DE1088644B - Aqueous, oil-free lubricant with a content of solid lubricants - Google Patents

Description

Aqueous, oil-free lubricant with a solid lubricant content The present invention relates to lubricants which are water, lubricating effective Solids, especially those with a layer lattice, such as MoS2, WS., Graphite, and more Compounds and dispersion stabilizers that loosen up the sliding surfaces contain.

Such lubricants are known. For example, they are lubricating or aqueous dispersions which can be used to produce lubricating coatings described which, e.g. B. molybdenum disulfide, phosphoric, nitric, hydrofluoric or oxalic acid, if necessary heavy metal phosphates, dispersants and dispersion stabilizers, such as methyl cellulose or methyl ethyl cellulose ether. It has meanwhile been shown that such lubricants for various reasons are the ones put in them Not meeting expectations.

First of all, these known dispersions are only unsatisfactory Stability on. So z. B. such a suspension in a glass cylinder from a diameter of 25 mm and a height of 160 mm within 30 minutes, that a layer of 15 mm molybdenum disulfide accumulates at the bottom of the glass cylinder. After 24 hours, this molecular disulphide layer has grown further down to 5 mm discontinued.

In addition, such preparations show such. B. after days that - the dispersion stabilizers, such as. B. Methyläthylcelluloseäther, by the presence of free acids, such as. B. phosphoric acid, nitric acid and hydrofluoric acid, are destroyed by hydrolysis, as a result flocculate and thus become ineffective.

Another known suspension sets in under the same circumstances within 24 hours to 12 mm molybdenum sulfide. Above that there is one perfect clear, green solution.

In addition, as confirmed by repeated attempts, this also shows known preparations, if they are applied to the sliding surfaces, as more solid Film present the disadvantage that the cellulose derivatives still contained in solid film and organic wetting agents coke at temperatures above 180 ° C.

These coking products in the applied film interfere with the lubricating effect of molybdenum disulphide, as it enables the formation of a sufficient number of free molybdenum disulphide surfaces prevent the Mo S2 particles with a hard film from the coking products be coated. Another disadvantage of this coking reaction is the reduction the adhesive strength of the applied film, since changes in volume due to the coking processes occur that tear the intimate bond of the film again.

Also show the known, in particular using nitric acid Preparations produced lubricating layers also in dry air strong susceptibility to corrosion. As tests have shown, the signs of corrosion occur within the first hour.

In other such preparations, the dispersion stabilizers used there form such as B. Methylethylcelluloseether, a self-contained; lacquer-like, however invisible layer, which significantly resets the capillary effect on lubricating oils.

It is also known to use waterglass for the production of drilling emulsions and optionally to mix graphite with oils or fats. Such preparations have the disadvantage that they are due to the lack of durability of the water glass in the air, d. H. under the action of carbonic acid, with the formation of colloidal Silica disintegrate. Apart from that, the use of the strongly alkaline would Water glass in the present case a complete inactivation of all acidic, result in connections loosening the sliding surfaces.

The present invention has now succeeded in all of these Eliminate disadvantages. According to the invention this is achieved in that lubricants, which in aqueous dispersion have lubricating solids, especially those with Layer grids, such as Mo S2, W S2 graphite, loosening up the sliding surface Compounds and dispersion stabilizers contain one as stabilizers Content of inorganic, capable of thixotropy, in particular swellable with water Have substances.

It is particularly advantageous to use more viscous stabilizers for formation Gels enabled magnesium-aluminum -Silicates used. Y For this include, for example, compounds such as bentonite, montmorillonite, attapulgite.

j) hardened aqueous dispersions show a remarkable stability. While, as already stated at the outset, the known dispersions show clear disintegration after 30 minutes, at the latest after several hours, the preparations according to the invention are. in particular if only water is contained as a dispersion medium, completely stable for weeks: such preparations can be applied completely homogeneously to surfaces, for example with spray guns. Even when water-alcohol mixtures are used as dispersion medium , results are quite satisfactory.

`It is known to use emulsions e.g. B. peanut oil. In. Water to produce that the substance to be emulsified is intimately mixed with a large amount of an adsorbent such as colloidal silica, aluminum oxide or iron oxide and this mixture is then introduced into water (German patents 495 934 and 502 237). For the present purposes, however, such preparations are just as unsuitable as those from. the German patent 837 243 known, -from silicic acid and aluminum salts == made colloidal products, - because they, in. B. Molybdenum disulfide with a density of @ 4.8 to keep in suspension. Finally, from the German Auslegeschrift 1 024 658 lubricating greases are known which can contain mineral substances and lubricating, layer-lattice-crystalline solids. Here we are dealing with very high consistency of fatty preparations: It could not be inferred in any way which remarkable effects the use of substances capable of thixotropy in aqueous Systems, that is to say in systems which - with regard to their viscosity are comparable with the aforementioned lubricating greases. - Furthermore, the lubricants according to the invention do not yet show any signs of coking or decomposition even at temperatures of 300 ° C. In this way, there are no products that interfere with the free surface formation of molybdenum disulphide crystals. Since the microcrystalline, inorganic. Dispersion stabilizers do not form a coherent solid film, the Mo S2 crystals are able to; . to align themselves in the most favorable, lubricating positions during the sliding load.

Since no coking occurs, the structure of the lubricant can also be effective Layer by high tem-. temperatures are not destroyed.-It also shows that the inorganic Stabilisa-_toren, which in the with -the lubricants according to the invention produced layer are present, both moisture and free acids, such as B. carbonic acid or sulphurous acid to absorb. Through this is .. corrosion in normal air, as experiments have shown, even with .months of storage -excluded.

_ - Connections that loosen up sliding surfaces are advantageous acidic phosphorus-oxygen compounds, especially orthophosphoric acid and./ i or -their compounds °: contain. Mixtures are preferred here. _ @ from orthophosphoric acid and heavy metal phosphates, especially zinc phosphate. Even if the lubricants are used directly as such, i. H. in the form of their aqueous Dispersion can be used, but with particular advantage are: parts or sliding surfaces treated with it drying either at room temperature or subjected to elevated temperature. Also in the form of such a dry smear layer the lubricants according to the invention are superior to the known lubricants, because the stabilizers used according to the invention, which increase the stability of the dispersion and thus cause the formation of uniform, lubricating layers, in contrast in addition to the stabilizers used so far, the lubricating effect of the dry layer not adversely affect. These dry smear layers also allow--. the. additional use. of, lubricating oils or: I aqueous lubricating oil emulsions. The . high capillary activity of the dry smeary layers can e.g. the opposite of the known smear layers. twice the height of rise of a spindle = Detect oil. Example A mixture of 1211 / o molybdenum sulfide powder with 6.8 l) / 11 orthophosphoric acid, 1.11 / o zinc phosphate, 40.2% water, 38 "/ o ethanol and 211 / a one. swellable bentonite is used on several races of Alpha Lubricant Testing Machine LEW 1 (Timken principle) injected and tempered for 20 minutes at 150 ° C. The solid smear layer of a few [. Strength is on of the .above mentioned machine: A metal block is - mechanically .with a Force of 285 kg pressed against the rotating ring (78 rpm). The coefficient of friction is 0.03. As soon as the layer no longer has any lubricating properties and the coefficient of friction increases to 0.1, the test is ended. The number of Revolutions of the ring up to this point is a criterion for the quality of the lubricant. Four rings prepared in this way show friction paths of 50,000 or 57,000 or 57,000 and 64,000 revolutions, an average of 6.3 km. Comparatively, they can Rings z. B. rubbed with commercially available molybdenum disulfide powder or with an oily paste - of molybdenum disulphide treated as usual, only revolutions of 350 or 2500. The friction paths are only 38.5 or 275 m.

Testing the effectiveness of the lubricant according to the invention can also be done on the Almen-Wieland machine (AWM): You rub the shaft and bearing shells with a commercially available molybdenum disulphide powder and removes the loosely adhering Excess, a bearing treated in this way can be used up to a load of 400 kg (in a second case up to 450 kg) - drive. Then welding of the bearing occurs a.

You spray with the mixture specified after the example shaft and Storage shells, dries 24 hours at room temperature, so a pretreated one can Bearings on the AWM can no longer be welded. In the event of an exposure from 2000 kg there is wave elongation. -

Claims (3)

PATENT CLAIMS: - 1. Aqueous, oil-free lubricant with a content of solid lubricants based on an aqueous dispersion of solid Lubricants, especially those with a layered lattice such as Mo S2, W S2, graphite, loosening up on the sliding surface active compounds as well as dispersion stabilizers, characterized; that the stabilizers are inorganic, capable of thixotropy, in particular, substances are swellable with water. 2. Aqueous oil-free lubricant according to claim 1, characterized in that the stabilizers form viscous gels Magnesium-aluminum silicates are. 3. Aqueous oil-free lubricant according to claim 1 or 2, characterized in that the sliding surfaces are loosening compounds, acidic phosphorus-oxygen compounds, in particular orthophosphoric acid and / or compounds thereof. Considered publications: German Patent Nos. 495 934, 502 237, 837 243; German interpretative document No. 1 024 658; Excerpts from German patent applications, Vol. 6 (1948), p. 810.