JPH0781587B2 - Carbon-based sliding material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a carbon-based sliding material, and more particularly to a carbon-based sliding material containing graphite and glassy carbon.

"Prior Art" Conventionally, as a carbon-based sliding material of this type, JP-A-59-1315
67, JP-B-57-25483, JP-A-59-43222 and the like are known.

The carbon-based sliding material disclosed in JP-A-59-131567 is 30-80 wt.
% Glassy carbon and 20 to 70 wt% graphite are added.

The carbon-based sliding material of Japanese Examined Patent Publication No. 57-25483 is 1 to 20 wt% of solid lubricant such as graphite or talc on glassy carbon.
% Is added.

The carbon-based sliding material disclosed in JP-A-59-43222 is made by adding oil to glassy carbon, and further adding graphite of 30 wt% or less and alumina of 50 wt% or less.

"Problems to be Solved by the Invention" The glassy carbon is hard and has high strength, and in a carbon-based sliding material containing graphite as a solid lubricant, excellent wear resistance and a small friction coefficient are obtained. However, it has been desired to achieve even higher wear resistance and low wear characteristics at the same time.

"Means for Solving Problems" In view of such circumstances, the present invention is a carbon-based material that can achieve further higher wear resistance and low wear characteristics at the same time as compared with conventional carbon-based sliding materials. A sliding material is provided.

That is, the present invention provides 50-88 wt% graphite and 10-88 wt% graphite.
48wt% glassy carbon, mullite, clay, talc,
Silica or alumina containing at least mullite 1
Basically, 2 to 20 wt% of the seeds are provided, 0.01 to 20 Vol% of pores are provided if necessary, and the pores are impregnated with oil as necessary.

"Function" The above-mentioned glassy carbon which is the additive of the present invention binds additives such as graphite, mullite, clay and talc, is hard, has high strength, and is excellent in impermeability, Improves overall strength and wear resistance. If the amount added is less than 10 wt%, the role as a binder will be weakened, resulting in poor strength and wear resistance. The addition amount is 48
If it exceeds wt%, the friction coefficient becomes too large. A more desirable range is 15 to 28 wt%.

The glassy carbon is a phenolic resin, a furan resin, a furfuryl alcohol, a thermosetting resin such as polyimide, or a mixed resin thereof is sintered and carbonized in a high temperature inert atmosphere, and graphite is further added as necessary. It is obtained by converting. It is also obtained by powder-forming a carbon precursor material having an oxygen functional group derived from a pitch with an adjusted hydrogen / carbon atom ratio, followed by firing in the same manner for carbonization and, if necessary, graphitization. .

Graphite, which is a solid lubricant, has a hexagonal crystal structure and is easily cleaved so that it has self-lubricating properties and reduces the friction coefficient. If the addition amount is less than 50 wt%, the lubricity is poor and the friction coefficient is large. On the other hand, if the addition amount exceeds 88 wt%, the strength and wear resistance of graphite itself are low, and the overall strength is low, and wear resistance is reduced. A more desirable range is 55 to 75 wt%.

As the graphite, artificial graphite or natural graphite can be used. The shape is uneven or granular, the particle diameter is 300 μm or less, and the crystal is d ₀₀₂ =
3.41Å or less can be used. Desirably,
Granular shape, grain size less than 200μm, crystallinity d ₀₀₂ = 3.37
Å The following is good.

One or more of mullite, clay, talc, mullite of silica or alumina is added as a friction modifier, and works to remove graphite and glassy carbon from the mating material with which the carbon-based sliding material is in sliding contact. There is. Since it is superior to graphite in hardness and wear resistance, the wear resistance of the whole is improved.

Among them, mullite is a compound that is produced when clay is fired at 950 ° C or higher, and the total strength such as wear resistance, self-lubricating property, strength, and hardness is other additives such as clay, talc,
It is superior to silica and alumina and must be added.

Clay is a general term for clay minerals, and the main clay minerals are kaolinite, halloysite, hydrohalogenite, sericite, illite, pyrophyllite, montmorillonite, etc., but in the present invention, the clay is fired and crystallized. It is desirable to apply those that have lost water and become amorphous, or those that have become Si-Al spinel.

Silica can be amorphous to crystalline, and it is possible to apply a crystal struvite or the like produced when clay or the like is fired at 1200 ° C. or higher.

If the addition amount is less than 2 wt%, the wear resistance is poor and the effect of removing the coagulate from the mating material cannot be exerted, resulting in unstable friction. On the other hand, if it exceeds 20 wt%, the mating material will be scratched or worn. A more desirable range is 5 to 15 wt%.

The holes provided as necessary are for reducing the friction coefficient. By providing holes, the friction surface during sliding will always have a certain degree of roughness, and since the material strength will be slightly lower than that of those without holes, a slight amount of wear will occur. The coefficient of friction can be lowered.

Also, since the surface roughness can be kept almost constant,
In particular, under the boundary lubrication condition, it becomes easy to hold a certain amount of hydraulic fluid on the friction surface, and the friction coefficient decreases.

When used as a sealing material for relatively low pressure fluid, no problem occurs, but when sealing high pressure fluid,
Since leakage from the pores is a concern, it is desirable to cover or apply resin, rubber, metal, etc. to the parts other than the sliding surface and perform the sealing treatment.

If the pores are less than 0.01 Vol%, the above curing is not exhibited, and 2
If it exceeds 0 Vol%, the strength is lowered and the wear resistance is also lowered. A more desirable range is 2 to 10% by volume.

Further, the oil that is impregnated as needed is impregnated in order to further reduce the friction coefficient, and if oil is present at the sliding interface, solid contact is reduced and wear resistance is also improved. Especially when using a mechanical seal that seals water,
Since oil has the effect of repelling water, it is effective in preventing water leakage from the interface. If the impregnated amount is less than 0.01 Vol% with respect to the total amount of the above-mentioned additives, the above effect is not exhibited,
On the other hand, when it exceeds 20 Vol%, that state means that there are many pores for impregnating oil, so that the many pores reduce the strength and also the abrasion resistance. A more desirable range is 2 to 10% by volume.

As the oil, mineral oil or synthetic oil used in spindle oil, dynamo oil, turbine oil, engine oil, diesel engine oil, gear oil and the like can be used.

[Examples] The present invention will be described below with reference to illustrated examples. First, the production method of the carbon-based sliding material according to the present invention will be described.
Phenolic resin, furan resin, furfuryl alcohol glassy carbon materials, graphite, mullite,
Clay, talc, etc. are mixed in a required mixing ratio and kneaded by a hot roll or a kneader. Next, after crushing this, it is molded at a pressure of 200 to 500 kg / cm ² , further heat-treated and fired. This calcination is performed with an inert gas at 800 to 1500 ° C. if only the glassy carbon material is carbonized.

Clay calcined in such a temperature range has a state of clay (calcined clay, calcined kaolin), spinel such as Si-Al spinel, mullite, and crislavite (silica), and these may be used alone or in a mixture. Generated, but applicable in any state. Also, these may be added from the time of blending. Further, talc shows almost the same change depending on the firing temperature.

The graphitization is performed with an inert gas at 1800 ° C or higher.

The holes provided to reduce the coefficient of friction, if necessary, can be formed to about 2% if the carbon-based sliding material is manufactured by the manufacturing method described above. If more pores are required, a heat treatment may be performed by adding a component that volatilizes during firing, such as aluminum bicarbonate, as a pore-forming agent in the above-described formulation, in an amount according to the porosity. .

Further, the oil to be impregnated as necessary impregnates the holes provided by the above-described manufacturing method with the oil. As a method of impregnating oil, the carbon-based sliding material may be immersed in heated oil, gradually cooled, and then taken out. Alternatively, the carbon-based sliding material is housed in a pressure container, and the inside of the pressure container is evacuated by a vacuum pump to remove air from the pores of the carbon-based sliding material. Then, oil may be injected in that state, heated in a pressurized state, and then gradually cooled.

Next, Tables 1 and 2 below show the composition of the carbon-based sliding material according to the present invention and the composition of the carbon-based sliding material as a comparative material, respectively, and the friction coefficient and the wear amount for each of them. It shows the result of measurement. And the first
The table relates to carbon-based sliding materials that do not contain oil,
Samples 1 to 18 show the products of the present invention and samples 19 to 24 show comparative materials. Further, Table 2 relates to a carbon-based sliding material impregnated with oil, Samples 25 to 35 show the products of the present invention, and Samples 36 to 38 show comparative materials.

The friction coefficient, using a mechanical test laboratory type thrust tester,
The measurement results are shown after the mating material was Al ₂ O ₃ , the load was 5 kgf / cm ² , the speed was 0.2 m / s, and the speed was maintained for 1 hour. The amount of wear is 0.2 m as described above under the above test conditions.
After maintaining the speed of / s for 1 hour, 0.5, 1, 1.5, 2m
The results are shown after the speed was sequentially increased up to / s every 1 hour and the last speed of 2 m / s was maintained for 1 hour.

1 and 2 show the results of measuring the friction coefficient at each point of 0.5, 1, 1.5 and 2 m / s described above in addition to the friction coefficient at 0.2 m / s described above. Shows the test results for the invention product 10 in Table 1 and the comparative materials 20, 24, and FIG. 2 shows the test results for the invention product 29 in Table 2 and the comparative material 36.

As shown in Table 1, the product of the present invention has excellent results in terms of friction coefficient and wear amount as compared with the comparative material. For example, when comparing the product 18 of the present invention and the comparative material 20, the comparative material 20 is obtained by adding a small amount of mullite as in the product 18 of the present invention to almost the same components of graphite and glassy carbon.
On the other hand, the friction coefficient can be reduced, and at the same time, the amount of wear can be dramatically reduced to less than half.

Further, even if the graphite is set to 80 wt% and the mullite is added to 15 wt% with respect to the comparative material 20 as shown in the comparative material 23, if the glassy carbon is as small as 5 wt%, the friction coefficient becomes small. As a result, the amount of wear increases. On the contrary, as shown in Comparative Material 22, 60 wt% of glassy carbon was added.
%, While reducing graphite to 30 wt% and adding 10 wt% of alumina, the wear amount becomes small, but the friction coefficient remains large.

On the other hand, as can be understood from Table 1 above, the graphite content is in the range of 50 to 88 wt% and the glassy carbon content is 10%.
By adding mullite or the like in an amount of 2 to 20 wt% after adjusting the amount to be 48 wt%, it is possible to reduce the friction coefficient and the wear amount at the same time.

Further, as shown in FIG. 1, the product of the present invention has a large degree of improvement in the friction coefficient particularly at a low speed, and therefore, when used in a mechanical seal for a water pump, it is effective in generating an abnormal noise that tends to occur during idling. Can be prevented.

Further, in the product of the present invention impregnated with oil, the second
As shown in the table and FIG. 2, it is possible to further reduce the friction coefficient and the wear amount as compared with the case where oil is not included.

"Effects of the Invention" The present invention is 50 to 88 wt% graphite, 10 to 48 wt% glassy carbon, and 2 to 20 wt% of at least one of mullite, clay, talc, silica or alumina containing at least mullite. Basically, it is 0.1 if necessary.
Porosity of ~ 20Vol% is provided, and if necessary,
Since the pores are impregnated with oil, it is possible to provide a carbon-based sliding material that can simultaneously achieve wear resistance and low wear characteristics.

[Brief description of drawings]

FIG. 1 shows the results of measuring the friction coefficient of the product 10 of the present invention and the comparative materials 20 and 24, and FIG. 2 shows the product 29 of the present invention and the comparative material.
It is a figure which shows the result of having measured the friction coefficient about 36 and.

Claims (3)

[Claims] 1. 50 to 88 wt% graphite and 10 to 48 wt%
2 to 20 wt% of at least one of mullite, clay, talc, silica, and alumina containing at least mullite. 2. The total amount of the carbon-based sliding material is 0.01 to
The carbon-based sliding material according to claim 1, which has pores of 20 Vol%. 3. The carbon-based sliding material according to claim 2, wherein the pores are impregnated with oil.