JPH04157140A - Ferrous sintered sliding member - Google Patents

Abstract

PURPOSE:To improve the machinability, wear resistance and plastic workability of a member by dispersing a prescribed amt. of lubricating substance constituted of Mg metasilicate or the like into a metallic matrix constituted of a pearlite matrix and a steadite phase and executing compacting and sintering. CONSTITUTION:This ferrous sintered sliding member is formed of a compsn. constituted of, by weight, 1.5 to 4% C, 1 to 5% Cu, 0.1 to 2% Sn, 0.1 to O.5% P, 0.5 to 2% intercrystalline inclusions and the balance Fe. Then, its structure is formed of a one in which free graphite and intercrystalline inclusions are dispersed into a metallic matrix having a mixed structure of a pearlite matrix and intercrystalline inclusions. The above intercrystalline inclusions are constituted of an Mg metasilicate series mineral or, together with this, an Mg orthosilicate series mineral or an Mg metasilicate series mineral and/or an Mg orthosilicate series mineral and B nitride and/or Mn sulfide.

Description

[Detailed description of the invention] <Industrial field of application> The present invention provides an iron-based sintered sliding part made of a sintered alloy with excellent wear resistance and free machinability, suitable for use in various bearings, etc. This is related to ヰ4.

<Conventional technology> Conventionally, in order to impart wear resistance to iron-based sintered materials, a large amount of graphite, which has a solid lubricating effect, was added, and a portion of it was diffused into the matrix during sintering. There is a wear-resistant sliding part I4 which is left as free graphite after drying and is suitable for various uses utilizing the lubricating effect of the residual graphite.

Therefore, in order to obtain free graphite in this material,
The sintering temperature needs to be lower than that for general iron-based materials, but as a result, the bond between particles becomes weaker, resulting in a sliding member that is more likely to wear under conditions of high surface pressure. There were drawbacks.

Therefore, a predetermined amount of copper, tin, and phosphorus were further added, and liquid phase sintering was performed at a temperature of 980 to 1100'C to form free graphite in a pearlite base mixed with Fe-p-c ternary products (steadite phase). An iron-based sintered alloy which eliminates the defects found in the above-mentioned iron-based sintered sliding members by forming a structure in which ions are dispersed is disclosed in Japanese Patent Publication No. 54-42335 or Japanese Patent Publication No. 55-348.
This method has been proposed in Publication No. 58 and the like.

<Problem to be solved by the invention> By the way, the iron-based sintered sliding member improved as described above has the following problems:
Even when sintered at a relatively low temperature, the strength of the sintered material does not weaken as in conventional methods, and its strength can be increased, making it suitable for sliding members such as bearings used under high surface pressure. However, it has the disadvantage of poor machinability, so it has been desired to improve the machinability of parts that require cutting.

This invention was made in view of the circumstances mentioned in 1.The purpose of this invention is to be able to use it even under high surface pressure, and to be able to use it even under high surface pressure, compared to conventional sintered sliding members. The object of the present invention is to provide an iron-based sintered sliding member made of a sintered alloy that mainly improves machinability and has excellent wear resistance and free machinability.

<Means for Solving the Problems> In order to achieve the objects mentioned in 1-, the iron-based sintered sliding member according to the present invention has an overall composition of C1.
%, Cu1-5%, Sn0.1-2%, Po, 1-0.
It is a structure in which free graphite and intergranular inclusions are dispersed in a metal matrix, which is a mixed structure of pearlite base and steady phase, with 0.5 to 2% of intergranular inclusions and the balance Fe, 1; The intergranular inclusions are magnesium metasilicate minerals, or magnesium metasilicate minerals and magnesium orthosilicate minerals, magnesilate metasilicate type minerals or magnesila orthosilicate type minerals, at least one of the minerals and boron nitride or manganese sulfide. It is characterized by being at least one of the following.

In addition, the above-mentioned magnesila metasilicate mineral is at least one such as enstatite, clinoenstatite, enstenite, hyperstene, etc., and the magnesium orthosilicate mineral is at least IN such as forsterite and chrysolite. It is characterized by

0.1 to 2% Sn contained in the Fe base has the function of generating a liquid phase and promoting sintering at the low sintering temperature required to leave graphite as free graphite. Improves material strength.

The effect is produced when the addition amount is 0.1% or more, but if added in excess, the material becomes brittle and the dimensional instability of the product increases, so the limit is 2%.

Cu, like the Sn mentioned above, contributes to the promotion of sintering and increases the strength, and is effective when added in an amount of 1% or more, but no effect is produced if it is added in an amount exceeding 5%.

When blending Cu and Sn, single powders may be used, but it is preferable to use them in the form of a Cu-Sn alloy powder because the timing of liquid phase formation is different and the mixture tends to be non-uniform.

C is added in the form of natural graphite, and after sintering, part of it remains in the form of free graphite, and the other part is solidly dissolved in the Fe base, forming a hard Fe- P-C
ternary) 1 product (for steadite) is precipitated.

In addition, when the amount of graphite powder added was 1.5%, free graphite was 0.
．． If the free graphite content is less than 0.3%, it will wear out the sliding mating part. make it easier

On the other hand, if the amount of graphite powder added exceeds 4%, the strength of the base material will decrease, so the carbon content should be in the range of 1.5 to 4%.

P forms an intermetallic compound with Fe, and the aforementioned Fe-p-c
It forms a ternary phase (steadite phase) and contributes to wear resistance, but in order to form the desired wear-resistant structure, 0.
It is necessary to add more than 196%, and adding more than 1.5% is not preferable because the base material becomes brittle and machinability decreases.

Further, in order to obtain a homogeneous structure, it is preferable to add this P in the form of Fe-2 alloy powder.

On the other hand, magnesium silicate is a solid lubricant and acts as an intergranular inclusion.

Magnesium metasilicate (magnesium *eLa
silicate) is expressed as Mg S t O3,
It is said that there are several types of enstatite with different crystal structures, but one type of enstatite (ensLaLiLe) is a diagonal one-piece type.
, pyroxene), monoclinic clinoenstatite (cl
1nnensLaLite, clinopyroxene) corresponds to this.

In addition, those refined from natural ores are generally in the form of a solid solution of Mg silicate and Fe silicate, or a solid solution of this solid and Mg silicate.
It is expressed as Fe)S io3, and examples of this type include enstenite and hyperstenite.

In this invention, magnesium metasilicate and silicates containing the same are referred to as magnesium metasilicate minerals.

On the other hand, magnesium orthosilicate (magnesium
orLhosllicate) is represented by Mg 5i04, and industrial '2 is forsterite (f'orsL).
It is an ore called eriLe (Kura L-11 攬石).

Similarly, it is generally in the form of a solid body with silicates of Mg or Fe, and examples of such a form include chrysolite.

Chrysolite is forsterite (Mg
5104) and 1'ayaliLe%F
e 5104), or even Terraloy L (Lcph
r.

ite, Mn 5in4), (Mg.

Fe)2SiO4 or (Mg, Fe, Mn)2SiO
It is represented by 4.

In this invention, ortho-magnesium 1-acid and silicates containing the same are referred to as ortho-magnesium-acid minerals.

Magnesium metasilicate minerals and magnesium orthosilicate minerals have a specific gravity of 3.2 to 3.9 degrees and have interfold properties, so they act as solid lubricants, improving the free machinability, sliding properties, and It not only improves compatibility and wear resistance, but also improves the ability to retain lubricating oil due to its lipophilic properties.

When magnesium silicate is added in an amount of 0.1% or more, a solid lubricating effect is observed, and as the amount added increases, the effect increases, but on the other hand, when more than 2% is added, the volume increases and sintering This is undesirable as it reduces the strength of the body. -Comparing magnesium metasilicate minerals and magnesium orthosilicate minerals, see the diagram on the back right)
Since j is hard and does not easily crease, it is desirable to use it in combination with magnesium metasilicate minerals.

In addition, the machinability and wear resistance of sintered sliding members are improved.
In order to achieve this, in addition to -h or both of magnesila metasilicate t-based minerals or magnesium orthosilicate minerals,
If at least one of boron nitride or manganese sulfide is dispersed, the boron nitride or manganese sulfide acts as a solid lubricant. Comparing the rain sounds of boron nitride and manganese sulfide, boron nitride is superior in machinability, while manganese sulfide is superior in wear resistance.

Further, the amount added is set to be in a range of 0.1 to 2 times in combination with the magnesium silicate mineral for the same reason as the lubricating effect of the magnesium silicate mineral.

The combination ratio of the magnesium silicate mineral and at least one of boron nitride or manganese sulfide is not limited, but since boron nitride and manganese sulfide are about 10 to 30 times more expensive than the magnesium silicate mineral, it should be taken into consideration from a cost perspective. It is preferable to reduce the amount by half or less.

<Function> According to the present invention, even if sintered at a relatively low temperature necessary to leave free graphite, the strength of the sintered material can be increased without decreasing the strength as in the past. , and has free machinability, so it can be used as a sliding member suitable for bearings and the like used under high surface pressure.

In addition, it is relatively stable against heat, and furthermore, since dehydration and decomposition do not occur during sintering, it can be manufactured at low cost by a normal sintering method.

<Example> The present invention will be explained below with reference to Examples.

Note that the composition and blending ratio are weight ratios.

Examples of preparing a sintered sample according to the present invention (hereinafter referred to as the invention material) and a comparative sample (hereinafter referred to as the comparative material) will be described below, and the wear resistance and machinability of each sample will be clarified in a table.

Comparative material 1 is a conventional material with 2.5% natural graphite powder.

A mixed powder of 5% Cu-10%Sn alloy powder, 4% 85%Fe-15%P alloy powder, and 0.596 zinc stearate and the remainder atomized iron powder was formed into the specified shape of a valve guide for an internal combustion engine, and then It was sintered at 100θ°C for 30 minutes in an oxidizing atmosphere gas.

In addition, to the mixed powder used in Comparative Material 1, powder that forms interphase inclusions, that is, magnesila metasilicate 1, enstatite powder as an example of minerals, forsterite powder as an example of magnesium orthosilicate minerals, and forsterite powder as an example of magnesium orthosilicate minerals. Talc, which is a conventionally used magnesium metasilicate mineral, as well as boron nitride powder and manganese sulfide powder, were added in the prescribed amounts as shown in the table below, and then molded and sintered in the same manner as Comparative Material 1 for comparison. Materials 2 to 4 and invention materials 1 to 8 were produced.

Regarding machinability, the 6.5 mm inner diameter of each sample was cut with a 7 mm diameter reamer under a load of 3. The shellfish passing time was measured by cutting at a rotational speed of 50 rpm while weighing 2 kg, and expressed as an index with Comparative Sample 1 as 100.

In addition, for the wear test, each sample of the valve guide processed to the specified dimensions was mounted on an engine simulation test device, and
After the 0-hour test, the inner diameter of the sample and the amount of wear on the valve were measured.

From this measurement result, the maximum load for extracting the molded body of each sample from the mold is approximately 4% smaller for Comparative Material 2 containing talc, other Comparative Materials 3 and 4, and each invention material compared to Comparative Material 1. , its effectiveness as a molding lubricant was recognized.

Furthermore, as is clear from the table, Comparative Material 2, a talc-added material, has good machinability but is subject to large wear.

This is because talc (M g 3 S l 40
The crystal water of t+・H2O) dehydrates and contaminates the gas in the sintering furnace, resulting in an increase in the ferrite structure of the base, resulting in good machinability and large sample wear. It is thought that this turned into silicon dioxide (S i02 ) and caused the valve to wear out.

Comparative materials 3 and 4 and invention materials 1 to 3 show the effect of enstatite content, and the amount added is 0. It can be seen that in the range of 5 to 2%, both the machinability and the wear resistance of the sample and the valve, which is a mating part, are good.

However, a sample containing 3% enstatite, such as Comparative Material 4, has good machinability and does not wear out the valve, which is a mating part, but the sample itself suffers a large amount of wear.

On the other hand, invention material 4 is a sample containing fustellite, and its machinability is not as good as enstatite.

It also has good wear resistance.

Further, Invention Key 5 is a sample containing both enstatite and forsterite, and has characteristics that are intermediate between Invention +12 and Invention +4.

Furthermore, it can be seen that invention materials 6 to 8 are samples in which enstatite or forsterite and boron nitride or manganese sulfide coexist, and are superior in machinability and wear resistance compared to each of the above-mentioned samples.

<Effects of the Invention> As explained in 1-1 below, the iron-based sintered sliding member of the present invention does not reduce the strength of the sintered material even when sintered at a relatively low temperature, unlike conventional methods. While increasing strength, the required amount of free graphite, solid lubricating magnesium silicate minerals, boron nitride, manganese sulfide, etc. are interposed in the grain boundaries of the alloy matrix, so it has excellent resistance to q under high surface pressure. If it has excellent wear resistance, it can extend the life of cutting tools and improve productivity when used in bearings that require cutting.

In addition, especially in bearings for high blood pressure such as valve guides of internal combustion engines, the oil retention property is improved, and the life of the bearings themselves can be further extended.

Furthermore, it is relatively stable against heat and does not dehydrate and decompose during sintering, so it can be manufactured using the normal sintering method, reducing costs. It has the effect of

Therefore, it has a suitable resistance for various types of bearings used under high surface pressure.
An iron-based sintered sliding member made of a sintered alloy with excellent wear resistance and free machinability can be provided at low cost.

Patent applicant Hitachi Powder Metallurgy Co., Ltd.

Claims (2)

[Claims] 1. The overall composition is C1.5-4%, Cu1-5 by weight.
%, Sn 0.1-2%, P 0.1-0.5%, intergranular inclusions 0.5-2%, and the balance Fe. It has a structure in which intergranular inclusions are dispersed, and the intergranular inclusions are magnesium metasilicate minerals, or magnesium metasilicate minerals and magnesium orthosilicate minerals, or magnesium metasilicate minerals or magnesium orthosilicate minerals. 1. An iron-based sintered sliding member characterized by comprising one of the following: and at least one of boron nitride and manganese sulfide. 2. Magnesium metasilicate minerals are enstatite,
The metal sinter according to claim 1, wherein the mineral is at least one of clinoenstatite, enstenite, hyperstene, etc., and the magnesium orthosilicate mineral is at least one of forsterite, chrysolite, etc. Sliding member.