DE1942702C - Solid lubricant - Google Patents

Description

The lirlind relates to a solid lubricant HiiM.s a self-lubricating component within a refractory metal carbide matrix made up of

1. 20.0 to 97.0 weight percent molybdenum disulfide as a self-lubricating component,

2. 0.01 to 10.0 percent by weight of a carbonaceous one Component, in the present case at least a small part in the form of metal carbides,

1 2, ') 9 to 80.0 percent by weight of molybdenum, niobium, tantalum, tungsten or a combination these metals as a carbide-forming component and optionally from

4. 0.01 to 5.0 weight percent of a boron component, in this case at least a small part in the form of a solid boron solution and, where ^'5 appropriate, from

5. 0.1 to 53.0 percent by weight iron, nickel, chromium, cobalt, or a combination of these metals as the metallic lubricating material.

Self-lubricating substances with low friction and low abrasion properties also show Still varying degrees of electrical conductivity, ranging from electrical insulators to good ones Extend electrical conductors, each depending on the mixture present. This self-absorbing masses can be used as high-performance masses in air, vacuum or inert atmospheres over a temperature range of -251 ^ o until I ?. 16 '(' can be used.

Several solid self-lubricating materials are known which have good lubricating properties and low shear strength. Typical examples are molybdenum disulfide, molybdenum diselenide, tungsten disulfide and graphite. These materials generally have a suitable field of application in all areas where low friction properties are desired under low load conditions. If, however, high loads are applied to the system, then these known materials cannot withstand the high load conditions and their use under such circumstances leads to premature failure of the lubrication system. With the possible exception of graphite, these known solid self-lubricating materials have a low tolerance to high temperatures and soiT.it cannot be used in systems with more than a few hundred degrees Fahrenheit. Among these known materials, graphite alone shows a substantial electrical conductivity, but this substance cannot be used in systems which work in a vacuum, since the particles of the graphite have a certain abrasive effect in the case of vacuum conditions. ^

While the well-known sclbslsi hmicmulni fabrics are suitable for a relatively small-scale area, they can be extrain. ηίι H ·. instinctual, inshcsoiuli-ri at ImIi. η Hclastungen, high temperatures and in a vacuum, not "> be used (. Further, their electrical l.citungseigenschaftcn first inie 1 for the respective material fixed. Therefore, the well-known self-lubricating materials / ur fiir lubrication systems at more extreme conditions . aibeilen (<·, are not used and therefore it muli be provided a lubrication äul.lere I "ie cons of this äuKcicn Schmiei i / nt'cn, however, are obvious:. High maintenance costs, contamination, evaporation, uneven application, etc. External lubrication is particularly difficult to use in systems which contain electrical, electronic and optical elements which are to be operated in a vacuum, although such extreme operating conditions as mentioned above, for which the known lubricants are not suitable, have been used up to now encountered little, they are now typical of space technology. Hence the need to Obtaining lubricants that can withstand these severe operating conditions has become an issue.

The high-performance characteristics of self-lubricating ends Materials of the invention are made primarily through the incorporation of a refractory metal achieved in the mixture, so that after processing under pressure and at high temperature, the converts refractory metal with the carbon present in the compacts to form carbides. learner is contain molybdenum disulphide in the masses, which imparts lubricity. Thus, through combination of a high strength, carbide-forming refractory metal with a self-lubricating ^ material that generally characterized by a low strength, low temperature tolerance, a final blend obtained which is excellent in both pressure and bending resistance and which is next to it has excellent friction and abrasion properties. The compositions of the invention can either can be produced in their final form, or they can be prepared in large batches and subsequently can be processed into their final form. In any case, the masses have structural properties which they enable it to be used under high load conditions, high temperatures and in a vacuum will.

Although molybdenum disulfide is generally a shows high electrical resistance, but its incorporation into the mass destroys the electrical conductivity, which is bestowed by the refractory metals does not. The electrical conductivity of the final mass depends on which refractory metal or which combination of refractory metals for the Incorporation has been selected. An average mass can be obtained by varying the components which has a wide range of electrical properties that differ from gi / tsn electrical insulation properties up to / u good electrical conduction properties extends

The objects of the invention are achieved through three classes of masses reached in different proportions have the following components

I I ii> e first class of mixtures, consist i from molybdenum disulfide oiler materials, you contain Mohbdäudisiilfid, a carbidbildui selected the metal; nis of the group Mohh Danish, niobium, tantalum. Tungsten and its combination nationeii, and a carbon-containing compo ncnle, which either in the form of metallic arbidi or as solid carbon solution or in inn heider is present

II. Riiie second k. , se of mixtures, consist " from a self-lubricating May. il voi Molybdenum disulfide or materials containing mnlyb contain iliindisulfid, a carbiil-forming egg

Metal selected from the group consisting of molybdenum, niobium, tantalum, tungsten and their combinations, a carbonaceous component in the form of either metallic carbides or a solid carbon solution or in the form heider and a component of boron, which is either in the form of a solid boron solution or is in the form of free boron or both.

Fine third class of mixtures, consisting of a self-lubricating component of Molybdenum disullide or materials containing molybdenum disullide; a carbide-forming Material selected from the group molybdenum, niobium, tantalum, tungsten and their combinations, a carbonaceous component either in the form of metal carbides or a solid carbon solution, or both, a component of boron in the form a solid boron solution, free boron or both plus a metal component with a Melting point, which is significantly lower than that of the carbide-forming metals made from the group of iron, nickel, chromium, cobalt is selected. as well as their combinations.

Embodiments for the mixtures described above are given below:

class

mixture

read part

Weight percent

Molybdenum disulfide (MoS ₂ ) 20.0 to 97.0

Carbon (C) 0.01 to 10.0

Molybdenum (Mo) 0.01 to 80.0

Mixture 2
Part of Geun.htspro / ei, i

Molybdenum disulfide (MoS ₂ ) 20.0 to 97.0

Carbon (C) 0.01 to 10.0

Niobium (Nb) 0.01 to 80.0

Mixture 3

readsiindteil

Molybdenum disullide (MoS ₂ ).

Carbon (C)

I antal (Ta)

Mix 4

component

Mol> diindisiillide (MoS ₂ ). . .

Carbon (C)

Tungsten (W)

Mix 5

Gcwithtspro / enl

20.0 to 97.0 0.01 to 10.0 0.01 to 80.0

20.0 to 97.0 0.01 to 10.0 0.01 to 80.0

component

(icwichlspro / cni

Molybdenum disulfide (MoS ₂ ) 20.0 to 97.0

Carbon (C) 0.01 to 10.0

Molybdenum (Mo) 0.01 to 80.0

Tantalum (Ta) 0.01 to KO.O

Mixture 6 component Gewichi-.pioA. · »!

Molybdenum disullide (MoS ₁ ) 20.0 to 97.0

Carbon (C) 0.01 to 10.0

Molybdenum (Mo) 0.01 to 80.0

Tungsten (W) 0.01 to 80.0

Mix 7

Weight pro / L-nl

component

Moiybdenum disulfide (MoS ₁ ) 20.0 to 97.0

Carbon (C) 0.01 to 10.0

Molybdenum (Mo) 0.01 to 80.0

Niobium (Nb) 0.01 to 80.0

Tantalum (Ta) 0.01 to 80.0

Tungsten (W) 0.01 to 80.0

Class Il

mixture

component

Molybdenum disulfide (MoS ₁ ) 20.0 to 97.0

Carbon (C) 0.01 to 10.0

Boron (B) 0.01 to 5.0

Molybdenum (Mo) 0.01 to 80.0

Mixture 2

component

Weight percent

Molybdenum disulfide (MoS ₂ ) 20.0 to 97.0

Carbon (C) 0.01 to 10.0

Boron (B) 0.01 to 5.0

Niobium (Nb) 0.01 to 80.0

Mixture 3

Ingredient weight percent

Molybdenum disulfide (MoS ₂ ) 20.0 to 97.0

Carbon (C) 0.01 to 10.0

Boron (B) 0.01 to 5.0

Tantalum (Ta) 0.01 to 80.0

Tungsten (W) 0.01 to 80.0

Mix 4

component

Molybdenum disulfide (MoS ₂ ) 20.0 to 97.0

Carbon (C) 0.01 to 100

Boron (B) 0.01

Niobium (Nb) 0.01

Tantalum (Ta) 0.01

Tungsten (W) 0.01

Class 111

up to 10.0 up to 5.0 up to 80.0 up to 80.0 up to 80.0

mixture

component

Molybdenum Disulfide (MoS ₂ ) 45.0 to 90.0

Carbon (C) 0.01 to 10.0

I antal (Ta) 2.0 to 55.0

F.ivn IFc) 0.1 to 53.0

5 6

Mixture 2 The reason for this lubrication mechanism is that the molybdenum

j. .. ·, tliindisulful a »sliding lubrication« or lubricating

licwichiKpro / Kiii has transmission properties. Below is to

Molybdenum Disulfide (MoSj) 45.0 to 90.0 understand that when a material containing molybdenum

Carbon (C) contains 0.01 to 5.0 5 disulfide, with a MoUiH which this

Tantalum (Ta) 2.0 to 55.0 mixture does not contain, brought into sliding contact

Nickel (Ni) O ₁ I to 53.0, the weak bond between the sulfur atoms of the molybdenum disulfide crystals becomes the larger

Mischunc 3 forces acting between the sulfur atoms and the

ίο Atoms of the new metal exist, gives way. on

The remaining weight percent in this way becomes some of the molybdenum disulfide

Molybdenum disulfide (MoS ₂ ) 45.0 to 90.0 smeared or over-

Carbon (C) 0.01 to 10.0 ^ruhrl ; ^ ⁶³⁶ "SchmicrmiUel-transfer mechanism-

Tantalum (Ta) 2 0 to 55 0 ^{mus "n" el man in a "en} hrlindung mixtures of these.

Chromium (Cr) 01 to 530 ' ⁵ ^ ^r ' ^{sl is} particularly important when used in a vacuum.

At first glance, lubrication problems in the vacuum do not appear to be any different from those in the

Mixture 4 air occur. In fact, vacuum conditions

_n . .. more serious problems arose, and it is with one

uesianateil weight percent ₂₀ faster abrasion on the compilation too

Molybdenum disulfide (MoS ₂ ) 45.0 to 90.0 are calculated as when operating in air. Every co-

Carbon (C) 0.01 to 5.0 material formed from metal and im

Tantalum (Ta) 2.0 to 55.0 vacuum is operated, vei, <ali different than that

Cobalt (Co) 01 to 53.0 same composition when exposed to air in

25 is put into operation. It was found that

From the table above, what blends the absence of an oxide film on the surfaces This invention indicates, it will be seen that all of the parts of the assembly affect the cohesion of the Mixtures of molybdenum disulfide, which is primarily metal between several parts of the joint causes the self-lubricating properties of the end position when operating in a vacuum. The Mixtures is responsible, included. The molyb-metal sticks to other metallic surfaces Dändisulfid in these mixtures can also be due to or depends on when there is a cohesive contact other self-lubricating materials are replaced. exists, and breaks with the others when it operates A typical substitute for this is tungsten disulfide. metallic surfaces. The transfer of Me-However tungsten disulfide is much more expensive than particles moving from one surface to another Molybdenum disulfide. Furthermore, with mixtures, 35 takes place quickly, so that after a short period of operation the contain this substance, tests carried out periodically a visible hole formation occurs. this demonstrated that the resulting mixtures do not cause the metal surfaces to become rough, Have properties that increase the noise level and also the properties of molybdenum Mixtures containing disulfide are superior to increase the required operating force. Takes place in the air and thus the increased costs justify 4 ° this cohesion, which the roughening of a bearing in the became. Vacuum causes, not instead, what to the property-the self-lubricating properties of molyb- an oxide film on the surface of the metal dändisulfids, if it can be traced back to itself or together with.

other materials used are known. If a normal lubricant is on the upper

The crystals of molybdenum disulfide have a 45 surface area of the metal compositions, which in the Va

Plate structure in which successive pluckuum are operated is applied therein

ten of molybdenum atoms with successive evaporates the lubricant due to its high

Layers of sulfur atoms between each layer of vapor pressure. Thus, the lubricant is after

arranged by molybdenum atoms. A large one no longer available for a short period of operation.

Molybdenum disulphide crystal is therefore considered to

layering layers of molybdenum as well as molybdenum disulfide, in combinations that

see, which are operated by strong ionic bonds with those in a vacuum, reduces the pro-

butting layers of the eye connected. caused by cohesive erosion,

where the successive sulfur- Whenever the molybdenum disulfide occurs with a

layers by weak homeopolar bonds 55 when the metal surface comes into contact

be held together. will contain a small amount of the molybdenum disulfide

While the sulfur layers transfer the metal surface in contact during formation, where-

of a complete molybdenum disulfide crystal to one another by which cohesive erosion is avoided. Aul

others only have a weak attraction, have this way of doing things.

the sulfur atoms have a much greater affinity for & ° conditions about the same function as dei

Metals, so that the molybdenum disulphide plates at oxidic surface areas at atmospheric conditions

Apply certain conditions firmly to metals. conditions. In addition, however, the molyb

The sulfur atoms are, since they are only dändisulfid better lubricating properties than the oxy

have a weak affinity, not by so dische surface film, so that upon collision

strong forces held, such as the sulfur on the ⁶ 5 lungs, which öti the air operated, the one

Metal is held in place, nor are they as great as the use of molybdenum disulfide as a lubricant

Metal-to-metal adhesion forces. Therefore, the coefficient of friction acts between those in contact

Sulphide as a lubrication mechanism, and it is said to be greatly reduced on standing metal plates.

From the foregoing it can be seen that the use of molybdenum disulfide as a self-tapping Material in mechanical compositions, either in a vacuum or in air are in operation is highly desirable. However, the use of this lubricant has serious implications Problems with yourself. Although molybdenum disulfide has a wide range of operating temperatures has considerable stability, this material lacks many of the metallic properties that are essential for mechanical purposes, including ductility. the pressure resistance, the tensile strength, lubricity, impact resistance and resistance to embrittlement.

Considerable effort has been made to expand the scope of molybdenum disulfide undertaken to find a suitable matrix in which the molybdenum disulfide would be suspended should, / u develop. This matrix must. to be suitable / u, the mixture the above mechanical I confer properties and allow the M olybdenum disulphide, its lubricity, the transfer of lubricant and the high temperature resistance gives the resulting mixture. An example for a matrix developed for this purpose is one in which molybdenum disulfide was combined with iron to give a mixture that would improve the lubricating properties of the Molybdenum disulfide and also many of the structural properties of iron retained. Unfortunately, however, iron also held some of its undesirable effects i properties in the resulting mixture. niimhch its susceptibility to oxidation, which results had limited the scope in which the mixture could be used would. The replacement of iron by nickel, as suggested in the patent mentioned was allowed, while reducing many of the difficulties associated with the use of iron even the use of nickel does not limit the range of properties of molybdenum disul- :; ds to evaluate.

Extensive studies have been made to determine the maximum temperature at which the molybdenum disulfide can be sintered without dissociation of the molybdenum disulfide occurring during sintering. It has been found that if a pressure of 352 kg / cm ^{2 is} applied to the molybdenum disulfide during sintering, dissociation of this material can be avoided at temperatures up to about 182 ° C. This result is surprising in that molybdenum disulfide normally dissociates at temperatures between 1093 and 1204 "C at atmospheric pressure. After this surprising ability of molybdenum disulfide to withstand high sintering temperatures was discovered, it was clear that the full potential of this material was not realized using iron or nickel as the binder in the matrix. These objects were achieved by the compositions of the invention using molybdenum disulfide as the lubricating mechanism and a refractory metal as the binder for the matrix. Chemical analyzes of these mixtures indicate that When graphite punches are used for the production of these mixtures at high temperatures and pressures, carbon from the punches combines with the refractory metal and forms a carbide were coated with molybdenum disulfide. This surprising metallurgical configuration appears to be primarily responsible for the extremely low abrasion rates exhibited by these blends. In addition, certain of these blends exhibit the ability ^{to withstand compressive loads in excess of 17,600 kg / cm 2} , while others can be operated at sliding surface speeds of 3657.6 m / min. The temperature range over which these materials will be used. is equally impressive. Many of these mixtures can be operated up to 399 C in air and up to 1316 C in a vacuum. With regard to the temperature resistance, operation in liquid hydrogen at -251 ("has been demonstrated. It has been shown that these mixtures have unique electrical properties. Mixtures characterized either as good conductors for electrical current or as good insulators can be produced It is possible to control the clever properties by varying the composition of the metal matrix chosen.These results can be obtained although molybdenum disulfide by itself does not have good electrical conductivity and is in fact characterized by such a high degree of electrical resistance that it is is used as an insulating material in many systems where the prevention of electrical conductivity is desired, It should also be noted that the refractory metals used in these mixtures are not specifically mentioned in terms of their electrical conductivity and that carbon-graphite, although generally low in electrical resistance, often has opposite properties in terms of electrical conductivity. However, the metal carbides formed in the matrix of the blends of the invention do not exhibit opposite properties and have the unexpected result that when combined with the highly insulating material molybdenum disulfide, they exhibit excellent electrical conductivity.

In the mixtures of the second class of this invention, small amounts of Boron, up to 5 percent by weight, · added to further improve the structural properties.

The boron component is believed to enter the matrix as a solid solution, with the possibility insists that some metallic borite is formed. Relatively small boron additions of approximately 1 percent by weight increases the ultimate pressure resistance of some blends significantly while Additions of boron in excess of 5 percent by weight for a decreasing pressure resistance have led. There are also certain facts. which suggest that the boron component during of the manufacturing process acts as a lubricant, creating a mixture with a greater degree of compression, than is otherwise the case. In addition to the components molybdenum disulphide. Carbon and tantalum, the Class III mixtures of this invention contain a further metal component. selected from the group iron.

109 684/314

Nickel, chromium and cobalt. The main purpose of adding these metals to the matrix is to provide lubrication during the manufacturing process. These metals have melting points which are considerably below those of the carbide-forming metals. Your presence contributes does not significantly contribute to the structural properties of the resulting matrix. Their primary function is in w ah read the manufacturing process to act as a lubricant, thus greater compression of the resulting matrix can be obtained. Of course, the mixtures of class III can be certain Limitations are imposed due to the inclusion of these components are. In particular, the mixtures of Class III cannot withstand the high temperatures like those of classes I and II.

Furthermore, the Class III mixtures containing nickel and chromium show considerably higher levels Abrasion speeds than the class I and II blends. During the manufacture of the Class III mixtures include the iron, nickel, chromium or cobalt in the molten material State before. It has been found that due to the high level used in manufacture These metals are pressed to the outer edges of the mixture and come into contact with the pressure Press tool come. There are certain reactions between the molten metal and instead of the graphite pressing tool, which accelerate the abrasion on the pressing tools, thereupon damage effect and prohibit their use for more than three or four operational operations. Therefore, the Class III mixes should not be used when manufacturing many identical parts is desired.

The following methods of production of the mixtures given herein are representative methods of hot pressing or compaction. These procedures are intended to be representative of any method of making the materials of the invention stand.

The self-lubricating component molybdenum disulfide can be in powder form in a wide range of sizes can be used, but a range of 7 to 64μ is successful in making these mixtures been used. The powdered molybdenum disulphide which forms the self-lubricating component was examined to find that it had an oil in addition to molybdenum disulfide Contains petroleum base with a content of 0.02 to 0.05 percent by weight. It is believed that the petroleum oil is a distributor for carbon for the final mixes. The metal powder, molybdenum, tantalum, Niobium and Tungsten as used in Class I, as well as that used in Class II compounds Boron and the iron, nickel, chromium and cobalt used in the IN class mixtures Taken from commercial sources and have a purity of over 99.9%. Although all Metal powder obtained as 325 mesh particles is any particle size that can be sintered suitable for the production of these mixtures.

After weighing in the appropriate quantities of the components used, the metal powders, if more than one metallic component is used, first mixed together before using the molybdenum disulfide component are mixed.

The following procedures for mixing the metal powders with the molybdenum disulfide have been satisfactory Mixtures result in:

1. Sieving: The powder mixture is transferred through a 100-mesh sieve into collecting pans, placed in a container. The sieving is repeated two more times. The powder is then put into the Graphite press tool transferred.

2. Automatic mortar: The powder mixture is placed in an alumina mortar and an amount of acetone sufficient to obtain a free flowing sludge is added. In the An alumina pestle is inserted into the mortar and automatic mixing begins. Mixing is continued for 20 minutes with periodic addition of acetone to to maintain the mud. During the last 5 minutes hes automatic shuffling no acetone is added so that the mixture is made into a thick paste. The pasty Mixture is removed from the mortar with a spatula and dried in a vacuum oven for 1 hour at 93 "C. The dried Powder is then passed through an 80-mesh screen and placed in a graphite press tool.

The graphite press tool used in sintering is the source of carbon that is used in the Final mixtures occurs and forms carbides there with the refractory metals. The amount of in the final mix Incoming carbon is controlled by the length of the hot pressing period.

For the hot pressing, the powdery mixture is brought into the Graphif pressing tool, whereupon by means of induction heating the pressing tool is initially brought to a temperature of 149 ° C is brought and kept there long enough at this temperature to remove water vapor that is in the Powder might be included to drive off. The duration of this dry period is not critical and lasts usually about 5 minutes.

The following steps are applicable to the preparation of Class I and II compounds. The steps for making the Class III mixes are discussed in detail later. After the press tool has ^{been held at 149 °} C. for about 5 minutes in order to drive off trapped water vapor, the temperature of the press tool is increased to 1371 to about 1800 ^° C., and a load of about 70.3 to 633 kg / cm ^{2 is} applied exerted the graphite pressing tool, which contains the powdery mixture of class I or II, which is done by means of a hydraulic cylinder or a lever system. The pressure is applied in two stages as follows: First, half of the final pressure is applied and maintained until the temperature of the assembly has increased to the sintering temperature. This usually takes about 20 minutes, the exact time depending on the size of the press tool and the capacity of the induction heating Applying full pressure determines the grain size and carbon content of the final mix, with longer periods of time larger grains

1

sizes and higher carbon contents result. Quality Sintering results were with a full press load applied for a period of 10 minutes was obtained.

In the preparation of the class III compounds, after the assembly has been held at 149 ° C for about 5 minutes to drive off the water vapor, a load of 70.3 to ^{4.2 kg / cm 1 is} applied to the press tool, which by means of a hydraulic cylinder or a lifting system happens. After Aulbringen the load, the temperature is raised to 1093 to 1482 ⁰ C, << un namely within a period between 2 and i0 minutes, the exact period of the available power towie depends on the size of the Prel3werkzeugs. After the sintering temperature has been reached, the temperature is maintained for 2 to 10 minutes.

After the sintering together of the mixtures of classes I, II or III has ended, induction heating is used turned off and the die is allowed to cool to room temperature. the Load can be removed from the presses immediately after the power has been switched off if there is a risk of that shattering or other destruction will take place during cooling that will affect the different thermal expansion of the mixtures and of the press tool can be attributed to i <t if if such a hazard is not present, the exposure will generally not be removed until the Composition has cooled to a temperature of around 149 ° C to form a firmer compact Material to receive.

In all cases, the Induction furnace flushed with argon, nitrogen or another inert gas so that it is inert Atmosphere around the pressing plant.: Eug around is ensured that the oxidation of the powdery Mixture and the pressing tool itself prevented. The following are specific exemplary approaches of the mixtures of the invention are given together with some electrical and physical properties.

example 1

The following material, which is typical of Mixture 1, Class I, was pressed at a pressure of 352 kg / cm ² and a temperature of about 1800 "C.

^Ingredient weight percent

Molybdenum Disulfide (MoS ₂ ) 79.3

Carbon (C) 0.9

Molybdenum (Mo)! 9.8

Experiments carried out with the examples of Mixurg I class! Show that the physical and electrical properties of this material are somewhat dependent on variations in the manufacturing process, to an extent that has not been observed for other mixtures of this invention. Nonetheless, it was found that the mixture of this example has exceptionally good abrasion properties with a value of 2.54 χ 10 ^ cm 3Ί00 minutes, the test specimen originally having a straight line contact with the tent surface, which was carried out at a surface speed of 274.3 m / min was moved. The test sample had a final compressive strength greater than 3020 kg / cm ² and a coefficient of friction of 0.07. The electrical properties of this sample showed an electric resistance of 1.5 χ ~ 10 ⁴ ohms / cm. From these measurements it can be seen that this embodiment of the invention can find particular application where primarily low abrasion properties are of importance and frictional and electrical resistance properties are of lesser importance.

'Example 2

The following material, typical of Mixture 2, Class I, was subjected to a pressure of 352 kg / cm² at a temperature of 1649 "C hot pressed.

Ingredient weight percent

Molybdenum disulfide (MoS ₂ ) 6 - /, 8

Carbon (C) 0.6

Niobium (Nb) 29.6

The analyzes carried out with the batches of mixture 2, class L show that those samples with higher percentage contents of molybdenum disulphide have higher carbon contents. This proves that part of the molybdenum disulfide is converted into molybdenum carbide during the manufacturing process. Those samples having low percentage levels of molybdenum disulfide, ie, 30 to 50%, show a very low electrical resistance of 1.2 χ ~ 10 ⁴ ohms / cm. The particular example described herein showed a final compressive strength of about 9490 kg / cm ² (3700 Qpsh with a low coefficient of friction of 0.045. Suitable uses for this material include those where low friction properties are desired under high load conditions.

Example 3

The following material, which is typical of Mixture 3 Class I, was ^{hot-pressed under a pressure of 352 kg / cm 2} in the manner described above.

Ingredient weight percent

Molybdenum disulfide (MoS ₂ ) 79.2

Carbon (C) 1.0

Tantalum (Ta) 19.8

It has been found that the ultimate compressive strength of this example depends somewhat on the temperature at which the material was hot pressed. For example, if the material with a composition corresponding to this example is hot-pressed at a temperature of 137TC, a relatively low final compressive strength of 408 kg / cm ^{2 is} found. Another test sample, with the exception of a compression temperature of. 1649 ° C. was identical, showed a final compressive strength of 1690 kg / cm ² . Both test probes showed an electrical resistance of 3.1 χ ΙΟ ' ⁴ Ohm / cm.

B e i s ρ i e 1 4

The following material, which is typical of Mixture 3 Class I, was ^{hot pressed at a pressure of 352 kg / cm 2} at 1482 "C.

$ 942,702

Ingredient weight percent

Molybdenum disulfide (MoS ₂ ) 69.3

Carbon (C) 1.0

Tantalum (Ta) 29.7

This example is notable because it shows exceptionally good friction and abrasion properties "when used against a titanium alloy containing 6% aluminum and 4% vanadium. This example shows a final flexural strength of about 949 kg / cm ² (13 625 psi) and has a coefficient of friction between 0.19 and 0.25 at lower surface speeds. At higher surface speeds (457.2 m / min) the coefficient of friction is 0.04 to 0.08. In further tests carried out with this example, a Ball separator made of this material to produce a 20 mm ball bearing assembly. The bearing was operated in air at room temperature at 3450 rpm with an axial load of 4.53 kg. After 10 088 hours of operation, the separator and the bearing assembly showed extremely low wear .

Example 5

The following material, typical of a 4th Class 1 mixture, was subjected to a pressure of 352 kg / cm * hot-pressed at around IROO "C.

Ingredient weight percent

Molybdenum disulfide (MoS ₂ ) 79.1

Carbon (C) 1.1

Wolfram (W) 19.8

In general, Mix 4, Class I runs with a high molybdenum disulfide content (about 80 weight percent) exhibit the highest electrical resistance of all the runs of this invention. Thus, even if one of the primary objects of this invention is to provide a self-lubricating material having a high degree of electrical conductivity, electrical conductivity can be modified by taking appropriate approaches. Such a procedure would result in a suitable application in the manufacture of an electrical switch with low-friction oil contacts by alternating the approaches of the selected contacts. Thus, alternating contacts would exhibit high and low electrical conductivity properties that would result in circuit function through high and low electrical conductivity paths. The given here particular example shows a relatively high electrical conductivity value of greater than 4100 χ ~ 10 ⁴ Ohm / cm, which was begießet of a reasonably low coefficient of friction of 0.07. The material is suitable for low-friction, low-friction purposes.

Example 6

There? The following material, typical of Mixture 4, Class I, was ^{hot pressed by hot pressing at a pressure of 352 kg / cm 2} at a temperature of about 1800 ° C.

Ingredient weight percent

Molybdenum disulfide (MoS ₂ ) 19.9

Carbon (C) 0.2

Tungsten (W) 79.9

The mixture of this example has a high metallic tungsten content and it can be assumed from the good high temperature properties of tungsten, which are well known in the art, that this material also has excellent high temperature properties. The mixture of this example has a final flexural strength of 2040k;: / cm ² and an electrical resistance of 0.33 χ 10 " ⁴ ohms / cm.

B c i s pie I 7

The following material, typical of a 5th Class I mix. was hot-pressed under a pressure of 562 kg / cm ² at 1538 "C.

■ Part of weight / cm

Molybdenum disulfide (MoS ₂ ) 79.1

Carbon (C) 1.2

Molybdenum (Mo) 14.8

Tantalum (Ta) 4.9

This material has exceptionally good sliding friction properties. when used in conjunction with a copper surface. The transfer of funds or the sliding lubrication was extremely good. Due to the relatively high carbide content was able to remove excess of the transferred lubricant from the copper surfaces will. The electrical resistance was

} o 14.9 χ 10 " ⁴ ohms / cm. Accordingly, this material has found successful use in sliding electrical contacts or electrical motor brushes used in conjunction with a copper commutator.

Example 8

The following material, which is typical for a 5th class 1st is ¹ mixture, was hot-pressed under a pressure of 633 kg / m3 at a temperature of 1454 ° C.

component

Weight percent

_4S molybdenum disulfide (MoS ₁ ) 44.7

Carbon (C) 0.7

Molybdenum (Mo) 14.9

Tantalum (Ta) 39.7

This example shows excellent behavior as a self-lubricating material under high loads and at high surface speeds. In addition, relatively constant low friction properties were seen over a considerable range of stress levels. A self-lubricating agent made according to this approach can be used successfully if it is used as a sleeve or as a ball bearing. These superior abrasion properties were demonstrated in such a way that a ball bearing 1.90 cm was produced and this was examined in air at 21, Γ C. The bearing was through an angle of ± 7 '/ ₂ ° with a speed of 200 cycles / min oscillated with a load of 141 kg / cm ^{2 being} applied

After completion of 10 χ IfJ ⁶ cycles, the measured abrasion on the ball bearing was only slightly; 0.058 cm. The electrical resistance of this material: is 1.23 χ 10 ~ ⁴ ohm / cm.

U eis ρ ie 1 9

The pentagonal material, which is used for a mixture 6, Class I, which is typical, was hot pressed under a pressure of 352 kg / cm * at 1482 C.

Ingredient weight percent

Molybdiine disulfide (MoS ₁ ) 49.6

Carbon (C) "0.9

Molybdenum (Mo) 39.6

Tungsten (W) 9.9

By varying the weight-based content of the molybdenum disulfide in the mixture 6, class I, batches were prepared from about 40 to 95%, the electrical resistance of continuous, but in a nonlinear manner χ of 1.1 ~ 10 ⁴ to 3.1 10 ~ ⁴ χ Ohm / cm can be varied. In this way, control over the electrical resistance properties can be exercised by controlling the composition, and the self-lubricating properties can be maintained. The electrical resistance of this example is given / cm 1.1 ~ χ 10 ⁴ ohms. The abrasion and frictional properties of this material were low.

Example 10

The following material, which is typical for a mixture 6, Klaf> e 1, was hot-pressed ^{under a pressure of 352 kg / cm * at about 1800 ° C.}

Ingredient weight percent

Molybdenum disulfide (MoS ₂ ) 79.1

Carbon (C) 1.1

Molybdenum (Mo) 13.9

Tungsten (W) 5.9

This material has an electric resistance of 3.1 χ ~ 10 ⁴ Ohm / cm, and represents a self-lubricating material which can be manufactured relatively cheap. Thus, this material is the logical choice for low cost applications.

Example 11

The following material is tvpisch for a mixture 7, Class I, was hot pressed under a pressure of 352 kg / cm * at 1510 ⁰ C.

Ingredient weight percent

Molybdenum Disulfide (MoS ₂ ) 39.8

Carbon (C) 0.5

Molybdenum (Mo) 14.9

Niobium (Nb) 14.9

Tantalum (Ta) 14.9

Tungsten (W) 14.9

The approaches of the mixture 5, class I, showed the electric resistance of resistors of 0.41 χ 10 ⁴ to 17.0 χ ~ 10 ⁴ Ohm / cm, in general, wide variations measured in certain samples. These electrical resistance variations appear to be related to the weight percentage of tungsten present in these batches, with the higher tungsten batches showing the higher electrical resistances. The example given above has an electrical resistance of 0.41 χ ΙΟ " ⁴ Ohm / cm and be

sits a relatively high coefficient of friction of 0.14, which is accompanied by a low abrasion speed. These friction and abrasion velocity properties, along with a high final compressive strength of about 1300 kg / cm ² (ISKOOOpsi), show that this example can be used in high performance, high temperature braking devices.

Example 12

The following material, which is typical for mixture 1, class II, was ^{hot-pressed at a pressure of 352 kg / cm 2} at 1593 ° C.

Ingredient · weight percent

Molybdenum Disulfide (MoS,) 79.2

Carbon (C) * 1.0

Boron (B) 0.5

Molybdenum (Mo) 19.3

This example exhibited a very low wear rate of 4.6 χ 10 ~ ⁵ cm 3/100 min, wherein the pattern was originally set in line contact with a test surface made of stainless steel at a surface speed of 274 m / min moved. This is in comparison with an abrasion speed of 15.5 χ 10 " ³ cm 3/100 min, as was measured in the other examples of mixture 1, class II.

Example 13

The following material, which is typical of Mixture 2, Xlasse II, was ^{hot pressed at a pressure of 352 kg / cm 2} at 1510 ° C.

Ingredient weight percent

Molybdenum Disulfide (MoS ₂ ) 29.8

Carbon (C) 0.7

Boron (B) 0.5

Niobium (Nb) 69.0

Small proportions of boron, in the region of ¹ I ₂ to 1%, which are present in Mixture 2, Class II, result in a self-lubricating material which exhibits an extremely high ultimate compressive strength. In an example of Mix 2, Class II, with 20 weight percent molybdenum disulfide, half of a 1 weight percent addition of boron resulted in one

so approach with a final compressive strength of over 17,600 kg / cm ² . Larger additions of boron, however, reduced the final pressure resistance considerably: an example with the same proportion by weight of molybdenum disulfide, but with 5 percent by weight of boron, resulted

a final compressive strength of 8090 kg / cm ² . In the example described herein, tests showed that this material had a relatively high ultimate compressive strength of 17,200 kg / cm ² and a coefficient of friction of 0.042. Presumably, the high niobium content of this example is responsible for the high ultimate flexural strength, which was determined to be 3160 kg / cm ¹ . The electrical resistance of this example was 0.33 χ 10 "* ohm / cm. These measurements show that this material

6s is particularly suitable for purposes that require a resistance to very high stresses and where a reasonable level of electrical conductivity is desired,

I 942 702

Example i4

The following material, typical of Mix 3, Class II, was ^{hot pressed at a pressure of 352 kg / cm 2} at 1649C.

Ingredient weight percent

Molybdenum disullide (MoS ₂ ) 90.2

Carbon (C) 0.9

Boron (B) 3.0

Tantalum (Ta) 3.0

Tungsten (W) 3.0

Laboratory evaluations of this example indicate that this material has a very low level Has a coefficient of friction of 0.025, which leads to the variation of surfaces with high surface speeds are subject to, is suitable. The electrical resistance of this example was slightly higher than that of most of the other mixtures of the invention and was determined to be 25.5 χ 10 "* ohm / cm.

Example 15

The following material, typical of Mixture 4, Class II, was ^{hot pressed at a pressure of 352 k ^ / cm 2} at 1649 ° C.

Ingredient weight percent

Molybdenum disulfide (MoS ₂ ) 91.2

Carbon (C) 0.9

Boron (B) 0.5

Niobium (Nb) 2.0

Tantalum (Ta) 3.5

VS Dlfram (W) 2.0

Friction measurements carried out with various batches of Mixture 4, Class II, showed that the coefficient of friction remained relatively constant, although the production temperature and the molybdenum disulfide content were varied. The coefficient of friction of the example given is 0.032. It is believed that this value will remain fairly stable over a wide range of operating conditions. The mixture of this example has an electrical resistance of 8.1 χ 10 ⁴ Ohm / cm.

H e i s ρ i c 1 16

The following material, typical of Mix 4, Class II. was hot-pressed at a pressure of 352 kg / cm ^{2 at 1510C.}

IhM.an'Jtcil

(ieuiihhpro / cnt

Molybdenum disulfide (MoS ₂ ) 39.8

Carbon (C) 0.5

Boron (H) 4.0

Niobium (Nb) 18.6

Tantalum (Ta) 18.6

Tungsten (W) 18.6

This example has a coefficient of friction of O ₁ OSO and an electrical contradiction of 0.86 χ 10 "* ohms / cm. Other experiments indicate that this material can be used in devices that are operated at extreme temperature, pressure and other circulating conditions , plays an important role.

Example 17

The following material ill for a mixture 1, class, is typical, was hot pressed at a pressure of 352 kg / cm ² at about I288 ^U C.

Ingredient weight percent

Molybdenum disulfide (MoS-.) 90.0

Carbon (C) 0.2

ίο tantalum (Ta) 5.0

Iron (Fe) 4.8

Example 18

The following material, typical of Mix 1, Class III, was ^{hot pressed at a pressure of 352 kg / cm 2} at about 1288 ° C.

Ingredient weight percent

Molybdenum disulfide (MoS ₁ ) 45.0

Carbon (C) 0.4

Tantalum (Ta) 50.0

Iron (Fe) 4.6

In Examples 17 and 18, the iron component is contained in the matrix not as a binder, but rather as a processing lubricant, so that during hot forcing the mixture melts the iron and allows the grains of the other components condense into a dense mass. Other lubricants, one of which too They have been found to contribute to matrix densification include nickel, chromium and Cobalt. Numerous other examples could be given of mixtures containing these ingredients will. In general, the mixtures given in Examples 17 and 18 show a wear rate which is higher than that of most mixtures of classes I and II.

X-ray diffraction tests carried out with Mixture 3, Class I indicate that this molybdenum disulfide-carbon-tantalum mixture has the structure of a cemented conglomerate. which is composed of at least four phases. These phases appear in the order they appear

4.S optical reflectivity, with no etching taking place.

Phase 1 is a shiny, lacy network, that shows no grain structure. A micro test shows that this phase is rich in molybdenum disulphide.

so phase 2 is slightly gray < Composed of surfaces which have an almost oval shape and which cmc normally surrounded by phase 3 material and having irregular inclusions of material from Phase 4 included. The microprobc indicates that the

ss areas of phase 2 are rich in tantalum and that this phase also shows no grain structure

Phase 3 is a dark gray area in the (A total mixture with a fine grain structure Heim Polishing shows that these laughs are soft and

'*) / wipe the grains can be broken easily . The microsample indicates that these areas have varying levels of molybdenum disulfide. Phase 4 of this mixture is a very dark one

f> 5 gray area with an irregular shape and one relatively small size. The chemical composition of this phase could be determined by the microprobc cannot be determined due to the

Smallness and the irregularity of these girls. In general, a cross section of this mixture shows a fairly uniform distribution of molybdenum disullide and of tantalum.

X-ray diffraction experiments were also carried out with the class III compounds which represent the four components molybdenum disulfide, carbon, tantalum and another metal from the iron group, Contains nickel, chromium and cobalt. These blends exhibited a structure made up of at least three Phases. The first is a lighter area with a network of molybdenum disulfide, which is from narrow, oval surfaces of a second tantalum-rich phase is surrounded. Show the tantalum-rich surfaces a pronounced grain formation, similar to a metallic material. The distribution d ^ r other metals (iron, nickel, chromium or cobalt) seem to follow the molybdenum disulfide surfaces. the The third phase appears as a small, bright surface with an irregular shape, which does not collapse could be determined exactly.

The physical properties of the examples of the blends of the present invention were as follows Way determined:

Bending tests

The bending tests were carried out with samples with the dimensions 5.08 χ 0.76 * 0.25 cm. Three tests were performed, generally by center loading, on a bar ridden on knife edges 3.8 cm apart. The final bending load was calculated using the following formula:

F = ³ ^ '
² 2Wt '

Breaking load in pounds,

Span between the knife edges in cm,

Bar width in cm,
Bar thickness in cm.

Comprcssionsver.suchc

Fin broken billet from bending test turned into compression music with dimensions 0.76 χ 0.76 χ 0.25 cm processed. The test samples were placed between two hardened steel plates and loaded to break at a rate of 0.13 cm / min in a test device.

Abrasion tests

The abrasion tests were carried out. by placing the narrow edge of a rectangular bar pattern with dimensions 1.8 0.76 χ 0.25 cm against a hardened 440C stainless steel (Rc 58) shaft with a diameter of 5.08 cm, which is moving at a speed of 1750rpm ( 274 m / min) was rotated, pressed. The abrasion swatches were pressed against the shaft with a 5 pound load and left in contact for 100 minutes. The measurements of the width of the abrasion notches were used to determine the volume of abrasion of the mixtures.

W. t

Friction seal ";

The friction measurements were made by placing a pattern against the periphery of a circumferential

the steel disk 440C (Rc 58) was pressed. The measurements were made at a surface speed carried out at a speed of 884 m / min. The frictional characteristics of these components are a function several different factors, one of which is the

ίο the most important are the following:

factor

Weight percent
MoS ₂

load
(Stress value)

Surface speed

Hardness of the touching
Materials

Surface condition
touching
Materials

the atmosphere

General influence

Under fixed conditions
takes the friction with it
increasing MoS _r content

The coefficient of friction
increases with increased
Stress value

The friction increases
increased surface speed

The friction increases
increased surface hardness

The friction increases
decreasing surface roughness

The friction increases in
Absence of air

The frictional character risks also depend on the specific elements in the metal matrix. The addition of boron in proportions of 4% or less results in minimal friction _{values with low MoS 2} contents.

The abrasion of the mixtures also depends on the above factors that affect the frictional properties. A mixture that has minimal wear for a set of operating parameters (load, speed, hardness of the material encountered, surface structure and atmosphere) may not have the minimal wear if one of these factors is changed significantly. In general, mixtures with a high MoS ₂ content (over 75%) are best suited for operation at high surface speeds (up to 3658 m / min) and with low loads (less than 352 kg / eni ^2). For operation at high load values (7030 kg / cm ² ) and low surface speeds (3 m / min or less), mixtures with 20 to 50% MoS _{2 show} minimal : \ n abrasion properties.

Claims (5)

Claims: I. Solid lubricant based on a self-lubricating component within a refractory metal carbide matrix, consisting of 1. 20.0 bit 97.0 percent by weight molybdenum disulfide as a self-lubricating component, 2. 0.01 to 10.0 percent by weight of a carbon-containing component, in the present case at least a small part in the form of Metal carbides, 3. 2.00 to 80.0 wichlspr? Ent M < > lybdiin, niobium, tantalum, tungsten or a combination these metals as a carbide-forming component and optionally from 4. 0.01 to 5.0 percent by weight of a dark component, present at least a small part in the form of a solid boron solution, and optionally from 5. 0.1 to 53.0 percent by weight iron, nickel, chromium, cobalt or a combination of these Metals as a metallic lubricating material. 2. Solid lubricant according to claim 1, characterized in that it is used as carbide-forming Component 3 is a combination of 0.01 to 80.0 percent by weight molybdenum and tantalum or us 0.0 'to 80.0 percent by weight molybdenum and Tungsten or from 0.01 to 80.0 (icwichtspm / enl Molybdenum, Tuntul and Tungsten or from 0.01 to Contains 80.0 percent by weight of niobium, tantalum and tungsten. 3. Solid lubricant according to claim 1, revealing 1. 45.0 to 90.0 percent by weight molybdenum disulfide as a self-lubricating component, 2. 9.89 to 55.0 weight percent carbide-forming metal component and 3. 0.1 to 53.0 percent by weight iron, nickel, chromium, cobalt or a combination of these Metals as a metallic lubricating material.