DE1038690B - Process for the deposition of a coating from a sulfur compound of molybdenum on metal parts - Google Patents

Description

GERMAN

It is known that through the use of solid substances, e.g. B. graphite or molybdenum sulfide, for covering the contact surfaces of metal parts subjected to friction is the coefficient of friction and the wear and tear on these parts is considerably reduced. In general, this coating using a colloidal suspension of graphite or molybdenum sulfide in a lubricant (oil or grease) is applied, creating a deposit that removes the unevenness of the surfaces compensates. However, these coatings are difficult to apply and their adherence to one smooth metal surface is low. Namely, the adhesiveness depends on the particle size of the used Solid substance from, and especially in the case of molybdenum sulfide, the levels required for satisfactory adhesion can be removed do not achieve small particle sizes. In addition, such colloidal graphite and share Molybdenum sulfide suspensions with other colloidal suspensions have the disadvantage that they and changes in pressure easily flocculate, thereby losing any effectiveness. These disadvantages are supposed to can be avoided by the present invention.

The invention therefore relates to a method for depositing a coating made from a sulfur compound of molybdenum on metal parts from a liquid containing sulfur and molybdenum Medium in which these metal parts are treated with a solution of 0.5 to 10 percent by weight of a molybdenum alkyl xanthate in 99.5 to 90 percent by weight of a lubricating oil and this solution by external heat supply or by that caused by the mutual friction of the metal parts Heating to a temperature above the decomposition temperature of the molybdenum alkyl xanthate brings lying temperature.

The molybdenum alkyl xanthates that can be used correspond to the general formula

R -OC-S.

.S - C - OR

Mon-O-Mon

R —OC — S O S — C —OR

where R is an alkyl radical. It has been found that these molybdenum alkyl xanthates, which are soluble in oils and fats, are able to decompose at the temperatures reached by friction. Some representatives of this class of compounds, namely the ethyl, isobutyl and isoamyl derivatives, are already known (Montequi, An. Espan. Fis. Quim., 28, p. 481 [1930]) to use them

Method of deposition
a coating of a sulfur compound of molybdenum
on metal parts

Applicant:

Institut Frangais du Petrole,
des Carburants et Lubrifiants, Paris

Representative: Dr. F. Zumstein, patent attorney,
Munich 2, Bräuhausstr. 4th

Claimed priority:
France 7 January 1954

Dr. M. Hügel and Dr. M. Courtel, Paris,
have been named as inventors

However, it has not yet been suggested for lubrication purposes.

In the context of the present invention it has also been shown that the xanthates of higher alcohols are still superior to the known compounds in terms of their lubricating effect, which is why they are preferred be used. This increases the solubility of the xanthates of the formula given above in Mineral oils with the chain length of the radical R, and for alkyl radicals with 6 to 12 carbon atoms is the Solubility in oils is already considerable. The introduction of longer hydrocarbon residues still offers Another advantage: the temperature at which the molybdenum compound in the oil decomposes humiliated. While it is around 300 ° C. for the isobutyl compound, for example, it is around Use of the decyl compound only about 170 ° C.

There are various procedures for carrying out the process according to the invention in practice are available that can be used alone or in combination.

In one embodiment of the invention, the metal parts are immersed in a bath consisting of a solution from 0.5 to 10 percent by weight of a molybdenum alkyl xanthate in 99.5 to 90 percent by weight of a Lubricating oil and heats the bath to a temperature above the decomposition temperature of the Molybdenum alkyl xanthate used, preferably at a temperature in the range from 170 to

809 637/447

380 ° C. This temperature is maintained for a duration Maintained for about half an hour to two hours.

Good results are particularly good at a temperature of about 300 to 320 ° C for 2 hours obtain. The treatment time can also be shortened if the work is carried out at a higher temperature will.

By the bath treatment described above, a coating of a solid is made on the metal parts adhering brown-black layer of a sulfur compound of molybdenum deposited. The exact The composition of this compound could not yet be determined.

In a further embodiment of the invention one can use the same solution as for the bathroom is used directly for the continuous lubrication of metal parts subjected to progressively increasing pressures, as the solution decomposed under the influence of the heat generated by the friction and thus also a coating a sulfur compound of molybdenum is deposited on the metal parts.

Finally, the metal parts can first be subjected to the bath treatment described above and then, for the duration of the friction, the coating produced by smearing with a molybdenum alkyl xanthate solution or equivalent means, which will be discussed in more detail below shall be.

The value of the coating produced by the bath treatment results from the test results, which are obtained with the four ball machine: When using unprevented balls and an oil.

ίο the 2 percent by weight molybdenum decyl xanthate contains, as a lubricant, loads of 140 kg for a eating time of 2 seconds and of about Do not exceed 120 kg for an eating time of 60 seconds. On the other hand, the balls will be released before the attempt provided with the coating described above, so the pressure can with a seizing time of 15 seconds can be brought up to 310 kg. This result is also surprising and remarkable in that the impression left on the balls is the plastic impression caused by these strong pressures Does not exceed deformation. So there is practically no wear and tear. The following table gives the results of experiments again carried out with an oil containing 2% molybdenum decylxanthate became.

Table I.
oil SAE 30 f 2 percent by weight molybdenum decyl xanthate

Bullets not treated

Balls subjected to a pretreatment

Applied load
Eating time

70
> 60

120
> 60

130 18.3 140
0.1

180
> 60

220
55

250
43

280
26.5

310
15th

From this table it can be seen that one better with prior application of the protective coating Results obtained when using the lubricant alone when a high load is applied immediately will.

However, this coating can be removed during rubbing. In order to preserve it, a Applied lubricant, which contains organic compounds of molybdenum in solution, which are under able to decompose under the influence of the pressures and temperatures caused by the friction. A Such a lubricant brings about constant renewal of the protective coating in proportion to its wear.

The lubricants that meet these conditions include, in particular, the following compound solutions:

1. A solution of 0.5 to 10 percent by weight of a molybdenum alkyl xanthate in 99.5 to 90 percent by weight a lubricating oil, d. H. a solution that is suitable for the bathroom or for direct lubrication that used metal parts that were not pretreated and subjected to friction under increasing pressures Solution is the same. Solutions containing 0.5 to 6 percent by weight of the molybdenum alkyl xanthate 99.5 to 94 percent by weight of a lubricating oil is preferred.

2. A solution of 0.5 to 6 percent by weight of a thiomolybdate of a nitrogenous base in 99.5 up to 94 percent by weight of an oil consisting of a mixture of esters of fatty acid and alcohol or from synthetic products obtained by esterification of mono- or polyalcohols with fatty acids or obtained by esterification of dicarboxylic acids with monoalcohols, or a diol, Glycol, polyalcohol or polyethylene glycol.

3. A solution of 0.5 to 6 percent by weight of an organic molybdenum blue in 99.5 to 94 percent by weight of a lubricating oil.

The lubricants, the organic molybdenum blues or thiomolybdates of nitrogenous bases are the subjects of patent 1 003 895 or application I 12763 IVc / 23 c.

The test results for the use of a 2 percent by weight molybdenum decyl xanthate containing Oils have already been specified. The results of the investigations can be found in the following table with a lubricating oil containing 1% of a molybdenum blue type in the four-ball machine.

Table II

oil with 1 percent by weight of a molybdenum blue type and a pretreatment in a molybdenum alkyl xanthate lubricating oil bath subjected balls

Applied
load
in kg Eating time
in seconds before eating Coefficient of friction
maximum after eating diameter
the impression area
in mm 280
350 > 60
39 0.14
0.22 extremely weak Welding
of the balls
57 seconds 0.82

This table shows that the properties obtained by maintaining the protective coating obtained with a lubricant based on molybdenum blue types are noteworthy as one can reach a pressure of 350 kg with a eating time of 39 seconds.

However, comparable results are obtained even if metal parts have not been pretreated be subjected to progressively increasing pressures and continuously lubricated. Under the Influence of the temperature reached by friction is set when the initial load is a certain Does not exceed the limit on the metal parts subject to friction in successive layers a sulfur compound of molybdenum; Formation and maintenance of the protective coating take place then at the same time.

The following table shows the results of tests that were carried out when used alone a lubricant containing 2 percent by weight molybdenum decyl xanthate were obtained under these conditions.

Table III
SAE 30 oil (viscosity at 5O ⁰ C = 54 cP) + 2 weight percent Molybdändecylxanthogenat

Eating time
in seconds Coefficient of friction
I. before eating maximum after eating Diameter, the impression Applied
load 0.09 area in mm for each
Burden with the same
Balls at continuous
increasing pressures and > 60 0.14 - - without preceding
Overlay 130 > 60 0.16 - - 1.0 150 > 60 0.13 - - 1.0 180 > 60 0.25 - - 1.0 200 > 60 0.23 - -. 1.0 240 > 60 0.24 -. - 1.0 260 > 60 0.18 -. 1.0 280 > 60 0.18 - - 1.0 300 > 60 0.15 - - 1.0 320 > 60 0.11 - - ■ 1.0 340 > 60 1.0 380 1.1

In the following examples, the method of Montequi (op. Cit.) Is carried out Production of the decyl, dodecyl and hexyl xanthate of molybdenum, as they are new compounds. This manufacturing process does not form the subject of the present invention. The percentages are based on weight and the yields given are molar yields.

example 1
Manufacture of molybdenum decyl xanthate

Dissolve 1 mole of anhydrous ammonium molybdate (196 g) in 11 water, which is crushed with 10 kg Ice is mixed and contained in a flask that is externally cooled with ice.

On the other hand, a solution of 2 moles (512 g) of sodium decyl xanthate in 2.5 l of water is prepared. This solution is slowly introduced into the ammonium molybdate solution obtained above with vigorous stirring. A white precipitate then forms, which turns pink in the air. After the introduction of the total xanthates and stirring for two and a half hours, about 2 liters of acetic acid (1 volume Acetic acid to 4 volumes of water) pour in, always cooling sufficiently with ice until a Pu 'value of 4 is obtained. The red precipitate can then be extracted with light petroleum ether.

After decanting, the solution in petroleum ether is dried over anhydrous magnesium sulfate, filtered and freed from petroleum ether by evaporation on a water bath in vacuo. One receives as Residue 400 g of molybdenum decylxanthate in the form of an oily mass of dark red, almost black Color (this corresponds to a yield of 70% of theory). This is extraordinary in mineral oils soluble and should be kept in the refrigerator until use.

Example 2
Manufacture of molybdenum dodecyl xanthate

The procedure described in Example 1 is followed. However, the ammonium molybdate solution is mixed intimately with a solution of 2 mol (568 g) sodium dodecyl xanthate in 21 water. After, as in example 1 has been worked up, 450 g of molybdenum dodecyl xanthate are obtained, which is a yield of 71% corresponds to theory.

Example 3
_ ₀ Manufacture of molybdenum hexyl xanthate

20 g of ammonium molybdate are dissolved in 100 ecm of water. The liquid obtained is crushed to 1 kg Poured ice, then 300 g of a solution of 50 g of sodium hexylxanthate are added dropwise introduced into 250 ecm of water. Then gradually 25 ecm of a 20% aqueous solution is added Glacial acetic acid too. The organomolybdenum compound is then extracted with benzene and the latter expelled on a boiling water bath under ordinary pressure and then under a pressure of 10 mm. Finally 37 g of molybdenum hexyl xanthate are obtained in this way, which is one molar Yield of 76.4%.

Claims (6)

Claims 1. Process for the deposition of a coating made of a sulfur compound of molybdenum Metal parts from a liquid medium containing sulfur and molybdenum, characterized in that that these metal parts with a Solution of 0.5 to 10 percent by weight of a molybdenum alkyl xanthate in 99.5 to 90 percent by weight of a lubricating oil brings into contact and this solution by external heat supply or by due to the mutual Friction of the metal parts caused heating to a temperature above the decomposition temperature brings the molybdenum alkyl xanthate lying temperature. 2. The method according to claim 1, characterized in that the solution by external Brings heat supply to a temperature in the range of 170 to 380 ° C. 3. The method according to claim 1, characterized in that for the deposition of the coating The reason for the heating caused by the mutual friction of the metal parts is the molybdenum alkyl xanthate solution a solution of 0.5 to 6 percent by weight molybdenum alkyl xanthate in 99.5 to 94 percent by weight of an ao lubricating oil. 4. The method according to claim Γ to 3, characterized in that the molybdenum alkyl xanthate is that of a higher alcohol having 6 to 12 carbon atoms. 5. The method according to claim 2, characterized in that these parts are also during the duration of friction with a solution of 0.5 to 6 percent by weight of a thiomolybdate a nitrogenous base in 99.5 to 94 percent by weight of an oil obtained from a mixture of esters made up of fatty acids and alcohol, lubricates. 6. The method according to claim 2, characterized in that these parts also during the duration of friction with a solution of 0.5 to 6 percent by weight of an organic molybdenum blue species lubricates in 99.5 to 94 weight percent lubricating oil. Considered publications:
Chem. Zentralblatt, 1930, II, p. 3729. When the registration was announced, eleven pages of priority document were laid out. © 809 637/447 9.5 &