JPH01165930A - Apparatus for measuring hot modulus of elasticity of ceramics - Google Patents

Abstract

PURPOSE:To enhance measuring accuracy, by a method wherein a nonresistant seal mechanism extending and contracting in connection with a press rod is provided between a sample heating furnace and the press rod of a load applying apparatus and narrowing the displacement measuring space of a sample and a sample support stand to the displacement degree of the sample. CONSTITUTION:In order to apply load to the sample set to a heating oven 2 with accuracy of 1gf or less from the outside by a press rod 8, metal bellows 11 is mounted to the heating oven 2 and the pre rod insert part and a silicone rubber disc 9 is fixed to the upper part of said bellows 11 in an airtight state. The movement difference of the press rod 8 and the bellows 11 is not detected as load by a load detector 15 because not only the strain of the strain gauge part of the load detector but also the strain of the disc 9 are set to an extremely small value of several mum. Further, by setting the measuring space between the under surface of the sample 1 and the upper end of a sample support stand to a range from the bending quantity of the sample - 2mm, the flow and convection of atmospheric gas are suppressed and the generation of fluctuation is suppressed. By this method, displacement measuring accuracy can be enhanced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a hot elastic modulus measuring device for ceramics, etc., and uses a bending deflection type non-contact displacement measuring device to automatically measure accurately in various atmospheres. The present invention relates to a hot elastic modulus measuring device.

[Conventional technology]

When fine ceramics are used in hot conditions as high-strength materials such as mechanical parts and structural materials, the modulus of elasticity in hot conditions is an extremely important property for estimating mechanical strength, thermal shock resistance, etc. .

As a prior art, the title of the invention is ``Hot Displacement Measuring Device for Ceramics, etc.'' (Japanese Unexamined Patent Publication No. 7452/1983).
There are also resonance methods, ultrasonic pulse methods, etc. The bending resonance method is easily affected by the natural vibration of the vibration transmission mechanism, and the ultrasonic pulse method has a problem in that the vibrator has low heat resistance and cannot measure high temperatures. Among these, a conventional example of a hot elastic modulus measuring device described in Embodiment 4 of ``Hot Displacement Measuring Device for Ceramics, etc.'' in Japanese Patent Application Laid-Open No. 617452 will be described.

Fig. 9 is a diagram schematically showing a conventional hot elastic modulus measuring device for ceramics, etc., Fig. 10 is a front cross-sectional view of the pressure furnace part and load loading device, and Fig. 11 is a diagram showing the conventional device. It is a figure showing the displacement measurement position of.

In addition, in the figure, 1 is the sample, 2 is the pressure furnace, 3 is the sample support stand, and 4
5 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-bearing 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, 2
7 is a digital plotter, 28 is a printer, 30 is an oscilloscope, and 33 is a silicon carbide heating element.

This hot elastic modulus measuring device is designed to place a sample 1 (width 10 mm x thickness 2.5 mm x length 60 mm) on two support rolls 4 provided on an alumina sample support 3 in a heating furnace 2. Then, from a loading device 12 installed outside the furnace 2, a load equivalent to 50 to 70% of the fracture strength of the sample 1 was applied via a pressure rod 8 every 100°C up to 1500°C using a three-point bending method. load.

At that time, point A, which is directly below the load application point of sample 1, and point B, which is closest to the contact point between the support roll and sample 1, are illuminated by illumination device 24, and solid-state scanning light reception is placed outside the furnace opposite to illumination device 24. Working distance 460mmF with built-in camera 5
Telephoto lens 6 with number 8 and infrared range 0.8 μm to 1000
Using a filter 7 that removes light with a wavelength of μm, the dark area where the light is blocked by the sample 1 and the bright area where the light can directly reach are enlarged and projected onto the solid-state scanning photoreceptor surface using a telephoto lens 6. While measuring the displacement, bright areas and dark areas are displayed on the oscilloscope 30. Then, a digital signal corresponding to the displacement is outputted from the camera controller 25, and this output signal and the digital signal from the digital thermometer 23 are inputted to the personal computer 20 via the interface 26, and stored and calculated, and the result is sent to the printer 28. At the same time, the digital plotter 27 is used to draw 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.

[Problem that the invention seeks to solve]

As described above, the conventional method of measuring elastic modulus using a hot displacement measuring device for ceramics or the like has a problem in that samples that are easily oxidized cannot be measured because the heating furnace is in an atmospheric atmosphere. Originally, it is desirable for this type of device to be able to perform measurements in various atmospheres, including oxidizing and non-oxidizing atmospheres, but there are restrictions depending on the type of heating element, etc. - For boat fishing, it is limited to either oxidizing or non-oxidizing atmospheres. The reality is that this is the case.

To prevent oxidation of the sample, it is necessary to make the heating furnace airtight and create an atmosphere of inert gas or the like.

However, in this case, as shown in FIGS. 12 and 13, since an O-ring 34 or a metal alloy 11 is used for the seal between the heating furnace 2 and the pressure rod 8, the resistance when the pressure rod 8 is moved is reduced. As a result, the load application accuracy is significantly reduced. In order to measure the elastic modulus of small samples such as fine ceramics using the bending/deflection method, the load application accuracy must be less than Igf, and with the conventional seal structure, the mechanical resistance due to the movement of the pressure rod 8 is large and it is not practical. . In addition, some fine ceramics are very easily oxidized at high temperatures of 1000°C or higher, and even if the heating furnace 2 is made airtight and a 99.999% pure inert gas is flowed, the May be oxidized by trace amounts of oxygen.

On the other hand, when measuring the bending deflection of the sample 1 in FIG. 9 using the camera 5 with a built-in solid-state scanning light-receiving element, there is a problem in that when the temperature rises, a fluctuation phenomenon occurs in the sample image due to the convection of the atmospheric gas, and the measured values vary. In other words, the deflection displacement of the sample 1 is determined by applying a load to the center of the sample 1 set on the support roll 4, and measuring the displacement of the edge of the sample directly below the load point using the camera 5 with a built-in solid-state scanning photodetector as shown in FIG. They were measuring a range like C.

However, in this method, when measuring with the camera 5 with a built-in solid-state scanning photodetector, the measurement space between the bottom surface of the sample 1 and the sample support 3 is large, so fluctuations occur in the atmospheric gas at the part C in Figure 11 in the high temperature range. This caused a decrease in displacement measurement accuracy.

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

The present invention is intended to solve the above-mentioned problems.The present invention is based on the Fine Ceramic NOX, which can accurately and fully automatically measure the deflection displacement of a sample without the influence of fluctuations, regardless of oxidizing or non-oxidizing atmosphere. The purpose of the present invention is to provide a hot elastic modulus measuring device such as the following.

[Means for solving problems]

The hot elastic modulus measurement device for ceramics, etc. of the present invention has a lighting device facing a window on one side of a sample heating furnace, and a detection device facing the window on the opposite side. In the elastic modulus measuring device, a non-resistance sealing mechanism that expands and contracts in conjunction with the pressurizing rod is installed between the sample heating furnace and the pressurizing rod of the load loading device, and the displacement measurement space between the sample and the sample support is connected to the sample displacement. It is characterized by being narrowed to a certain extent.

[Effect]

The hot elastic modulus measuring device for fine ceramics, etc. of the present invention is equipped with a heating furnace that has a non-resistance pressure rod sealing mechanism and can adjust various atmospheres in a high-precision load-applying device controlled by a coscipulator. Displacement can be measured accurately without contact using a sample support stand that eliminates the effects of fluctuation, and the hot elastic modulus of fine ceramics, etc. can be measured. Furthermore, by adding an automatic temperature control device, it becomes possible to measure the hot elastic modulus of fine ceramics etc. fully automatically.

〔Example〕

Examples will be described below with reference to the drawings.

Fig. 1 shows an embodiment of the apparatus for measuring the hot elastic modulus of ceramics, etc. according to the present invention, and Fig. 2 shows the centrifugal conditions of the heating furnace, the sealing part of the pressure rod, and the sample support stand of the apparatus of the present invention. Figure 3 is a plan view of the sample support stand of the present invention, Figure 4 is a diagram showing the displacement measurement range of the device of the present invention, and Figure 5 is its A.
-A sectional view, FIGS. 6 and 7 are diagrams showing an oxidation-preventing graphite cover, and FIG. 8 is a diagram showing an example of measurement results by the apparatus of the present invention. In the figure, the same numbers as in FIGS. 11 and 12 indicate the same contents, and 9 is a silicone rubber disk, 10 is
11 is a metal bellows, 13 is a crosshead, 14 is a connecting iron, 15 is a load detector, 16 is an edge, 17 is a sample cover, 18 is a measurement lighting window, 19 is a ring, 21 is a load control device, 22 is a thermocouple, 29 is a vacuum device, 31 is a temperature control type, 32 is a Cyrisk power control device,
33 is an O-ring, and 35 is a hole.

The heating furnace 2
A metal bellows 11 is attached to the pressure rod insertion portion of the pressure rod 8, and a silicone rubber disc 9 is airtightly fixed to the pressure rod 8 with a fixing hardware 10 on top of the metal bellows 11. 4 connecting rods 14 to crosshead 13
Connect with the upper part of the metal rose 11 and the cross head 13
By making the movements of the metal bellows 11 exactly the same,
The structure is such that the force required for expansion and contraction is not detected as a load by the load detector 15 attached to the crosshead 13.

The difference in movement between the pressure rod 8 and the metal bellows 11 is that the strain in the strain gauge part of the load detector 15 is several microns, and therefore the strain in the silicone rubber disc 9 is also very small, several microns. is not detected as a load. Thereby, the heating furnace 2 can be made into a completely airtight structure without reducing the accuracy of the load applied to the sample 1, and measurements can be performed with high accuracy under various atmospheres.

Further, as shown in FIG. 4, the present invention reduces the measurement space between the lower surface of the sample 1 and the upper end of the sample support 3, for example, by reducing the deflection of the sample to 2 m/m or less, thereby improving the flow of atmospheric gas. , suppresses convection and suppresses the occurrence of fluctuations. Furthermore, as shown in FIG. 5, by providing a displacement measurement edge 16 on the upper part of the sample support 3, the displacement measurement accuracy can be further improved. Note that this method can be applied not only to displacement measurement using the camera 5 with a built-in fixed scanning light receiving element, but also to other non-contact displacement measurement devices.

In addition, as a method for preventing oxidation of materials that are particularly susceptible to oxidation at high temperatures and cannot be measured in a general inert gas atmosphere, it is effective to cover the sample support stand 3 together with the sample 1 with a sample cover 17 made of graphite, which is more active than the sample. It is.

As shown in FIG. 6, the sample cover 17 of the present invention has a hole 35 in the upper part 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 come into contact with the pressure rod 8. Alternatively, a large gap (difference in hole diameter) between the pressure rod 8 and the sample cover 17 may be made, and the seventh
As shown in the figure, a ring 19 with a small difference in hole diameter from the pressure rod 8
1 to prevent inert gas from entering and exiting the heating furnace inside the sample cover, preventing oxidation of the sample 1, and preventing load errors due to contact between the sample cover 17 and the pressure rod 8. can.

Next, the measurement of elastic modulus using the apparatus of the present invention will be explained.

When the sample 1 is placed on the support roll 4 of the sample support stand 3 disposed in the heating furnace 2 and the measurement conditions are input into the personal computer 20, the computer 20 displays the temperature controller 3.
A setting signal is sent to the silicon carbide heating element 3 from the SiRisk power control device 32 in response to a signal from the temperature controller 31.
Electric power is sent to Furnace 3 to raise the temperature of Furnace 2. The sample temperature at this time is detected by a thermocouple 22 set near the sample 1, and is manually input to the personal computer 20 as a BCD output signal from a digital thermometer 23. When the temperature of the sample 1 reaches a preset temperature, it is maintained at that temperature for a certain period of time, and then a load signal is sent to the load application device 12 via the personal computer 20 and the load control device 21, and the sample 1 is pressurized. A load is applied via the rod 8. At this time, the gap between the bending point of the sample 1 and the edge 16 provided on the sample support stand 3 is
The displacement of the sample 1 is obtained by measuring using the camera 5 with a built-in solid-state scanning light-receiving element and the illumination device 24 disposed opposite the camera 5. This measurement is performed by enlarging and projecting the dark area where the light from the illumination device is blocked by the sample 1 and the bright area to which the light directly reaches onto the surface of the solid-state scanning light-receiving element using the telephoto lens 6.

The signal from the camera 5 with a built-in solid-state 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 combined into a personal computer using a program created using a general method.
The information is inputted to the personal computer 20 via the interface 26, and calculations are performed based on the relationship between stress and the amount of deflection, and the relationship between temperature and elastic modulus is written using the digital output signal 27 and printer 28.

In addition, in this device, if the sample support roll 4 is deformed,
To avoid displacement measurement errors, the displacement of the contact point between the sample 1 and the sample support roll 4 may be measured and corrected using another illumination device and a camera with a built-in fixed scanning light receiving element (not shown). It is possible.

Additionally, as a method for preventing oxidation of materials that are particularly susceptible to oxidation at high temperatures and cannot be measured in a general inert gas atmosphere, it is effective to cover the sample support stand 3 with a sample cover 17 made of graphite, which is more active than the sample. It is.

As shown in FIG. 6, the sample cover 17 of the present invention has a hole 35 in the upper part 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 come into contact with the pressure rod 8. Alternatively, a large gap (difference in hole diameter) between the pressure rod 8 and the sample cover 17 may be made, and the seventh
As shown in the figure, a ring 19 with a small difference in hole diameter from the pressure rod 8
is installed in the sample cover to prevent inert gas from entering and exiting the heating furnace, preventing oxidation of sample 1, and
It is possible to eliminate load loading errors caused by contact between the pressure rod 7 and the pressure rod 8.

A measurement example of the apparatus for measuring hot elastic modulus of ceramics, etc. of the present invention will be explained below.

A silicon carbide sample with a width of 5.0 mm is placed on the support roll 4 of the support stand in the heating furnace 2 of the apparatus of the present invention shown in FIGS. 1 and 2.
mm, thickness 1.0 mm, and length 75 mm with a support roll gap of 60 mm, cover the graphite cover 17 on the support stand 3, evacuate the inside of the heating furnace at room temperature with the vacuum device 29, and evacuate it with argon. Replace with gas. While flowing argon gas at 200ml/min, the temperature was raised at a rate of 10°C/min.
After reaching a predetermined temperature, the temperature was maintained for 10 minutes.

After the holding time has elapsed, a signal is sent from the personal computer 20 to the load loading device 12, and 5
A load up to 00 g was applied three times each.

The deflection displacement of the sample under each load at this time is the working distance of 460
mm, telephoto lens 6 with F number 8 and 0.8 μm in the infrared range
Using a filter 7 that removes light with a wavelength of ~1000 μm and a camera 5 with a built-in solid-state scanning light receiving element, the positions shown in the fourth diagram were measured. Measurements are made at 140 degrees at intervals of 100 degrees from room temperature.
The elastic modulus was determined from the load-displacement data obtained by the following calculation formula. The results are shown in FIG.

Note that the elastic modulus can be determined using the following equation.

4, wt"y E-Modulus of elasticity (Kgf/mm") l-Distance between support rolls (mm) P-Load (Kgf) W-Sample width (mm) -Sample thickness (mm) y- (Displacement amount of load point Cmm) [Effect of the invention] As described above, according to the present invention, a non-resistance airtight mechanism is provided between the pressure rod of the computer-controlled high-precision loading device and the heating furnace, and measurement with the sample is performed. By using a sample support stand with a reduced space, the hot elastic modulus of the sample can be measured with high accuracy regardless of whether it is an oxygen atmosphere or an oxygen-free atmosphere, and without the influence of fluctuations due to atmospheric gas circulation or convection. Also,
By covering the sample support stand with the sample cover made of graphite, which is more active than the sample, oxidation of the sample due to atmospheric gas can be further prevented. Furthermore, by adding an automatic temperature control device, it becomes possible to measure the hot elastic modulus fully automatically.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of the apparatus for measuring the hot elastic modulus of ceramics, etc. according to the present invention, and Fig. 2 is a diagram showing the state of the heating furnace, the sealing part of the pressure rod, and the sample support stand of the apparatus of the present invention. 3 is a plan view of the sample support of the present invention, FIG. 4 is a diagram showing the displacement measurement range of the device of the present invention, FIG. 5 is a side sectional view thereof, and FIGS. FIG. 7 is a diagram showing an oxidation-preventing 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, etc. , FIG. 10 is a front cross-sectional view of the heating furnace part and load-bearing device of the apparatus shown in FIG. 9, and FIG.
Figure 12 shows an example of a method that uses an O-ring to seal the heating furnace and pressure rod, and Figure 13 shows an example of a method that uses a metal rosette. FIG. 1... Sample, 2... Heating furnace, 3... Sample support stand,
4... Support roll, 5... Camera with built-in solid-state scanning light receiving element, 6... Telephoto lens, 7... Filter, 8...
... Pressure rod, 9 ... Silicone rubber disc, Work 0 ... Fixed hardware, 11 ... Metal bellows, 12 ... Loading device, 13 ... Cross head, 14 ... Connection rond , 15... Load detector, 16... Edge, 17...
- Sample cover, 18... Measurement lighting window, 19... Ring, 20... Personal computer, 21... Load control device, 22... Thermocouple, 23... Digital thermometer, 24... ...Lighting device, 25 camera controller,
2G...Personal computer interface,
27...Digital plotter, 28...Printer, 2
9... Vacuum device, 30... Oscilloscope, 31.
...Temperature regulator, Cyrisk, 32... Cyrisk power control device, 33...Silicon carbide heating element, 34...0
Ring, 35...hole. Applicant Director of the Agency of Industrial Science and Technology Figure 10 Figure 12

Claims (5)

[Claims] (1) In an apparatus for measuring hot elastic modulus of ceramics, etc., which has a lighting device facing a window on one side of the sample heating furnace and a detection device facing the window on the opposite side, the sample heating furnace and the load Ceramics, etc., characterized in that a non-resistance sealing mechanism that expands and contracts in conjunction with the pressure rods is provided between the pressure rods of the loading device, and the displacement measurement space between the sample and the sample support is narrowed to the extent of the sample displacement. hot elastic modulus measuring device. (2) The non-resistance sealing mechanism is characterized in that the upper end of the metal bellows attached to the heating furnace is connected to a load loading device member, and the pressure rod and the upper end of the metal bellows are connected by a rubber disk. A device for measuring hot elastic modulus of ceramics, etc., according to item 1. (3) The apparatus for measuring the hot elastic modulus of ceramics or the like as set forth in claim 1, wherein a displacement measuring edge is provided on the sample support stand. (4) The apparatus for measuring hot elastic modulus of ceramics or the like according to claim 1, wherein an oxidation-resistant sample cover that is more active than the sample is disposed on the sample support stand. (5) The apparatus for measuring hot elastic modulus of ceramics or the like according to claim 1, wherein the sample heating furnace is equipped with a temperature control device.