JP3071361B2 - Method of forming film on inner surface of pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a coating on the inner surface of a pipe, and more particularly to a cylinder for a plastic injection molding machine.
The present invention also relates to a method for forming a film on the inner surface of a tube, which can form a film having excellent heat resistance and abrasion resistance on the inner surface of a small-diameter tube or the like that requires heat resistance and abrasion resistance.

[0002]

2. Description of the Related Art Generally, for parts requiring heat resistance or wear resistance, the whole or only necessary parts are formed of a material having a required function. In particular, as for a method of forming a part of the material having a required function, various methods have been proposed depending on the shape of a part, a part requiring a function, characteristics of a material satisfying a required function, and the like.

[0003] The present invention is directed to a component having a tubular shape and requiring heat resistance and wear resistance on its inner surface. It is generally known that ceramics or a metal-based material to which ceramics are added exhibit excellent performance in applications where heat resistance or wear resistance is extremely required.

[0004] In such a target field, various inventions have been proposed as prior art, but the technology which the inventors have paid particular attention to is the technology of Japanese Patent Application No. 3-3 filed by ourselves.
No. 51633, entitled "Title of Invention; Method for Forming Film on Inner Surface of Tube" (hereinafter referred to as "prior art 1").

The outline of the prior art 1 is as follows. As shown in FIG. 1, a core tube 3 made of a metal tube such as stainless steel.
A material 1 (hereinafter, referred to as "inner tube 1") is formed by forming a coating 4 such as a ceramic-added alloy on the outer surface of the material. In addition, a metal pipe such as carbon steel is used as a material 2 (hereinafter, referred to as “outer pipe 2”). As shown in FIG. 2, the inner pipe 1 is fitted inside the outer pipe 2 via the insert metal 5, the lid plate 7 is seal-welded, and then the hot isostatic press (HIP apparatus) is used. The inner tube 1 and the outer tube 2 are liquid-phase joined while applying pressure and heating from the outside. After the joining, as shown in FIG. 3, the core tube portion 3 of the inner tube 1 is removed by a cutting blade 6 or the like, so that a film is finally formed on the inner surface of the tube. Prior art 1
Is a very reasonable method for economically forming ceramics or a ceramic-added alloy lacking ductility on the inner surface of a pipe.

[0006]

When the prior art 1 was practiced, it was found that cracks often occurred in the solidified insert metal layer. Such cracks do not necessarily occur, but occur at a certain frequency. However, from the viewpoint of product yield, it is necessary to reduce the occurrence of cracks to a frequency that is economically acceptable.

Accordingly, an object of the present invention is to provide a condition for hardly causing cracks in an insert metal, to suppress the cracks as much as possible, and to provide an economically advantageous method for forming a film on the inner surface of a pipe. It is in.

[0008]

According to the method of forming a film on the inner surface of a tube according to the present invention, a film is formed on the outer surface of a core tube to prepare an inner tube, and then the inner tube is removed via an insert metal. A hot insert that is inserted into the pipe, then seal-welded a disc-shaped lid plate to both ends of the outer pipe, and then presses the outer pipe into which the inner pipe has been inserted only from the outside of the outer pipe. Applying a hydrostatic pressure treatment to join the inner pipe and the outer pipe via the insert metal, and then removing the core pipe, wherein the insert metal has a liquidus temperature of 500 And a foil made of a eutectic low-melting alloy in the range of 1 to 1100 ° C. and 50 wt. % And a foil having a total thickness of 1 mm or less by laminating a plurality of foils with a foil of a base metal contained in the alloy, and the total thickness of the foil of the base metal is made of the eutectic low melting point alloy. Not less than the total thickness of the foil, the hot isostatic pressing
The treatment temperature is set to be lower than the liquidus temperature of the eutectic low melting point alloy by 5
The present invention is characterized in that the process is performed under processing conditions in which the temperature range is 0 to 150 ° C. higher.

In the above method for forming a coating on the inner surface of a pipe, the insert metal may be one or more of the above-mentioned base metal foil and a coating made of the eutectic low melting point alloy formed thereon. Multiple layers are stacked to a total thickness of 1m
m, and the total thickness of the foil made of the base metal is not less than the total thickness of the film made of the eutectic low melting point alloy.

[0010]

The reason why the present invention prevents cracking of the insert metal portion will be described in detail below. If the insert metal is composed of one simple low melting point alloy,
All of the insert metal becomes a melt-solidified layer. On the other hand, due to the cooling after the end of the joining, a thermal stress is generated at the joining interface due to a difference in thermal expansion coefficient between the outer tube and the inner tube. In addition, the external pressure applied during joining is also released. As a result, a vertical residual stress is generated at the interface between the outer tube and the inner tube. Although the thermal stress is a compressive stress, the release of external pressure affects the tensile stress, but ultimately, the residual stress becomes a tensile stress.

Accordingly, tensile stress acts on the solidified portion of the insert metal existing between the outer tube and the inner tube, but most of the low melting point alloy constituting the insert metal is eutectic, and after the solidification, Eutectic materials generally lack ductility to tensile loads. In particular, Ni-base and Fe-base insert metals proposed in Prior Art 1 are low-ductility materials corresponding to this.

Next, the operation of the insert metal in the present invention will be described with reference to FIG. The present invention is a device in which the eutectic solidification metal of the insert metal is not parallel to the interface between the outer tube and the inner tube.

FIG. 4A shows the arrangement of the first insert metal. The insert metal is composed of a foil (alloy foil 9) made of a eutectic low melting point alloy and 50% of the eutectic low melting point alloy.
wt. % Of base metal (base metal foil 10). The base metal foil 10 is made of a base metal X, and the alloy foil 9 is made of a eutectic low melting point alloy XY alloy. FIG. 5 shows a phase diagram when Y is added to X. In the composition used here, Y is aw
t. % Eutectic composition.

FIG. 4B shows a state immediately after heating to the bonding temperature T1. Although the XY alloy is in a liquid phase, since the pressing force is applied from the outside, it is squeezed out to the outside,
The remaining liquid phase becomes smaller than the initial amount of the XY alloy foil.

FIG. 4C shows the case where the junction temperature is kept at T1. The remaining liquid phase and solid phase react, and the liquid phase expands. In this case, the reaction takes place in a direction in which the reaction is easy, such as a crystal grain boundary of the solid phase portion, so that the liquid portion becomes a network. Further, as the liquid phase portion expands, the liquid phase composition proceeds in a direction in which the Y component decreases. The composition of the Y component is as shown in FIGS.
In the intermediate composition b, the portion parallel to the interface between the outer tube and the inner tube always becomes thinner due to the squeezing effect by the pressing force, but such a phenomenon does not occur in the vertical direction. Is characterized by being thick.

FIG. 4 (4) shows a state in which the liquid phase has solidified by cooling. Coagulation is 100 wt. % X solid phase forms as primary crystals and continues to crystallize during cooling. As is clear from FIG. 5, the Y component of the remaining liquid phase gradually increases, and at the eutectic point temperature T2, the composition of the Y component becomes a and the eutectic solidification occurs at the same time. Since the liquid phase parallel to the interface between the outer tube and the inner tube has a small thickness, all of the liquid phase is replaced by crystallized X. As a result,
The eutectic solidification metal is only in the direction perpendicular to the interface. Primary crystal X
Has the same composition as the solid phase portion of (3) in FIG.
A eutectic metal part which is indistinguishable and finally solidifies is observed as shown in FIG. 4 (4).

In such a state, even if there is a residual tensile stress in the direction perpendicular to the interface, the brittle eutectic solidified metal is surrounded by the highly ductile X metal, so that no crack is formed.

These phenomena were confirmed by a laboratory reproduction sample designed so as not to apply a residual stress. FIGS. 7, 8, 9 and 10 show cross-sectional photographs of the sample.
7 and 9 show the joints of the prototype cylinder, and FIGS. 8 and 10 show the joints produced in a vacuum furnace. Here, the insert material used is a laminate of two 50 μm-thick pure Ni foils, each having a 10 μm-thick Ni
It is a stack of P alloys. 9 and FIG.
P alloy is 8 wt. % P-Ni and a solidus temperature of 88
0 ° C., liquidus temperature 1010 ° C. Joining temperature 950 ° C
In this case, since the liquid is in a solid-liquid two-phase state and has poor fluidity, the squeezing effect is unlikely to occur, and in the lateral direction at the center of FIGS.
A eutectic solidification structure is observed parallel to the interface (poor joining material).
On the other hand, in FIG. 7 and FIG. % P-
Ni and the liquidus temperature is 880 ° C. Joining temperature 9
At 50 ° C., a complete liquid phase is obtained, so that the squeezing effect is apt to occur, and no eutectic solidification structure is observed in the direction parallel to the interface (good joining material).

FIG. 6 shows the above-mentioned 8 wt. % P-Ni
5 is a drawing corresponding to FIG.

The factors necessary for controlling the distribution form of the eutectic solidification metal as described above are summarized as follows. (1) Squeeze out liquid metal by pressing force. (2) Network-like enlargement of the liquid phase due to the reaction with the base metal. (3) Reduction of the liquid phase thickness parallel to the interface by squeezing the liquid metal by the pressing force. (4) Crystallization of base metal by cooling. (5) Liquid metal remaining in the direction perpendicular to the interface. (6) Distribution of the eutectic solidified metal in the direction perpendicular to the interface.

The relationship between these factors and the claims is shown below. (1) and (3) are processes that require a pressing force, and the pressing force is an essential factor. (2) means that the coexistence of a metal that easily reacts with the liquid metal and a low melting point alloy is indispensable, and is the basis for the existence of the base metal foil. In addition, since the object cannot be achieved if the entire surface is in a liquid phase without forming a network, the base metal is required to have a certain limit or more for the low melting point alloy. On the other hand, as the joining temperature is increased from the liquidus temperature, the liquid phase due to the reaction increases. Considering the deterioration of the materials of the outer tube and the inner tube to be joined, the lower the joining temperature, the better.
For this reason, as a temperature that can be stably controlled in consideration of the uniformity of the temperature distribution, a temperature equal to or higher than 50 ° C. and equal to or lower than 150 ° C. of the liquidus temperature of the low melting point alloy is set as the bonding temperature. On the premise of such a temperature, a numerical value of 1 or more times that of the low melting point alloy was determined from experiments as the lower limit of the thickness of the base metal capable of obtaining a network-like liquid phase distribution.

If the above conditions are obtained, (4)
The conditions (5) and (6) are automatically achieved. In the present invention, a temperature higher than the liquidus temperature of the insert metal is used. At an intermediate temperature between the liquidus temperature and the solidus temperature, the low-melting alloy is in a solid-liquid two-phase state and has low fluidity, so that the squeezing effect by pressure is unlikely to occur.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described by way of embodiments with reference to FIGS. As shown in FIG. 1, length 0.2 m, outer diameter 26 mm, inner diameter about 22 mm, wall thickness 2 mm
3 mm thick ceramic-added alloy (40 VCvol.%) On the outer surface of the stainless steel (SUS304) core tube 3.
-Co) film 4 was formed by powder overlay welding. Next, as shown in FIG.
Through a nickel chrome molybdenum steel (SNCM439) through an insert metal 5 under predetermined conditions (see Table 1).
Was inserted into the outer tube 2 consisting of The insert metal 5 provided here is obtained by laminating a base metal foil and a low melting point alloy foil.

[0024]

[Table 1]

Next, a disc-shaped lid plate 7 is seal-welded to both ends of the outer tube 2 in which the inner tube 1 is disposed as described above. Thereafter, the inside of the tube is evacuated and sealed. The tube assembled in this manner is housed in a HIP device, and (800 ° C. × 500 atm × 1 hour) → (joining temperature ×
A two-stage HIP process (350 atm × 1 hour) was performed, and the inner tube 1 and the outer tube 2 were integrated. Here, the first cut is a step of preliminarily bringing the inner and outer tubes into close contact with each other, and the joining step is performed by the second cut.

Next, an ultrasonic flaw detection test was performed from the outer surface of the tube after the treatment, and cracks in the interface parallel direction at the insert metal joint were examined. Table 1 shows the test results.
Shown in

The joining temperature is 50 to 150 ° C. below the liquidus temperature.
It has been confirmed that at a high temperature, good bonding can be achieved regardless of the material of the low melting point alloy if the total thickness of the base metal foil is at least one time the total thickness of the low melting point alloy foil or the coating. It is also confirmed from the test results that good bonding cannot be obtained when the bonding temperature is lower than a temperature higher than the liquidus temperature by 50 ° C. or when the bonding temperature exceeds 150 ° C. than the liquidus temperature.

[0028]

As described above, according to the present invention, it is possible to easily form a coating (coating layer) having excellent heat resistance and abrasion resistance on the inner surface of a small diameter pipe. In the method of forming a film on the inner surface of the pipe accompanied by pressure treatment, the occurrence of cracks in the insert metal, which has been a problem in the past, is eliminated, which contributes to an improvement in yield, and thus has an industrially useful effect.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a process of the present invention.

FIG. 2 is a sectional view illustrating a process of the present invention.

FIG. 3 is a cross-sectional view illustrating a process of the present invention.

FIG. 4 is a schematic diagram illustrating the operation of the insert metal according to the method of the present invention.

FIG. 5 is a phase diagram of an insert metal.

FIG. 6 is a schematic diagram for explaining the operation of the insert metal according to a method outside the scope of the present invention in correspondence with FIG. 4;

FIG. 7 is a micrograph showing a metal structure of an insert metal according to the method of the present invention.

FIG. 8 is a micrograph showing the metal structure of the insert metal according to the method of the present invention.

FIG. 9 is a micrograph showing a metallographic structure of an insert metal according to a method outside the scope of the present invention.

FIG. 10 is a micrograph showing the metallographic structure of an insert metal according to a method outside the scope of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner tube 2 Outer tube 3 Core tube 4 Coating 5 Insert metal 6 Cutting blade 7 Lid plate 8 Seal welded part 9 Alloy foil 10 Base metal foil

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI C23C 4/16 C23C 4/16 (72) Inventor Kyoichi Sasaki 2068 Ooka, Numazu-shi, Shizuoka Pref. 72) Inventor Naotaka Kawaguchi 2068-3 Ooka, Numazu-shi, Shizuoka Pref. Toshiba Machine Co., Ltd. Numazu Office (56) References JP-A-6-218556 (JP, A) JP-A-5-138239 (JP, A) JP-A-4-317476 (JP, A) JP-A-3-234380 (JP, A) JP-A-3-234381 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 20 / 00

Claims (8)

(57) [Claims] 1. An inner tube is prepared by forming a film on the outer surface of a core tube, and then inserting the inner tube into the outer tube via an insert metal. The cover plate is seal-welded, and then subjected to a hot isostatic pressurizing process that presses the outer tube into which the inner tube has been inserted only from the outside of the outer tube, and the inner tube and the outer tube Is bonded through the insert metal, and then the core tube is removed. The insert metal has a liquidus temperature of 500 to 110.
A foil made of a eutectic low melting point alloy in the range of 0 ° C .; % And a foil having a total thickness of 1 mm or less by laminating a plurality of foils with a foil of a base metal contained in the alloy, and the total thickness of the foil of the base metal is made of the eutectic low melting point alloy. Not less than the total thickness of the foil, and the hot isostatic pressing is performed under processing conditions in which the processing temperature is set to a temperature range higher by 50 to 150 ° C. than the liquidus temperature of the eutectic low melting point alloy. A method for forming a film on the inner surface of a pipe, characterized by the following. 2. The insert metal is formed by laminating one or a plurality of eutectic low-melting alloy films formed on the base metal foil to a total thickness of 1 mm or less. The method for forming a coating on the inner surface of a pipe according to claim 1, wherein the total thickness of the foil made of the base metal is equal to or greater than the total thickness of the coating made of the eutectic low melting point alloy. 3. The method according to claim 1, wherein the coating is formed on the outer surface of the core tube by overlay welding. 4. The method according to claim 1, wherein the coating is formed on the outer surface of the core tube by thermal spraying. 5. The core tube of the inner tube is made of carbon steel, low alloy steel or stainless steel, and the outer tube is made of carbon steel, low alloy steel or stainless steel. Method of forming a film on the inner surface of a tube. 6. The coating according to claim 1, wherein the coating is a Co-based alloy, a Ni-based alloy or
3. A metal material such as an Fe-based alloy, or a ceramic material such as an oxide, a carbide, a nitride or a boride, or a composite material of the metal and one or more of the ceramics. The method for forming a film on the inner surface of a pipe as described in the above. 7. The insert metal is an alloy containing one or more of P, B and Si in Ni or an alloy containing one or more of B and Si in Fe. 3. The method for forming a coating on the inner surface of a pipe according to claim 1, comprising: 8. The liquidus temperature of the insert metal is:
The method for forming a film on the inner surface of a tube according to claim 7, wherein the temperature is lower than the solidus temperature of any of the core tube material, the outer tube material, and the film material.