JPH09106892A - SUS sheath type component and manufacturing method thereof - Google Patents

Abstract

(57) Abstract: The present invention provides a heat-resistant and corrosion-resistant SUS sheath type component capable of preventing a conductor wire from being broken, and a method for manufacturing the same. SOLUTION: This SUS sheath type component is applied as a protection tube 7 of a glow heater 6. Protective tube 7 is SUS
A pipe 1 having a hollow portion made of a substrate, a coating layer 5 for coating the surface of the pipe 1 and forming a uniform layer containing at least all elements of Ni, Cr, Al, and the pipe 1 and the coating layer 5. The intermediate layer 4 having a composition rich in Al interposed therebetween is formed. A filling member 3 made of MgO powder is filled so that the coil 2 is embedded in the pipe 1. The coil 2 includes a heating portion wire 2H and a resistance portion wire 2R.
It is composed of

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a SUS sheath type component applicable as a pipe for glow heaters, thermocouples, heat exchangers and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, a sheath type component has been used as a protective tube for a metal glow plug or a sheath type thermocouple used at a high temperature, and there is one made of a metal such as SUS. Some sheath type components are used in an atmosphere of 1000 ° C. or higher, and in that case, they are made of a special heat-resistant alloy such as Inconel. Further, the ceramic sheath type component is developed as a glow plug or a glow heater of a fuel ignition auxiliary device in a diesel engine,
It has been developed as a thermocouple that accurately measures the temperature of high-temperature liquids and gases. The thermocouple measures various temperatures in the temperature range of 300 ° C. to 1400 ° C., and thus various measuring materials are used. By the way, regarding the production of the glow heater,
A raw material containing Si and Ti is infiltrated into the W coil to prepare a molded body, which is inserted into a sheath or pipe made of Si ₃ N ₄ and then this is subjected to reaction sintering, and the glow heater has a uniform composition. (For example, see Japanese Patent Laid-Open No. 7-217886). Further, the thermocouple was similarly constructed. That is, the wires of the thermocouple are often weak against an oxidizing or reducing atmosphere, and the wires are generally put in a protective pipe for use.

[0003] Japanese Patent Application Laid-Open No. 6-160200 discloses a sheath-type thermocouple with an airtight terminal. The thermocouple does not cause a measurement error even if a temperature gradient occurs in a terminal portion due to a transient temperature change or the like, and a thermocouple element wire composed of a dissimilar metal wire of an alumel wire and a chromel wire is made of a stainless steel sheath. The sheath is housed in an insulated state together with an inorganic insulating material, and the base end side of the sheath is hermetically sealed by an airtight terminal portion. An insulating sleeve is inserted inside two copearl through pipes attached to the ceramic end plate of the hermetic terminal portion, and each thermocouple wire is drawn out without passing through the inside and directly contacting the through pipe. Have been.

[0004]

However, when a conventional protective tube is made of SUS, the protective tube has a low heat-resistant use temperature of about 900 ° C. and has a low heat-resistant temperature in sulfur gas. In use, the metal in the protective tube is attacked by sulfur gas, so that use in sulfur gas is difficult. Further, when the protective tube is made of a special heat-resistant alloy such as Inconel, the heat-resistant temperature of the protective tube is higher than that of the SUS protective tube, but the cost is approximately doubled.

Further, the sheath type thermocouple with an airtight terminal disclosed in Japanese Patent Laid-Open No. 6-160200 mentioned above uses a stainless steel sheath as a protective tube, but the stainless steel sheath is directly exposed to the outside atmosphere. In a state where, for example, a gas such as sulfur gas exists in the atmosphere,
There is a problem that corrosion occurs in the sheath itself and durability is reduced.

[0006]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems by producing a hollow pipe from a SUS substrate and fusing metal particles to the surface of the pipe.
Next, the present invention relates to a SUS sheath type component in which a uniform particle fusion coating is formed by swaging to improve heat resistance and corrosion resistance of SUS to improve durability, and a manufacturing method thereof.

The present invention is characterized by comprising a pipe having a hollow portion made of a SUS substrate, and a uniform coating layer containing at least all elements of Ni, Cr and Al for coating the surface of the pipe. The present invention relates to a SUS sheath type component. An Al-rich intermediate layer is interposed between the pipe and the coating layer.

Further, in this SUS sheath type component,
The intermediate layer is composed of an alloy of Al and Si.

Further, the SUS sheath type component is applied to a glow heater by filling a filling member so that a heater coil is embedded in the pipe.

Further, this SUS sheath type component is applied to a thermocouple by filling a filling member so that a pair of different kinds of wires are embedded in the pipe.

Further, this SUS sheath type component is applied to a heat exchanger for exchanging heat in which a fluid flows inside and outside the pipe.

Alternatively, according to the present invention, a step of forming an Al film containing one of Al and Al alloys on the surface of a pipe having a hollow portion made of a SUS substrate, the Al film formed on the pipe. Forming a particle film by heat-fusing particles containing all elements of Ni, Cr, Al on the pipe, and swaging the pipe coated with the particle film to make the particle film uniform and form a coating layer. And a step of forming the SUS sheath type component.

This SUS sheath type component has the above-mentioned structure, and in the process of heat-fusing Ni-Cr-Al particles on the surface of the SUS substrate, the S of the substrate constituting the pipe is S.
A reaction layer is formed between the US and the Ni-Cr-Al particles, and the two are firmly bonded. Of the Ni-Cr-Al particles, Cr and Al form an oxide protective film on the surface,
The amount of oxygen diffused inside is reduced, and the progress of oxidation of itself is suppressed. Further, the Al-rich layer as the intermediate layer is SU
Since it is present on the surface of the S substrate, the bond between the coating layer and the intermediate layer is strengthened, and the oxide protective film is stabilized for a longer period of time, and the durability is improved accordingly.
Further, in this SUS sheath type component, the surface layer of the coating layer is N
Since i is the main component, it is stable even in an atmosphere containing a corrosive gas such as sulfur gas.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the SUS sheath type component and the manufacturing method thereof according to the present invention will be described below with reference to FIG. FIG. 1 is a sectional view showing an embodiment of a glow heater as this SUS sheath type component.

As shown in FIG. 1, there is shown an embodiment in which this SUS sheath type component is applied to the protective tube 7 of the glow heater 6. The protective tube 7 of this SUS sheath type component is SU
Pipe 1 having a hollow portion made of S substrate, pipe 1
The coating layer 5 forms a uniform layer containing at least all the elements of Ni, Cr and Al for coating the surface of. Further, an intermediate layer 4 having a composition rich in Al is interposed between the pipe 1 and the coating layer 5. Specifically, the intermediate layer 4 is composed of an alloy of Al and Si. A glow heater 6 using this SUS sheath type component as a protective tube 7 is filled with a filling member 3 in which a coil 2 as a conductor wire is embedded in a pipe 1. Also, this S
When the US sheath type component is configured as the protection tube 7 of the glow heater 6, the coil 2 is configured by, for example, the heat generating part wire 2H made of an Fe—Cr coil and the resistance part wire 2R made of a Ni coil. Further, as the filling member 3,
It is possible to use MgO powder and densely fill the pipe 1.

Next, a method of manufacturing this SUS sheath type component will be described. In the method of manufacturing the SUS sheath-type component, first, the intermediate layer 4 made of any material of Al and Al alloy is formed on the surface of the pipe 1 having a hollow portion made of the SUS substrate (step 1). Then, particles containing all elements of Ni, Cr, and Al are heat-fused on the intermediate layer 4 formed on the pipe 1 to form a particle film (step 2). Finally, the pipe 1 covered with the particle film is reduced to a predetermined size by swaging to form a uniform coating layer 5 on the particle film (step 3).

Next, an embodiment in which this SUS sheath type component is applied to the protective tube 17 of the thermocouple 10 will be described with reference to FIG. FIG. 2 is a sectional view showing an embodiment in which this SUS sheath type component is applied to a thermocouple protection tube. This SUS
When the sheath type component is manufactured as the protection tube 17 of the thermocouple 10, the conductor wire 12 is composed of two kinds of wire, one wire 12A is composed of W-5% Re, and the other wire 12B is composed of W. It is composed of -26% Re. Also, protection tube 1
A long pipe 11 having a small diameter is used as 7.
As the filling member 13, MgO powder can be used as in the above-mentioned embodiment. The thermocouple 10 is filled with a filling member 13 in which a wire 12 is embedded in a pipe 11.
The pipe 11 has a hollow portion made of a SUS base,
At least Ni, Cr, A covering the surface of the pipe 11
a coating layer 15 forming a uniform layer containing all elements of 1;
And an intermediate layer 14 having a rich Al composition interposed between the pipe 11 and the coating layer 15. Or
The intermediate layer 14 is made of an alloy of Al and Si.

Although not shown, this SUS sheath type component can also be applied to a heat exchanger in which a fluid flows in a pipe. When applied as a heat exchanger pipe,
Even if the fluid flowing outside the pipe is a fluid such as sulfur gas, it improves the corrosion resistance of the pipe itself,
The durability can be improved.

[Embodiment 1] In this SUS sheath type component manufacturing method, an embodiment for producing a glow heater is shown in FIG.
This will be described with reference to FIG. First, a pipe 1 made of SUS304L and having an outer diameter of 8 mm was immersed in an Al melt to form an Al film on the surface of the pipe 1. Next, a fixing agent such as glue is applied on the Al film formed on the pipe 1,
Ni, Cr and Al powders are made to dive into the bed and
These powders were deposited on the I film. Ni, Cr and A
The pipe 1 to which the powder is attached is heated to 1100 ° C. in a vacuum, and Ni, Cr and Al powder are heat-fused on the Al film of the pipe 1 to form a protective tube 7 as a SUS sheath type component.
Was prepared. Next, in the protective tube 7, the Fe-Cr wire 2A and N
A coil 2 in which the end 8 of the i-wire 2B is welded and connected in series.
Is placed in the protective tube 7 so that the coil 2 is embedded.
The filling member 3 made of gO powder was filled.

The protection tube 7 filled with the coil 2 and the filling member 3 is swaged by using a swaging machine or the like, the outer diameter of the protection tube 7 is reduced to 4 mm, and the filling density of the filling member 3 inside is reduced. The glow heater 6 was manufactured by increasing the thickness of the heat-resistant particle layer on the surface of the coating layer 5 in a uniform manner. In the glow heater 6, the Al film interposed between the pipe 1 and the coating layer 5 forms the intermediate layer 4, and the intermediate layer 4 enhances the bonding strength with the coating layer 5 composed of Ni, Cr and Al particles, and Al ₂ O in a high temperature oxidizing atmosphere
₃ was generated, and the oxidation resistance could be improved. Further, in the glow heater 6, the coil 2 is designed so that the saturation temperature becomes 1000 ° C.

In order to measure the characteristics of the glow heater 6, the tensile strength (MPa) with respect to the oxidation temperature (° C.) after the protection tube 7 is exposed to an oxidizing atmosphere is measured, and the life of the protection tube 7 with respect to the number of times of use is measured. did. Glow heater 6
For comparison with the conventional glow heater, a conventional glow heater having a protective tube made of SUS itself was prepared. FIG. 3 shows the measurement results of the tensile strength (MPa) with respect to the oxidation temperature (° C.) after exposing the glow heater 6 (invention product) to the conventional glow heater (conventional product) in an oxidizing atmosphere. As shown in FIG. 3, the tensile strength of the product of the present invention was hardly reduced even in an atmosphere having an oxidation temperature of 1100 ° C. However, when the oxidation temperature of the conventional product was 700 ° C. or higher, the tensile strength was significantly decreased. It was found that in the atmosphere of 1100 ° C., the tensile strength was almost lost, and the heat resistance was also significantly reduced.

In order to test the durability of the glow heater 6, 11 V was applied to the glow heater 6 and the life at that time was measured. FIG. 5 shows the results of the durability test of the glow heater 6 (the present invention product) and the conventional glow heater (the conventional product).
As can be seen from FIG. 5, in the conventional product, the SUS forming the protective tube was damaged after 400 cycles (times) or less, and the coil was oxidized and disconnected. On the other hand, the product of the present invention reached a life of 4400 cycles (times), and was found to have sufficient durability.

[Embodiment 2] In this method of manufacturing a SUS sheath type component, an embodiment of manufacturing a thermocouple protection tube will be described with reference to FIG. In this embodiment, as the wire rod 12, two kinds of wire rods 12 connected in series in which end portions 18 of a wire rod 12A made of W-5% Re and a wire rod 12B made of W-26% Re are connected are selected. The protective tube 17 was manufactured in the same manner as in the above example. That is, a pipe 11 made of SUS304L and having an inner diameter of 6 mm was dipped in an Al molten metal to form an Al film on the surface of the pipe 11. Next, a fixing agent such as glue is applied onto the Al film formed on the pipe 11, and this is dipped in the bed of Ni, Cr and Al powders,
These powders were deposited on the Al film of the pipe 11. N
The pipe 11 on which the i, Cr and Al powders are adhered is heated to 1100 ° C. in vacuum, and N is formed on the Al film of the pipe 11.
The i, Cr, and Al powders were heat-fused to produce a protective tube 17 as a SUS sheath type component. Next, the protection tube 17
Wire rod 12A consisting of W-5% Re and W-26% Re
The wire rod 12 connected to the wire rod 12B was placed, and the protective tube 17 was filled with the filling member 13 made of MgO powder so that the wire rod 12 was buried.

The protection tube 17 filled with the wire 12 and the filling member 13 is swaged using a swaging machine or the like to reduce the outer diameter of the protection tube 17 and increase the filling density of the filling member 13 inside. The heat-resistant particle layer on the surface was uniformly formed on the film-shaped coating layer 15 to prepare the thermocouple 10. The thermocouple 10 is the same as in the above-mentioned embodiment.
1 and the coating layer 15 form an intermediate layer 14 which enhances the bonding strength with the coating layer 15 composed of particles of Ni, Cr and Al, and the Al layer in the high temperature oxidizing atmosphere. ₂ O ₃ was generated and the oxidation resistance could be improved.

The tensile strength (MPa) with respect to the oxidation temperature (° C.) after exposing the protective tube 17 constituting the thermocouple 10 to the oxidizing atmosphere was measured, and the life of the protective tube 7 with respect to the number of times of use was measured. With respect to the characteristics of the protective tube 17 of the thermocouple 10, the same results as in Example 1 could be obtained. That is,
It was found that the product of the present invention showed almost no decrease in tensile strength even in an atmosphere having an oxidation temperature of 1100 ° C., and the oxidation resistance was improved.

In order to test the durability of the thermocouple 10, it is assumed that the thermocouple 10 is used in a chemical plant and temperature measurement is performed, and the thermocouple 10 is subjected to 600 ° C. in a sulfur gas atmosphere.
The thermocouple 10 was used at a temperature of ℃, and the thermoelectromotive force change (%) with respect to the number of times of use of the thermocouple 10, that is, the number of cycles (times) was measured. Also,
In order to compare the thermocouple 10 with the conventional thermocouple, a protective tube made of SUS itself was prepared as the conventional thermocouple. FIG. 4 shows the results of changes in thermoelectromotive force with respect to the number of cycles (times) between the thermocouple 10 (the product of the present invention) and the conventional thermocouple (the conventional product). As can be seen from FIG. 4, the conventional product is 30
When the number of cycles exceeds 0 (time), the SUS that constitutes the protective tube is damaged, the internal wire rod is oxidized and deteriorated, and the thermoelectromotive force change becomes 1% or more. Has grown. On the other hand, the product of the present invention is
It was found that the change in thermoelectromotive force was 1% or less even when the life reached 500 cycles or more (cycles), and the durability was sufficient.

Example 3 In this example, an Al layer was used as the intermediate layer 4 in Example 1, but an Al—Si layer was used instead of the Al layer. The same test as in Example 1 was conducted on the obtained glow heater, and it was found that the glow heater had durability equal to or higher than that in Example 1.

[0028]

The SUS sheath type component and the method for manufacturing the same according to the present invention are configured as described above and have the following advantages. That is, this SUS sheath type component is
The surface of the pipe made of the substrate should be at least Ni, C
Since a coating layer forming a uniform layer containing all elements of r and Al is formed, and an intermediate layer having a composition rich in Al is interposed between the pipe and the coating layer, the SUS of the pipe itself is inserted. Is protected by the coating layer, and the corrosion resistance and heat resistance can be improved without lowering the strength even after exposure to an oxidizing atmosphere. Moreover, this SUS
The sheath type component firmly holds the wire rod placed in the protective tube in a state where the density of the filling member is increased, and is protected by the oxidation-resistant and heat-resistant protective tube. Excellent, the temperature measurement accuracy is high when applied to a thermocouple, and a stable and reliable thermocouple can be provided, which is particularly suitable for measuring high temperature in an oxidizing / reducing atmosphere. .

When this SUS sheath type component is used as a protective tube for a glow heater, the saturation temperature is 10%.
When the temperature was set to 00 ° C, the number of times of use was significantly extended, and the life could be extended. That is, the protective tube did not corrode, and the wire rod was not broken due to oxidation, and a glow heater having a high durability could be provided. In addition, when this SUS sheath type component is used as a protective tube for a thermocouple, it is possible to improve the corrosion resistance even when used in sulfur gas, the thermoelectromotive force change is small, and the thermocouple is highly durable. Could be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment in which a SUS sheath type component according to the present invention is applied to a glow heater.

FIG. 2 is a sectional view showing an embodiment in which the SUS sheath type component according to the present invention is applied to a thermocouple.

FIG. 3 is a graph showing the tensile strength of the product of the present invention and the conventional product with respect to the oxidation temperature.

FIG. 4 is a graph showing a change in thermoelectromotive force with respect to the number of cycles of the product of the present invention and the conventional product.

FIG. 5 is a graph showing the cycle life of the product of the present invention and the conventional product.

[Explanation of symbols]

 1,11 Pipe 2 Coil (conductor wire) 2H Heat generating wire 2R Resistance wire 3,3 Filling member 4,14 Intermediate layer 5,15 Covering layer 6 Glow heater 7,17 Protective tube 10 Thermocouple 12, 12A, 12B Wire

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location F28F 19/06 F28F 19/06 B // B21D 53/06 B21D 53/06 Z

Claims (7)

[Claims] 1. A pipe having a hollow portion made of a SUS substrate, and at least N coating the surface of the pipe.
A SUS sheath type component comprising a uniform coating layer containing all elements of i, Cr and Al. 2. An Al-rich intermediate layer is interposed between the pipe and the coating layer.
SUS sheath type parts. 3. The SUS according to claim 2, wherein the intermediate layer is composed of an alloy of Al and Si.
Sheath type parts. 4. The SUS sheath type component according to claim 1, wherein a filling member is filled so that a heater coil is embedded in the pipe and is applied to a glow heater. . 5. The thermocouple according to claim 1, wherein the pipe is filled with a filling member so that a pair of different kinds of wires are embedded in the pipe.
The SUS sheath type component according to the item. 6. The heat exchanger according to claim 1, wherein the heat exchanger exchanges heat with a fluid flowing in and out of the pipe.
The SUS sheath type component according to any one of 3 above. 7. A step of forming an Al film containing a material of Al or an Al alloy on the surface of a pipe having a hollow part made of a SUS substrate, Ni on the Al film formed on the pipe, Forming a particle film by heat-sealing particles containing all elements of Cr and Al, and forming a coating layer by uniformizing the particle film by swaging the pipe coated with the particle film, A method of manufacturing a SUS sheath type component, comprising: