EP0308759A1

EP0308759A1 - Shockproof, wearproof metal lubricant, with restoring action and relative manufacturing process

Info

Publication number: EP0308759A1
Application number: EP88114875A
Authority: EP
Inventors: Nicola Trotta
Original assignee: LUBRALLOY Srl
Current assignee: LUBRALLOY Srl
Priority date: 1987-09-24
Filing date: 1988-09-12
Publication date: 1989-03-29
Anticipated expiration: 2008-09-12
Also published as: IT1223305B; DE3876561D1; ATE83268T1; ES2053657T3; EP0308759B1; IT8722016A0; GR3007187T3; DE3876561T2

Abstract

Shockproof, wearproof metal lubricant with restoring action of worn metal surfaces, consisting in a stable, homogeneous dispersion of microspheres in a quaternary alloy comprising copper, lead, tin and silver in a mixture of paraffin and naphthene mineral oils, in presence of specific additives, to guarantee complete, perfect homogeneity and stability of said dispersion.

Description

This invention refers to a shockproof, wearproof metal lubricant with restoring action of worn metal surfaces and the relative production process.
As noted, the task of lubrication is to increase the mechanical efficiency of the machines, through a reduction of the friction between moving surfaces rubbing against each other, and to prevent or reduce wear on said moving parts, increasing their lifespan, by placing between them a veil of greasy substances more or less viscous than the lubricants, and help to maintain a suitable thermic state, subtracting continuous heat from the machine.
Although the lubricating action may be exercised by both solid and liquid, gaseous lubricants, in practice liquid or semisolid lubricants, like oil or lubricating grease, are almost exclusively used. The solid lubricants comprise graphite, talc, bentanite and molybdenum bisulphide, all substances with a lamellar structure, almost always used in suspension of liquids, e.g. graphitic oils. Also noted is the use of metal powders which act as support to the liquid or semisolid lubricants to improve their poor shockproof and wearproof qualities. The interest in attempting to use metal products is based on the necessity to form a permanent protective layer on the mechanical moving parts submitted to friction. The metal powders, added to traditional lubricants, serve, in fact, to fill the natural pores and flaws, invisible to the naked eye, of the metal surfaces of the moving mechanical parts subject to wear. The results obtained with the use of metal powders are a reduction of friction, an increase in flowability, a lowering of the operating temperature and rate of wear, an improvement in lubrication, a restoration of the clearances and coupling provided by the constructor and consequently a reduction also in energy consumptions. Among the most tested metals appears, in first place, lead, which offers excellent lubricating and anti-seizing qualities. However, due to its too low melting point (327.5°C), it has never been possible to use this metal as auxiliary for traditional lubricants.
To solve this problem, it has been proposed to encapsulate the lead in another metal with a higher metling point and at the same time flexible; the metal used for this purpose is copper, which has a melting point of 1083°.
This solution, while making it possible to obtain products with satisfactory characteristics, does not solve the problems linked with the various types of friction, wear and lubrication of the different mechanical systems for which these products are to be used, due to the unstable structure of said products, problems of approximate micronization, oleosolubility and excessive operating cost.
The object of this invention is to optimize the copper and lead alloy so that it may be used for the formulation of lubricating products free from the above problems.
Another object of this invention is to provide a copper and lead alloy which can be dispersed in traditional liquid or semisolid lubricants and solves all problems linked with different types of friction, wear and lubrication of the various mechanical systems.
According to a general aspect of this invention, these objects are obtained adding to the copper-lead alloy other metals with function of activators.
The object of this invention is therefore a shockproof, wearproof metal lubricant with restoring action of the worn metal surfaces, consisting of a stable, homogeneous dispersion of microspheres of a quaternary alloy with a heterogeneous mixture of copper, lead, tin and silver stably and homogeneously dispersed in a mixture of naphthene and paraffin oils.
The microspheres of the alloy can be obtained by means of melting and subsequent process of atomization in a micronized spheric powder in various measures. Its spheric structure, with respect to the lamellar one, offers the advantage of a greater flowability on the surface to be treated, and, in the case of unsuitable thicknesses, ejection or non-reception. The new formulates, specific for lubricants for the lines Industry, Car Drive in general and Navigation, are also characterized by the fact of comprising also special auxiliary substances which must stabilize, standardize and often all keep in suspension, in the mixture of paraffin and naphthene oils, the microspheres of quaternary alloy to guarantee complete homogeneity and stability of said formulates.
The alloy used in the manufacture of the lubricants object of this invention can be obtained by means of melting and subsequent atomization process of the metals in the following preferred quantities:
COPPER, between 40 and 60%, preferably 56%, with respect to the weight of the alloy;
LEAD, between 30 and 50%, preferably 40%, with respect to the weight of the alloy;
TIN, between 1 and 5%, preferably 3%, with respect to the weight of the alloy;
SILVER, between 0 and 2%, preferably 1%, with respect to the weight of the alloy.
The quaternary alloy is present in the various types of lubricants in quantities of between 12 and 16% in weight and preferably 14% in weight of the total lubricant composition.
The most important metal to be put in oily suspension, and, using the lubricant, distributed in all points affected by said lubricant, is lead, as it is well known that it has a high lubricating power.
Due to its low melting point (327.5°C), however, it must be encapsulated, as already mentioned, in another metal, copper, with characteristics of considerable flexibility, but a higher melting point (1083°C). The copper, encapsulated in the quaternary alloy dispersed in the oily phase, does not cause phenomena of oil oxidation as said phenomena are prevented by the antixodiating agents present in the formulates. Tests made by the applicant have shown that this stabilizing action of said antioxidating agents is improved by the addition, during melting of the alloy, of small quantities of silver.
These tests have also demonstrated that the presence of tin seems to improve the anchoring of the microspheres of said alloy to the surfaces to be treated. It is also noted that, in general, tin exercises stabilizing properties in shockproof alloys.

Through atomization of the alloy different fractions of various grain sizes are separated, usable according to the sections to which the various formulates are destined. In fact, if a grain size too fine for the needs of the parts to be treated is used, more time is necessary to obtain satisfactory results, while, if too coarse a grain size is used, it is probable that it does not find a sufficient entrance angle among the surfaces to be treated. This, while not causing problems for the treated parts, does not permit results sufficiently appreciable to justify their use to be obtained. The microspheres are therefore separated in various fractions, generally four, with different diameter intervals, usable for the formulation of four main types of metal lubricants in the following sectors:

Diameter in microns	Sector	Use/Destination
0.1 to 40	Car drive (and motor cycling)	2 and 4-stroke diesel and petrol engines
40 to 60	Car drive	Transmissions, gear-shifts, differential gears);
	Industry	compressors, pumps, small reduction gears;
	Navigation	transmissions, gear-shifts, U-drive,V-drive etc.;
60 to 90	Industry	Pinions for lamination trains, pumps, hoisting reduction gears, convertors, cog-wheels, helical gears, etc.;
90 to 115	Industry	Any type of industrial plant where excessive clearances and wear are found, e.g. in old and neglected plants.

The above does not, however, limit the field of application of said alloy as it has been experimentally demonstrated that it is possible to use fractions with different grain size interval from that comprised between 0.1 and 115 microns; for example, grain sizes over 115 microns to prepare formulates for specific uses and destinations and particulars different from those indicated.
The composition of the four main formulates prepared with the four grain size fractions of quaternary alloy previously indicated is shown in table A, where the raw materials and relative percentages, the characteristics and function of each of them are specified.
The products obtained are compatible and perfectly mixable with any lubricating oil for either engines or transmissions, but are not compatible with oils additivated with graphite or molybdenum bisulphide and with other solid lubricants. They are suitable for each type of lubrication of any metal surface, both sliding and rolling, with circulation of the lubrication or with fixed chamber. For example, for rapid engines with internal combustion, tests carried out by the applicant have established that, in any type of lubrication, a quantity of metal lubricant not exceeding 4% in weight is recommended.
Greater quantities do not, however, create problems for the treated parts, but represent a useless excess cost. The job of the metal microspheres dispersed in the oily matrix is to reach, transported by normal lubricant, all lubricated points of the parts to be treated, deposit themselves at the scorings, abrasions or pittings, and, exploiting the mechanical action of said part and the heat produced by friction, weld together until they restore optimal conditions of the piece.
This protective film protects, through time, the actual piece, withstanding its loads and future wear and improving, according to the shockproof properties of the mixture, its operation.
The improvements obtainable with said metal lubricant on mechanical parts in general are:
- notable reduction of friction;
- high, constant reduction of energy conumptions, restoring them to the minimum values provided by the constructor;
- reduction of noise by many decimals;
- reduction of approximately 20°C in the operating temperature of the parts treated;
- possibility of planning and reducing maintenance costs, with consequent decrease of machine stops and rise in productivity.
In endothermic petrol engines, the following improvements can also be obtained:
- restoration of compression;
- reduction of lubricant and fuel consumptions;
- wear locking in its state at the moment of the first application, by means of continuous intervention;
- restoration of the tolerance and clearances provided by the constructor.
The diameter interval within which said metal lubricant can be used without undergoing substantial modifications of quality and characteristics is very wide and varies from -200° to +800°C.
The properties of the metal microspheres of being naturally self-lubricating makes it possible to create, within the diameter limits indicated, a self-lubrication process of the treated parts, even when faults or temporary breaks in lubrication take place, with consequent overheating of said parts, guaranteeing, when temperatures do not exceed 830°, the prevention of seizing.

Table B shows the results of some technical tests to which the metal lubricant produced and only the quaternary alloy were submitted. SAid tests were carried out with the 4-sphere SHELL EP machine at the Testing Station for the Oil and Grease Industries of Milan, operating on samples of lubricating oil in its present state additivated with the metal lubricant produced with 60 micron alloy (lubricating 60 micron alloy (lubricating oil/metal lubricant ratio = 97/3) and on samples of lithium and silicone grease in their present state additivated with quaternary alloy in powder from 63 to 115 micron (ratio of grease/alloy in powder = 70/30). These results emphasize the highly positive effects obtained in presence of both the metal lubricant and only the alloy in powder as regards the seizing and welding loads and the rate of load/wear and demonstrate the excellent shockproof and wearproof properties also of only the quaternary alloy which forms the base of the metal lubricant.

TABLE B

TESTS CARRIED OUT WITH 4-SPHERE SHELL EP MACHINE
SAMPLES IN TEST	SEIZING LOAD	WELDING LOAD	LOAD/WEAR RATE
	Kg.	Kg.	Kg.
1. Lubricating oil in present state	148	300	62
2. Lubricating oil (97%) + metal lubricant with 60 micron alloy (3%)	200	over 800	over 98
3. Lithium grease in present state	80	160	31
4. Lithium grease (70%) + 63 micron alloy in powder (30%)	126	800	94
5. Lithium grease (70%) + 115 micron alloy in powder (30%)	100	800	95
6. Silicone grease in present state	100	200	42
7. Silicone grease (70%) + 63 micron alloy in powder (30%)	126	620	89
8. Silicone grease (70%) + 115 micron alloy in powder	126	800	103

Manufacturing process of the lubricant of this invention

In a preparation tank, equipped with stirrer and Cowless movable dispersor turbo, are mixed, at environmental temperature and in equal parts, pure naphthene oil with 2.7 Engler viscosity at 50°C and pure paraffin oil with 8 Engler viscosity at 50°C. Said oils will be present, according to the type of lubricant formulated, in a percentage in weight comprised between 68% and 74% of the total. The mixture thus obtained is stirred at 1200 r.p.m. with 40 disk strokes per minute, said stirring representing the optimal value to guarantee total dispersion of the components subsequently inserted. At this point the addition of the other raw materials starts, each taken in the proportions indicated in table A.
First the colloidal mixture with suspending action formed by the metal lithium and dodycihydroxistearic acid components is inserted, continuing stirring for the time necessary for its complete dispersion, at any rate until, with a dripping test, there are no lumps or deposits of said mixture. Said dripping test will then be repeated after the insertion of each other component. The following are then loaded in this order, the thixotropic agent uncompressed silica gel, the greasy, absorbent agent trioleate glyceryl, the mixture with wearproof, rustproof, detergent action, formed by components metal zinc, metal magnesium and phosphor and the alloy in copper, lead, tin and silver powder (56%-40%-3%-1%). After obtaining perfect distribution and homogeneity of the product and at any rate always and only as last component, is inserted, to improve viscosity and lower freezing point, the linear copolymer of olefins (ethylene-propylene copoline). Stirring continues to disperse everything well for several minutes, then interrupted and the product allowed to rest for not less than 12 hours, time necessary to determine the thixotropicity necessary to guarantee an effective, constant suspending action of the alloy in powder.
During this period, the preparation tank must not be submitted to agitation or vibrations of any type (ultrasounds included), to avoid damaging the product.
The above process is started, as mentioned, at environmental temperature, but the friction produced by the COWLESS dispersor causes, through time, an inevitable rise in the temperature of the mixtures, which must be kept within 50-55°C to avoid creating problems to the end product. To maintain temperature within the above limits, the tank is contained in thermostat bath.

Claims

1. Shockproof, wearproof lubricant, with restoring action of worn metal surfaces, consisting in a stable, homogeneous dispersion of microspheres of a quaternary alloy and a heterogeneous mixture of copper, lead, tin and silver in a mixture of naphthene and paraffin oils.

2) Metal lubricant according to claim 1, characterized by the fact that said quaternary alloy comprises:
40-60% in weight of copper, preferably 56%, 30-50% in weight of lead, preferably 40%; 1-5% in weight of tin, preferably 3%; and 0.1-2% in weight of silver, preferably 1%.

3) Metal lubricant according to claim 1 or 2, characterized by the fact that the microspheres of said metal alloy have a diameter comprised between 0.1 and 115 microns.

4) Metal lubricant according to any of the previous claims, characterized by the fact that said quaternary alloy is present in quantities comprised between 12% and 16%, preferably 14% in weight of the lubricant.

5) Metal lubricant according to any of the previous claims, characterized by the fact that the mixture of mineral oils is composed 50% of napthene oil with 2.7 Engler viscosity at 50°C and 50% of paraffin oil with 8 Engler viscosity at 50°C.

6) Metal lubricant according to any of the previous claims, characterized by the fact that the mixture of mineral oils is present in quantity comprised between 68 and 74% in weight, with respect to the lubricant.

7) Metal lubricant according to any of the previous claims, characterized by the fact that it also comprises:
- 1.1 to 2% in weight, with respect to the lubricant, of a colloidal mixture with suspensive action;
- 5 to 7% in weight, with respect to the lubricant, of a thixotropic agent;
- 2.14 to 5.24% in weight, with respect to the lubricant, of an agent with greasy, absorbent action;
- 0.76% in weight, with respect to the lubricant, of additives with wearproof, detergent and rustproof action, and
- 3% in weight, with respect to the lubricant, of an agent which improves viscosity and lowers the freezing point.

8) Metal lubricant according to any of the previous claims, characterized by the fact that it is added in quantity not lower than 4% in weight of the lubricating oils for both engines and transmissions.