DE2028804A1 - - Google Patents

Description

DR. ING. E. HOFFMANN · DIPL. ING. W. EITLE DR. HER. NAT. K. HOFFMANN

D-8000 MONKS 8! · ARABE LlASTRASSE 4 ■ TELEPHONE (0811) 911087

Oiles Kogyo Kabushiki Kaisha Tokyo / Japan

Solid lubricant

The invention relates to a solid lubricant which consists of a predetermined amount of sodium fluoride and Graphite or a mixture of graphite and tungsten disulfide exists, especially for lubrication purposes at high Temperatures is suitable.

00905 2/1933

Graphite and molybdenum disulfide have as solid lubricants found wide use. In particular, graphite is used at significant temperatures. graphite however, it tends to be in a certain temperature range, e.g., up to about 400 ° C during the increase in temperature of the lubricant from room temperature to the working temperature, to increase its coefficient of friction and Losing the ability to form films on the sliding surfaces as well as the durability of the film.

Although molybdenum disulfide in terms of its film-forming ability on the bearing surfaces and the surfaces in contact therewith and with regard to the Migration of the lubricant to the opposite ends has better properties, it tends to lose the lubricating properties due to significant oxidation that occurs when the working temperature of the lubricant rises above 35O ° C.

It is important that the solid lubricant, especially a high temperature lubricant, has properties such as that there is a stable, solid film of lubricant between the sliding surfaces of the bearing and the rollers forms that is stable over long periods of time and creates direct contact between the clashes Materials is avoided.

However, the solid lubricants must have a low coefficient of friction in order to dissipate electrical energy. and to save electrical elements connected to the warehouse, small size and light weight

009 852/1933

OBlQlNAL

to enable. In particular, if the solid lubricant is to be used at high temperatures, then is it is necessary that the coefficient of friction is not greater than that of the commonly used lubricants.

To overcome the difficulties outlined above Many attempts have already been made, with either metal oxides in addition to graphite or metal sulfides in addition to molybdenum disulfide were given. However, solid lubricants that are suitable at high temperatures of 400 to 500 C have not been found.

It has now been found that a solid lubricant can be obtained which is resistant to oxidation and which extends the life of that formed on the sliding surfaces Film can be lengthened by adding a predetermined amount of sodium fluoride to either graphite or a mixture made of graphite and tungsten sulfide. If necessary, can Sodium methaphosphate can be added as a binder.

The erfindungsgeraäße solid lubricant has superior film-forming properties and a significant high-temperature lubricity, which makes it suitable for use in the temperature range of 500 ⁰ C Raumtemperatur'bis suitable.

For example, Ceylon graphite with an ash content can be used as graphite of less than 1% by weight and a Mohs hardness of 1 to 2 can be used.

-As sodium fluoride is a product with a purity of more than 95 wt -.% Suitable.

009852/1933

Sodium methaphosphate, which has the usual purity, can be added to the lubricant as a binder.

The particle size of each component to be mixed together would be from the viewpoint of increase the heat resistance, a graphite powder with a relatively large particle size, but% ias in view of the increase in ash content is not preferable.

Therefore, graphite powder with a particle size of less than about 0.10 mm (less than about 150 mesh) is desirable suitable for satisfactory results.

From the standpoint of improving the quality of the solid lubricant, the use of sodium fluoride is important as small a particle size as possible is preferable, since the use of sodium fluoride powder with relatively large Particles tend to affect lubricity. Therefore, sodium fluoride powder is one particle size of less than 0.074 mm (less than about 200 mesh) is suitable for satisfactory results.

Two types of tungsten sulfide are commercially available, the mean particle sizes of which are 2 yu and 0.2 λχ, respectively. From the standpoint of increasing the heat resistance of a solid lubricant, as shown in the case of graphite, it is preferable to use tungsten disulfide having an average particle size of 2 yu.

Some examples of the invention are given below.

009852/1933

1) · ■ "The solid Sehmiermittel, which is to be introduced is suitable in the camp is produced in that finely powdered sodium fluoride with a particle size of less than 0.074 mm with flaky graphite powder having a particle size less than about 0.10 mm is uniformly mixed and that the mixed materials

ο under a pressure of around 1000 kg / cm in a metal mold be pressed.

2) The solid lubricant, which is to be introduced is suitable in the camp is produced in that fine powder of tungsten disulfide with an average particle size of 2yu; and fine powder of sodium fluoride with a particle size of less than 0.074 mm, the flake-like Graphite powder is admixed with a particle size of less than about 0.10 mm and that thereupon the Mixture under one pressure

Metal mold is pressed.

Mixture under a pressure of about 1000 kg / cm in one

J>) The lubricant in pasty form, which is suitable for coating surfaces, is produced in that finely powdered sodium fluoride with a particle size of less than 0.074 mm is mixed with the flaky graphite with a particle size of less than about 0.10 mm and that then the mixed materials are kneaded with an aqueous sodium methaphosphate solution which acts as a binder.

4) The lubricant in the pasty state, which is suitable for coating surfaces, is produced in that fine-powdered tungsten disulfide with an average particle size of 2λχ and fine-powdered

009852/1933

Sodium fluoride with a particle size less than 0.07 ^ mm the flaky graphite powder with a particle size of less than about 0.10 mm is admixed and that the mixed materials are mixed with a binder aqueous sodium methaphosphate solution used kneaded four den.

5) The solid lubricant having a high strength is produced by removing most of the water contained in the paste produced according to J5) and 4) that the obtained materials
be deformed under a pressure of about 1000 kg / cm in a metal mold and that the deformed material in a hot air oven
is dried.

a hot air oven at a temperature of about 200 ^° C

The table below shows the composition of the individual batches.

009852/1933

Table 1

component

»'R.des
\ r: set

graphite
(Wt .- ^

WS NaF (Wt .- ^)

6th
7th
8th

10
11
12th

13th

14th

99
97
95
93
90
88

85
8o
75
70
65
60

55
50

0 0 0 0 0 0 0 O 0 0 0 0 0 0

5 7

10 12

15 20

25 30 35 40 45 50

15th
16
ι ·?
18th
19th

20th
21
22nd

89
85
80

75
70

65
60
50

10 10 10 10 10 10 10 10

009852/1933

g / \ D ORIGINAL

In Table 1, samples 1 to 14 were after Method 1) and samples 15 to 22 according to the method 2) manufactured.

Samples 1 to 22 were examined to determine the relationship between the degree of wear of the lubricant lubricated bearing material and the quantities of the Determine lubricant.

The following test conditions were used:

Ten test pieces with a diameter of 4 mm and one Height of 5 mm, which contained various amounts of sodium fluoride, were inserted into 10 holes, which on one sliding surface of a cylindrical thrust bearing made of cast bronze (BC6) were provided. The dimensions goods: inner diameter 16 mm, outer diameter 28 mm, height 15 mm (see A.S.T.M. B30, Alloy

The ratio of the total surface of the test pieces to the total sliding surface of the thrust bearing is 30 %,

On the test pieces, which had been embedded in the bearing material for 20 hours, a cylindrical sliding piece made of the material S45C, which had the same dimensions as the bearing material, ran. The temperature was 500 ^° C., the sliding speed was 3.5 m / min and the surface pressure was 30 kg / cm.

After sliding, the amount (mg) of abrasion loss became of the storage material measured, with the increase in weight

009852/1933

20288OA

des 345c (ASTM 1045 steel) as the amount of des solid lubricant was determined.

The results obtained are in Tables 2 and 3 as well as shown in FIGS. 1 and 2. Table 2 and Figure 1 show the relationship between the degree of abrasion the lubricant and the amount of sodium fluoride contained in the lubricant. ,

Table 2

NaF content
(Wt .- ^) O 2 5 7th 10 12th 15th 20th 30th 40 45 50 Abrasion of the
Lubricant
(ms) 200 120 50 20th 14th 15th 23 32 69 96 128 200 <

Table 3 and Figure 2 show the relationship between the amount of lubricant migrating to the slider and the sodium fluoride content of the lubricant.

Table 3

FaF content
(Weight >%) 3 5 10 20 30 40 45 50 Wanderer
Incense
amount (mg) 11 34 10 34 50 150 <

009852/1933

Table 4 and Figure j5 show the relationship between the amount of migratory lubricant to the slider and the trial time.

Table 4

A.
B.
C. 5 10 20th 30th +4
+10
+5, ■ ^ experimental
Weight- "^ time (h)
Change
similar sliding piece
(mg) D.
E. - if
+4 + a
+5 +4
+9
+5 - According to the invention
Schmi ermi 11 e1 -15
-20 -4o
-4j5 -180
-178 - Control attempt
j

The sample A is the Run No. 5 of Table 1. B is the Run No. 18, C is the sample of the batch number is coated 18 with the film of the solid lubricant, in which 8 wt -...% Sodium metaphosphate as a binder has been mixed on the sliding surface of the sample B, D is graphite, e is graphite with an addition of 10 wt -.% tungsten.

The comparative tests relating to the heat resistance of the solid lubricant according to the invention in comparison for the individual components were carried out as follows:

009052/1933

A test piece containing 10 mg of slowly from room temperature
(20 ⁰ C) ^{heated to 50O 0} C, the temperature was increased at a rate of 4 ° C / min in an air stream with a flow rate of 15 cm / min. The change in weight in mg was determined using a thermal tension balance.

The results obtained are in Table 5 and in Figure 3 compiled.

Table 5

Storage material (Oew.-ίί) 100 ⁰ C 200 ⁰ C ? 00 ° C 400 ⁰ C 500 ⁰ C Components - Graphic 0 0 0 0 ⁰ tin
" ^α 2 0 0 1.7 2.3 5.0

Solid lubricant according to the invention

Graphite 90-WaF 10

Graphite 75-WS ₅ 15

- NaF 10 ^&

(Graphite 75-WS ₉ 15 - NaF 10) 92-NaP0, 8

0.5

1.0

1.5

The test results confirm that there was no significant weight loss occurs, even if the sample is exposed to the elevated temperature for an extended period of time will. This can be seen from the fact that the weight of the sample at temperatures above 100 ° C by a weight loss of 3 mg obtained an almost constant value.

009852/1933

It has been found that although the sodium fluoride used has a Mohs hardness greater than 5.0, the sodium fluoride itself has no lubricating properties. It results in the change of the coefficient of friction is avoided as a result of temperature and that the film-forming properties are improved when 1 wt -% sodium fluoride is added to the graphite.. In the case of dry friction, adding about 5% by weight of sodium fluoride to the graphite has the effect of increasing the life of the film coated on the lubricant. The maximum effect as regards the durability of the film, which is coated on the lubricant is present when about 10 wt -% of sodium fluoride are added to the graphite. "

The greater the proportion of sodium fluoride in the lubricant the more the amount of lubricant migrating to the slider increases *

If the proportion of sodium fluoride in the lubricant more than 50 wt -.% Is then the amount of the migrating leads to the slider lubricant to a deterioration of the lubricating properties.

Therefore, it was found that it is preferable that sodium fluoride with less than 45 wt -.% In the lubricating medium incorporated in order to obtain satisfactory results.

Although the tungsten disulfide has better lubricating properties it lacks the necessary heat resistance compared to graphite «,

0096 52/1933

Since the addition of the sodium fluoride to the lubricant brings about an improvement in the heat resistance, it enables work in the temperature range of 400 to 50O ⁰ C or more. ·

The effect of adding tungsten disulfide to graphite results an improvement in the lubricating properties and an improvement in the film-forming properties on the surface of the lubricant at a relatively low temperature.

It is preferable less than jjo wt -.% Tungsten to use. When used at relatively low temperatures, the tungsten disulfide can be added to the lubricant in the upper side of the above range.

At elevated operating temperature of the lubricant, the added amount can of Wolframdisulfids be reduced because at high temperatures, in particular 4OO to 500 ⁰ C, the durability of the film formed on the lubricant is considered more important than a low friction property, and because the addition of tungsten to a Reduction of the coefficient of friction contributes. However, this entails that the durability of the film formed on the lubricant is lowered.

Accordingly, when working at high temperatures often a lubricant that does not contain tungsten disulfide can be used.

Sodium methaphosphate is used as a binder for the individual components of the lubricant. Sodium methaphosphate

00 9852/1933

however, as such, it has no lubricating property, so it is not preferable to add it to the lubricant in too large an amount. Rather, it is expedient, the lubricant in the case of formation of films 5 to 10 wt .- ^ sodium phosphate, and in the case of the block-shaped use less than 20 wt -% add sodium metaphosphate..

By varying the amount to be incorporated into the lubricant It can be used for various purposes will.

Table 3 and Figure 2 show the change in migrating amount of the solid lubricant to the slider under the same test conditions as in Table 2 and in Figure 1.

It has been found that the migration considerably increases when 50 wt -.% Of sodium fluoride may be incorporated in the lubricant, resulting in a reduction in lubrication. However, it was found that the variation of the friction coefficient in the case of up to 45 wt - not holding% sodium fluoride the friction coefficient to about 0.2 and the coefficient of friction in the case of more than 50 wt -..% Sodium fluoride reached 0.4.

From the test results of samples A, B and C in table and in Figure 3 it can be seen that there was satisfactory migration of the solid lubricant over the test periods to the slider and that the weight of the slider increases.

009852/1933

BATH ORIGINAL

It was found that the on the surface of the Slider formed by the migration of the lubricant Film is smooth and black in appearance.

It was found that the coefficient of friction of Samples A and B after 20 hours from the start of the test 0.15 to 0.20, after 40 hours was 0.20 to 0.25 while the coefficient of friction of Sample C was 0.08 to 0.10 after 20 hours.

It was observed that in the case of sample C, a good There was run-in behavior and that the lubricant was uniform migrated to the slider to form a smooth film thereon. It became a similar coefficient of friction as that of Samples A and B observed after the lapse of 40 hours * In contrast, in the case of Samples D and E found that the lubricant did not hit the slider forming a smooth film migrated, whereby many notches were obtained on the friction surface of the bearing material. Also entered Weight loss of the slider.

In those shown in Table 3 and in Figures 2 and 3 Experimental results, when the weight of the slider increases by 50 mg, the thickness of the migration film reaches an average value of 4 to 6 / u. With an increase of 10'mg reaches the thickness of the migration film less than 1 / ü.

The following shows the uses of the solid lubricant of the invention.

Pellets of the solid lubricant formed by deforming the binder-free powders obtained under high pressure according to methods 1) and 2) are for use as solid

0098 52/1933

Lubricant suitable for embedding.

It is useful to use the solid lubricant of the invention to be used so that holes are created in the sliding surface of the bearing and that the solid lubricant is inserted into these holes. ,

In this case it will be on the sliding surface of the bearing a load is applied and the lubricant used in the bearing is deposited in the holes of the sliding surface of the Fixed bearing.

There is therefore no deformation or destruction on orund the load of the lubricant takes place in the pellet state.

The lubricant in the KLIet state, which according to "5) to 5) obtained by molding the binder-containing powder under high pressure is suitable for making a film on the sliding surface of the bearing to "form what." happens as follows * One manufactured according to J5) to 5) Paste is spread on the sliding surface of the bearing and heated to about 20 ° C, to remove moisture from the To remove the paste, which is followed by a burn.

The lubricant can be used in the form of a block by either heating the paste-like lubricant to remove most of the moisture contained therein, deforming it in the metal mold under pressure and then ^{heating it at about 200 °} C. in a hot air oven, or by being deformed using a heated press under heating and pressure.

00985271933

ORiGiSSiAL INSPECTED

As the binder-containing solid lubricant in block form has good mechanical strength, it can be used without adding any reinforcement to the Lubricant must be provided around to protect it from deformation and destruction. The lubricant in block form can also be used as a bearing body itself.

009852/1933

Claims (4)

Claims 1. Solid lubricant consisting of 55 to 97 wt.% Graphite and 3 to 45 wt. % Sodium fluoride. 2. Solid lubricant consisting of less than 30 wt .-% tungsten disulfide, 3 to 45 wt .- # sodium fluoride and the rest of graphite. 3. Solid lubricant consisting of 55 to 97 parts by weight J ^ graphite, 3 to 45 wt -.% Sodium fluoride and 5 to 20 Qew .- # Natri'ummethaphosphat, based on the total weight of the graphite and the sodium fluoride. 4. Solid lubricant, consisting of less than 30 wt .-% tungsten disulfide, 3 to 45 wt .- ^ sodium fluoride, the remainder of graphite and from 5 to 20 wt .- ^ sodium methaphosphate, based on the total amount of graphite, sodium fluoride and of tungsten disulfide. 009852/1933 Blank page