DE2422212A1 - HYDRAULIC FLUIDS WITH INHIBITED WEAR EFFECT - Google Patents

Description

LAWYERS DR. JUR. NPL-CHEM. WALTER BEIL

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623 FRANKFURT AM MAiN-HOCHSf

ABELOisSTRASSe58

Our no. 19 256

Chevron Research Company San Francisco, CaI., V.St.A.

Hydraulic fluids with inhibited wear effects

The invention relates to fluids used for power transmission are useful in hydraulic systems, and particularly relates to compositions that are prone to wear of the hydraulic systems, as well as means to combat this wear-and-tear.

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Organic phosphate esters have been considered beneficial for some time Media recognized for power transmission in hydraulic systems Systems of this type are return devices, Power lines for the fluid transmission and hydraulic systems of aircraft. In the latter in particular, phosphate esters have proven themselves Proven because of their special properties, including high viscosity index, low pour point, good lubricity, Low toxicity, low density and flame retardancy are among “Therefore, for several years now, in numerous Aircraft types, especially in jet airliners, phosphate esters used in hydraulic systems. Other fluids found use as power transmitting healing contain larger or smaller amounts of τοη hydrocarbons, Amides of phosphoric acid, silicate esters, silicones and Polyphenyl ethers, additives that perform special functions, e.g. improving the viscosity index and preventing foaming are also used in these liquids.

Contained the hydraulic systems of a modern airplane a hydraulic tank, pressure lines and numerous pressure valves, which operate the various moving parts of the aircraft, such as landing flaps, elevators, rudder and landing gear. In order for these valves to function as precise control mechanisms, they often have nozzles with a clearance on the order of magnitude of a few thousandths of an inch (2.5 cm) or less through which the hydraulic fluid must pass. In In many cases, significant wear and tear on the nozzles from the hydraulic fluid flowing through them has been observed Yerechleii increases the size of the nozzle and increases the

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ability of the valve to act as a precision mechanism the tolerable limits lowered. On many aircraft, the flaps could sag during landing and take-off can be interpreted as a result of valve wear.

Recent research has shown that wear is caused by cavitation or cavitation in the fluid which occurs when the liquid is at high speed flows from the high pressure side to the low pressure side of the valve. It was found that by adding Adding water to the hydraulic fluid can delay the wear and tear, but longer experience has shown that still significant wear problems remain.

Recent research shows that some signs of wear and tear at valves are to be brought into connection with the electrokinetic flow stream flowing through the high velocity flowing liquid is induced.

One treatment of the problem of whether valve wear is attributable to fluid flow induced flow can be found in Beck et al, "Corrosion of Servovalves from ^{Electrokinetic Flow 11} , Boeing Scientific Research Document D1-82-0839 (September 1969). Experiments," To combat pressure valve wear and treat the problem as a result of cavitation in the fluid, see Hampton, "The Problem of Cavitation Wear in Aircraft Hydraulic Systems," Aircraft Engineering, XXXVIII, No. 12 (December 1966). In Organophosphorus Compounds Kosolapoff (Wiley, New York, 1950) uses methods for

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position of organic phosphorus derivatives described. Various patents describe Phosphatester as hydraulic fluids, including the US patents 2,636,861, 2,636,862, 2,894,911, 2 & 03,428 and 3,036,012.

It has now been found that soluble salts of perhalometallic acids and perhalogeno-non-metallic acids or their mixtures when added to non-aqueous hydraulic fluids in act in such a way that they decrease the electrical flow of the fluid, which occurs with the wear of the control valves is brought together in the system · The improvement is particularly in the formulation of the hydraulic fluid in the addition of 0.0001 to 2 percent by weight of the soluble salt of perhalo-metallic acid or perhalo-non-metallic acid to the hydraulic fluid. The hydraulic fluid preferably contains 0.001 to 1 percent by weight of the soluble Salt of these acids and consists of organic phosphate esters.

The terms "perhalo-metallic acid" and "perhalo-non-metallic acid", as used herein include all perhaloacids of the metals and non-metals of the periodic Systems that can form perhalo acids. These acids are sometimes referred to as "super acids". Metals and Non-metals that can form perhalo acids are beryllium from group IIA, thorium from group IIIB, titanium and zirconium from group IVB, niobium and tantalum from group VB, chromium from group VIB, manganese and rhenium from group VIIB, iron, nickel, ruthenium, Rhodium, palladium, osmium, iridium and platinum from Group VIII, gold from Group IB, aluminum, gallium and boron Group IIIA, silicon, germanium, tin and lead from group IVA,

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Phosphorus, arsenic and antimony from group VA and tellurium from group VIA. Suitable perhalogenometallic acids are, for example, heiafluoaluminum acid, hexafluoantimonic acid, hexafluoroiron (III) acid, heiafluotitanic acid, hexafluothoric acid, hexafluogermanium acid, hexafluozirconic acid, tetrafluoberyllium acid *, trifluorotinic acid, hexafluorochromic acid, (hexafluoro) fluochromic acid, hexafluoro peptic acid, hexafluoro peptic acid, hexafluoro peptic acid, hexafluoro peptic acid (IV) hexafluoric acid (IV). III) acid, hexafluoniobic acid, Hexafluomanganese (III) acid, tetrafluoboric acid, hexafluo- and Tetrafluorophosphoric acid, hexafluosilium acid, hexafluoroarsenic acid, hexachloroiridic acid, hexaehlorooBmiumsäure, tetrachloro- and hexachloropalladic acid, tetrachloro- and hexachloroplatinic acid, hexachlororhodic acid, hexajodoplatinic acid, Hexabrooiridium acid, hexabromoplatinic acid, etc.

The salts of perhalogeno-metallic acids and perhalogeno-non-metallic acids can be prepared by combining the perhalogenoic acid with a basic compound such as a.B, an alkali base, an alkaline earth base, ammonium bases, substituted Amaoniuiabasen, Phosphoniumbaeen and substituted phosphonium bases is implemented. Other basic compounds can also be used, provided that they form a salt with the perhaloacid and the salt formed is sufficiently soluble in the hydraulic fluid to cause a reduction in the flow of the fluid. Suitable basic Compounds are, for example, alkali hydroxides, oxides and carbonates such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium oxide, potassium oxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, etc., alkaline earth hydroxides, oxides and carbonates such as calcium hydroxide, Ba-

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rium hydroxide, calcium oxide, barium oxide, calcium carbonate, calcium bicarbonate, etc., ammonium hydroxide, substituted quaternaries Ammonium hydroxides such as tetramethylammonium hydroxide, trimethylbenzylammonium hydroxide, tetrapropylammonium hydroxide, Tetrabutylammonium hydroxide, etc., phosphonium hydroxide, tetramethylphosphonium hydroxide, tetrabutylphosphonium hydroxide, rime methylbenzylphosphonium hydroxide, etc. Other basic compounds are zinc hydroxide, zinc carbonate, zinc bicarbonate, etc.

The salts of perhalo-metallic acids and perhalo-non-metallic acids can also be prepared by halogenating a metal or non-metal with an ammonium or phosphonium halide or a substituted ammonium halide or substituted phosphonium halide is reacted. Reactions of this type are, for example, the reaction of ammonium fluoride with boron trifluoride, phosphonium fluoride with boron trifluoride, ammonium fluoride with phosphorus pentafluoride, phosphonium fluoride with phosphorus pentafluoride, phosphonium chloride with boron trifluoride, Setramethylammoniumchlorid with boron trifluoride, tetrabutylammonium fluoride with phosphorus pentafluoride, Methylbenzylphosphoniumchlorid with phosphorus pentafluoride, Methylbenzylphosphoniumchlorid with BortriChäorid, Ammoniumvhlorid with antimony pentachloride, Iriäthyloxonlumfluorid with Boron trifluoride, triphenylcarbenium chloride with phosphorus pentafluoride, etc.

A preferred group of perhalogeno-metallates and perhalogeno-non-metallates, which form the basis of the invention, has the following general formula:

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where are:

A is a metal or non-metal, preferably a non-metal;

M is a solubilizing cation; X is a halogen, preferably chlorine or fluorine, and most preferably Fluorine;

y is an integer from 3 to 7 and is equal to the positive valence of A plus an integer from 1 to 3; and preferably an integer equal to 4 for the metals and non-metals of the second group of the periodic table and equal to 6 for the metals and non-metals of all other groups of the periodic table; ζ an integer from 1 to 3 and sufficient to keep the salt electroneutral.

In the above formula, A is an amphoteric metal or non-metal of the type described supra which is capable of forming perhalo acids. In a preferred embodiment, A belongs to the group consisting of phosphorus, boron and antimony and is preferably phosphorus or boron. M can be any stable cation that gives the salts significant solubility in the hydraulic fluid. This solubility is preferably at least 0.01 g / l of the perhalogeno salt in the hydraulic fluid, a solubility of at least about 0.01 g / l is particularly favorable. The preferred solubilizing cations are alkali metals, ammonium, phosphonium, with ^G 1 ~ ^C 30 ^{£ ο1ι} 1 ^{βηνει 38} erstoffgruppen substituted ammonium, with C.-C, Q hydrocarbon groups substituted phosphonium,

Λ 0 9 8 5 0 '/ 0 7 6 2 -

Carbenium trisubstituted with C_-C, Q hydrocarbon groups and _{oxonium trisubstituted with C 5} -C ₅₀ hydrocarbon groups. Sodium, potassium and ammonium are best suited as solubilizing cations «

Some of the preferred perhalogenometallates and perhalogenonichtmetallates are ammonium hexafluophosphate (NH.PiV), N-benzyl-Ν, Ν, Ν-trimethylammonium _{hexafluophosphate (CH 5} ) - (CgH ₅ CH ₂ ) NPF ₆ , potassium hexafluophosphate (tetophosphate, ammonium, xetrabutylammonium ,), N _a trium tetrafluoborate, zinc tetrafluoborate, sodium hexafluoantimonate (NaSbPg), ammonium hexafluoantimonate, N-benzyl-H, N, N-triethylphosphonium hexafluophosphate, potassium hexafluoantimonate, etc.

Processes for the production of the various perhalogenometallates and perhalogenometallates are known to the person skilled in the art from chemical Known literature and many products are from Ozark-Mahoning Tulsa, Oklahoma «u refer ·

The concentration of the perhalogeno-metallate or perhalogeno-non-metalate in the hydraulic fluid is different and depends on the salt selected, the operating temperature, etc. In general, however, 0.0001 to 2 percent by weight, preferably 0.0005 to 1 percent by weight of the salt are added to the hydraulic fluid and an amount of 0.001 to 0.01 percent by weight is particularly favorable.

Basic fluid

The hydraulic fluids according to the invention contain one Basic fluid, which makes up the main part and in which the

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halogen-containing compounds and other additives are used. Suitable base fluids are one Variety of materials such as organic esters of phosphoric acids, mineral oils, synthetic hydrocarbon oils, silicate esters, Silicones, esters of carboxylic acids, aromatics and aromatic halides, esters of polyvalent substances, aromatic Ether (e.g. polyphenyl & ether), thioether etc.

The phosphate esters are the base fluids preferred according to the invention and own the formula

R ₁ O - P - OR ₂

OR,

where R /, R ₂ and R ~ each denote an alkyl or aryl group (as used herein, "aryl" is aryl, alkaryl or aralkyl and "alkyl" is an aliphatic or alicyclic radical.) All three groups can be the same or all three can be different, two groups can be the same and the third can be different. A typical base fluid contains at least one phosphate ester and is generally a mixture of two or more phosphate esters

According to a particularly preferred embodiment, there is basic liquid according to the invention essentially of a mixture of trialkyl and triaryl phosphate esters, the trialkyl phosphate esters predominate. The irialkyl phosphate esters can be present in amounts of 70 to 98 percent by weight of the phosphate ester content in the total liquid. Preferably do the irialkyl phosphate esters 80 to 92 percent by weight of the phosphate

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ester portion of the composition. Me best results are obtained with trialkyl phosphate esters in which each alkyl group 1 to 12 carbon atoms and preferably 4 to 9 carbon owns atoms. The alkyl groups can in each case be straight-chain or branched-chain. A single trialkyl phosphate ester can have the same alkyl group in all three positions or it can have two or three different alkyl groups exhibit. Mixtures of different! Erialkyl phosphate esters can can also be used. Erialkyl phosphate esters particularly suitable according to the invention are iributyl phosphates, in particular Sri (η-butyl) phosphate, trihexyl phosphate and trioctyl phosphate, but this is not intended to mean a restriction. Tri (n-butyl) phosphate or the branched-chain isomers are particularly preferred the trioethyl phosphates such as 33ri (2-ethylhexyl) phosphate.

The triaryl phosphate ester used in the composition according to the invention can in amounts of from about 2 to about 30 percent by weight of the phosphate ester portion of the total liquid must be present. The best results will be with triaryl phosphate esters achieved in which each aryl group between 6 and 15 carbon atoms and preferably has 6 to 10 carbon atoms. These include phenyl groups and alkyl-substituted phenyl groups. As with the trialkyl phosphates, a single triaryl phosphate ester have the same aryl group in all three positions or a mixture of two or three different ones Have aryl groups. Various mixtures of iraryl phosphates can also be used *. Particularly suitable triaryl phosphates are triphenyl phosphate, trypresyl phosphate, Diphenyl cresyl phosphate, diphenyl xylyl phosphate, diphenyl (ethyl

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phenyl) phosphate and dicresylphenyl phosphate. Are preferred the Triarylphopfhate, in which at least one aryl group monoalkyl-substituted aryl group containing one or two carbon atoms in the alkyl group and preferably one carbon atom in the alkyl group.

The multi-component phosphate ester portion of the composition according to the invention makes at least 70 percent by weight of the total composition and preferably at least 90 percent by weight of the total composition of "

In a further embodiment, the base material can consist of a mixed alkylaryl phosphate ester such as dibutylphenyl phosphate, Butyl diptienyl phosphate, methyl ethyl phenyl phosphate etc. Particularly preferred is dibutyl phenyl phosphate.

Additives

The hydraulic fluids according to the invention generally contain a number of additives that make up a total of 5-25 percent by weight of the finished liquid »including Water that may have been added on purpose, but often got into the liquid when the system was operating " This can happen when a hydraulic system is refilled and exposed to air, especially in a humid environment is. Inadvertent ingress of water can also occur during the manufacture of a phosphate liquid. In practice, water is expected to get into the liquid and measures are taken to the water content of the total liquid to about 0.1-1 percent by weight to regulate. Preferably the water should ± -

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content in the range of 0.1-0.8 percent by weight and the most favorable Trap at 0.1-0.3 weight percent.

Hydrolysis inhibitors to retard corrosion are often added to hydraulic fluids. There are various epoxides, such as the glycidyl ethers described in US Pat. No. 2,636,861. Suitable epoxides are glycidyl methyl ether, glycidyl isopropyl ether, styrene oxide and epichlorohydrin. Hydrocarbon sulfides, especially hydrocarbon disulfides such as dialkyl disulfide, are often used in combination with the epoxides to further retard corrosion. Suitable hydrocarbon disulfides are dibenzyl disulfide, dibutyl disulfide and diisoamyl disulfide. A particularly preferred group of epoxies for use as hydrolysis inhibitors are compounds containing two linked cyclohexane groups, each fused to an epoxy (oxirane) group. Compounds of this Airfc are, for example, 3 ^ 4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (available from Union Garbide under the brand name ERL-4221), bis (3 , ^ -epoxy-ö-methylcyclohexylmethyl) adipate, 2 (3 _> 4 ~ Epoxycyclohexyl) -5-5-spiro (3,4-epoxy) -cyclühexan-m-dioxane (available from Union Carbide under the brand name ERL-4234).

A particularly preferred diepoxide for use in accordance with the invention makes 0.1-15% by weight of the total composition and preferably 0.1-5% by weight of the total composition and has the following general formula:

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wherein X is a divalent organic radical having 1 to 10 carbon atoms, 0 to 6 oxygen atoms and 0 to 6 nitrogen atoms, and R is the same or a different substituent, namely hydrogen or a lower aliphatic radical is «As" lower aliphatic ^ radicals "are here aliphatic Defined substituents containing 1 to 5 carbon atoms In a preferred embodiment, R is hydrogen. According to another preferred embodiment, two of the six R groups are methyl radicals and the remaining four are hydrogen.

Each radical X is preferably a divalent (1) carboxylate group, (2) a dioxane group, (5) an amine group, (4) a group Amide group or (5) an alkoxy group; combinations are also possible.

The real part in the molecular structure of the diepoxyde is the Epoxy group fused to the ring, of which at least two are preferably present in the molecule. "Each" ring-fused epoxy group "consists of an oxirane oxygen which is mixed with is linked to two adjacent carbon atoms in a cyclohexane or substituted cyclohexane ring.

In order to be able to exert their inhibiting function, the ring-fused spoxide groups should preferably be present in a small but significant amount. This amount is practically

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table regardless of the nature of the remainder R and can be conveniently used as a "Oxirane oxygen" content of the total liquid can be measured. The oxirane oxygen content should preferably be in the range of about 0.05 to about 1.5 percent by weight of the seed composition lie·

The hydraulic fluid usually contains 2-10 percent by weight, preferably 5-10 percent by weight, one or more additives to improve the viscosity index, such as alkyl styrene polymers, polymerized organic silicones, or preferably polyisobutylene, or the polymerized alkyl esters of the acrylic acid series, especially acrylic and methacrylic acid esters These polymeric materials generally have a number average molecular weight of from about 5,000 to 500,000.

EXAMPLE 1

It has recently been found that the degree of valve wear in aircraft hydraulic systems is influenced by the electrical flow potential of the hydraulic fluid flowing through the valve. A definition of the flow potential can be found on pages 4-30 of the Electrical Engineers Handbook by Pender and Del Mar (New York, Wiley, 194-9). 2s is the electromotive force generated when a liquid is forced through a narrow opening; it is one! function of several factors, such as electrical properties and viscosity of the liquid, applied pressure and physical characteristic values of the opening, D _{a is} the streaming potential depends on several factors, it appears that with a given liquid at a given

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Device with a given time obtained MeP results vary within a narrow range. It is therefore common practice to select a fluid that has acceptable wear properties as the reference medium. The apparatus is calibrated every day by measuring the streaming potential of the standard liquid and then comparing the streaming potential of the liquids to be tested with this standard. The device used to measure the streaming potential is described in detail by Beck et al at the point cited above. The measurements are carried out at room temperature and the liquid pressure is regulated to 105 kg / cm ² . For the sake of simplicity, the streaming potential detected by the apparatus is applied to a normal resistance of 100,000 ohms, a current being obtained which is indicated as the "current current". Table I shows the reduction in the flow rate which is achieved by adding small amounts of the perhalometalates or perhalogeno-nonmetallates according to the invention to a hydraulic fluid. The hydraulic fluid, which is referred to below as fluid A, consists of about 82 percent by weight tributyl phosphate, 9 percent by weight tricresyl phosphate, 7 percent by weight of a polyacrylate to improve viscosity, 2.5 percent by weight of 3,4-epoxy-cyclohexylmethyl-5,4-epoxycyclohexanecarboxylate, 0.5 percent by weight of water and traces of a foam inhibitor and a colorant. The hydraulic fluid referred to below as fluid B is tributyl phosphate.

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! TABLE I.

Wear protection properties of Type No Additive
Conc. (Wt.%) Hydraulic fluids Current
current (uA) test NH. PP.
4 b - Reason-
liquid -0.8 1 UCH ₂ ³¹ XCH, 0.001 A. -0.07 2 NaBP.
4th ₅ ) ₅ NPP ₆ 0.002 A. -0.28 3 CPP ₆ 0.01 A. +0.08 4th (C ₄ H ₉ ) ₄ PC1 0.01 A. -0.3 VJl (C ₄ H ₉ ) ₄ PC1 0.05 A. -0.7 6th NaSO.
4th 0.25 A. -0.08 7th LiCl
TNBP ** 0.5 A. 2.2 8th No 0.002
0.1 A. 3.2
2.6 9
10 NH.PP.
4 D - A.
A. -2.6 11 (CVXX \ (^ C ^ XX 0.05 B. +0.02 12th CPP _{6 ?} ^X ) NPP ₆ 0.1 B. -0.12 13th NH. PP.
4 4 0.1 B. -0.11 14th NaBP.
4th 0.1 B. -0.2 15th Zn (BP ₄ ) ₂ 0.1 B. -0.12 16 NaSbP ₆ 0.1 B. +0.12 17th NaSbP ₆ 0.1 B. -0.02 18th 0.005 B. -1.05 19th B.

is benzyl
IENBP is the trioctylamine salt of the phosphoric acid butyl ester

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The above table contains the remarkable 3eweis for the Decrease in flow for two different types of hydraulic fluids through the halogen-containing ones according to the invention Links. Experiments 6 and 7 show the lower effectiveness of non-perhalogenated non-metal compounds, unless they are used at higher concentrations. Experiments 8-10 show the disadvantage Effect of various other non-perhalogenated salts and non-metallic salts.

EXAMPLE 2

The influence of the additives according to the invention on the actual Wear of a simulated pressure valve is illustrated in this example. The hydraulic fluid used as the basic medium is a high density dibutylphenyl phosphate. The liquid containing the various perhalogeno-metallates according to the invention or perhalogeno-nonmetallates is tested in a pressure valve simulator, its general design can be seen in the drawing of U.S. Patent 3,649,721. Two nitrided "Nitralloy" blocks are separated by a sealing ring, leaving a clearance of 1.9-2.5 µm (75-100 micro-inches). description and execution of the experiment can be seen from the above patent specification. The increase in fluid flow shows that wear has occurred, with a greater increase (speed) meaning a poorer hydraulic fluid. The results of this test are given in Table II.

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TABLE II Valve wear test

Average

Test type conc. (Weight weight / Q Legkage speed (ml / min / h)

1 None - 1.6

2 ^NH 4 ^Pil 6 Of ° 1 <0.01

The above table clearly shows the significant reduction in valve wear by adding a small amount of a perhalogenonium metalate to the hydraulic fluid.

EXAMPLE 3

This example serves to illustrate the

practical implementation of the inventive method for Manufacture of hydraulic fluids containing a perhalometalate or perhalogeno-nonmetallate. The following Hydraulic fluids can be produced by adding the respective wear protection agent to a dibutylphenyl phosphate will. A common viscosity index improver and a common epoxy acid accept can also be present. gate.

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TAB III Type Conc. (Wt.%) Hydraulic fluids Ealium hexafluogermanate 0.01 Plissiness Potassium hexafluomanganate 0.01 sample Potassium hexafluophosphate 0.5 1 Wear resistance additive Kaliwnh exafluo silicate 0.005 2 Potassium hexafluotantalate 0.1 3 Potassium heptafluotantalate 0.01 4th Potassium hexafluothorate 0.01 5 Potassium hexafluo titanate 0.01 6th Potassium hexafluo zirconate 0.1 7th Potassium tetrafluoborate 0.01 8th Potassium tetrafluoteryllate 0.01 9 Potassium tetratromoaurate 0.01 10 Potassium lexabromoplatinate 0.01 11 Potassium hexachloroiridate 0.1 12th Potassium hexachlorοοsmiat 0.01 13th Potassium hexachloropalladate 0.01 H Potassium tetrachloropalladate 0.01 15th Potassium hexachlοrorhenat 0.001 16 Potassium hexachlororhodate 0.001 17th Potassium hexachlororuthenate 0.001 18th 19th 20th

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TABLE III (Ports.)
Hydraulic fluids

Fluid wear protection additive

protoe type conc. (wt.%)

21 Potassium hexachlorotellurate 0.001

22 ammonium lexaclilorogallate 0.1

23 ammonia hexafruogallate 0.001

24 ammonium hexafluogermanate 0.01

25 Amonitunhexafluotitanate 0.01

26 ammonium xajodoplatinate 0.01

27 sodium tetrachloroaurate 0.1

28 sodium xachloroiridate 0.1

29 sodium lexachlororhodate 0.01 50 sodium hexafluoaluminate 0.01

31 Sodium hexafluoantimonate "0.01

32 sodium tetrafluoberyllate 0.01

33 zinc hexacliloroplatinate 0.01

34 zinc hexafluosilicate 0.01

35 Magnesium hexafluosilicate 0.01

36 Magnesromtiexaohlorostannate 0.001

37 iron hexafluasilicate 0.01

38 AmTnonimnhexafluttselenat 0.001

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Claims (1)

Claims 1 hydraulic fluid based on a basic fluid, characterized in that in the composition 0.0001 to 2 percent by weight of a soluble salt of a perhalometallic acid or perhalogeno-non-metallic acid are contained « 2. Hydraulic fluid according to claim 1, characterized in that that the base fluid is an ester of a phosphoric acid, a hydrocarbon oil, a silicate ester, a silicone or is a polyphenyl ether. 3 hydraulic fluid according to claim 2, characterized in that that the liquid is a phosphorous ester. 4. Hydraulic fluid according to claim 3, characterized in that the phosphate ester is a mixed alkylaryl ester. 5 × hydraulic fluid according to claim 3 _t characterized in that the Phosphatester is a mixture of a predominant amount of a Trialkylphosphatesters and a minor amount of a triaryl phosphate ester. 6. Hydraulic fluid according to claim 5, characterized in that that the trialkyl phosphate ester is xributyl phosphate ester and the iriaryl phosphate ester is! tricresyl phosphate ester. 7ο hydraulic fluid according to claim 3, characterized in that that the perhalogeno-nonmetallate is an alkali, ammonium or phosphonium hexafluophosphate. £ 09850/0762 8. Hydraulic fluid after. Anapruch 3, characterized in that that the perhalogeno-metallate is an alkali, ammonium or is phosphonium tetrafluorate. 9 · Hydraulic fluid according to claim 3 »characterized in that that the soluble perhalogeno-metallate or perhalogeno-non-metallate has the following formula: where are: A is a metal or non-metal; M is a solubilizing cation; X is a halogen; Ϊ an integer from 3 "to 7 and equal to that positive valence of A plus an integer from 1 to 3 years and ζ an integer from 1 to 3 and sufficient, to keep the salt electroneutral. 10. Hydraulic fluid according to claim 9, characterized in that M is an alkali metal, ammonium, ammonium substituted with C.-C ^ q hydrocarbon groups, phosphonium substituted _{with C.-G Q} hydrocarbon groups, trisubstituted carbenium ^{with c} ^ - ^{c -zq hydrocarbon groups and} oxonium trisubstituted with C ^ -Cq hydrocarbon groups. 11 ο hydraulic fluid according to claim 10, characterized in that that M is ammonium, an alkali metal or a hydrocarbon-substituted phosphonium. 409850/0762 12. Hydraulic fluid according to claim 9, characterized in that that the perhalogeno-nonmetallate is ammonium hexafluophosphate, sodium tetrafluoborate or sodium hexafluophosphate is. 13. Hydraulic fluid according to claim 9, characterized (acid scavenger) shows that an epoxy is also present as an acid acceptor. 14. Hydraulic fluid according to claim 13, characterized in that that the epoxy has the following formula: wherein X is a divalent organic radical having 1 "to 10 carbon atoms, 0 to 6 oxygen atoms and 0 to 6 nitrogen atoms and R is the same or a different substituent namely hydrogen or an alkyl residue having 1 to 5 carbon atoms. 15 hydraulic fluid according to claim 13, characterized in that that the epoxy is 3,4-epoxycyclohexylmethyl-3,4-epoxy ~ is cyclohexane carboxylate. 16. Hydraulic fluid according to claim 13, characterized in that that the epoxy 2 (3,4-epoxycyclohexyl) -5-5-spiro- (3,4-epoxy) cyclohexane-m-dioxane is. 17. Method for inhibiting the wear effect of a 409850/0762 Hydraulic fluid, characterized in that the hydraulic fluid an effective amount of a soluble perhalometalate or perhalogenononmetallate is added. 18. The method according to claim 17, characterized in that that the hydraulic fluid is an ester of a phosphoric acid, a hydrocarbon oil, a silicate ester, a silicone or contains a polyphenyl ether. 19 · The method according to claim 17 »characterized in that that the liquid contains a phosphate ester. 20. The method according to claim 18, characterized in that that the phosphate ester is a mixed alkylaryl phosphate ester. 21. The method according to claim 17, characterized in that that the pearl halogeno-nonmetallate ammonium hexafluophosphate, Sodium tetrafluorate or sodium hexafluorophosphate. For: Chevron Research Company San Francisco ^ CaL ₃ V.St.A. Dr W. Beil lawyer 409850/0762