JP2767470B2 - Lubrication method between two sliding members - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of lubricating between two sliding members at least one of which is made of ceramics.

2. Description of the Related Art For example, lubrication between two sliding members in an automobile engine has been performed by oil. By the way, use of ceramic parts has been considered for the purpose of reducing cooling loss, reducing weight, and improving durability under severe use conditions. Since ceramic parts have excellent heat resistance, they do not need to be cooled, so that cooling loss can be reduced.

However, if not cooled, the temperature of the ceramic component will be 300 ° C. or higher, so it is clear that oil currently used for lubricating such high-temperature components cannot be used. Therefore, it is conceivable to use a solid lubricant, but there is a problem that the cost increases.

An object of the present invention is to provide a method of lubricating between two sliding members which solves the above-mentioned problem.

Means for Solving the Problems A lubricating method between two sliding contact members according to the present invention is a method for lubricating between two sliding contact members, at least one of which is formed of ceramics, in which a hydrocarbon fuel is burned. The resulting soot is supplied between the sliding members.

The present invention has been completed in the following manner. That is, soot has conventionally been considered to be a substance that causes serious damage to the sliding member of the engine and deteriorates the engine performance. However, as a result of various studies conducted by the inventor of the present invention, it is found that the soot damages the sliding member because the soot mixed in the oil is deposited on the surface of the sliding member or between the two sliding members. It has been found that the cause is that oil is not supplied between the sliding contact members due to intrusion. Then, they found that the above-mentioned problem never occurred with soot alone, and completed the present invention.

In the above description, the two sliding members include a member that slides on each other and a member that rotates on each other, for example, a cylinder and a piston of an engine. In the case of a cylinder and a piston of an engine, soot generated in the cylinder is preferably introduced into a friction surface between the two.

Examples of hydrocarbon fuels include aliphatic hydrocarbons such as methane, ethane, and propane; monocyclic hydrocarbons such as benzene, toluene, and cumene; condensed cyclic hydrocarbons such as indene and naphthalene; and biphenyl cyclic hydrocarbons. And spirocyclic hydrocarbons.

When soot generated by burning a hydrocarbon-based fuel is supplied between two members in sliding contact with each other, a film is formed on the surface of the ceramic sliding member by the soot. The friction surfaces of the members do not come into direct contact with each other. Soot has a large surface area, and a plurality of small particles (primary particles) of about 300 to 600 mm exist in the form of particles (secondary particles) of several μm due to van der Waals force. Since they are small, they are easily separated into fine primary particles. In addition, the secondary particles have a large molecular adhesion to the surface of the sliding member, and easily enter the friction surface between the two members. When the two members come into sliding contact with each other, it is considered that the secondary particles are separated into primary particles, and as a result, the lubrication performance is improved.

EXAMPLES Hereinafter, examples of the present invention will be described together with comparative examples.

Test 1 As shown in FIG. 1, a cylindrical member (1) having an outer diameter of 26 mm, an inner diameter of 20 mm, a length of 15 mm, a side length of 30 mm, and a thickness of a ceramic obtained by adding MgO to α-Al ₂ O ₃ was used. A square square plate (2) having a length of 5 mm was formed. The firing temperature of α-Al ₂ O ₃ is 1630 ° C,
The specific gravity is 3.9, the specific resistance is 10 ¹¹ , the bending strength is 39 kgf / mm ² , and the Vickers hardness (HV) is 1200. Slits (1a) facing each other were formed on one end of the cylindrical member (1) on one diameter. Then, the tubular member (1) was placed on the square plate (2) such that the end where the slit (1a) was formed faced downward, and the tubular member (1) was obtained from the diffusion flame of benzene in the tubular member (1). A soot (benzene soot) is put in the furnace and heated and maintained at various temperatures (room temperature to 400 ° C.) while rotating the tubular member (1) and the square plate (2) under the following conditions to perform a friction test. went. During this rotation, the benzene soot enters the friction surface between the tubular member (1) and the square plate (2) via the slit (1a).

Load 29.4N Speed 0.1m / s Sliding distance 1500m And at each ambient temperature, the sliding distance is 1000m
The coefficient of friction at the time when the coefficient of friction reached a steady state was measured. At each ambient temperature, the slip distance is 1500
The specific wear after reaching m was measured. The specific wear amount was obtained by calculating the reduced volume from the relationship between the change in weight of the tubular member (1) and its specific gravity, and dividing this volume by the load and the slip distance (volume / load / distance).

For comparison, graphite powder known as a solid lubricant was placed in the tubular member (1) instead of benzene soot, and the friction coefficient was measured in the same manner as described above. Further, the friction coefficient and the specific wear amount were measured in the same manner as described above without putting anything in the tubular member (1).

These results are summarized in FIGS. 2 and 3.
As is clear from FIG. 2 showing the relationship between the ambient temperature and the friction coefficient, when benzene soot was used, the friction coefficient was smaller than when nothing was used, and excellent lubrication performance was imparted. You can see that. In particular, the ambient temperature
If the temperature is within a predetermined range around 300 ° C,
It has a lower coefficient of friction than graphite powder.

Further, as is clear from FIG. 3 showing the relationship between the ambient temperature and the specific wear amount, the specific wear amount when benzene soot was used was smaller than the case where nothing was used at each ambient temperature, and was between room temperature and 300 ° C. In the vicinity of ° C., it can be seen that it is less than or similar to the case where graphite powder is used.

Test 2 When benzene soot was put in the cylindrical member (1), when graphite powder was put, and when nothing was put,
The ambient temperature was set to 400 ° C., the load was changed variously, and the friction test was performed by rotating the cylindrical member (1) and the square plate (2) under the same conditions as in the above test 1 except for the load, and the slip distance was reduced. The specific wear amount after reaching 1500 m was measured. These results are summarized in FIG. As is clear from FIG. 4, the specific wear amount when benzene soot was used was smaller than that when nothing was used at each load, and when the load was small, the specific wear amount was almost the same as when graphite powder was used. You can see that.

Test 3 700 ℃ × 1h, 1100 ℃ × 1h and 150 ℃ in nitrogen gas atmosphere
Using benzene soot heat-treated at 0 ° C x 1 h and benzene soot without heat treatment, respectively,
At 0 ° C., a friction test was performed by rotating the tubular member (1) and the square plate (2) under the same conditions as in Test 1 above, and the friction coefficient at each slip distance was measured. These results are
Shown in the figure. As is clear from FIG. 5, when the slip distance becomes longer, the non-heat-treated one has a smaller friction coefficient and is more stable than the heat-treated one. Further, among the heat-treated benzene soots, the lower the heat treatment temperature, the lower the friction coefficient and the more stable the benzene soot.

Test 4 Using the same four types of benzene soot as in Test 3, and the ambient temperature
At 300 ° C., the friction test was performed by rotating the tubular member (1) and the square plate (2) under the same conditions as in the above Test 1, and the specific friction amount after the slip distance reached 1500 m was measured. These results are shown in FIG. As is clear from FIG. 6, the specific wear amount does not change in any of the soots.

Test 5 Using the same apparatus as in Test 1 above, (a) A friction test was performed at 300 ° C. using benzene soot, and the benzene soot after the test was collected and placed in a cylindrical member (1), and the ambient temperature was set to room temperature. The friction test was performed by rotating the cylindrical member (1) and the square plate (2) with each other.

(B) After putting benzene soot into the cylindrical member (1), 200
A heat treatment was performed at a temperature of 10 ° C. × 10 hours, and then an atmospheric temperature was set to 300 ° C., and the friction test was performed by rotating the cylindrical member (1) and the square plate (2) with each other.

(C) After putting benzene soot into the cylindrical member (1), 300
A heat treatment was performed at a temperature of 10 ° C. × 10 hours, and then an atmospheric temperature was set to 300 ° C., and the friction test was performed by rotating the cylindrical member (1) and the square plate (2) with each other.

The load, speed, and slip distance are the same as those in Test 1. Then, the friction coefficient at each slip distance was measured. These results are shown in FIG. As is clear from FIG. 7, when the slip distance becomes longer, the friction coefficient obtained under the condition (b) has a smaller and more stable friction coefficient than those performed under the conditions (a) and (c). I have. And
When this result is compared with the result of the test 1 on benzene soot and the result of the test 3 on the benzene soot not subjected to the heat treatment, the following is presumed. That is, it is considered that the soot undergoes some change when heated to 300 ° C., and the coefficient of friction decreases due to this change. The above change is irreversible and does not return to the original state even after cooling after heating, and it is important that the ambient temperature during the friction test is within a predetermined temperature range around 300 ° C. It is speculated that there is.

Test 6 The same four types of benzene soot as in Test 3 were used, and these soots were heated in the atmosphere at a heating rate of 10 ° C./min, and the weight loss (%) was measured. The result is shown in FIG. As is clear from FIG. 8, the weight loss of benzene soot without heat treatment increased from around 200 ° C., whereas the weight loss of heat treated soot increased from around 450 ° C. Is increasing. This is considered to be because the soot that had been subjected to the heat treatment had already decreased in weight during the heat treatment.

Test 7 Benzene soot without heat treatment, benzene soot heated and held at 300 ° C. for 4 hours, and 300
Using benzene soot subjected to a friction test at 0 ° C., these soots were heated in the air at a heating rate of 10 ° C./min, and the weight loss (%) was measured. The results are shown in FIG. As is clear from FIG. 9, the benzene soot without any treatment has a large weight loss around 200 ° C., whereas the treated soot has a weight loss around 300 ° C. The amount is increasing. This is probably because the treated soot has already been reduced in weight during the treatment.

The following is presumed from the results of Tests 6 and 7 above. That is, benzene soot without any treatment is
At 200-400 ° C., the weight of carbon, hydrogen, nitrogen and oxygen, which are components of soot, is reduced by being partly desorbed from soot and released in the form of polycyclic aromatic hydrocarbons, and 450
When the temperature exceeds ℃, carbon, which is the main component of soot, reacts with oxygen in the air and burns, thereby reducing the weight. And
Carbon, hydrogen, nitrogen and oxygen, which are soot components at 200 to 400 ° C., are partly desorbed from the soot, so that the particles constituting the soot are easily separated from each other, and the friction surface between the sliding contact members. It is considered that this contributes to the improvement of lubrication performance.

Test 8 Using a benzene soot that had not been subjected to any treatment, a friction test was performed at 100 ° C., 300 ° C., and 400 ° C. under the same conditions as in Test 1 above. During the 30 minute friction test, the atmosphere gas in the furnace was sucked out with an aspirator,
H) ₂ solution, and BaCO ₃ was precipitated by a reaction of Ba (OH) ₂ + CO ₂ → BaCO ₃ + H ₂ O. Then, precipitated B
Using the ACO _3, replaced precipitation of BaCO ₃ to BaSO ₄ by the reaction of _{BaCO 3 + H 2 SO 4 →} BaSO 4 + H 2 O + CO 2, and therefrom determine the amount of CO ₂ in the furnace. In addition, the temperature inside the furnace
℃, 400 ℃, the gas in the furnace is sucked out by an aspirator, CO
_Two quantities were determined. Then, subtract the amount of CO ₂ when the friction test was not performed from the amount of CO ₂ when the friction test was performed, obtain the amount of CO ₂ generated by the friction test in the furnace, and determine the amount of soot reduction due to combustion from the value. I asked. The results are shown in the table below.

As is clear from the above table, the higher the temperature at which the friction test is performed, the greater the amount of soot reduction in the furnace. If the temperature exceeds 400 ° C., the oxidation reaction of soot on the friction surface between the tubular member (1) and the square plate (2) becomes intense, so that the soot hardly adheres to the friction surface.

This causes the friction and wear characteristics to deteriorate around 400 ° C.

Test 9 The cylindrical member (1) and the square plate (2) were formed of SiC, and benzene soot was used as soot, and soot obtained from a fuel diffusion flame obtained by adding zinc to benzene was used.
A friction test was performed in the same manner as described above. Then, at each ambient temperature, the friction coefficient was measured when the slip distance reached a steady state at a slip distance of 1000 m, and at each ambient temperature, the specific wear amount after the slip distance reached 1500 m was measured. . These results are shown in FIG. 10 and FIG.

Test 10 A cylindrical member (1) and a square plate (2) were formed from Si ₃ N ₄ ,
Using benzene soot as a soot, soot obtained from a diffusion flame of a fuel obtained by adding zinc to benzene, and soot obtained from a diffusion flame of a fuel obtained by adding nickel to benzene. The test was performed. Then, at each ambient temperature, while measuring the friction coefficient when the friction distance reaches a steady state at a slip distance of 1000 m,
At each ambient temperature, the specific wear after the slip distance reached 1500 m was measured. FIG. 12 and FIG.
Figure 13 shows.

From the results of the above tests 9 and 10, even when the material of the sliding contact member is changed to another ceramic, particularly when the ambient temperature is within a predetermined temperature range around 300 ° C., the case where soot is used In comparison with the case where no lubricant was used and the case where graphite was used, the coefficient of friction was smaller and the specific wear amount was smaller except for the case of benzene soot of Si ₃ N ₄ , which was more excellent. It can be seen that the lubrication performance was given.

Effects of the Invention According to the lubrication method of the present invention, the lubrication performance is the same as that of the solid circulating agent, and the cost is reduced.

[Brief description of the drawings]

FIG. 1 is a vertical longitudinal sectional view showing an apparatus for performing a friction test, and FIG.
The figure shows the results of Test 1 and is a graph showing the relationship between the ambient temperature of the friction test and the friction coefficient. FIG. 3 is the graph showing the results of Test 1 and the relationship between the ambient temperature of the friction test and the specific wear. , FIG. 4 shows the results of Test 2, a graph showing the relationship between the load of the friction test and the specific wear, FIG. 5 shows the results of Test 3, and shows the relationship between the slip distance and the coefficient of friction,
FIG. 6 shows the results of Test 4, showing the specific wear of various soots. FIG. 7 shows the results of Test 5, showing the relationship between the slip distance and the coefficient of friction. FIG. 9 is a graph showing the relationship between the heating temperature and the weight loss, FIG. 9 is a graph showing the relationship between the heating temperature and the weight loss, and FIG. Is a graph showing the relationship between the friction coefficient and the ambient temperature in the friction test.
FIG. 11 shows the results of Test 9, showing the relationship between the ambient temperature of the friction test and the specific wear. FIG. 12 shows the results of Test 10, showing the relationship between the ambient temperature of the friction test and the coefficient of friction. FIG. 13 is a graph showing the results of Test 10 and showing the relationship between the ambient temperature and the specific wear in the friction test.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F16N 15/00 F16C 33/24 F16C 33/10

Claims (1)

(57) [Claims] 1. A method of lubricating between two sliding members, at least one of which is made of ceramics, wherein soot produced by burning a hydrocarbon-based fuel is supplied between the two sliding members. Lubrication method between two sliding contact members.