built-in scanning light receiving element. Then, the position shown in FIG. 4D was measured. The measurement was performed from room temperature to 1400 ° C. at 100 ° C. intervals, and the elastic modulus was determined from the obtained load-displacement data by the following calculation formula. The results are shown in FIG.

The elastic modulus can be calculated by the following equation.

E = Elastic modulus (kgf / mm ² ) l = Distance between supporting rolls (mm) P = Load (kgf) W = Width of sample (mm) t = Thickness of sample (mm) y = Displacement at load point (Effects of the Invention) As described above, according to the present invention, a load application device, a load detection mechanism, a displacement detection mechanism, and an airtight structure are provided, and a heating furnace capable of adjusting various atmospheres is provided, A sample oxidation-preventing cover that is more active than the sample is placed on the sample support to suppress the effect of fluctuations on the flexural displacement of the sample, prevent oxidation, and perform accurate non-contact measurement, and the hot elasticity of fine ceramics, etc. The rate can be measured. Furthermore, by adding an automatic temperature control device, it becomes possible to measure the hot elastic modulus fully automatically.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a hot elastic modulus measuring apparatus for ceramics or the like according to the present invention, and FIG. 2 is a setting state of a heating furnace of the apparatus of the present invention, a seal portion of a pressure rod, and a sample support base. FIG. 3, FIG. 3 is a plan view of the sample support base of the present invention, FIG. 4 is a view for showing a displacement measurement range in the device of the present invention, FIG. 5 is its side sectional view, FIG. FIG. 7 is a diagram showing an antioxidant graphite cover, FIG. 8 is a diagram showing an example of measurement results by the device of the present invention, and FIG. 9 is a diagram schematically showing a conventional hot elastic modulus measuring device for ceramics and the like. FIG. 10 is a front sectional view showing a heating furnace portion of the apparatus of FIG.
The figure shows the displacement measurement position in the conventional device, FIG. 12 shows an example of the method of using the O-ring to seal the heating furnace and the pressure rod, and FIG. 13 shows an example of the method of using the metal bellows. It is a figure. 1 ... Sample, 2 ... Heating furnace, 3 ... Sample support, 4 ...
Support roll, 5 ... Camera with built-in solid-state scanning light receiving element, 6 ...
... Telephoto lens, 7 ... Filter, 8 ... Pressure rod, 9 ...
… Silicon rubber disk, 10… Fixed hardware, 11… Metal bellows, 12… Load application device, 13… Crosshead, 14… Connecting rod, 15… Load detector, 16…
… Edge, 17 …… Sample cover, 18 …… Measurement illumination window,
19 ... Ring, 20 ... Personal computer, 2
1 ... Load control device, 22 ... Thermocouple, 23 ... Digital thermometer, 24 ... Lighting device, 25 ... Camera controller, 26 ... Personal computer interface, 27 ... Digital plotter, 28 ... Printer, Two
9 ... Vacuum device, 30 ... Oscilloscope, 31 ... Temperature controller, thyristor, 32 ... Thyristor power control device, 33 ... Silicon carbide heating element, 34 ... 0 ring, 35
……hole.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-7452 (JP, A) JP-B-60-4935 (JP, B1) JP-B 47-41949 (JP, B1)

Claims (3)

[Claims] 1. A temperature adjusting device for a hot elastic modulus measuring device such as ceramics, wherein a lighting device is arranged on one side of a sample heating furnace so as to face a window, and a detecting device is arranged on the opposite side so as to face the window. A metal bellows that expands and contracts in conjunction with the pressure rod is installed between the sample heating furnace equipped with the and the pressure rod of the load applying device, and the displacement measurement space between the sample and the sample support is narrowed to the extent of sample displacement. An apparatus for measuring a hot elastic modulus of ceramics or the like, characterized in that an oxidation resistant sample cover, which is more active than the sample, is provided on the sample support base. 2. The metal bellows, wherein the upper end of the metal bellows attached to a heating furnace is connected to a load applying device member, and the upper ends of the pressure rod and the metal bellows are connected by a rubber disc. An apparatus for measuring the hot elastic modulus of ceramics or the like according to the item. 3. A hot elastic modulus measuring device for ceramics or the like according to claim 1, wherein a displacement measuring edge is provided on the sample support base.