JPS6075553A - Diaphragm - Google Patents

Abstract

PURPOSE:To obtain a diaphragm having superior accuracy in measurement and stable performance for a long term by using a precipitation-hardening permanentlyelastic alloy prepd. by adding specified percentages of Ni, Cr, Ti, Al and Zr to Fe. CONSTITUTION:A precipitation-hardening permanently-elastic alloy having a composition consisting of, by weight, 40.0-44.5% Ni, 4.0-6.5% Cr, 0.5-1.9% Ti, 0.1-1.0% Al, 0.2-2.0% Zr and the balance accompanying impurities or further contg. 0.1-5.5% one or more among Mo, Nb, Ta and W is prepd., and a diaphragm is made of the alloy. The resulting diaphragm has superior strength and shows its permanent elasticity up to about 130 deg.C. The pressure-volume change rate is within 1% up to about 110 deg.C.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a diaphragm, and in particular to a semiconductor differential pressure transmitter,
It relates to a diaphragm used in the detection section of semiconductor pressure transmitters, etc.

[Technical background of the invention and its problems]

As a semiconductor differential pressure transmitter, one having the structure shown in FIG. 1, for example, is known. That is, numeral 1 in the figure is a pressure-sensitive element in which a resistance layer is formed by diffusion on a pressure-receiving diaphragm made of silicon single crystal. One pressure-receiving surface (lower surface) of this pressure-sensitive element 1
is in contact with a high-pressure side filling liquid 2a for protecting the diffusion resistance layer of the element 1 from moisture and corrosive atmosphere.

The high-pressure sealed liquid 2a on the side opposite to the pressure-sensitive element 1 is in contact with the high-pressure medium 4a via the high-pressure diaphragm 3&.

The other pressure-receiving surface (upper surface) of the pressure-sensitive element 1 is in contact with the low-pressure side filled liquid 2b, and the low-pressure side filled liquid 2b on the opposite side to the element 1 is connected to the low-pressure side diaphragm 3b. Low 2- Contact with pressure medium 4b. In such a differential pressure transmitter, when the high-pressure medium 4a and the low-pressure medium 4b are introduced separately into the wetted parts of the sealed liquids 2a and 2b, the high-pressure side diaphragm 31L and the low-pressure side diaphragm 3b are adjusted depending on the magnitude of the pressure. It is displaced and pressurizes the high-pressure side filled liquid 2a and the low-pressure side filled liquid 2b.

As a result, a pressure difference is generated on both sides of the pressure sensitive element 1, causing distortion. The resistance value of the resistance layer of the pressure-sensitive element 1 changes in proportion to this strain, which is converted into a voltage signal by the bridge circuit and the differential pressure is detected.

On the other hand, the pressure transmitter has the configuration shown in Fig. 2, and when pressure is applied to the medium 4, the pressure is transferred to the diaphragm 3
is transmitted to the sealed liquid 2 via the pressure-sensitive element 1, and is guided to one side of the pressure-sensitive element 1, causing distortion. After this, pressure is detected using the same function as the differential pressure transmitter described above.

The thickness of the diaphragm in the transmitter described above.

The constant determined by the shape and diameter is A1 The elastic modulus due to temperature change is E(t) N The volume change caused by the displacement of the diaphragm is ΔV, then the differential pressure or pressure (p-p')
is expressed as (P-P')=E(t)-A-ΔV. Therefore, in order to measure (P-P') with high precision, it is necessary that the elastic modulus of the diaphragm material has little variation even with changes in ambient temperature. Moreover, repeated pressure or excessive pressure is applied to the diaphragm by the pressure medium. Therefore, it is necessary to use a material with excellent mechanical properties for the diaphragm so that the actual measured values of the differential pressure and pressure transmitters do not change over time.

Incidentally, stainless steel (Sun 316L) has been widely used as a material for diaphragms. However, diaphragms made of such materials have a large variation in elastic modulus with respect to temperature changes, and therefore have the disadvantage that errors occur in the measured differential pressure or pressure as the temperature of the pressure medium increases.

Furthermore, recently there has been an increasing demand for semiconductor pressure/differential pressure transmitters that can accurately measure temperatures up to 100° C. and exhibit stable performance over a long period of time.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and has high accuracy up to a temperature of 100°C (pressure-volume change rate ΔV/P - P' is 1).
130 to enable measurement of differential pressure and pressure within
Constant elastic properties up to temperatures of ℃ (thermoelastic function is ±20 x 1
0-' 1. The present invention aims to provide a diaphragm that has excellent properties equivalent to or better than conventional materials (tensile strength 95 Wm2) in terms of strength to reduce hysteresis after pressure is applied.

[Summary of the invention]

The present invention contains nickel (Nl) in weight% from 40.0 to 44
．． 5%, chromium (Cr) 4.0-6.5%, titanium (T
I) 0.5 to 1.9 inches, aluminum (At) 0.1 to
The first invention consists of a precipitation hardening constant modulus alloy having a composition of 1.0% zirconium (Zr), 0.2 to 2.0% zirconium (Zr), the balance iron (F6) and incidental impurities, and further comprising molybdenum (M
o) A precipitation hardening type constant modulus alloy having a composition in which 0.1 to 5.5 g of one or more metals selected from niobium (Nb), tantalum (Ta), and tungsten (W) are added. The second invention consists of the following.

Next, the action of each component constituting the diaphragm of the present invention and the reason for limiting the amount added thereof will be explained.

Nickel (Nl) is the most effective element for maintaining constant elastic properties, and its addition amount is less than 40.01 and 4
If it exceeds 4.5%, effective constant elastic properties cannot be obtained.

Chromium (Cr), like nickel, is an effective element for maintaining constant elastic properties, and if the amount added is less than 4.0 or more than 6.5, sufficient constant elastic properties cannot be obtained. . Addition of chromium is also effective in improving the corrosion resistance of the alloy.

Titanium (TI) is an element that precipitates during aging treatment and is effective in improving alloy strength, and its addition amount is 0.5%.
If it is less than 1.9, sufficient strength improvement cannot be obtained;
If it exceeds %, the constant elastic properties will deteriorate.

6-Aluminum (At) is an effective element for improving alloy strength like titanium, and if the amount added is less than 0.11, sufficient strength improvement cannot be achieved, and on the other hand, i, o
If it exceeds s, the constant elastic properties will deteriorate.

Zorconium (Zr) contributes to strength improvement by being added in combination with titanium and aluminum. If the amount of zirconium added is less than 0.2%, sufficient strength improvement cannot be achieved, whereas if it exceeds 2.0%, the constant elasticity properties will deteriorate.

Furthermore, the addition amount of molybdenum (Mo), niobium (Nb), mental (Ta), and tungsten (W) is 0.1 to
By specifying it within the range of 5.5 inches, it is possible to improve the mechanical properties of the alloy without deteriorating the constant modulus properties, even when used alone or in combination of two or more.

Next, the method for manufacturing the constant modulus alloy of the present invention will be briefly explained.

First, it is melted into a predetermined alloy composition by induction melting or the like in a vacuum or an inert gas atmosphere, and then processed into a predetermined shape by hot working. Furthermore, after performing cold working to form a predetermined shape, an aging treatment is performed to manufacture a diaphragm. In this case, the cold working is performed at a working rate of 10 to 90%, and it is particularly preferable to use a working rate of 40 to 60%.

If the processing rate is less than 10 inches, the alloy will have insufficient strength.
On the other hand, if it exceeds 90q6, the constant elastic properties will be significantly reduced.

In addition, the aging treatment conditions are, for example, 200 to 750°C and 0.
It is preferable to perform heating for 1 to 100 hours. 200
If the temperature is less than 0.1 hour at 750°C, aging will be insufficient and it will be difficult to obtain good strength and constant elastic properties, while if the temperature exceeds 100 hours at 750°C, the aging will be excessive and it will be difficult to obtain good constant elastic properties. .

The diaphragm is made from the material obtained by the method described above and has a diameter of approximately 70 mm.
- It is obtained by punching out a disk and applying corrugated processing. This corrugation processing is carried out by hydraulic forming when the plate thickness is 0.2 mm or less, and by press forming when the plate thickness is 0.2 mm or more.

〔Example〕

Next, the present invention will be explained in detail.

Example 1 An alloy having the composition shown in the table below was produced by high-frequency vacuum melting, and the obtained ingot was hot-processed to a thickness of 2 m.
It was made into a plate material. Next, this plate material was heated and held at 1000° C. for 1 hour, water quenched, and further cold rolled by 50% to a thickness of 1 m.

After aging treatment, the obtained plate material was used as a test material, and its constant elastic properties and tensile strength were measured. The results are also listed in the same table.

Constant elastic properties are evaluated using thermoelastic coefficients, and measurements are made using Il
Evaluation was made based on the temperature dependence of the natural frequency (transverse vibration method) of a test piece cut into a size of X10X100+. The elastic modulus (Young's modulus E) was determined based on this measured value, and the state of change due to temperature is shown by curve 1 in the characteristic diagram shown in FIG.

Further, if the temperature dependence (rate of change) of the elastic modulus is 61 and the temperature dependence (rate of change) of the coefficient of thermal expansion is α and 9−, then the thermoelastic coefficient is expressed as e+α. This thermoelastic coefficient is used as an index to evaluate the constant elasticity property, and the closer it is to zero, the better the constant elasticity property is. However, the alloy of Example 1 has a thermoelastic coefficient of 130% from room temperature (20°C).
It showed an extremely low value of 8×10-'[1,'C] between . On the other hand, the tensile strength was 115 kg/m+2, which is higher than the conventional material (SUS 316L).

Next, the performance when the alloy of Example 1 is used as a diaphragm will be described. A disk with a diameter of 70 m was punched out from the above plate material and corrugated by a press molding machine.

This diaphragm is tightly fixed between the flang and the casing, and one side of the diaphragm is pressurized with pressure (P) to control the pressure (P') and volume change (Δ■) of the pressure chamber formed by the diaphragm and the casing. Measure. Regarding the relationship between the differential pressure (p-p') and the amount of change in volume (ΔV), it is ideal that the value of ΔV/P - P' remains constant even if the temperature of the pressure medium changes.

According to these test results, the value of ΔV/P-P' of the diaphragm made of alloy 10-alloy of Example 1 varied within 1% in the temperature range from room temperature to 120°C.

Examples 2 to 9 Alloys having the composition shown in the table below were manufactured in the same manner as in Example 1, test pieces were cut out from the obtained plates, and the temperature range and tensile strength showing constant elastic properties were measured. did. Furthermore, a diaphragm was made from the plate material, and ΔV/
A temperature range was determined in which the rate of change in the P-P' value was within 1 inch. The results are also listed in the same table. In addition, in the table, an alloy that deviates from the composition of the alloy of the present invention is also listed as Comparative Example 1゜2, and a conventional alloy is also listed as a conventional example.

Regarding the conventional alloy, the temperature dependence of the elastic modulus is already shown as a curve in FIG.

As is clear from the above table, the elastic modulus of the conventional diaphragm changes significantly with heating temperature, and does not exhibit constant elastic properties at all. Furthermore, compared to the composition of the alloy constituting the diaphragm of the present invention, both Comparative Example 1 and Comparative Example 2 have a large amount of titanium at 2.2 T and a total amount of tantalum and tungsten added at 5.9 T, respectively. The temperature range that exhibits constant elastic properties does not meet the required conditions. In contrast, the diaphragm of the present invention exhibits constant elastic properties up to temperatures of 130°C or higher, and ΔV/P
-The maximum temperature at which the rate of change of P' value is within 1 inch is 110℃
has reached. Moreover, it has a tensile strength of 110 kg/m2 or more, which is higher than that of conventional products.

〔Effect of the invention〕

As detailed above, according to the present invention, it exhibits constant elastic properties up to a temperature of 130°C, the temperature at which the rate of change in ΔV/P - P' value is within 1 inch reaches 110°C, and it also has excellent strength. It is possible to provide a diaphragm for a semiconductor differential pressure/pressure transmitter that can detect pressure differentials and pressures with high precision and has stable performance over a long period of time.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a differential pressure transmitter, Fig. 2 is a schematic diagram of a pressure transmitter, and Fig. 3 is a characteristic diagram showing the temperature dependence of the elastic modulus of the alloy constituting the present invention and the conventional diaphragm. . 1... Pressure sensitive element, 2*, 2b, 2... Filled liquid, 3a
, 3b, 3... diaphragm, 4 a p 4 b
+4...Pressure medium.

Claims (2)

[Claims] (1) Nickel (Ni) 40.0-44 in weight%
．． 5%, chromium (Cr) 4.0-6.5%, titanium (Ti) 0.5-1.9%, aluminum (At)
0.1-1.0%, zirconium (Zr) 0.2
``A diaphragm comprising a precipitation hardening constant modulus alloy having a composition of 2.0%, balance iron (Fe) and incidental impurities. (2) Nickel (Ni) 40.0-44 in weight%
．． 5%, chromium (Cr) 4.0-6.5%, titanium (Ti) 40.0-44.5%, aluminum (
At) 0.1 to 1.0 t, zirconium (Zr) 0.2
~2-Oq6, molybdenum (MO), niobium (Nb
), 0.1 to 5.5% of one or more metals of tantalum (Ta) and tungsten (W), the balance iron (
1. A diaphragm comprising a precipitation hardening constant modulus alloy having a composition of (Fa) and incidental impurities.