JP6774861B2 - Strain resistance film and strain sensor for high temperature, and their manufacturing method - Google Patents

Description

The present invention relates to a strain resistance film having excellent properties at high temperatures, a strain sensor for high temperature using such a strain resistance film, and a method for manufacturing the same.

The strain sensor utilizes a phenomenon in which the electrical resistance of a thin film, fine wire, or foil-shaped sensor material changes due to elastic strain, and is used for measuring and converting strain and stress by measuring the resistance change.

The sensitivity of the strain sensor is determined by the gauge factor K, and the value of K is generally given by the following equation (1).
K = (ΔR / R) / (Δl / l) = 1 + 2σ + (Δρ / ρ) / (Δl / l) (1)
Here, R, σ, and ρ are the total resistance, Poisson's ratio, and specific electrical resistance of the thin film, thin wire, or foil that is the sensor material, respectively. Further, l is the total length of the object to be measured, and Δl / l represents the strain generated in the object to be measured. In general, since σ in metals and alloys is approximately 0.3, the sum of the first term and the second term on the right side in the above equation is about 1.6, which is a substantially constant value. Therefore, in order to increase the gauge ratio, it is an essential condition that the third term in the above equation is large. That is, when the material is subjected to tensile deformation, the electronic structure in the length direction of the material changes significantly, and the amount of change in specific electrical resistance Δρ / ρ increases.

Therefore, in recent years, attention has been paid to chromium (Cr), which has been reported to have a very large bulk gauge ratio of 26 to 28. Although Cr is very difficult to process, it can be applied to a strain sensor by thinning it without processing, and even if Cr is thinned, the gauge ratio is still large at about 15, so the Cr thin film can be used as a strain sensor. It is attracting attention (for example, Patent Document 1).

On the other hand, in recent years, sensing of various dynamic quantities with high gauge ratio and high sensitivity in the high temperature range of 200 to 700 ° C, such as internal combustion engine related to automobiles and aircraft, injection molding, geothermal power generation, oil field development, turbine related to thermal power generation, etc. It is strongly requested.

Patent Documents 2 and 3 disclose a technique for sensing a mechanical quantity at such a high temperature by using a Cr-based thin film.

Japanese Unexamined Patent Publication No. 61-256233 Japanese Unexamined Patent Publication No. 2005-69685 Japanese Unexamined Patent Publication No. 2012-207985

By the way, even in strain gauges used in a high temperature region, a gauge ratio having a practical size of 3 or more is required, but in the above Patent Documents 2 and 3, the gauge ratio at a high temperature is not measured. It is unknown.

The present invention has been made in view of such circumstances, and a strain resistance film exhibiting a high gauge ratio in a predetermined high temperature region, a method for producing the same, and a strain for high temperature using such a strain resistance film. An object of the present invention is to provide a sensor and a method for manufacturing the same.

The present inventor first uses a Cr thin film as a strain resistance film and heat-treats it in the air at a temperature 50 ° C. or higher higher than the upper limit of the operating temperature range at a predetermined high temperature for a predetermined time at that high temperature. We have found that a practical gauge ratio can be obtained in the operating temperature range of (Japanese Patent Application No. 2016-169410).

However, such a Cr thin film has a gauge ratio value of about 14 at 100 ° C., but the gauge ratio decreases when the temperature exceeds 100 ° C., about 6 when the temperature exceeds 250 ° C., and 4 when the temperature exceeds 350 ° C. It drops to a degree. Although this value can be put to practical use, it is considerably smaller than the gauge ratio at room temperature to 100 ° C. Therefore, in order to find a material that exhibits a larger gauge ratio at high temperatures, a Cr-based thin film in which other elements are added to Cr was examined.

As a result, it was found that by using Mn or Al as an element to be added to Cr and adjusting the amount appropriately, a gauge ratio of 6 or more, which is higher than that of the Cr thin film, can be stably obtained at 250 to 500 ° C. ..

The present invention has been made based on such findings, and provides the following (1) to (16).

(1) General formula Cr _100-x Mn _x
(However, x is an atomic ratio (at.%), 0.1 ≦ x ≦ 34), and the operating temperature range is 250 ° C. or higher and 500 ° C. or lower, and the gauge is in the operating temperature range. A strain resistance film having a ratio of 6 or more.

(2) General formula Cr _100-x Al _x
(However, x is an atomic ratio (at.%), Which is 4 ≦ x ≦ 25), and the operating temperature range is 250 ° C. or higher and 500 ° C. or lower, and the gauge ratio is high in the operating temperature range. A strain resistance film having a temperature of 6 or more.

(3) The description according to (1) or (2), wherein the operating temperature range is 250 ° C. or higher and 450 ° C. or lower, and the stability of the resistance value is within ± 0.2% in the operating temperature range. Strain resistance film.

(4) The strain resistance film according to (3), wherein the operating temperature range is 250 ° C. or higher and 400 ° C. or lower, and the stability of the resistance value is within ± 0.02% in the operating temperature range. ..

(5) General formula Cr _100-x Mn _x
(However, x is an atomic ratio (at.%), And 0.1 ≦ x ≦ 34), and forms a thin film, which is 50 than the upper limit temperature used in the range of 250 ° C. or higher and 500 ° C. or lower. A strain resistance film having a gauge ratio of 6 or more in a temperature range of 250 ° C. or higher and 500 ° C. or lower by heat treatment in the air at a temperature higher than ° C. for 30 minutes or longer and 4 hours or lower. Manufacturing method.

(6) General formula Cr _100-x Al _x
(However, x is an atomic ratio (at.%), And 4 ≦ x ≦ 25.) A thin film is formed, and the temperature is 50 ° C. or higher than the upper limit temperature used in the range of 250 ° C. or higher and 500 ° C. or lower. Manufacture of a strain resistance film having a gauge ratio of 6 or more in a temperature range of 250 ° C. or more and 500 ° C. or less by performing a heat treatment at a high temperature in the atmosphere for 30 minutes or more and 4 hours or less. Method.

(7) Heat treatment is performed in the atmosphere for 30 minutes or more and 4 hours or less at a temperature 50 ° C or more higher than the upper limit temperature used in the range of 250 ° C or more and 450 ° C or less, and the resistance value is in the range of 250 ° C or more and 450 ° C or less. The method for producing a strain resistance film according to (5) or (6), wherein the stability of the strain resistance film is within ± 0.2%.

(8) Heat treatment is performed in the atmosphere for 30 minutes or more and 4 hours or less at a temperature 50 ° C or more higher than the upper limit temperature used in the range of 250 ° C or more and 400 ° C or less, and the resistance value is in the range of 250 ° C or more and 400 ° C or less. The method for producing a strain resistance film according to (7), wherein the stability of the strain resistance film is within ± 0.02%.

(9) General formula Cr _100-x Mn _x
(However, x is an atomic ratio (at.%), And 0.1 ≦ x ≦ 34), and the operating temperature range is 250 ° C. or higher and 500 ° C. or lower. A strain sensor for high temperature characterized in that a strain resistance film having a gauge ratio of 6 or more is formed on a strain generating structure in a temperature range.

(10) General formula Cr _100-x Al _x
(However, x is an atomic ratio (at.%), And 4 ≦ x ≦ 25), and the working temperature range is 250 ° C. or higher and 500 ° C. or lower. A high temperature strain sensor characterized in that a strain resistance film having a gauge ratio of 6 or more is formed on a strain generating structure.

(11) The operating temperature range is 250 ° C. or higher and 450 ° C. or lower, and the resistance stability of the strain resistance film in the operating temperature range is within ± 0.2% (9) or (10). Distortion sensor for high temperature described in.

(12) The high temperature according to (11), wherein the operating temperature range is 250 ° C. or higher and 400 ° C. or lower, and the resistance stability of the strain resistance film in the operating temperature range is within ± 0.02%. Distortion sensor for.

(13) General formula Cr _100-x Mn _x
(However, x is an atomic ratio (at.%), And 0.1 ≦ x ≦ 34) is formed on the strain-causing structure and used in the range of 250 ° C. or higher and 500 ° C. or lower. Heat treatment is performed in the air for 30 minutes or more and 4 hours or less at a temperature higher than the upper limit temperature of 50 ° C. or more to obtain a strain resistance film having a gauge ratio of 6 or more in a temperature range of 250 ° C. or more and 500 ° C. or less. A method for manufacturing a high-temperature strain sensor, which comprises using it to manufacture a high-temperature strain sensor.

(14) General formula Cr _100-x Al _x
(However, x is an atomic ratio (at.%), And 4 ≦ x ≦ 25.) A thin film represented by is formed on the strain-causing structure, and the upper limit of use in the range of 250 ° C. or higher and 500 ° C. or lower. A strain resistance film having a gauge ratio of 6 or more in a temperature range of 250 ° C. or higher and 500 ° C. or lower is obtained by heat treatment in the air at a temperature higher than the temperature of 50 ° C. or higher for 30 minutes or longer and 4 hours or shorter. A method for manufacturing a high temperature strain sensor, which comprises manufacturing a high temperature strain sensor.

(15) The operating temperature range is 250 ° C. or higher and 450 ° C. or lower, and the resistance stability of the strain resistance film in the operating temperature range is within ± 0.2% (13) or (14). The method for manufacturing a strain sensor for high temperature described in 1.

(16) The high temperature according to (15), wherein the operating temperature range is 250 ° C. or higher and 400 ° C. or lower, and the resistance stability of the strain resistance film in the operating temperature range is within ± 0.02%. Manufacturing method of strain sensor for.

According to the present invention, there is provided a strain resistance film capable of stably obtaining a high gauge ratio in a high temperature region and a method for manufacturing the same, and a strain sensor for high temperature using such a strain resistance film and a method for manufacturing the same. ..

It is a figure which shows the relationship between the amount of element X added to Cr, and the Néel temperature. It is a figure which shows the relationship between the amount of element X added to Cr, and the Néel temperature. It is a figure which shows the relationship between the addition amount of Al of Cr—Al alloy and the Néel temperature. It is a figure which shows the relationship between the addition amount of Mn of a Cr—Mn alloy, and the Néel temperature. It is a schematic block diagram which shows the electric resistance measuring apparatus which applied high temperature strain. It is a figure which shows the bending test sequence. It is a figure which shows the relationship between the measurement temperature of a Cr thin film (sample A), and the gauge ratio. Cr thin film (Sample A) and Cr-3.0 at. It is a figure which shows the relationship between the measurement temperature of% Mn thin film (sample B), and the gauge ratio. Cr thin film (Sample A) and Cr-14.1 at. It is a figure which shows the relationship between the measurement temperature of% Al thin film (sample C), and the gauge ratio. It is a figure which shows the value of the gauge ratio and resistance with respect to the measurement temperature of a Cr thin film (sample A). Cr-3.0 at. It is a figure which shows the value of the gauge ratio and resistance with respect to the measurement temperature of a% Mn thin film (sample B). Cr-14.1 at. It is a figure which shows the temperature change of the gauge ratio and resistance with respect to the measurement temperature of a% Al thin film (sample C). Cr-3.0 at. It is a figure which shows the resistance change rate (ΔR / R ₀ ) of% Mn thin film (sample B). Cr-14.1 at. It is a figure which shows the resistance change rate (ΔR / R ₀ ) of% Al thin film (sample C). A comparative example of Cr-4.4 at. It is a figure which shows the relationship between the measurement temperature and the value of resistance in% Ni thin film, and the figure which shows the relationship between the measurement temperature and a gauge ratio.

Hereinafter, embodiments of the present invention will be described in detail.
In a Cr-based thin film, in general, its electric resistance changes with a positive gradient with respect to a temperature change like a normal metal over a wide temperature range, but the Néel temperature related to the antiferromagnetism of Cr. It is known to take a minimum value in. That is, in the temperature range below the Néel temperature near the Néel temperature, the inclination of the electric resistance becomes negative or the inclination decreases to reach the minimum point Néel temperature, and in the temperature range above the Néel temperature, the inclination becomes positive again. Shows the behavior of increasing electrical resistance. Therefore, as a result of actually investigating the temperature dependence of the resistance values of various Cr-based thin films, a minimum value considered to be the Néel temperature was found in the temperature change of the electrical resistance.

On the other hand, in the past literature (E. Fawcett et al .: "Spin-density-wave antiferromagnetism in chromium alloys", Rev. Mod. Phys., 66 (1), (1994).), Elements added to Cr The relationship between the amount of X and the nail temperature is shown. The relationship between the amount of the additive element X and the Néel temperature actually shown on pages 40 and 39 is shown in FIGS. 1 and 2. As shown in these, while the Neel temperature of Cr is about 300K (127 ° C.), by adding Al, Mn, Pt, Re, Ru, Rh, Os, Ir, Ga, and Ge to Cr, It can be seen that the nail temperature rises according to the amount added.

Among these, it was confirmed that the elements other than Mn and Al can raise the Néel temperature up to about 300 ° C, whereas Mn and Al can raise the Néel temperature up to a temperature exceeding 500 ° C. ..

The magnetic phase diagram of the Cr—Al alloy, that is, the relationship between the amount of Al added and the Néel temperature is shown on page 48 of the above document, and the figure is shown in FIG. From FIG. 3, it can be seen that the Néel temperature rises to about 25 at% of the amount of Al added to Cr, and the maximum temperature is about 800 K, that is, about 530 ° C.

The relationship between the amount of Mn added and the Néel temperature is shown on page 85 of the above document, and the figure is shown in FIG. In this figure, 1 to 20 have different amounts of Mn added, and 1 is Mn: 0 at. % 2 is Mn: 0.1 at. % 3 is Mn: 0.2 at. %, ... 8 is Mn: 0.7 at. %, 9 is 1.0 at. %, ... 16 is Mn: 6.0 at. %, ... 19 is Mn: 30 at. %, 20 is Mn: 34 at. %. As shown in this figure, the amount of Mn added is 34 at. It can be seen that the Néel temperature rises uniformly up to%, and its maximum temperature is about 780 K, or about 510 ° C.

On the other hand, as a result of measuring the gauge ratio at a high temperature as described later, it was confirmed that in most cases, the gauge ratio peak appears on the immediately low temperature side of the Néel temperature in the Cr-based thin film. In the case of the above-mentioned Cr-Mn thin film and Cr-Al thin film having a high Néel temperature, the peak of the gauge ratio or the base of the slope on the high temperature side of the peak becomes the high temperature side with the Néel temperature as the amount of Mn or Al component increases. The behavior of shifting to was observed.

From this, it was found that the Cr-Mn thin film and the Cr-Al thin film show a large gauge ratio in the high temperature region as the Néel temperature increases to follow the amount of Mn and Al.

Then, in the case of the Cr—Al alloy, as shown in FIG. 3, Al is 4 at. If it is less than%, the Néel temperature decreases, and 4 to 25 at. The Néel temperature increased in%, and in the case of the Cr—Mn alloy, Mn was 0.1 to 34 at. As shown in FIG. Since the Néel temperature rises in%, the amount of Al in the Cr—Al thin film is 4 to 25 at. In the Cr-Mn thin film in the range of%, the amount of Mn is 0.1 to 34 at. In the% range, it was found that a high gauge ratio of 6 or more was stably exhibited in the high temperature region of 250 to 500 ° C.

As described above, the Cr-Mn thin film and the Cr-Al thin film in the above composition range have good characteristics as resistance thin films used for high temperature strain sensors. Further, by using such a resistance thin film as a strain material, a practical strain sensor for high temperature can be obtained.

Further, the resistance thin film made of the Cr—Mn thin film or the Cr—Al thin film exhibits a characteristic that the stability of the resistance value is within ± 0.2% in addition to the above characteristics in the range of 250 ° C. or higher and 450 ° C. or lower. Further, in the range of 250 ° C. or higher and 400 ° C. or lower, the stability of the resistance value is within ± 0.02%, which is more excellent resistance stability.

Next, a device and a method for measuring the gauge ratio at high temperature will be described.
As described above, the present invention provides a resistance thin film and a strain sensor having a high gauge ratio in a high temperature region, and it is necessary to grasp the gauge ratio at a high temperature. The measurement method has not been established.

Therefore, as a result of various studies on a device and a method capable of measuring the gauge ratio at a high temperature, the high temperature strain applied electric resistance measuring device shown in FIG. 5 was conceived.

The device of FIG. 5 has an electric oven 1 having a temperature control function capable of heating to around 1000 ° C. in the atmosphere, and a window 2 is formed above the electric oven 1. The window 2 is closed by a lid member 3, and a support rod 4 extending downward toward the inside of the electric oven 1 is fixed to the lid member 3. The support rod 4 supports the measuring table 5 in the electric oven 1.

A fixing member 6 is provided on the measuring table 5, and a sample 20 in which a Cr-based thin film 8 having a predetermined pattern is formed on the substrate 7 by high-frequency sputtering or the like is fixed to the fixing member 6 with a cantilever. There is. The measuring table 5 has a box shape, and a terminal block 10 having a terminal 11 inside is provided. The Cr-based thin film 8 and the terminal 11 are connected by a bonding wire 9.

A heat-resistant wiring cable (not shown) is connected to the terminal 11. The heat-resistant wiring cable is pulled out through the window 2 and connected to the measurement system (DMM) 14. The power supply 15 is also connected by a heat-resistant wiring cable.

A micrometer 12 is fixed to the lid member 3, and a strain applying push rod 13 extends downward from the micrometer 12 so as to come into contact with the vicinity of the free end of the sample 20. As a result, the strain applying push rod 13 can be lowered by a predetermined length by the micrometer 12 to apply a predetermined strain to the sample 20.

When measuring the gauge ratio at a high temperature with such a high temperature strain application electric resistance measuring device, the temperature inside the electric oven 1 is set to a predetermined temperature up to about 800 ° C., and the micrometer 12 is measured from the outside of the electric oven 1. By operating the strain applying push rod 13, a predetermined strain is applied to the sample 20 and the resistance of the strain resistance film is measured. Such an operation is performed at each temperature, and the resistance change rate obtained at each temperature is calibrated with a gauge rate separately measured at 100 ° C. to obtain a gauge rate at a high temperature. As a result, the gauge rate at high temperature can be accurately obtained.

Next, a method for manufacturing the strain resistance film and the strain sensor of the present invention will be described.
In the present invention, after the above-mentioned Cr—Mn thin film or Cr—Al thin film is formed as a strain resistance film on the substrate, the temperature is 50 ° C. or higher higher than the upper limit of the operating temperature range at 250 ° C. or higher and 500 ° C. or lower in the atmosphere. Heat treatment is performed for 30 minutes or more and 4 hours or less. For example, when the upper limit of the operating temperature range is 300 ° C., such heat treatment is performed at a temperature of 350 ° C. or higher.

As a result, as described above, it is possible to manufacture a strain resistance film that stably exhibits a high gauge ratio of 6 or more in the range of use of 250 ° C. or higher and 500 ° C. or lower. Further, the strain resistance film produced in this manner has a stable resistance value within ± 0.2% in addition to the above characteristics in a range of 450 ° C. or lower, and a stable resistance value in a range of 400 ° C. or lower. It shows good resistance stability with properties within ± 0.02%.

Then, by using such a strain resistance film, a strain sensor for high temperature can be manufactured.

In the present invention, as the base material (distortion-causing structure) for forming the Cr—Mn thin film and the Cr—Al thin film constituting the strain resistance film, alumina, which is an insulating ceramic having good heat resistance, is preferably used. Can be done. Further, not limited to alumina, various other ceramics can also be used. Further, as the base material, various metal plates such as stainless steel (SUS) coated with an insulating coating can also be used. Further, the method for forming the Cr—Mn thin film and the Cr—Al thin film constituting the strain resistance film is not particularly limited, but sputtering, particularly high frequency sputtering is preferable. As the high-frequency sputtering apparatus, a magnetron type apparatus is preferable. The gas pressure during high-frequency sputtering is preferably 16 mTorr (2.13 Pa) or less, for example, 5 mTorr (0.67 Pa). As the pattern of the Cr-based thin film used as the strain resistance film, a pattern usually used as a strain sensor may be used, and for example, a grid pattern can be used. The target used for high-frequency sputtering may be a composite target in which a predetermined number of Mn or Al chips are attached to a high-purity Cr disk, but an alloy target prepared in advance to Cr-Mn or Cr-Al having a predetermined composition may be used. You may use it.

Hereinafter, examples of the present invention will be described.
Here, first, sample A in which a Cr thin film having a lattice pattern was formed as a comparative material was prepared as a comparative material on an alumina substrate as a base material (distortion structure) by high-frequency sputtering. Then, the sample was heat-treated in the air at 500 ° C. for 0.5 hours by the apparatus of FIG. 5, and then the gauge ratio in the temperature range up to 450 ° C. was measured by the apparatus of FIG.

When measuring the gauge ratio, the sample is set at a predetermined position on the measuring table, and the sample is held at each temperature by operating the strain applying push rod with the micrometer of the device of FIG. A bending test was performed in which a strain of about 0.05% was applied in the sequence, and resistance was measured at each temperature up to 450 ° C. The resistance change rate obtained at each temperature was calibrated with a gauge rate separately measured at 100 ° C., and the gauge rate at each temperature was obtained.

The result is shown in FIG. As shown in this figure, it was confirmed that the gauge ratio was 3 or more and the temperature change of the gauge ratio was small at 350 ° C. or higher and 450 ° C. or lower.

Next, on an alumina substrate as a base material (distortion structure), high-frequency sputtering was performed to obtain Cr-3.0 at. Sample B on which a% Mn thin film was formed and Cr-14.1 at. Sample C on which a% Al thin film was formed was prepared. Then, the sample was heat-treated in the air at 500 ° C. for 0.5 hours by the apparatus of FIG. 5, and then the gauge ratio in the temperature range up to 450 ° C. was measured by the apparatus of FIG.

When measuring the gauge ratio, the sample is set at a predetermined position on the measuring table, and the sample is held at each temperature by operating the strain applying push rod with the micrometer of the device of FIG. A bending test was performed in which a strain of about 0.05% was applied in the sequence, and resistance was measured at each temperature up to 450 ° C. The resistance change rate obtained at each temperature was calibrated with a gauge rate separately measured at 100 ° C., and the gauge rate at each temperature was obtained.

The results are shown in FIGS. 8 and 9. FIG. 8 shows Sample A on which a Cr thin film was formed and Cr-3.0 at. The results of Sample B on which a% Mn thin film was formed are compared. FIG. 9 shows Sample A and Cr-14.1 at. The results of Sample C on which a% Al thin film was formed were compared. As shown in these figures, Cr-3.0 at. % Mn thin film (Sample B) and Cr-14.1 at. The% Al thin film (sample C) has a higher gauge ratio than the Cr thin film (sample A) at 250 ° C to 450 ° C, and sample A has a gauge ratio of 6, at 250 ° C and a gauge ratio of 5,350 to 350 ° C. The gauge ratio was about 4 at 450 ° C., whereas it was about 6 or more in Sample B and Sample C.

The details of the production conditions and the like of the samples A to C are summarized below.
1. 1. Film formation method: Sputtering method 2. Film forming apparatus: RF sputtering apparatus 3 target, Cr of magnetron: Cr disc-Cr-Mn diameter 75.5mm nominal purity 99.9%, Cr-Al: at 5 × 5 mm ² in diameter in the Cr discotic Composite target with 8 Mn chips and Al chips with a thickness of 1 mm 4. Substrate: Alumina plate with a purity of 99.9% and a thickness of 0.1 mm 5. Film formation conditions-Deposition vacuum degree (background vacuum degree): 1 × ^10-5 Pa
-Target-board distance (TS distance): 43 mm
・ Sputter gas pressure: 5mTorr (0.67Pa)
・ Sputter gas flow rate: 5 sccm
・ Input power: 10W
-Substrate temperature: 20 ° C water cooling 6. Patterning and heat treatment of thin film strain sensor (strain gauge) elements ・ Sensitive part shape: Lattice consisting of 8 folds ・ Lattice line width and spacing: 0.05 mm
・ Lattice length: 2 mm
-Thin film thickness: Approximately 100 nm
・ Pattern shape: Utilizes photolithography technology and corrosion shaping technology using Cr etching solution ・ Heat treatment: Holds at a predetermined temperature in the air for 30 minutes ・ Electrode formation: Lift-off method of Au / Ni / Cr laminated thin film at a predetermined position of sensor thin film -Cut out the evaluation element: Cut out the element individually using a dicing device.

Next, sample A on which a Cr thin film was formed and Cr-3.0 at. Sample B on which a% Mn thin film was formed and Cr-14.1 at. The temperature dependence of the gauge ratio and resistance of the sample C on which the% Al thin film was formed was grasped. FIG. 10 is a diagram showing the gauge ratio and resistance values of the Cr thin film (sample A) with respect to the measured temperature, and FIG. 11 is a diagram showing Cr-3.0 at. It is a figure which shows the value of the gauge ratio and resistance with respect to the measurement temperature of a% Mn thin film (sample B), and FIG. 12 is a figure which shows Cr-14.1 at. It is a figure which shows the temperature change of the gauge ratio and resistance with respect to the measurement temperature of a% Al thin film (sample C).

As shown in these figures, since the Cr thin film (Sample A) has a low Néel temperature of about 170 ° C., the gauge rate peaks at about 100 ° C., and the gauge rate tends to decrease at high temperatures. An example of the present invention, Cr-3.0 at. % Mn thin film (Sample B) and Cr-14.1 at. The% Al thin film (Sample C) has a Néel temperature of around 500 ° C., and the peak of the gauge ratio is about 350 to 400 ° C., and due to the high Néel temperature, the gauge ratio in the high temperature region is high. It was confirmed to show.

Next, the resistance change rate (ΔR / R ₀ ) at each measurement temperature was determined for the samples B and C. Figure 13 is a graph showing the resistance change ratio in the sample B of (ΔR / _{R 0),} FIG. 14 is a diagram showing the resistance change ratio in the sample C of (ΔR / _{R 0).} As shown in FIG. 6, the resistance change rate was obtained from the resistance values before and after holding for 30 minutes including bending. The heat treatment after the film formation was carried out at 500 ° C. in the air for 0.5 hours.

As shown in these figures, heat treatment at 500 ° C. for 0.5 hours in the atmosphere showed high stability with a resistance change rate of ± 0.02% or less up to 400 ° C.

Next, for comparison, Cr-4.4 at. Using Ni, which lowers the Néel temperature, was used as an element to be added to Cr. For the% Ni thin film, the resistance value and the gauge rate change were measured at each measurement temperature. The measurement method, manufacturing conditions, etc. were the same as in Samples A to C. The result is shown in FIG. FIG. 15A is a diagram showing the relationship between the measured temperature and the resistance value, but in the case of the Cr—Ni thin film, the Neel temperature shifts to the low temperature side and becomes invisible. Further, FIG. 15B is a diagram showing the relationship between the measured temperature and the gauge rate, but due to the shift of the Neel temperature to the low temperature side, there is no peak of the gauge rate at room temperature to 500 ° C., and the gauge rate is It was stable at an almost constant value from room temperature to 500 ° C., but no increase in the gauge rate was observed at high temperature. Since the Ni-Cr alloy has a stable gauge ratio with respect to temperature, it has been conventionally used as a strain gauge for high temperature, but the value of the gauge ratio is about 2, which is insufficient.

1; Electric oven, 2; Window, 3; Lid member, 4; Support rod, 5; Measuring stand, 6; Fixing member, 7; Substrate, 8; Cr-based thin film (distortion resistance film), 10; Terminal block, 11 Terminal, 12; Micrometer, 13; Push rod for strain application

Claims (16)

General formula Cr _100-x Mn _x
(However, x is an atomic ratio (at.%), 0.1 ≦ x ≦ 34), and the operating temperature range is 250 ° C. or higher and 500 ° C. or lower, and the gauge is in the operating temperature range. A strain resistance film having a ratio of 6 or more. General formula Cr _100-x Al _x
(However, x is an atomic ratio (at.%), Which is 4 ≦ x ≦ 25), and the operating temperature range is 250 ° C. or higher and 500 ° C. or lower, and the gauge ratio is high in the operating temperature range. A strain resistance film having a temperature of 6 or more. The strain resistance according to claim 1 or 2, wherein the operating temperature range is 250 ° C. or higher and 450 ° C. or lower, and the stability of the resistance value is within ± 0.2% in the operating temperature range. film. The strain resistance film according to claim 3, wherein the operating temperature range is 250 ° C. or higher and 400 ° C. or lower, and the stability of the resistance value is within ± 0.02% in the operating temperature range. General formula Cr _100-x Mn _x
(However, x is an atomic ratio (at.%), And 0.1 ≦ x ≦ 34), and forms a thin film, which is 50 than the upper limit temperature used in the range of 250 ° C. or higher and 500 ° C. or lower. A strain resistance film having a gauge ratio of 6 or more in a temperature range of 250 ° C. or higher and 500 ° C. or lower by heat treatment in the air at a temperature higher than ° C. for 30 minutes or longer and 4 hours or lower. Manufacturing method. General formula Cr _100-x Al _x
(However, x is an atomic ratio (at.%), And 4 ≦ x ≦ 25.) A thin film is formed, and the temperature is 50 ° C. or higher than the upper limit temperature used in the range of 250 ° C. or higher and 500 ° C. or lower. Manufacture of a strain resistance film having a gauge ratio of 6 or more in a temperature range of 250 ° C. or more and 500 ° C. or less by performing a heat treatment at a high temperature in the atmosphere for 30 minutes or more and 4 hours or less. Method. Heat treatment is performed in the air for 30 minutes or more and 4 hours or less at a temperature 50 ° C or more higher than the upper limit temperature used in the range of 250 ° C or more and 450 ° C or less, and the stability of the resistance value in the range of 250 ° C or more and 450 ° C or less. The method for producing a strain resistance film according to claim 5 or 6, wherein the temperature is within ± 0.2%. Heat treatment is performed in the air for 30 minutes or more and 4 hours or less at a temperature 50 ° C or more higher than the upper limit temperature used in the range of 250 ° C or more and 400 ° C or less, and the stability of the resistance value in the range of 250 ° C or more and 400 ° C or less. The method for producing a strain resistance film according to claim 7, wherein the temperature is within ± 0.02%. General formula Cr _100-x Mn _x
(However, x is an atomic ratio (at.%), And 0.1 ≦ x ≦ 34), and the operating temperature range is 250 ° C. or higher and 500 ° C. or lower. A strain sensor for high temperature characterized in that a strain resistance film having a gauge ratio of 6 or more is formed on a strain generating structure in a temperature range. General formula Cr _100-x Al _x
(However, x is an atomic ratio (at.%), And 4 ≦ x ≦ 25), and the working temperature range is 250 ° C. or higher and 500 ° C. or lower. A high temperature strain sensor characterized in that a strain resistance film having a gauge ratio of 6 or more is formed on a strain generating structure. The ninth or tenth aspect of the present invention, wherein the operating temperature range is 250 ° C. or higher and 450 ° C. or lower, and the resistance stability of the strain resistance film in the operating temperature range is within ± 0.2%. Distortion sensor for high temperature. The strain sensor for high temperature according to claim 11, wherein the operating temperature range is 250 ° C. or higher and 400 ° C. or lower, and the resistance stability of the strain resistance film in the operating temperature range is within ± 0.02%. .. General formula Cr _100-x Mn _x
(However, x is an atomic ratio (at.%), And 0.1 ≦ x ≦ 34) is formed on the strain-causing structure and used in the range of 250 ° C. or higher and 500 ° C. or lower. Heat treatment is performed in the air for 30 minutes or more and 4 hours or less at a temperature higher than the upper limit temperature of 50 ° C. or more to obtain a strain resistance film having a gauge ratio of 6 or more in a temperature range of 250 ° C. or more and 500 ° C. or less. A method for manufacturing a high-temperature strain sensor, which comprises using it to manufacture a high-temperature strain sensor. General formula Cr _100-x Al _x
(However, x is an atomic ratio (at.%), And 4 ≦ x ≦ 25.) A thin film represented by is formed on the strain-causing structure, and the upper limit of use in the range of 250 ° C. or higher and 500 ° C. or lower. A strain resistance film having a gauge ratio of 6 or more in a temperature range of 250 ° C. or higher and 500 ° C. or lower is obtained by heat treatment in the air at a temperature higher than the temperature of 50 ° C. or higher for 30 minutes or longer and 4 hours or shorter. A method for manufacturing a high temperature strain sensor, which comprises manufacturing a high temperature strain sensor. The 13th or 14th claim, wherein the operating temperature range is 250 ° C. or higher and 450 ° C. or lower, and the resistance stability of the strain resistance film in the operating temperature range is within ± 0.2%. A method for manufacturing a strain sensor for high temperature. The strain sensor for high temperature according to claim 15, wherein the operating temperature range is 250 ° C. or higher and 400 ° C. or lower, and the resistance stability of the strain resistance film in the operating temperature range is within ± 0.02%. Manufacturing method.

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