JP3257694B2 - Manufacturing method of composite member - 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 manufacturing a composite member in which a material having a predetermined function is compounded on the surface of a base material to form a functional material layer on the surface of the base material. The present invention relates to a method for eliminating internal defects of a functional material at the same time as the formation.

More specifically, steel materials, Ni alloys, C
o When applying a functional material having excellent corrosion resistance and abrasion resistance to the surface of an alloy, the method relates to a method of not generating pores (voids) inside the functional material.
The present invention relates to a method for producing a composite member particularly suitable for applications such as a screw.

[0003]

2. Description of the Related Art As a conventional technique for forming a functional material layer by compounding a material having a predetermined function on the surface of a base material, as shown in FIG. Then, after degassing and sealing by welding, there is a method of sintering under hydrostatic pressure (Kobe Steel Engineering Report Vo)
l. 40 No. 1 (1990) pp. 30-33). This method has advantages such as high bending strength and high impact value because a sintered layer without pores is obtained. However, since the hermetic welding process and the degassing process are required, the manufacturing process is long. In addition, since the gasket is pressurized and deformed at a high temperature, the hermetic weld may be damaged. Since a hermetic welding process is required, a material that cracks by welding (for example, a material having good hardenability or a hard and brittle material) cannot be used as the base material. This is because, if a material having good hardenability is used as a base material, cracks occur in the welded portion during welding, airtightness cannot be maintained, and as a result, production by this method is impossible. In addition, in this method, since the sintering is performed under hydrostatic pressure, the base material is deformed. For this reason, especially when manufacturing a complex member having a complicated shape, an advanced welding technique and a technique for predicting deformation at a high temperature are required. Actually, it is empirically determined by performing a preliminary test for each dimension and shape.

Accordingly, the present inventor has proposed a technique as shown in FIG.
A method has been proposed in which a raw material powder filling space is formed in a base material, and then the raw material powder is filled therein and sintered in a vacuum or a reducing atmosphere (Japanese Patent Application No. 2-338635). This method
There is no welding or degassing process, and the process is simplified. Since no pressure is applied at a high temperature during composite sintering, deformation of the base material is small. Therefore, it is easy to predict the finished dimensions of the functional material layer and the base material. Further, since there is no airtight welding step and no degassing and airtightening steps, there is an advantage that there is no breakage of the welded portion during heating.
However, in this method, a small amount of pores may be generated in the obtained functional material layer, and in this case, there is a problem that mechanical strength, bending strength, and impact value are reduced.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to eliminate the steps of welding and degassing, simplify the steps, and improve the hardenability. Good materials, hard and brittle materials can be used as the base material, and even if the raw material powder is deformed in the high-temperature pressing step, the amount of deformation can be accurately predicted and no pores are generated.
An object of the present invention is to provide a method for producing a composite member having high bending strength and impact value.

[0006]

According to the present invention, there is provided a process for forming a raw material powder filling space in a predetermined portion of a base material, wherein the filling space contains at least two kinds of components and is heated at a lower temperature than the base material. A step of arranging a raw material powder having a temperature region in which a solid phase and a liquid phase coexist, and a step of heating the base material and the raw material powder thus arranged at a sintering temperature in the temperature region, 100kgf / cm ² Heating at a sintering temperature in the temperature range under an inert gas atmosphere.

[0007]

According to the method of the present invention, a raw material powder filling space 12 is formed at a predetermined position of a base material 10 (see FIGS. 2A and 2A). The material powder filling space 12 is formed by, for example, a surface release material (not shown) that does not wet the melt generated from the material powder 16 on the surface of the jig 14.
Is applied, and the jig 14 is combined with the substrate 10. After forming the raw material powder filling space 12, the raw material powder 16 is filled therein (see FIG. 2B). The base material 10 has a melting point higher than the temperature at which the raw material powder 16 generates a liquid phase. The raw material powder 16 includes a Ni alloy, a Co alloy, a mixture thereof, a mixed powder of a Ni alloy and a carbide, a mixed powder of a Co alloy and a carbide, a mixed powder of a Ni alloy, a Co alloy and a carbide, and a Ni alloy. Composite particles (carbide and Ni produced by sintering or casting, carbide and Co, mixed powder of carbide and Ni and Co), mixed powder of Co alloy and composite particles, Ni alloy and Co alloy and composite particles And the like. The base material 10 includes a metal or an alloy having a melting point equal to or higher than the liquidus point of a Ni self-fluxing alloy or a Co self-fluxing alloy, such as a steel material, a Ni alloy, and a Co alloy.

Next, as shown in a thermal cycle of FIG. 1, a soaking step, a temperature raising step, and a sintering step are sequentially performed on the base material 10 filled with the raw material powder 16. The soaking step is performed at a temperature just below the solidus point of the raw material powder.
Preferably, the temperature is 2.0 ° C./min.

In the sintering step, the sintering of the raw material powder 16 and the substrate 1
The functional material layer 18 is formed on the surface of the base material by performing a compounding process (sintering) with the substrate material (see FIG. 2C). First, vacuum sintering is performed, followed by hydrostatic pressure sintering. Perform knotting continuously. In vacuum sintering, the raw material powder 16 is vacuum-heated in a temperature region where a liquid phase and a solid phase are generated, and the sintering of the raw material powder 16 and the joining with the base material 10 are advanced. The reason for performing vacuum sintering in the range of coexistence of the solid phase in the method of the present invention is as follows. (1) The functional material layer formed by sintering does not collapse due to gravity. (2) A functional material close to true density can be obtained. (3) No shrinkage cavities (voids) are generated.

(4) When the temperature is low and only solid particles are used, a functional material having a density close to the true density cannot be obtained, sintering does not proceed, and the material becomes porous. On the other hand, when the temperature is high and only the melt is used, the flow-down shape cannot be maintained due to gravity. Generates shrinkage cavities (vacancies). The degree of vacuum is the degree of vacuum in ordinary vacuum sintering (generally, 1 × 10 ^{−2 to} 1.0 Torr).

In the hydrostatic pressure sintering to be performed next, after the vacuum sintering, an inert gas such as an argon gas is sealed and pressurized, and the above-described sintered layer (functional material layer 18) is pressurized. Is filled with a liquid phase (see FIG. 1, d). This pressure is 1
00kgf / cm ² As described above, the pores are extinguished by the pressure. This pressure is adjusted according to the viscosity and quantity of the melt. In this case, pressure is also applied to the surfaces of the base material 10 and the jig 14, but since a space is formed between the “base material and jig” and the “liquid phase and solid phase particles”, the pressure ( 1 and d) to prevent the substrate 10 and the jig 14 from being deformed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments shown in the drawings. (Example 1)

Embodiment 1 shown in FIGS. 3 to 5 will be described. A barrel 14 for a twin-screw extruder (material SCM440C, outer diameter D: 450 mm, length 1; 480 mm), a jig 14
(Material S25C, outer diameter d; 160 mm, distance between center axes s; 156 mm), and tighten the filling space 12 (width 4
mm). Alumina is sprayed on the surface of the jig, and a treatment is performed so that the melt of the raw material powder 16 (hereinafter, referred to as a liquid phase) and the jig 14 do not get wet. As a result, the raw material undergoes sintering shrinkage on the base material side, and the functional material is compounded on the base material 10. As the raw material powder 16, 9.8% Ni by weight%,
24.2% Cr, 2.9% B, 3.2% Si, 7% W,
An alloy powder having the balance of Co was used. Since the alloy having this composition has excellent corrosion resistance and abrasion resistance, it satisfies the performance of a barrel for an extruder. The particle size of the raw material powder 16 is 180 μm or less. The solidus point of this alloy is 1030 ° C and the liquidus line is 1
Since the solid phase and the liquid phase coexist in a temperature range of 1030 to 1130 ° C, sintering is performed in this temperature range. The reason is that when sintering in the temperature range of solid-liquid coexistence,
This is because a dense layer can be obtained without the functional material layer 18 falling down. If sintering is performed at a temperature lower than the solidus point, sintering is not completed and many bores remain. Collapse occurs and shrinkage nests occur.

Next, while the raw material powder 16 was dropped and filled from above the space shown in FIG. 3, the outer diameter portion of the base material 10 was vibrated with a copper hammer. At this time, the filling rate was 60%. The raw material powder 16 is sufficiently dried before filling. Drying conditions are 120 ° C. for 2 hours.

After filling the raw materials, sintering was performed by the thermal cycle shown in FIG. First, heating was performed in a vacuum (0.2 Torr). Here, the temperature is kept at 1020 ° C. for 4 hours, so that the whole processed product has a uniform temperature. This temperature (1020 ° C.) is about 10 ° C. lower than the solidus point of the raw material powder. Thereafter, the mixture was gradually heated at a heating rate of 0.5 ° C./min, and heated to a sintering temperature of 1090 ° C. When kept at 1090 ° C. for one hour, the raw material powder 16 sintered almost close to the true density. However, at this point, slight pores still remain, so that argon gas was sealed and pressurized to remove the pores. The pressure applied at this time depends on the viscosity of the liquid phase. In this embodiment, 500 kgf / cm ² And kept in that state for 30 minutes and then cooled.

After cooling, the jig 14 was removed, and the inner diameter and the pitch between the inner diameters of the barrel base material for a twin-screw extruder were measured to be 163.4 ± 0.2 mm, 156 ± 0.
The dimensions were in the range of 2 mm (see FIG. 5). The inner diameter dimension almost coincided with the value 163.2 predicted from the packing ratio of the raw material. Although a small amount of excess liquid phase solidified substance R adheres to the lower portion of the sintered layer (functional material layer 18), there is no problem in function. When the bending strength and impact value of the functional material layer 18 (sintered layer) obtained by the method of Example 1 were measured at the time of finishing, 135 kgf / mm ² , 0.8kgf / c
m ² It became. When this value was compared with the value of the composite material obtained by the prior application method shown in FIG. 13, the values were 30% and 24% better, respectively. (Example 2)

Embodiment 2 shown in FIGS. 6 and 7 will be described. Cylinder substrate 10 for injection molding machine (material SCM440C,
Height 1; 1250 mm), jig 14 (material SUS30)
4) was bolted to form a filling space 12 (the inner diameter d of the space: 36 mm, the outer diameter D: 38 mm) with the spacer 20 interposed therebetween. The surface of the jig is subjected to alumina spraying so that the melt of the raw material powder 16 (hereinafter, referred to as a liquid phase) and the jig 14 are not wetted. As a result, the raw material undergoes sintering shrinkage on the base material side, and the functional material is compounded on the base material 10. In the raw material powder 16, 10.0% Cr by weight%,
An alloy powder having a composition of 2.2% B, 3.2% Si, and the balance Ni was used. Since the alloy having this composition is excellent in both corrosion resistance and abrasion resistance, the performance of the barrel for an extruder was satisfied. The raw material powder 16 used had a particle size of 180 μm or less. This alloy has a solidus point of 960 ° C. and a liquidus point of 1060 ° C.

The outer diameter of the substrate 10 was vibrated with a copper hammer while the raw material powder 16 was dropped and filled from above the space shown in the figure of the embodiment. At this time, the filling rate was 61%. The raw material powder 16 is sufficiently dried before filling. Drying conditions are 120 ° C. for 2 hours.

After filling the raw materials, sintering was performed by the thermal cycle shown in FIG. First, it was heated in vacuum (0.2 Torr) and kept at 950 ° C. for 2 hours. This is to ensure that the whole processed product has a uniform temperature, which is about 10 ° C. lower than the solidus. Thereafter, the temperature was gradually increased at a rate of 0.5 ° C./min, and the temperature was raised to a sintering temperature of 1025 ° C. When the raw material powder 16 was maintained at 1025 ° C. for 1 hour, the sintering of the raw material powder 16 was almost close to the true density. However, at this time, since slight pores still remain, next, argon gas is sealed and pressurized to remove the pores.
In this case, 100 kgf / cm ² And kept in that state for 30 minutes and then cooled.

After cooling, the jig 14 was removed and the inner diameter was measured. As a result, the size was in the range of 36.8 ± 0.25 mm. The inner diameter dimension almost coincided with the predicted value of 36.8 mm calculated from the filling rate of the raw material. Then, the functional material layer 18 having no pore was obtained, and the functional material layer 18 and the base material 10 were firmly bonded. Next, after sintering, a predetermined machining was performed to finish. When the bending strength and impact value of the functional material layer 18 (sintered layer) obtained by the same treatment as in Example 2 were measured, it was 124 kgf / mm ^2. , 0.74kgf / cm ²
Which are 20% and 26% respectively compared to the method of the earlier application.
% Value was excellent. (Example 3)

A third embodiment shown in FIGS. 8 and 9 will be described. Check valve base material 10 for injection molding machine (material SKH4, height l; 3)
A jig 14 (material S25C) is bolted to the outer periphery of 2 mm) to form a filling space 12 (inner diameter d; 35 mm, outer diameter D; 39 mm). The surface of the jig is sprayed with alumina and melted as a raw material powder 16 (hereinafter referred to as a liquid phase).
And the jig 14 are treated so as not to get wet. As a result, the raw material undergoes sintering shrinkage on the substrate 10 side, and the functional material is composited on the substrate 10. In the raw material powder 16, weight%
A mixture of 70 parts of an alloy powder having a composition of 3.0% B, 4.3% Si and the balance of Ni having a particle size of 180 μm or less and tungsten carbide having a particle size of 10 μm or less was used. Since the mixture of this composition has excellent corrosion resistance and abrasion resistance, it satisfies the performance of a barrel for an extruder. The raw material powder 16 has a particle size of 180
Those having a size of μm or less were used. The solidus point of this alloy powder is 76
The liquidus point is 1065 ° C at 0 ° C.

The outer diameter of the substrate 10 was vibrated with a copper hammer while the raw material powder 16 was dropped and filled from above the space shown in FIG. At this time, the filling rate was 63%. The raw material powder 16 is sufficiently dried before filling. Drying conditions are 120 ° C. for 2 hours.

After filling the raw materials, sintering was performed by the thermal cycle shown in FIG. First, heating was performed in a vacuum (0.2 Torr). The temperature is kept at 950 ° C. for 20 minutes in order to keep the whole processed product at a uniform temperature, which is about 10 ° C. lower than the solidus line. Thereafter, the temperature is gradually increased at a rate of 1 ° C./min, and the temperature is raised to a sintering temperature of 1080 ° C. When kept at 1080 ° C. for 20 minutes, the raw material powder 1
In No. 6, sintering proceeds almost at the true density. However, at this point, slight pores still remain, so that argon gas was sealed and pressurized to remove the pores. In this case, 100 kgf / cm ² , And kept in this state for 20 minutes, and then cooled.

After cooling, the jig 14 was removed and its outer diameter was measured. The outer diameter was 37.4 ± 0.1 mm. The inner diameter is the value calculated and predicted from the filling rate of the raw material.
It almost coincided with 7.5 mm. Then, the functional material layer 18 having no pore was obtained, and the functional material layer 18 and the base material 10 were firmly bonded. The hardness of the substrate 10 (SKH4) is H _R C45.
The hardness was good as a check valve. After sintering, it was machined and finished. When the bending strength and impact value of the functional material layer 18 (sintered layer) obtained by the same method as the method of the present invention at the time of finishing were measured, it was 113 kgf / mm ^2. ,
0.49kgf / cm ² This is 18% and 21% better than the method of the previous application, respectively. (Example 4)

A fourth embodiment shown in FIGS. 10 to 11 will be described. Screw base 10 (material Stellite # 12, the hardness H _R C47, ingredient; wt% with 1.3% C, 1.2% S
i, 29.0% Cr, 8.0% W, balance Co, height l;
The jig 14 (material: SUS304) is bolted to the outer periphery of 62 mm) to fill the space 12 (the inner diameter d of the space; 46 m).
m, outer diameter D; 50 mm). The surface of the jig is sprayed with alumina so that the melt of the raw material powder 16 (hereinafter referred to as a liquid phase) and the jig 14 are not wetted. This is because the raw material causes sintering shrinkage on the base material side, and the functional material is compounded on the base material 10. Raw material powder 1
No. 6, 10.0% by weight, 2.2% B, 3.2% by weight.
An alloy powder having a composition of% Si and the balance of Ni and having a particle size of 180 μm or less was used. Since the alloy having this composition has excellent corrosion resistance and abrasion resistance, it satisfies the performance of a barrel for an extruder. The raw material powder 16 used had a particle size of 180 μm or less.
This alloy has a solidus point of 960 ° C. and a liquidus point of 1060 ° C.

The outer diameter of the base material 10 was vibrated with a copper hammer while the raw material powder 16 was dropped and filled from above the space shown in FIG. At this time, the filling rate was 61%. The raw material powder 16 is sufficiently dried before filling. Drying conditions are 120 ° C. for 2 hours. After filling the raw materials, sintering was performed by the same thermal cycle as in Example 3.

After sintering, it was finished by predetermined machining.
Then, a uniform functional material layer 18 of about 1 mm is formed on the surface of the substrate 10.
Was manufactured. When the outer diameter was measured with the jig 14 removed, the dimensions were in the range of 48.4 ± 0.1 mm. The outer diameter dimension almost coincided with the predicted value of 48.4 mm calculated from the filling rate of the raw material. Then, the functional material layer 18 having no pore was obtained. Functional material layer 18 and substrate 1
0 was tightly bound. Further, the base material 10 (SKH4)
Had a hardness of H _R C45, which was good as a check valve.

[0028]

According to the present invention, space formation, material filling,
By a simple process of sintering, the functional material having no bore and the substrate can be combined. Further, since a welding process (airtight process) is not required, it is possible to form a composite using tool steel and high-speed steel having excellent hardenability as a base material. In addition, since there is no welding step, the balancing operation after sintering becomes extremely easy. Further, since the substrate is pressed and crushed and does not deform, the dimensions of the substrate do not change. Although the thickness of the functional material varies, it is easy to predict and can be accurately calculated from the filling rate at the time of material filling. It is within an error of about ± 0.2 mm. The tensile strength and impact value of the functional material layer 18 obtained by the method of the present invention are equivalent to those obtained by the conventional method of hydrostatic pressure sintering, and are higher than those obtained by the method of the prior application. This is probably because the pores in the layer disappeared.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a thermal cycle of the method of the present invention.

FIG. 2 is a diagram showing changes of a base material and raw material powder in the heat cycle of FIG. 1 in the order of a to d.

FIG. 3 shows a cylinder for a twin-screw extruder (at the time of material filling) applied in Example 1, in which a is a plan view and b is a cross-sectional view.

FIG. 4 is an explanatory diagram of a heat cycle applied in Example 1.

FIG. 5 is a cylinder for a twin-screw extruder (after sintering) applied in Example 1, in which a is a cross-sectional view and b is a plan view.

FIG. 6 is an explanatory view of a cylinder for an injection molding machine (at the time of material filling) applied in Example 2.

FIG. 7 is an explanatory diagram of a heat cycle applied in Example 2.

FIG. 8 is an explanatory view of a check valve for an injection molding machine (at the time of material filling) applied in a third embodiment.

FIG. 9 is an explanatory diagram of a heat cycle applied in Example 3.

FIG. 10 is a plan view and FIG. 10B is a cross-sectional view of the screw (at the time of material filling) applied in Example 4.

FIG. 11 is a sectional view of a screw (after sintering) applied in Example 4.

FIG. 12 is an explanatory diagram of a conventional technique.

FIG. 13 is an explanatory diagram of the prior art.

[Explanation of symbols]

Reference numeral 10: base material, 12: raw material powder filling space, 14: jig, 1
6 ... raw material powder, 18 ... functional material layer.

Claims (10)

(57) [Claims] 1. A step of forming a raw material powder filling space at a predetermined position of a base material, wherein the filling space contains at least two kinds of components and a solid phase and a liquid phase coexist at a lower temperature than the base material by heating. Arranging the raw material powder having a temperature region to be heated; heating the base material and the raw material powder thus arranged at a sintering temperature in the temperature region under a vacuum atmosphere; and then, 100 kgf / cm ² Heating at a sintering temperature in the above temperature range under an inert gas atmosphere as described above. 2. A step of forming a raw material powder filling space in a predetermined portion of the base material is performed by combining a jig with the base material, and a surface release material that is not wet with the melt of the raw material powder is applied to the surface of the jig. 2. The method for manufacturing a composite member according to claim 1, wherein: 3. The raw material powder is selected from the group consisting of a Ni alloy, a Co alloy, and a mixture thereof.
A method for manufacturing a composite member. 4. The raw material powder according to claim 1, wherein the raw material powder is selected from the group consisting of a mixed powder of a Ni alloy and a carbide, a mixed powder of a Co alloy and a carbide, and a mixed powder of a Ni alloy, a Co alloy and a carbide. A method for manufacturing a composite member. 5. The raw material powder is selected from the group consisting of a mixed powder of Ni alloy and composite particles, a mixed powder of Co alloy and composite particles, and a mixed powder of Ni alloy, Co alloy and composite particles. Item 10. A method for producing a composite member according to Item 1. 6. The composite particles include carbide and Ni, and carbide and C.
6. The method for manufacturing a composite member according to claim 5, wherein said composite member is made of a material selected from the group consisting of a composite particle of carbide, Ni and Co. 7. The method according to claim 5, wherein the composite particles are manufactured by sintering or casting. 8. The method according to claim 1, wherein the base material is a metal or an alloy having a melting point equal to or higher than a liquidus point of a Ni self-fluxing alloy or a Co self-fluxing alloy. 9. The method according to claim 8, wherein the base material is a steel material. 10. The method according to claim 8, wherein the base material is a Ni alloy or a Co alloy.