JPH101704A - Sliding material and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain good joinability and to simplify the producing process by sinter-joining the surface of an ferrous base metal with a copper base sintering sliding material contg. titanium. SOLUTION: In this producing method, a green compact composed of lead- bronze powder is placed on a steel previously worked into a prescribed shape, which is passed through the inside of a reducing atmosphere, by which joining is executed together with sintering. At this time, titanmum as a sintering assistant is added to the lead-bronze powder for generating sufficient liq. phases in the joining and also preventing the coarsening of lead. In this way, the generation of a large amt. of liq. phases from the alloy components other than lead in the lead-bronze alloy can be suppressed, furthermore, the wettability of the lead-bronze alloy with the ferrous base metal can be improved, and moreover, the growth of the lead grains can be suppressed. In this way, the sliding material good in both of the sintering phases and joining state can be obtd. Moreover, since a plating stage is needless in the producing process, the process can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a copper-based sintered sliding material (sintered copper-lead alloy, lead-bronze alloy or bronze alloy) on a base material made of an iron-based material (iron or iron alloy). The present invention relates to a joined sliding member and a method for manufacturing the sliding member.

[0002]

2. Description of the Related Art Conventionally, the following method is known as a joining method for joining a lead bronze-based sliding material to iron or an iron alloy. Cutting the lead-bronze-based sliding material manufactured by casting etc., and placing this sliding material on a steel material whose surface is also copper-plated after being cut into a predetermined shape,
One that performs bonding by applying pressure at about 800 ° C. A weir is provided at a joint of steel materials cut into a predetermined shape, and a lead bronze-based material (a powder obtained by atomizing a cast material or an alloy material) is arranged in the weir. Charge into a furnace in a reducing atmosphere above the melting temperature of the material,
A lead bronze phase is melted and then cooled to obtain a melt-bonded lead bronze phase. Spread lead-bronze-based alloy powder on the backing metal, pass it through an electric furnace or gas furnace, perform primary sintering in a reducing atmosphere, crush the porous alloy layer by primary rolling, and again use the electric furnace. Through sintering to increase the degree of sintering of the alloy layer, and by secondary rolling to produce a sintered bimetal with improved backing metal strength, and join this bimetal by welding. This method is used for producing a copper-based bearing material. As an intermediate method to the above, after compacting a lead-bronze-based alloy powder, the formed material is placed on a steel material whose surface is subjected to copper plating after being cut into a predetermined shape. , Which are joined at a pressure of about 800 ° C. to increase the degree of sintering. According to this method, it is possible to join even a conical base material by applying pressure.

[0003]

However, in the above-mentioned method, since the casting material is plated and heated and pressurized, the plating cost is increased. Further, since the lead phase is likely to be continuously present in the cast structure, there is also a problem that the sliding material itself tends to be insufficient in strength and the sliding characteristics are not good.

[0004] In addition, the above-mentioned method has a problem in that the lead bronze melted in the furnace is liable to form sink marks on its surface when solidified. In addition, in order to prevent the occurrence of poor joining or casting defects due to insufficient wetting of the joining surface, it is necessary to increase the amount of lead bronze. As a result, there is a problem in that the processing cost increases and the cost increases. In addition, when the molten lead bronze solidifies, lead is likely to be continuously present in the vicinity of the bonding interface in accordance with the weight segregation phenomenon, which tends to lead to a remarkable reduction in bonding strength itself.

[0005] Next, in the above-mentioned method, since a process of manufacturing a sintered bimetal and a process of joining the sintered bimetal to a steel material are involved, the process becomes complicated and a cost increase cannot be avoided. There is a point.

Further, in the above-mentioned method, a lead bronze material having a uniform structure can be obtained by sintering, but there is a problem that the cost is increased due to the copper plating step. In particular, when the steel material has a large diameter and a large weight, the cost is remarkably increased.

Further, when a cast iron material is used as the base material in the above methods (1) to (4), graphite present on the joint surface is removed by, for example, corin treatment before copper plating,
Since it is necessary to avoid a significant wettability impairment during plating and joining with a copper-based material, there is a problem that the cost cannot be avoided.

In order to solve such problems, the present invention remarkably simplifies the manufacturing process by eliminating a costly plating process and employing a sliding material manufacturing process by sintering. It is another object of the present invention to provide a sliding member capable of obtaining good joining characteristics and a method for manufacturing the same.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a method in which a copper-based sintered sliding material is joined to a base material made of an iron-based material at the time of sintering without plating. ,
In addition, as a method for obtaining an appropriate sintered structure, attention has been paid to adding titanium as a sintering aid to a copper-based sintered sliding material. That is, the sliding material according to the present invention is:
The present invention is characterized in that a copper-based sintered sliding material containing titanium is joined to a surface of a base material made of an iron-based material by sintering.

According to this sliding material, since titanium is contained as a sintering aid, the wettability of the copper-based sintered sliding material to the iron-based base material at the time of joining is improved. A good joining condition can be obtained between the sintered sintered sliding material and the iron-based base material. In particular, when the copper-based sintered sliding material is a material containing lead such as a lead bronze material, The coarsening of the particles is suppressed, and a structure in which the lead is finely dispersed in the iron-based base material can be obtained. The addition of titanium can also improve the wear resistance of the sliding material.

The base material may be any one of a steel material, a cast iron material, and an iron-based sintered material. Further, the copper-based sintered sliding material may be any one of a copper-lead alloy, a lead-bronze alloy, and a bronze alloy. Further, the addition ratio of the titanium is preferably set to 0.2 to 3.0% by weight.

[0012] When using cast iron in which graphite has been precipitated as the base material, by incorporating titanium into the copper-based sintered sliding material, the graphite and titanium precipitated at the joint interface are positively reacted with each other, so that graphite can be obtained. , The wettability and the bondability can be improved.

Next, the method for producing a sliding material according to the present invention is as follows.
When joining a copper-based sintered sliding material to a base material made of an iron-based material, a copper-based sintered sliding material obtained by adding titanium is used, and this copper-based sintered sliding material is combined with the base material. And sintering to bond to the base material at the same time.

According to this manufacturing method, since the plating step is omitted and the sliding material manufacturing step by sintering is adopted, the manufacturing step can be simplified, and the cost can be prevented from increasing. A good joining state can be obtained between the base sintered sliding material and the base material made of an iron-based material.

The sintering is preferably performed in a reducing or neutral atmosphere gas having a dew point of -30 ° C. or less. If the purpose is to obtain a particularly stable dew point and to stabilize the wettability when the copper-based sintered sliding material is joined, N
_It is more preferable to carry out in a neutral gas reduced pressure atmosphere such as ₂ . However, under a reduced pressure of 10 torr or less, the composition variation due to the evaporation of Pb and Sn contained in the sintered material during sintering exceeds 1.0 wt%,
The problem is that the deposition of Pb and Sn in the furnace increases maintenance costs on equipment. Also, 600 to
Since the effect of reduced pressure is not remarkable at rr or more, an appropriate reduced pressure range is preferably 10 to 600 torr.

The base material may be any one of a steel material, a cast iron material and an iron-based sintered material. Further, the copper-based sintered sliding material may be any one of a copper-lead alloy, a lead-bronze alloy, and a bronze alloy.

Further, the addition ratio of the titanium is 0.2 to 0.2.
It is preferably 3.0% by weight. This addition ratio is 0.
If the content is less than 2% by weight, foaming properties, in other words, the swelling of the sintered body due to gas generated from the inside of the sintered body at the time of sintering will be exhibited. Opponent material (eg, SCM440H, SUJ2
Etc.).

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a compact formed of lead bronze powder is placed on a steel material previously processed into a predetermined shape, and is passed through a furnace in a reducing atmosphere, whereby sintering is performed simultaneously with sintering. Done.

In order to join a lead-bronze-based sintered material, the sintering must be performed at a high temperature. However, when the sintering temperature is increased in this way, lead particles that secure conformability in terms of sliding characteristics grow and grow, resulting in a decrease in strength of the sintered material. On the other hand, in order to finely disperse the lead particles, sintering must be performed at a low temperature. However, at a low sintering temperature, the amount of generated liquid phase is small, so that wetting is not sufficient and bonding is insufficient.

Therefore, in the present invention, in order to generate a liquid phase sufficient for bonding and not to coarsen lead, titanium is added to lead bronze powder as a sintering aid to improve. By adding titanium in this way, the generation of a large amount of liquid phase from alloy components other than lead of the lead bronze alloy is suppressed, and the wettability of the lead bronze alloy to the iron-based base material is improved, and further, the lead particles Growth will be suppressed. In this way, it is possible to obtain a sliding material having a good sintering phase and a good joining state. The sliding material according to the present invention is suitable for application to a lower wheel retainer such as a bulldozer.

[0021]

Next, specific examples of the sliding member and the method of manufacturing the sliding member according to the present invention will be described.

As shown in FIG. 1, Cu (copper),
Tests were conducted on 11 types of copper-based sintered sliding materials having different weight ratios of Sn (tin), Pb (lead), Ti (titanium), and Zn (zinc). In this test, each material was mixed with a V-type mixer, and then molded at a pressure of ² t / cm ² to obtain a green compact of a copper-based sliding material. The shape of the green compact is as shown in FIG.
FIG. 2B shows the shape of the iron-based base material. A characteristic feature of the base metal shape is to provide a weir at the inner diameter of the sintered body in consideration of the shrinkage allowance of the copper-based sintered body during sintering. The point is that the system sliding material can be bonded accurately. That is,
From the viewpoint of manufacturing technology, the fact that the sintered body can be joined by being placed on the top has great advantages in terms of productivity and handling. The base material is SCM440H and FC
D420 cast iron was used. As a material specifically used, Cu is an electrolytic copper material CE manufactured by Fukuda Metal Foil Powder Industry.
15, Sn is Sn-At2 also made by Fukuda Metal Foil Powder Industry
50 and Pb are also Pb-At2 manufactured by Fukuda Metal Foil Powder Industry
50, and Ti is a Ti-H powder manufactured by Sumitomo Snack.

No. 1 shown in FIG. The compact of the copper-based sliding material of 1 to 10 is placed on the iron-based base material of the SCM440H material,
The results of sintering at 850 ° C. and 890 ° C. for 1 hour in a nitrogen atmosphere at 600 torr are shown in FIG. 3 and FIG. Also,
Similarly, in the case of No. 1 shown in FIG. The compacts of copper sliding materials of 1, 3, 5, 11 were placed on the SCM440H material, and the dew point was -2.
FIG. 5 shows the results of sintering and joining at 840 ° C. in an ammonia decomposition gas atmosphere at 7 ° C. The hardness shown in FIGS. 3 to 5 was measured by a Vickers hardness tester with a load of 1 kg. Also, the area ratio in the figure is a measurement of the joint area ratio between the iron-based base material and the copper-based sliding material by an ultrasonic nondestructive inspection machine,
If it is 100%, it indicates that it is completely joined. Further, the foaming property is an evaluation of whether or not blisters are generated in the sintered body by a gas generated from the inside of the sintered body at the time of sintering at the time of sintering. In addition, No. in FIG. No. 4 * indicates the use of FCD420 cast iron as the iron base material. 4 satisfies the above-described object of the present invention without any problem. FIG. The structure of the 4 * joint was shown. The bonding shear strength at this interface (determined by the method shown below) is 1
The strength was very high at 5.2 kg / mm ^2, and the difference was hardly noticeable except that the base material was FCD420. This is considered to be because the shear fracture surface occurred on the copper-based sintered body side of the interface, and it was confirmed that the bonding interface had a sufficiently high strength.

Next, the bonding shear strength obtained by preparing a TP as shown in FIG. 7 from the sintered level test piece (TP) shown in FIGS. 4 and 5 is also shown in FIGS. Indicated. No. Although the TP of No. 1 is cut out from the portion having the highest bonding ratio as much as possible, the remarkable improvement of the bonding strength is clearly recognized by the addition of titanium.
As a cause of these, as described above, Pb is finely and uniformly dispersed in the sintered material by the addition of titanium to prevent segregating action such that Pb is continuously connected,
Further, as shown in FIG. 6, it is considered that the titanium component contained in the liquid phase generated at the time of joining and sintering is strongly joined by a reaction with graphite, carbon in iron, and even iron itself. In addition, the addition of a small amount of titanium significantly improves the wettability to Fe, thereby improving the bonding area ratio. This is also due to the remarkable reducing power of titanium contained in the liquid phase and the above-described reactivity. It is thought that there is.

Next, in order to investigate the effect of the addition of titanium on the sliding characteristics of the copper-based sliding material, the test piece No. 1 was used.
A test piece having a shape as shown in FIG. 8 was machined for 1, 2, 3, 5, 7, and 8, and a sliding friction and wear test (friction coefficient, abrasion amount of a sliding material and a mating material) was performed under the following test conditions. Measurement). The test results are shown in FIG. Test conditions: (1) surface pressure; 600 kg / cm ² (2) peripheral speed; 1 m / s (3) oil amount; 150 cc / min oil type; EO30 (4) mating material; SUJ2QT material (HRC50) 0 surface roughness .8S, lap finishing (5) Sliding time: 50hr

From these test results, the proportion of titanium added to the copper-based sliding material is preferably 0.2 to 3.0% by weight. If the addition ratio is less than 0.2% by weight, the sintered body exhibits foaming properties, and a remarkable effect on wear resistance as a sliding material is not expected. If it exceeds 3.0% by weight,
At the time of sliding, the mating material is attacked and the sliding characteristics deteriorate.

In this embodiment, titanium is added to the copper-based sliding material. However, the same effect can be obtained by adding a chromium-titanium alloy.

[Brief description of the drawings]

FIG. 1 is a table showing test materials of copper-based sintered sliding materials.

FIG. 2A is a diagram showing a green compact shape of a copper-based sliding material,
(B) is the shape of the iron-based base material.

FIG. 3 is a table showing sintering results of the material of FIG. 1;

FIG. 4 is a table showing the results of sintering of the material of FIG. 1;

FIG. 5 is a table showing the results of sintering of the material of FIG. 1;

FIG. 6 is a micrograph showing a metal structure of a joint.

FIG. 7 is a diagram showing a shear test piece.

FIG. 8 is a view showing a sliding test piece.

FIG. 9 is a table showing the results of a sliding friction and wear test on the test piece of FIG. 3;

Claims (8)

[Claims] 1. A sliding material characterized by joining a copper-based sintered sliding material containing titanium by sintering to a surface of a base material made of an iron-based material. 2. The sliding material according to claim 1, wherein the base material is any one of a steel material, a cast iron material, and an iron-based sintered material. 3. The sliding material according to claim 1, wherein the copper-based sintered sliding material is one of a copper-lead alloy, a lead-bronze alloy, and a bronze alloy. 4. The method according to claim 1, wherein the titanium is added in an amount of 0.2 to 3.
The sliding material according to any one of claims 1 to 3, wherein the content is 0% by weight. 5. When joining a copper-based sintered sliding material to a base material made of an iron-based material, a copper-based sintered sliding material obtained by adding titanium is used. A method for manufacturing a sliding material, comprising sintering in combination with the base material and joining the sintering to the base material at the same time. 6. The method according to claim 5, wherein the base material is one of a steel material, a cast iron material, and an iron-based sintered material. 7. The sliding material according to claim 5, wherein the copper-based sintered sliding material is any one of a copper-lead alloy, a lead-bronze alloy, and a bronze alloy. Method. 8. The addition ratio of the titanium is 0.2 to 3.
The method according to any one of claims 5 to 7, wherein the amount is 0% by weight.