JPH10259446A - Sliding member made of free graphite-precipitated ferrous sintering material excellent in seizuring resistance and wear resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sliding member made of a free graphite-precipitated ferrous sintering material excellent in seizuring resistance and wear resistance and showing excellent performance for a long period even in the case of practical use under severe conditions. SOLUTION: This sliding member is composed of a free graphite-precipitated ferrous sintering material contg., as forming components of free graphite to be precipitated, by weight, 1.1 to 4% C, 0.02 to 0.5% S and 0.01 to 0.5% B, as base strengthening components in solid solution, 0.5 to 2% Cu, as hardening particles, TiB2 and/or SiC by 0.5 to 2%, moreover as improving components of sintering property, 0.05 to 0.6% P if necessary, the balance Fe and inevitable impurities and having a structure in which finely precipitated free graphite and the hardening particles are dispersedly distributed among the base of pearlite.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a free graphite-precipitated iron-based sinter having excellent seizure resistance and abrasion resistance and exhibiting excellent performance for a long period of time even in practical use under severe conditions. The present invention relates to a sliding member made of a material.

[0002]

2. Description of the Related Art Conventionally, as described in, for example, JP-A-57-16148 and JP-B-57-8860, iron having a structure in which carbon powder blended as a raw material powder in a pearlite base material is dispersed and distributed. It is known that a sintered material is used as a sliding member such as a gear of an oil pump, a bearing of a rotary compressor, and a transmission part of an automobile. Further, the sliding member made of the iron-based sintered material is used to form a green compact formed from a mixed powder having a predetermined compounding composition in a reducing atmosphere. Low temperature, ie 900
It is also known that it is manufactured by sintering at a predetermined temperature in the range of ~ 1000 ° C.

[0003]

On the other hand, in recent years, various driving devices have been remarkably increased in output and reduced in weight, and accordingly, the use conditions of the above-mentioned sliding member, which is a structural member thereof, have become more severe. However, conventional sliding members made of iron-based sintered material, which has a structure in which relatively coarse unreacted residual carbon powder is dispersed and distributed in the above-described substrate, are subject to seizure when used under severe conditions. At present, the desired performance cannot be stably exhibited over a long period of time, in combination with the fact that the wear is facilitated and the progress of wear is promoted.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above-mentioned point of view, the seizure resistance and abrasion resistance
As a result of conducting research to develop
Finally, basically, Fe-BS alloy powder and carbon powder
Cu powder and titanium boride (hereinafter referred to as TiB) _TwoIndicated by
Powder) and / or silicon carbide (hereinafter referred to as SiC).
B) Using a powder, blending it into the prescribed formulation and mixing
A green compact formed from the mixed powder
Medium, relatively high sintering temperature of 1100-1250 ° C
Is heated to a predetermined temperature in the range of
-Sufficient solid solution in S alloy powder, and also solid solution in Cu powder
And cooling from this state, preferably at 40 ° C / min.
When sintering at a speed of cooling, the B and S are
Fine release of carbon dissolved in the substrate at sintering temperature during cooling
Acts to significantly promote precipitation as graphite
Therefore, fine free graphite is formed on the pearlite substrate.
Deposited and the TiB_TwoFine powder and SiC powder
Hard particles (preferably 2 μm or less in average particle size)
To obtain an iron-based sintered material with a dispersed structure
Composed of free graphite precipitated iron-based sintered material.
The sliding member is finely dispersed and distributed in the substrate.
It shows excellent seizure resistance due to free graphite and
Particles ensure good wear resistance.
Long-lasting performance even under severe conditions
The research result that it comes to demonstrate the ability
You.

The present invention has been made on the basis of the above-mentioned research results, and in terms of% by weight (hereinafter,% indicates% by weight), C: 1.1 to 4
%, S: 0.02 to 0.5%, B: 0.01 to
0.5%, and as a solid solution strengthening component,
0.5 to 4%, and it contains, as hard particles, TiB ₂ and / or SiC: 0.5 to 2% containing, if necessary, as a sintering resistance improving component, P: 0. 05-
0.6%, with the balance consisting of Fe and inevitable impurities, and a fine graphite precipitate free graphite and a free graphite precipitate iron-based sintered material having a structure in which the hard particles are dispersed in a pearlite base material. It is characterized by a sliding member made of a free graphite-precipitated iron-based sintered material having excellent seizure resistance and wear resistance.

Next, the reason why the component composition of the free graphite-precipitated iron-based sintered material constituting the sliding member of the present invention is limited as described above will be described. (A) C The C component forms a base pearlite to improve its strength, and precipitates as fine free graphite in the base due to the coexistence of B and S to improve seizure resistance. However, when the content is less than 1.1%, ferrite is precipitated in the base material and the strength is reduced. On the other hand, when the content exceeds 4%, grain boundary cementite is precipitated. As a result, the embrittlement rapidly occurs, so the content is set to 1.1 to 4%.
Desirably, the content is 1.5 to 2.5%.

(B) S and B These components have the effect of accelerating the coexistence of solid solution carbon in the matrix as fine free graphite during the cooling process. To demonstrate
As the raw material powder, it is desirable to use an Fe—B—S—S alloy powder formed by the atomization method from a molten metal containing predetermined amounts of B and S in Fe. Therefore, even if the content is either S or B, S : Less than 0.02% and B: less than 0.01%, not only the desired effect is not obtained in the above-mentioned effect, but also brittle grain boundary cementite is precipitated, while S is contained in either case. : 0.
If it exceeds 5% and B: 0.5%, the sinterability is impaired,
Since the strength is reduced, its content is set to S:
0.02 to 0.5%, B: 0.01 to 0.5%. Preferably, S: 0.1 to 0.3%, B: 0.1 to 0.3%.
The content is preferably from 0.5 to 0.2%.

(C) Cu The Cu component has the effect of improving the strength by forming a solid solution in the substrate, but if its content is less than 0.5%, the desired effect of improving the strength cannot be obtained. If the amount exceeds 4%, no further effect of improving the strength will be exhibited, and instead the expansion amount during sintering will increase, causing a decrease in dimensional accuracy.
Its content was determined to be 0.5-4%. Preferably 1-3
% Is good.

(D) TiB ₂ and SiC Since these components are extremely hard, they have an effect of improving the wear resistance by dispersing in a ferrite base material, preferably with an average particle size of 2 μm or less. If the content is less than 0.5%, the desired effect of improving wear resistance cannot be obtained,
On the other hand, if the content exceeds 2%, the strength decreases, so the content is set to 0.5 to 2%.
Preferably, the content is 0.8 to 1.5%.

(E) Since the PP component has a function of forming a liquid phase at the time of sintering to improve sinterability and contributing to improvement of strength, it is contained as necessary. If the amount is less than 0.05%, a desired strength improving effect cannot be obtained, while the content is 0.6%.
, The content becomes determined to be 0.05 to 0.6%. Preferably, 0.2
-0.3% is good.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the sliding member of the present invention will be specifically described with reference to embodiments. As raw material powders, various Fe—BS alloy powders, copper powders, carbon powders, and Fe—P alloys (P: 27%) each having variously changed contents of B and S each having a particle size of −300 mesh Contained)
A powder, further, a TiB ₂ powder having an average particle diameter of 1.5 μm and a SiC powder having an average particle diameter of 1 μm were prepared. Add 5% and add 3% in a V-type rotary mixer.
After mixing for 0 minutes, the mixture was pressed into a green compact at a pressure of 6 ton / cm ² , and then heated to a predetermined temperature in the range of 1100 to 1250 ° C. in an ammonia decomposition gas atmosphere in a mesh belt type continuous sintering furnace. After holding for 35 minutes, sintering was performed at a cooling rate of 35 ° C./min. To room temperature under the condition of cooling to obtain free graphite having substantially the same composition as the above-mentioned composition and the base structure shown in Tables 1 and 2. A tensile test piece composed of an iron-based sintered material and having the dimensions specified in JIS Z2550 and an outer diameter of 18 mm x an inner diameter of 8 mm x a thickness of 10 mm
Bearing members, which are one kind of sliding members, having the following dimensions: bearing members 1 to 12 of the present invention and comparative bearing members 1 and 2
Was manufactured respectively. The comparative bearing members 1, 2
Has a composition in which the content of any of the S and B components (marked with * in Table 2) affecting the precipitation of free graphite is out of the range of the present invention.

[0012]

[Table 1]

[0013]

[Table 2]

Next, for the purpose of evaluating the seizure resistance of the various bearing members obtained as a result, S4 was added to the bearing members.
While inserting a 5C carbon steel shaft and rotating the shaft at 4000 rpm (peripheral speed: 100 m / min.) Without lubricating oil, the surface pressure gradually increases, and the bearing member is rotated. The surface pressure (seizing load) at the time when the seizure phenomenon occurred was measured.
For the purpose of evaluating wear resistance, an S45C carbon steel shaft was inserted into the bearing member, and the shaft rotation speed was set to 4000.
A wear test was performed under the conditions of rpm, surface pressure: 20 kgf / cm ² , and operation time: 1 hour, and the maximum wear depth of the bearing sliding surface was measured. Further, for the purpose of evaluating the strength, a tensile test was performed using the above tensile test piece, and the tensile strength was measured. The results of these measurements are shown in Tables 1 and 2.

[0015]

From the results shown in Tables 1 and 2, all of the bearing members 1 to 12 of the present invention have a structure in which fine precipitated free graphite is dispersed and distributed in a pearlite base material, and thereby have excellent seizure resistance. And excellent performance coupled with improvement in wear resistance by fine hard particles dispersed and distributed on the base material. On the other hand, as seen in comparative bearing members 1 and 2, It is clear that if the content of any one of the components is out of the range of the present invention, the desired effect of improving seizure resistance cannot be obtained. As described above, the sliding member made of free graphite-precipitated iron-based sintered material of the present invention has excellent seizure resistance and abrasion resistance, so that even in practical use under severe conditions, excellent performance can be obtained for a long time. Therefore, the present invention has industrially useful characteristics such that it can sufficiently respond to high output and weight reduction of various driving devices.

Claims (2)

[Claims] 1. As a component for forming precipitated free graphite, C: 1.1 to 4%, S: 0.02 to 0.5%, and B: 0.01 to 0.5%. Cu: 0.5 to 4% as a reinforcing component, and titanium boride and / or silicon carbide: 0.5 to 2 as hard particles.
%, And the balance consisting of Fe and inevitable impurities (above, weight%), and a free graphite-precipitated iron-based sintered material having a structure in which fine precipitated free graphite and the hard particles are dispersed in a pearlite base material A sliding member made of a free graphite-precipitated iron-based sintered material having excellent seizure resistance and abrasion resistance, characterized by comprising: 2. As a precipitated free graphite-forming component, C: 1.1 to 4%, S: 0.02 to 0.5%, B: 0.01 to 0.5%. Cu: 0.5 to 4% as a reinforcing component, and titanium boride and / or silicon carbide: 0.5 to 2 as hard particles.
%, And further contains P: 0.05 to 0.6% as a sinterability improving component, with the balance being Fe and unavoidable impurities (the above, by weight%), and the base material of pearlite. Made of free graphite-precipitated iron-based sintered material with excellent seizure and abrasion resistance, characterized by being composed of free graphite-precipitated iron-based sintered material having a structure in which fine precipitated free graphite and the hard particles are dispersed. Sliding member.