JPH0427285B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a constant electrical resistance alloy and a method for manufacturing the same. In recent years, robots and automation technology have been widely adopted in factories and various workplaces, contributing to the elimination of hazardous work and improved productivity. It can be said that the performance of these technical systems is determined by the performance of the sensor that detects the measurement data to the microprocessor interface. However, there are few suitable work sites where sensors are handled, and rather they are usually accompanied by extremely harsh conditions and danger. Especially for various measurements such as temperature, pressure, or displacement in the steel industry, chemical industry, nuclear industry, space industry, etc., it has cleared environmental resistance, has good stability for long-term use, and has excellent maintainability. In addition, there is a growing demand for superior sensors with good stability. For example, in the case of a continuous casting process that allows integrated production of high-yield, high-quality steel, it is possible to measure the amount of raw material powder in the blast furnace, tundish, or mold, the level of the molten steel, and the thickness, width, and rolling speed of the slab. The sensors used are exposed to high temperatures of 800 to 1000 degrees Celsius and steam, so not only must they withstand these harsh environments, but their characteristics must remain stable over long periods of time. Conventionally, methods using ionizing radiation such as gamma rays and X-rays have been widely adopted for the above-mentioned measurements, but these methods have many disadvantages, such as the large size of the equipment and the danger to the human body. Therefore, in recent years, the use of eddy current displacement meters (hereinafter simply referred to as sensors), which are small and easy to handle, has come to be considered. Since the performance of a sensor is determined by the sensor coil material, its electrical characteristics and stability are particularly important. For example, in the case of the above continuous casting process,
Since the sensor coil material operates continuously at high temperatures of 800 to 1000°C for several months to several years, the temperature coefficient of electrical resistance in the temperature range of -150°C to 1000°C must be 100 ppm/°C or less. unchanged for a long time,
Furthermore, it is important that the material has good corrosion resistance, oxidation resistance, and processability, as well as excellent thermal stress fracture resistance, which is closely related to wire breakage. Since the characteristics of the sensor need to be calibrated not only in the high temperature range but also in the normal temperature range, the electrical characteristics must be as excellent in the normal temperature range as in the high temperature range. Since there is currently no sensor coil material that meets these conditions, there is a strong demand for its development from related industries. Conventionally, as this type of sensor coil material, palladium-silver alloy (Japanese Patent Application Laid-open No.
No. 55-122839) and palladium-iron alloy (Japanese Patent Application Laid-Open No. 113332/1982), each of these alloys has advantages and disadvantages as described below. In other words, the former alloy has good corrosion resistance, oxidation resistance, and workability at high temperatures, and also has -50 to 600
It has an extremely small temperature coefficient of electrical resistance of less than ±20 ppm/°C over a wide temperature range of °C, but at temperatures below -50°C and above 600°C, the temperature coefficient of electrical resistance is more than ±100 ppm/°C. Not only does it show a very large value, but when a sensor using this material is operated continuously at high temperatures for a long period of time, the crystal grains of the material become coarse and the characteristics deteriorate.
In the worst case, troubles caused by wire breakage often caused major problems in production management. In the case of the latter alloy, the temperature coefficient of electrical resistance is ±
Although it has the characteristics of being small (less than 100 ppm/°C) and having extremely stable characteristics even when used continuously at high temperatures for long periods of time, it is unstable due to large changes in electrical resistance at temperatures below the regular-irregular transformation point. Not only that, but it also has many drawbacks and restrictions, such as extremely poor oxidation resistance at high temperatures and poor workability, requiring a high degree of ingenuity in its manufacture and use. Therefore, the present inventors immediately developed the above-mentioned palladium in order to meet the urgent needs of related industries. As a result of comparative studies of silver-based alloys and palladium-iron alloys, we found that they are easy to handle in mass production;
We also attempted to improve palladium-silver alloys that have excellent processability and moldability. In other words, the present inventors found that the constant electrical resistance property of palladium-silver alloys is such that when the scattering of conduction electrons due to lattice vibration and the short-range regularity of the crystal are balanced, the scattering of electrons becomes constant and changes in electrical resistance are reduced. However, at temperatures below -50°C and above 600°C, the balance between these two factors is disrupted, leading to increased scattering of electrons and a loss of constant electrical resistance properties. Incidentally, FIG. 1 shows the average temperature coefficient of electrical resistance with respect to the amount of Ag in a palladium-silver alloy. Here, the curves and are respectively 0~400℃ and −150~
It is the average temperature coefficient of electrical resistance between 1000°C and -200 to 120°C. In Figure 1,
If the average temperature coefficient of electrical resistance is 100ppm/℃ or less,
Point c (Ag33.2%) to point d (Ag46.7%) of the curve
It is obtained in the composition range between point a (36.0%Ag) and point b (45.5%Ag) of the curve, but it is extremely large at +100ppm/°C or more over the entire composition of the curve. From the above explanation, the average temperature coefficient of electrical resistance over a wide temperature range of -150℃ to 1000℃ is
The composition range exhibiting 100 ppm/°C or less is limited to 36.0 (point a) to 45.5 (point b)% Ag, excluding the compositions between points c and a and points b and d in the curve. In addition, the disconnection phenomenon of the sensor coil is caused by recrystallization due to continuous heating of the processed material for a long period of time.
Furthermore, it was predicted that as the heating time increased, the crystal grains would grow coarser, and external factors such as expansion and contraction due to repeated heating and cooling would be added, leading to thermal stress fracture and eventual disconnection. That is, as a solution to improving the thermal stress fracture resistance, which is closely related to the high-temperature stability of the sensor, it is first necessary to increase the recrystallization temperature to suppress crystal growth and to reduce the crystal grain size as much as possible. Next, it is also important to set the upper limits of the sensor's operating temperature and service life low. Regarding the former, addition of multiple elements may be considered in order to refine the crystals of the alloy. The latter is deeply involved in the manufacturing method of the alloy and sensor, and it is necessary to adopt the optimal processing method and heat treatment method in conjunction with constant electrical resistance characteristics. Here, the method for evaluating thermal stress fracture resistance is the recrystallization temperature of the alloy,
It can be determined from the average crystal grain size and the stability of impedance after forming the alloy material into a sensor coil. That is, it can be said that the higher the recrystallization temperature, the smaller the average crystal grain size, and the smaller the change in impedance over time, the better the high temperature stability and thermal stress fracture resistance of the sensor. The present inventors conducted many experiments based on the above facts in order to solve the above problems and obtain a constant electrical resistance alloy that is stable even at high temperatures.
It has been found that addition of elements from groups a to b of the periodic table to a silver-palladium alloy is extremely effective and effective in improving the average temperature coefficient of electrical resistance and thermal stress fracture resistance at high temperatures. The purpose of the present invention is to solve the above-mentioned problems and -
The purpose of the present invention is to provide a constant electrical resistance alloy that shows extremely little change in electrical resistance over a wide temperature range of 150 to 1000°C, has excellent thermal stress fracture resistance, and is easy to process and form. That is, the features of the present invention are as follows. First invention A total of 0.1 to 10% of one or more of iridium 7% or less, platinum 5% or less, copper 7% or less, and gold 9% or less, 40.2 to 43% silver, and the balance palladium. Consists of a small amount of impurities, -
A constant electrical resistance alloy characterized by having constant electrical resistance characteristics and thermal stress fracture resistance with an average temperature coefficient of electrical resistance of 100 ppm/°C or less in a temperature range of 150°C to 1000°C. Second invention A total of 0.1 to 10% of one or more of iridium 7% or less, platinum 5% or less, copper 7% or less, and gold 9% or less, and 40.2 to 43% silver and the balance palladium. An alloy consisting of a small amount of impurities is melted, cast, forged, and heat-worked and cold-worked into a desired shape such as a wire or plate, and then heated in a non-oxidizing atmosphere or in a vacuum for 200°C.
A method for producing a constant electrical resistance alloy, characterized by heating at ~1200°C for 2 seconds or more and 100 hours or less. In the above explanation, to explain the meaning of the term constant electric resistance characteristic, the electric resistance of ordinary metal alloys changes greatly with temperature changes, but in the case of the alloy of the present invention, the electric resistance changes extremely in a specific temperature range. The name refers to the property that the temperature coefficient of electrical resistance is small or zero, in other words, the temperature coefficient of electrical resistance is extremely small or zero. As an example, manganin, which has been commonly used as a precision resistance material, has a constant electric resistance characteristic only near room temperature. Hereinafter, the present invention will be explained in detail with reference to the drawings. Figures 2, 3, 4, and 5 show the amounts of Ir, Pt, Cu, and Au added to the average temperature coefficient of electrical resistance of palladium-silver alloys between -150℃ and 1000℃, respectively. shows the effect of
Figure 6 also shows the Pd-42%Ag binary alloy with Au,
This shows the temperature coefficient of electrical resistance when Cu, Pt or Ir is added.Au is less than 9% and Cu is 7%.
% or less, Pt is added in small amounts of 5% or less, and Ir is added in small amounts of 7% or less, the temperature coefficient of electrical resistance becomes smaller than that of the alloy without addition. As you can see from the figure,
Addition of large amounts of Au, Cu, Pt, or Ir increases the temperature coefficient of electrical resistance and does not exhibit constant electrical resistance characteristics of 100 ppm/°C or less, which is not preferable as a material. As is clear from these Figures 2 to 6, Ir, Pt, and
The amount of Cu or Au added is less than 7% Ir, respectively.
It can be seen that Pt is 5% or less, Cu is 7% or less, or Au is 9% or less. Next, the method for manufacturing the alloy and sensor of the present invention will be explained in detail. First, to make the alloy of the present invention, a total of 0.1 to 10% of one or more of Ir 7% or less, Pt 5% or less, Cu 7% or less and Au 9% or more, Ag 40.2 to 43.0% and the balance Pd and a small amount. An appropriate amount of impurities is melted in a non-oxidizing atmosphere or in a vacuum using a suitable melting furnace, and thoroughly stirred to obtain a structurally uniform molten alloy. Next, the molten alloy is poured into iron molds of appropriate shape and size to obtain a sound ingot. After that, the scale, scratches, etc. on the surface of the ingot are ground to remove them, and the ingot is then subjected to a forging process where it is heated to various temperatures. It is formed into a desired shape, such as a round bar, a thin wire, or a thin plate, by cold working and cold working, such as swaging, wire drawing, rolling, or crushing. Next, these shapes are heated to 200~200℃ in a non-oxidizing atmosphere or vacuum.
By heating at 1200℃ for 2 seconds or more and 100 hours or less, it is possible to have a constant electrical resistance characteristic with a temperature coefficient of electrical resistance of 100ppm/℃ or less in the temperature range of -150℃ to 1000℃ and excellent thermal stress fracture resistance. becomes. In addition, when the alloy of the present invention is applied to heating elements, sensors, etc., it is usually formed into a coil shape and used, so the constant electrical resistance characteristics of the alloy of the present invention can be sufficiently improved by any of the methods described below. Providing electrical and thermal insulation must be provided. (1) After fixing the wire or plate material of the alloy of the present invention by directly wrapping it around a room-temperature insulator such as mica or a heat-resistant insulator such as ceramics, or by sandwiching it between insulators, if necessary, do not oxidize it. In order to evaporate harmful gases and organic substances in the insulator in a harsh atmosphere or vacuum, heat at 200 to 500℃ for several hours and then heat at 500 to 1200℃ for 2 seconds or more.
Heat for no more than an hour. (2) A wire or plate made of the alloy of the present invention is molded into a spiral or toroidal shape in a non-oxidizing atmosphere or in a vacuum.
After being heated at 500-1200℃ for 2 seconds or more and 100 hours or less, it is immersed in a solution made of room-temperature insulators such as water glass or heat-resistant insulators such as ceramic paste at 200-500℃. After heating for several hours to solidify, load it into an insulating case and seal it, and if necessary, heat it at 500 to 1200℃ for more than 2 seconds in a non-oxidizing atmosphere or in a vacuum.
Heat for up to 100 hours. (3) Apply or coat a room-temperature insulator such as formal to the surface of the wire or plate material of the alloy of the present invention, or apply a heat-resistant insulator such as polyimide resin or magnesia by an appropriate method such as electrodeposition or sputtering. After being applied, the wire is formed into a spiral or toroidal shape.
Heat at 200 to 500℃ for several hours to evaporate harmful gases and organic substances, load it into an insulating case and seal it, and if necessary, heat at 500 to 1200℃ for 2 seconds in a non-oxidizing atmosphere or in vacuum. Heat for more than 100 hours. (4) After the alloy of the present invention is deposited on the surface of an insulator such as glass or ceramic by an appropriate method such as electrodeposition or sputtering, it is etched, punched, or trimmed into a desired shape, and if necessary, fixed to the insulator. or packed in an insulator case. After that, homogenization treatment is performed by heating at 200-500℃ for several hours, and if necessary, further heating at 500-1200℃ in a non-oxidizing atmosphere or in vacuum.
Heat for 2 seconds or more for 100 hours. It has been revealed that the properties of the product completed through the above steps are exactly the same as those of the alloy of the present invention, and that it can sufficiently exhibit constant electrical resistance properties and thermal stress fracture resistance. Next, the production of the alloy of the present invention will be specifically described with reference to Examples. Example 1 Alloy number PAM-1 (composition Pd=55.5%, Ag=
42.0%, Ir = 2.5%) Production of alloy and sensor Pd, Ag and Ir with a purity of 99.9% were used as raw materials. To make the sample, raw materials with a total weight of 100 g were placed in a high-purity alumina crucible, melted in a high-frequency induction electric furnace while blowing argon gas, and stirred thoroughly to form a homogeneous molten alloy. difference
The ingot was cast into a 180mm iron mold, and any scratches on the surface of the ingot were removed. Then forged and hot rolled to a diameter of 10mm.
The wire was made into a thin wire with a diameter of 0.5 mm by cold working such as swaging and wire drawing, and then cut to a length of about 10 cm to prepare a sample for measuring electrical resistance. Electrical resistance was measured in a temperature range of -160°C to 1100°C in vacuum.
In addition, a sensor coil is made by coating the above wire (0.5 mmφ) with a colloidal solution of magnesia, and after drying, winding it around a ceramic bobbin with a shaft diameter of 2 mm 20 to 50 times.
This was loaded into a ceramic case and sealed with ceramic paste. Another 1 hour at 200℃, 400℃
It was baked at 1000°C for 30 minutes and then heated at 1000°C for 30 minutes. Next, the impedance change rate of this sensor Δη/η ₀ ×100=η _T −η ₀ /η ₀ ×100 (%) was measured by the bridge circuit method. The measurement frequency is
It was 1KHz. Here, η ₀ and η _T are the impedances of the sensor coil at the start of measurement and after time T, respectively. The wire rod sample and comparative alloy PA-4 (composition Pd=58%,
Figure 7 shows the temperature vs. electrical resistance curve of Ag=42%). In addition, the average temperature coefficient of electrical resistance 1/R・ΔR/ΔT obtained from this curve, and the performance and impedance of a sensor using the wire of the present invention alloy M-1 when continuously used for a long period of time at high temperatures of 800°C or higher The rate of change in is shown in Table 1. Incidentally, a comparative alloy prepared in the same manner as the invention alloy PAM-1
The sensor coil of PA-4 broke after 5 days at 800℃, but the sensor coil of PAM-1, the alloy of the present invention,
It operated normally and did not break even after more than a month at 1000℃.

[Table] Example 2 Alloy number PAM-19 (composition Pd=55.2%, Ag=
41.3%, Pt=3.5%) Production of alloy and sensor The raw materials are Pd, Ag and Pt of the same purity as in Example 1.
was used. The sample manufacturing method and experimental method are as in Example 1.
It is exactly the same. The electrical characteristics of the alloy sample and the sensor as well as the performance of the sensor are as shown in FIG. 8 and Table 2, and are similar to the results of Example 1.

【table】

[Table] Example 3 Alloy number PAM-25 (composition Pd=54.5%, Ag=
40.5%, Cu = 5.0%) Production of alloy and sensor The raw materials are Pd, Ag and Cu of the same purity as in Example 1.
was used. The sample manufacturing method and experimental method are as in Example 1.
It is exactly the same. The electrical properties of the alloy sample and sensor as well as the sensor performance are shown in FIG. 9 and Table 3, and are similar to the results of Example 1.

[Table] Example 4 Alloy number PAM-41 (composition Pd=47.3%, Ag=
40.7%, Au = 9.0%) Production of alloy and sensor The raw materials are Pd, Ag and Au of the same purity as in Example 1.
was used. The sample manufacturing method and experimental method are as in Example 1.
It is exactly the same. The electrical properties of the alloy sample and sensor as well as the sensor performance are shown in FIG. 9 and Table 3, and are similar to the results of Example 1.

[Table] In addition to the above-mentioned examples, experiments were also conducted on many alloys, and Table 5 shows the electrical properties, recrystallization temperature, average grain size, and alloy wire of the present invention of typical alloy samples. 10 at 800℃ for sensors using
It shows the rate of change in impedance when heated and held for days.

[Table] As shown in Table 5, the recrystallization temperature of the invention alloy is the comparative alloy (alloy number PA-4: Pd-42%Ag).
Approximately 50 to 100 degrees Celsius higher than that of Also, comparative alloy Pd−
The average crystal grain size of Ag is reduced by 1/2 to 1/7 by additive elements such as Ir, Pt, Cu, or Au, which has the effect of suppressing coarsening of the crystal grain size. Furthermore, the higher the recrystallization temperature and the smaller the average crystal grain size, the stronger the mechanical strength between crystal grains. From this, it can be said that the alloy of the present invention is superior in thermal stress fracture resistance to conventional comparative alloys. For example, the alloy of the present invention in Example 2 (alloy number
PAM-19) and comparative alloy (alloy number PA-4)
Next, a case will be described in which the method is applied to a sensor coil of an eddy current displacement meter. Alloy number PAM-19 (Pd-41.3%Ag-35%Pt)
and PA-4 (Pd-42%Ag) were applied to the sensor coil of an eddy current displacement meter, and as a result of repeating heating and cooling to a high temperature of approximately 700℃ approximately 20 times, the sensor coil using the comparative alloy was In this case, 7 out of 10 wires broke, but when the alloy of the present invention was used, none of the wires broke. Incidentally, a life test of a displacement meter was attempted using the present invention alloy and a comparative alloy (PA-4) for a sensor coil.
The test was conducted using a heating-air cooling method (HC) in which the sensor head was inserted into a Matsuful furnace kept at 1000°C, held there for 1 hour, then taken out of the furnace and returned to room temperature, and this operation was repeated. Two types of heat treatment are performed: a high-speed quenching method (HQ) in which immersion in water is returned to room temperature and this operation is repeated, and the number of heating-cooling cycles T is determined at the point when the output of the displacement meter disappears, that is, when the sensor coil is disconnected. I asked for Table 6 shows an example of the experimental results.

[Table] As shown in Table 6, in the case of the alloys of the present invention, there is not much difference in the heat treatment method, and moreover, the number of cycles until disconnection is reached is high. Therefore, it has been found that the alloy of the present invention has a life several tens of times longer than that of the comparative alloy. Also, the higher the number of these times, the better the material is, but 1000
If the temperature exceeds ℃, the oxidation of Ag in the alloy will proceed rapidly.
℃. Although Table 6 shows the case where the temperature is very high, it can be said that the lower the maximum heating temperature, the less likely the sensor coil will be disconnected. Judging from the solid line above, the cause of the disconnection of the sensor coil is thought to be that strong stress is applied to the grain boundaries of the crystals while the sensor coil repeats thermal expansion and contraction, causing grain boundary fracture. The alloy of the present invention has greatly improved this point, and at the same time, the sensor coil using the alloy of the present invention can sufficiently withstand even severe use at high temperatures, so that the thermal stress fracture resistance has been significantly improved. In other words, when the sensor coil material is repeatedly heated and cooled, strong stress is applied between the crystal grains due to thermal expansion and contraction. I found out that there was no disconnection. Therefore, the alloy of the present invention is
It was demonstrated that it has excellent thermal stress fracture resistance. As can be seen from the above Examples 1 to 4 and Table 5, a total of 0.1 to 10% of one or more of Ir, Pt, Cu, and Au, 40.2 to 43.0% of Ag, and a small amount of Pd as the balance. An alloy consisting of impurities of -
100ppm/in a wide temperature range from 150℃ to 1000℃
It has constant electrical resistance characteristics at ℃ and excellent thermal stress fracture resistance, and its major feature is that the change in electrical resistance with respect to temperature is significantly improved at high temperatures, as shown in Figures 7 to 10. . In addition, Fig. 11 A, B, C and D are Pd (50~
Ir, Pt, for specific electrical resistance ρ ₂₀ at 20°C of Pd-Ag alloy with composition range of
This is a characteristic diagram showing the effect of adding Ag or Au, and the discussion on the results is as follows. Generally, Ir, Pt, Ag or
When Au is added, ρ ₂₀ tends to increase. <Unfavorable as a material> However, when a small amount is added, the increase in ρ ₂₀ is extremely small or almost zero. <Preferred materials> Pd-Ag alloy and Ir, Pt, Ag or Au
The ρ ₂₀ of the additive alloys all reach a maximum when the Ag content is 35%, and gradually decrease as the Ag content increases. In other words, with a composition of Ag40.2-43.0,
Compared to when the Ag content is 40% or less, ρ ₂₀ is small, and the temperature coefficient of electrical resistance is extremely small. <These characteristics are very preferable as a material> The performance of the sensor using the alloy of the present invention also ranks fifth.
As shown in the table, Δη/η ₀ ×100 is extremely small, approximately 1/10 of that of comparative alloy PA-4, less than ±0.015%, and has excellent high-temperature stability, allowing the alloy of the present invention to fully exhibit its characteristics. I understand that. Here, in the composition of the alloy of the present invention, Ir7% or less,
A total of 0.1 to 10% of one or more of Pt5% or less, Cu7% or less, and Au9% or less, and Ag40.2 to
The reason for limiting it to 43.0% is as shown in Figures 1 to 6 and Figure 1.
As is clear from Figure 1, Examples 1 to 4, and Table 5, it exhibits constant electrical resistance characteristics with an average temperature coefficient of electrical resistance of 100 ppm/°C or less between -150°C and 1000°C. This is because the specific electrical resistance becomes relatively large as the amount of Ag increases. In addition, the impedance change rate of the sensor at high temperatures is less than ±0.100% and is extremely stable over a long period of time, but if the composition is outside this range, the average temperature coefficient of electrical resistance becomes large at 100 ppm/°C or more and becomes constant. This is because it is unsuitable for use as an electrical resistance alloy or as a sensor with excellent stability at high temperatures. The alloys shown in FIGS. 12A and 12B are the alloys of the present invention (PAM-19; Ag41.3%, Pt3.5 in Table 5), respectively.
%, Pd55.2% alloy) and comparative alloy (PA-4;
This is a sketch of a microscopic photograph of an alloy (58% Pd, 42% Ag) that was rapidly heated and cooled several times from room temperature to 700°C. The alloy of the present invention is a comparative alloy Pd
-Since Ir, Pt, Cu, or Au is added to Ag, the crystal grains do not become coarse like the comparative alloys even after heat treatment at 800℃ for 10 days, and the crystal grain size remains the same.
It is small, less than 50 μm, and exhibits a constant size. Incidentally, in the case of a comparative alloy, the crystal grain size becomes coarser to 100 to 500 μm by applying the same treatment, and the mechanical strength decreases, and furthermore, the sensor coil using this alloy does not have to be heated or cooled. As a result of repeated attempts, many wire breaks occurred, making it unsuitable as a wire for sensor coils. Therefore, the fifth
As shown in the table, it can be said that the smaller the crystal grain size of the alloy is, the more preferable it is. As mentioned above, in the case of the present alloy, as shown in Table 5, by adding a small amount of Ir, Pt, Cu or Au, the crystal grains are made finer (60 μm or less), Moreover, since the grain sizes are uniform, the contact bond between the crystal grains is good, and therefore the mechanical strength is high. Therefore, it was found that even when the sensor coil was repeatedly heated and cooled from room temperature to a high temperature of 700°C, there was little disconnection of the sensor coil wire. Furthermore, the reason why the temperature range in which the alloy of the present invention exhibits constant electrical resistance characteristics is limited to -150°C to 1000°C is as follows:
As is clear from Fig. 6, Examples 1 to 4, and Table 5, the average electrical resistance temperature coefficient within the above temperature range is 100 ppm/°C or less, which shows constant electrical resistance characteristics. Outside this temperature range, the average temperature coefficient of electrical resistance becomes 100 ppm/°C or higher, which not only does not meet the required properties of the alloy of the present invention, but also prevents the sensor from exhibiting its full performance. This is because it is inappropriate as a sensor with excellent stability. Furthermore, in the method for manufacturing the alloy of the present invention, the heat treatment is limited to 2 seconds to 100 hours at 200 to 1200°C, because within this temperature range and time, internal strain due to processing is sufficiently removed, and the stability is further improved. However, if heat treatment is performed at 200℃ or less for less than 2 seconds, constant electrical resistance characteristics cannot be obtained due to residual stress due to processing, and the sensor becomes extremely unstable when used at high temperatures. . Also
If heat treatment is performed at 1200°C or higher for 100 hours or more, the thermal stress fracture resistance deteriorates due to the coarsening of crystal grains, and furthermore, due to the evaporation of silver contained, not only is it impossible to obtain constant electrical resistance properties, but also the evaporated silver The electrical insulation properties may deteriorate due to contamination. Therefore, if the heat treatment conditions are deviated from the above, the sensor becomes unsuitable for use as a sensor with excellent constant electrical resistance characteristics or stability at high temperatures. The higher the heat treatment temperature, the shorter the treatment time. i.e.
Heat treatment at 1200°C for 2 seconds or 200°C for 100 hours sufficiently removes internal strain caused by processing and achieves the desired purpose. In short, the alloy and sensor of the present invention can be used at -150℃~
It has excellent constant electrical resistance characteristics with an average temperature coefficient of electrical resistance of 100 ppm/℃ or less in a temperature range of 1000℃, and excellent thermal stress fracture resistance, and even after long-term use at high temperatures, the impedance change rate is ±0.100% or less. These alloys and sensors are used as main components of device complexes and various measuring instruments, such as heating elements, hot wire anemometers, resistance thermometers, and thermometers. Even when applied to reference resistors such as constant current stabilizers, the excellent characteristics of the alloy and sensor of the present invention can be fully exhibited.

[Brief explanation of drawings]

Figure 1 shows the temperature of palladium-silver alloy from 0 to 400℃.
(), −150 to 1000℃ () and −200℃ to 1200
Characteristic diagrams showing the relationship between the average temperature coefficient of electrical resistance and the amount of Ag between temperatures in (), Figures 2 and 3
Figures 4 and 5 are respectively (Pd-Ag)
Shows the relationship between the average temperature coefficient of electrical resistance and Ag content at -150°C to 1000°C for +Ir-based, (Pd-Ag)+Pt-based, (Pd-Ag)+Cu-based, and (Pd-Ag)+Au-based alloys. Characteristic diagram, Figure 6 shows Pd-40%Ag alloy with Ir,
Characteristic diagrams showing the relationship between the amount of each element added and the average temperature coefficient of electrical resistance from -150℃ to 1000℃ when Pt, Cu or Au is added. Figures 7 to 10 are alloy number PAM-1. , PAM-19, PAM-25,
Characteristic diagram showing the relationship between electrical resistance and measurement temperature of PAM-39 and comparative alloy PA-4, Figure 11A,
B, C and D are Pd (50-70%)-Ag (30-50)
Ir for specific electrical resistance ρ ₂₀ of Ag alloy at 20℃,
Characteristic diagram showing the effect of adding Pt, Cu or Au,
Figure 12 A and B are alloys of the present invention (alloy number: PAM
-19; 41.3% Ag, 3.5% Pt, 55.2% Pd) and a comparative alloy (alloy number: PA-4; 58% Pd, 42% Ag).

Claims (1)

[Scope of Claims] 1 A total of 0.1 to 10% of one or more of iridium 7% or less, platinum 5% or less, copper 7% or less, and gold 9% or less, and silver 40.2 to 43% by weight. The remainder consists of palladium and a small amount of impurities, −
A constant electrical resistance alloy characterized by having constant electrical resistance characteristics and thermal stress fracture resistance with an average temperature coefficient of electrical resistance of 100 ppm/°C or less in a temperature range of 150°C to 1000°C. 2 A total of 0.1 to 10% of one or more of iridium 7% or less, platinum 5% or less, copper 7% or less, and gold 9% or less in weight ratio, 40.2 to 43% silver, the balance palladium and a small amount The alloy consisting of impurities is melted, cast, forged, and hot-worked and cold-worked into a desired shape such as a wire or plate, and then heated to a temperature of 200% in a non-oxidizing atmosphere or in a vacuum.
A method for producing a constant electrical resistance alloy, characterized by heating at ~1200°C for 2 seconds or more and 100 hours or less. 3. The constant electrical resistance alloy is heated at 200 to 500°C for several hours in a non-oxidizing atmosphere or in vacuum, cooled and solidified, and then further heated at 500 to 1200°C for 2 seconds or more and 100 hours or less. A method for producing a constant electrical resistance alloy according to claim 2, characterized in that: