JPS60174844A - Amorphous alloy for material of strain gauge - Google Patents

Abstract

PURPOSE:To obtain the titled alloy usable even in an environment at high humidity under high vibration by forming an amorphous thin film of a nonmagnetic Ni-Si-B alloy having a specified composition, a low temp. coefft. of electric resistance and high electric resistance on a substrate by a vacuum film forming technique. CONSTITUTION:An amorphous thin film having a composition represented by a formula NiaSibBc (where each of a, b and c is the atomic vol% of the element, a+b+c=100, 60<=a<=74, 16.5<=b, and 26<=b+c<=40) is formed on a substrate by a vacuum film forming technique such as sputtering. Unlike a conventional film formed by adhesion the resulting amorphous alloy film maintains its reliability and has stable strain gauge characteristics and high sensitivity, so the amorphous alloy film is most suitable for use as material for a strain gauge.

Description

[Detailed Description of the Invention] [Object of the Invention] The present invention provides an amorphous material for strain gauge materials that has a small temperature coefficient of electrical resistance (hereinafter referred to as TCR), high electrical resistance, and is non-magnetic. It concerns quality alloys.

[Prior art]

An example of this conventional amorphous alloy is ``Amorphous Alloy for Strain Gauge Material'' disclosed in Japanese Patent Application Laid-open No. 56-77356, which was invented by the present inventors.

This is manufactured by a single roll method or a twin roll method, and T
It has a low CR, high electrical resistivity, and is non-magnetic.
Formula N1aSibBc or NidMeSifBg (a
: 65.5 to 70.1 at%, b: 3 to 16 at%, c
: 13.9-31.5% atomic%, a+b+c=1
00, d: 5B, 6-73.0 atomic%, e: 0-
? atomic%, f: 3 to 16 atomic%, g: 11.0 to 3
It is an amorphous alloy with a content of 1.4 atomic % (d+e+f+g=IQO).

[Problems in the prior art and their technical analysis] This type of conventional amorphous alloy is manufactured by a single roll method or a twin roll method, so as the amount of Si is increased, the molten metal is cooled super rapidly. However, it is difficult to obtain an amorphous alloy with low TCR, high electrical resistivity, and non-magnetic properties, and furthermore, when used as a strain gauge, the shape is made of a thin plate. Because it is ribbon-shaped, (11) it needs to be small and thin foil-shaped or a thin wire to reduce changes within the measured position, and (2) it is used by pasting it with adhesive. It lacks durability and reliability as a strain gauge, (3) there are restrictions on where the measuring equipment can be used, such as using it in a place without large vibrations or in a low humidity environment, and (4) the electrical resistance is low. Since it is small, it is necessary to use a separate amplifier circuit for actual use, and (5) maintenance is required to measure the accuracy of the strain gauge several times a year.

[Technical issues]

Therefore, the present invention contains a large amount of Si, has a small TCR, has a high electrical resistance (and is non-magnetic), and can be used as a strain gauge even in environments with large vibrations and humidity, and is completely unaffected by the vibrations and has sensitivity. The technical objective is to obtain an amorphous alloy for strain gauge materials that is sensitive, durable, reliable, and requires little maintenance.

[Technical means and their effects]

The technical measures taken to solve the above technical problems are as follows: An amorphous alloy for strain gauge materials having a composition represented by the formula N1asibBc.

However, in the formula, Ni is nickel, Si is silicon, and B is boron, and a, b, and c represent the atomic volume % of each element, and B+b+
c is substantially 100, and 60≦a≦74.16.5
≦b, 26≦b+c≦40, and (2) Among the alloys shown in 11) above, a non-alloy for strain gauge materials having a composition shown by the formula NidMeSifBg in which a part of Ni is replaced with another element. Crystalline alloy・However, N in the formula is the element symbol (Hr, AI, Cu, Fe, V,
One or more elements among Ti, d, e, f, g represent atomic volume % of each element; d+e+f+g is substantially 2100, 405; d≦74. O≦e
≦20.16.5≦f, 26≦f+g≦40.

The above (1), (21) amorphous alloy is produced by vacuum evaporation method,
Using vacuum film-forming techniques such as CVD and sputtering, (al
On ceramic substrates such as glass.

(b) On a metal substrate with a suitable insulating film or layer formed thereon (C) On a resin or resin substrate (d) On a part to be measured whose surface is electrically insulated.

The reason for limiting the composition of the alloy of the present invention is as follows:
In the alloy of the first aspect of the present invention, if the Ni content is less than 60%, the TCR will be 150 ppm/'C or less, which is not preferable as a strain gauge, and if the Ni content is more than 74%, the TCR will be 1 and the TCR will be +50 ppm/'C.
”C or less, making it difficult to use as a strain gauge, and St is 16.5.
If B or St exceeds 40%, it is necessary to increase B, and the concentration tends to vary due to scattering of B, resulting in poor stability. If B or St exceeds 40%, TCR decreases to -50 ppm/
'C or below.

In addition, in the second alloy of the present invention, if the Ni content is less than 40%, the TCR will be less than 150 ppm/'c, which is undesirable as a strain gauge.
%, the TCR becomes +50 ppm/T: or more, making it difficult to use as a strain gauge.
If it is less than 5%, increasing B tends to cause concentration variations due to scattering of B, and if B or Si exceeds 40%, the TCR will be 159 ppm/°C or less.

Also, Cr, ^1. One or more elements selected from Cu, Fe, and V+Ti have the effect of increasing electrical resistivity and reducing thermoelectromotive force against copper, but 20
If the content of these elements is increased by 20% or more, the TCR may deteriorate, so the content of these elements needs to be 20% or less.

Next, the strain gauge manufactured with the above component composition does not require thin plate processing such as rolling, has few steps, and can be made into a very homogeneous and extremely thin film (~1 μm), so it has high electrical resistance and high sensitivity. It requires only a low magnification, high measurement accuracy, and since the film is formed directly on the substrate, no adhesive is required, making it reliable and resistant to vibrations and other environments. We can expect a dramatic improvement in performance, a significant reduction in the number of inspections, and lower costs.In particular, sputtering and ion-blating methods can significantly improve adhesion strength and significantly improve reliability. It will be improved.

Furthermore, it is possible to expand the formation range of N15iB-based and N1M5iB-based amorphous alloys depending on their composition. According to the conventional liquid quenching method, the limit of the St content was 16 at. Amorphousization has become possible over a wide range, and the TCRO area has accordingly been expanded as shown in the figure. (A) in the figure is TCR=Oppn+/
``A line showing the composition of C, where (B) and (C) are each about -
The lines (C) and (,B) indicate that the sum of the Si and B contents is approximately 26.39 at%, and (B) and (C
It is assumed that the composition shown in the range between ) satisfies the desired temperature characteristics as a strain gauge (it can be put to practical use sufficiently).

In addition, these characteristics are mainly due to Ni in the N15iB system.
It has been found that the same phenomenon occurs when 0 to 20 atom % of one or more of r+AI+Cu+Fe+V+Tt is substituted.

[Special effects of the present invention]

The present invention produces the following unique effects. That is, (11) the conventional composition containing a large amount of B causes a lot of B to scatter when the target is melted, and the reproducibility of the B concentration when casting the target is poor, resulting in many composition defects. By increasing the SL of the present invention, St will not scatter when the target is melted (therefore, there will be little variation in concentration, and targets can be created with good reproducibility. In order to double the amount, a composition containing a large amount of B becomes expensive, and if B is reduced and St is increased in order to keep TCR small, the cost effect is extremely large.

(Example) Hereinafter, a practical example 7iff+ showing a specific example of the above technical means will be described.
171 will be explained.

By sputtering, a glass substrate (!-30111
11) on which an amorphous thin film consisting of Nt, Si, and B was deposited.
．． 5. A film was formed to a thickness of c + m, and a strain gauge pattern was created by photo-etching.In this case, the resistance value on each side of the strain gauge was approximately 800Ω, and the resistivity was 15
At 2 μΩG, the TCR was -0.10 pp/'C, which is very close to 0.

Note that amorphization was confirmed using an X-ray diffraction device. Sputtering during film formation was carried out for about 40 minutes by reducing the pressure to 2 x 10-' Torr, then constantly flowing argon gas at a pressure of 3 x 10-J, and using an RF power source of 0.5-.

The Ni47Si8Bp amorphous alloy film obtained in this way does not suffer from the reliability degradation caused by conventional adhesion, has stable strain gauge characteristics, and is a highly sensitive element that does not require temperature correction from low temperatures to high temperatures of approximately 120°C. Ideal for

Next, the table shows the composition of each component and the values of TCR, specific resistance, and crystallization temperature.

[Brief explanation of the drawing]

The figure shows the distribution of TCH in the composition of the amorphous alloy of the present invention, and shows the relationship between the contents of Si and B. 0 f to zr 20 B rin+2

Claims (1)

[Claims] (11) A formula N1aSibBc characterized by having a small absolute value of electrical resistance temperature coefficient, high electrical resistance, non-magnetic properties, and being formed on a substrate by vacuum thin film production technology. An amorphous alloy thin film for strain gauge materials having the composition shown below.In the formula, Ni is nickel, St is silicon, B is boron, and a, b, and c represent the atomic volume percent of each element. and a+b+c is substantially 100 and 60
≦a≦74.16.5≦b, 26≦b+c≦40. (2. Among the alloys shown in claim 1, N
An amorphous alloy thin film for strain gauge material, having a composition represented by the formula NidMeStfBg in which part of 1 is replaced with another element. However, in the formula, H is the element symbol Cr, A1+C
One or more elements of u + Fe, V + Ti,
d + e + f + g is the atomic volume % of each element
, d+e+f +g is substantially 100, and 4
0≦d≦74. 0≦e≦20.16.5≦f, 26≦
f10g≦40.