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Publication numberUS3859219 A
Publication typeGrant
Publication dateJan 7, 1975
Filing dateNov 17, 1972
Priority dateNov 17, 1972
Publication numberUS 3859219 A, US 3859219A, US-A-3859219, US3859219 A, US3859219A
InventorsBruce W Hotten
Original AssigneeChevron Res
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Bisphosphoramide-sulfur compound containing lubricant
US 3859219 A
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Description  (OCR text may contain errors)

United States Patent 1191 Hotten *Jan. 7, 1975 [5 BISPHOSPHORAMIDE-SULFUR 2,574,516 11/1951 Walteret a1. 252/49.8 x COMPOUND CONTAINING LUBRICANT 2,722,518 ll/1955 Watson 252/46.7 2,736,707 2/1956 Morris 1 252/467 Inventor: ce W-H0tten.0r1nda.Cal1f. 3,071,548 1/1963 01611116161. ..252/46.6 3,174,931 3/1965 Matson 61 al.... 252/46.7 x [73] Assgnee' g l" f i cmpanyi 3,239,464 3/1966 Matson er a1. 252/46.6 ranclsco, 3,476,685 11/1969 01561611661 et al 252/46.7 1 1 Notice: The portion of the term of this 3,705,211 12/1972 Addor et al 1. 260/926 patent subsequent to Jan. 15, 1974, has been di l i d Primary Examiner-W. Cannon Attorney, Age/mar Firm-G. F. Magdeburger; C. J. [22] F1led. Nov. 17, 1972 Tonkin; D Nelson [21] Appl. No.: 307,732

[57] ABSTRACT [52] U.S.Cl. 252/42.7, 252/46.7, 260/551 P A u i ating omp siti n is disclosed having im [51] Int. Cl ..C10m1/48 pr d ultifun ti nal properties and c mprises a [5 1 F e d of Search 260/551 P; 252/49.9, 46.6, major amount of an oil of lubricating viscosity and 2513/46], 42,7 minor amounts of an oleophilic organic sulfur compound containing from 3 to 40 weight percent sulfur [56] References Cit d and a bisphosphoramide having from 30 to 300 car- UNITED STATES PATENTS atoms- 2.146,584 2/1939 Lipkin 252/49.8 11 Claims, N0 Drawings BISPHOSPHORAMIDE-SULFUR COMPOUND CONTAINING LUBRICANT BACKGROUND OF THE INVENTION This invention relates to an improved lubricating composition. More particularly, this invention relates to a lubricating composition containing an additive combination having improved anti-oxidation and extreme pressure properties.

Hydrocarbon oils are partially oxidized when contacted with oxygen at elevated temperatures for prolonged periods. The internal combustion engine is a model oxidator since it contacts a hydrocarbon motor oil with air under agitation and at high temperatures. Moreover, many of the'metals (iron, copper, lead, nickel, etc.) manufactured into the engine and in contact with both the oil and air are excellent oxidation catalysts which effectively increase the rate of oxidation. The oxidation of motor oils is particularly acute in the modern internal combustion engine which is designed to operate under heavy work loads and at elevated temperatures.

The oxidation produces acidic bodies within the motor oil which are corrosive to typical copper-lead and cadmium engine bearings. It has also been discovered that the oxidation of the oil additionally contributes to piston ring sticking, the formation of sludges within the motor oil and an overall break-down of the viscosity characteristics of the lubricant.

Several effective oxidation inhibitors have been developed by the lubricant industries and their employment has been utilized in almost all of the conventional motor oils today. Typical of these inhibitors are the sulfurized oil-soluble organic compounds, such as, sulfurized sperm oil, sulfurized fatty esters, sulfurizedterpenes, sulfurized polybutenes and others. These inhibitors, while exhibiting excellent anti-oxidation and extreme pressure properties, are burdened by economic and oil contamination problems. It is preferred to maintain the sulfur content of the oil as low as possible while at the same time receiving the benefits of anti-oxidation and extreme pressure properties. A need therefore exists for an improved anti-oxidant that is stable at elevated temperatures, that can be employed at reduced concentrations,'that is economical and easy to produce and that has improved ecological properties.

It is therefore an object of this invention to provide an improved lubricating composition.

It is an additional object of this invention to provide a lubricant composition having improved antioxidation properties.

It is another object of this invention to provide a lubricant composition containing an anti-oxidant.

It is another object to provide a lubricant composition having improved extreme pressure properties.

An additional object of this invention is to provide an improved anti-oxidant for use in lubricating oils.

A further object of this invention is to provide a method of inhibiting oxidation of a motor oil.

Other additional objectswill become apparent from the following description of the invention and accompanying claims.

SUMMARY OF THE INVENTION The aforegoing objects and their attendant advantages can be realized by incorporating into a major portion of an oil of lubricating viscosity a combination of two compounds complement each other in a synergistic manner resulting in a combination having properites superior to either additive alone.

With the instant combination, the amount of the sulfurized anti-oxidant necessary'in order to impart the desired properties to a motor oil blend is significantly less than that amount needed when the bisphosphoramide component is not present.

DETAILED DESCRIPTION OF THE INVENTION The compositions of this invention are highly stable lubricants and exhibit excellent oxidation stability, perform well in extreme pressure tests such as the Timken load test and display good anti-wear properties. These lubricants are quite useful in motor oils for internal combustion engines, particularly in gasoline engines operated under elevated temperature conditions and for gear oils and industrial lubricants.

The lubricant composition of this invention having improved anti-oxidation, extreme pressure and antiwear properties comprises (1)from 85 to about 99 parts'by weight of a stable organic oil and of lubricating viscosity, (2) from 1 to 15 parts by weight of an organic sulfur compound containing from 3 to 40 weight percent sulfur as organic sulfides and/or polysulfides and (3) from 0.05 to 1 parts by weightof a bisphosphoramide containing from 30 to 300 carbons. The ratio of the'organic sulfur-compound to the bisphosphoramide is maintained between about 5 and 80:1.

The OrganicSulfur Compound The organic sulfur compounds which may be employed in the practice of thisinvention include a wide range of compounds containing from 3 to 40 weight percent sulfur which ispresent within the compound as organic sulfides and polysulfides. The presence of sulfur in other forms, such as, sulfonates, sulfates, etc. may exist within the compound but is not included in thecalculation of the sulfur content of the organic sulfur compound. The'compound may contain elements other than carbon, hydrogen and sulfur without adversely affecting properties of the composition and include elements such as, oxygen which may be present as ethers, ketones, carboxyls, esters, alcohols, etc., phosphorus, nitrogen present as amines, amides, imides, etc. as well as metals such as alkali metals, alkaline earth metals,.etc.

One class of organic sulfur compounds which may be employed herein is the sulfurized fatty esters. These compounds are prepared by contacting sulfur with an unsaturated fatty ester under elevated temperatures. Typical esters include C, to C alkyl esters of C -C unsaturated fatty acids, such as palmitoleic, oleic, ricinoleic, petroselinic, vaccenic, linoleic, linol'enic, oleos-' tearic, licanic, parinaric, tariric, gadoleic, arachidonic,

cetoleic, erucic, nervonic, etc. Particularly good results esters such are obtained from animal fats and vegetable oils such as tall oil, linseed oil, olive oil, castor oil, peanut oil, rape oil, fish oil, sperm oil, etc.

Exemplary fatty esters include lauryl tallate, methyl oleate, ethyl oleate, lauryl oleate, cetyl oleate, cetyl linoleate, lauryl ricinoleate, oleyl acetate, oleyl stearate, etc.

These compounds can be phosphosulfurized by contacting the fatty esters with phosphorus pentasulfide along with the sulfur to produce a sulfurizedphosphosulfurized ester. They may be further reacted with a C to C alkylene polyamine having from 2 to nitrogens to impart varnish inhibiting properties to the lubricant.

Another class of organic sulfur compound which'may be employed in the practice of this invention includes sulfurized terpenes, such as sulfurized pine oil, sulfu rized terpinolene, sulfurized dipentene, sulfurized pinene, etc.

Sulfurized olefins such as C to C mono and poly ethylenically unsaturated aliphatic hydrocarbons may also be employed. Aromatic and alkyl sulfides may be employed such as dibenzyl sulfide, dixylyl disulfide, dicetyl sulfide, diparaffin wax sulfide and polysulfide, etc. Paraffin wax thiomers as described in U.S. Pat. No. 2,346,156 may be employed.

Another type of organic sulfur compound which may be employed is amido-substituted dithiazole-thiones. These compounds are believed to have the general structural formula:

f R NH-C:N

l s /o=s where R is a hydrocarbyl having from 8 to 24 carbons. Hydrocarbyl as defined herein is a monovalent organic radical composed essentially of hydrogen and carbon and may be aliphatic, aromatic, or alicyclic or combinations thereof and may be saturated or unsaturated. The preferred hydrocarbyl is an alkyl.

The amide substituted dithiazole compounds maybe prepared by reacting amino dithiazole-thione with a hydrocarbonyl chloride (RCOCL) in the presence of an inert reaction solvent at moderate reaction conditions.

Another class of sulfurized compounds include C to C sulfurized hydroxyesters. These compounds are prepared by reacting a fatty acid of the type mentioned supra with a C to C aliphatic epoxide and then contacting the reaction product with sulfur under elevated conditions.

Another class of sulfurized compounds which may be advantageously employed in, the practice of this invention comprise the polyalkylphenol sulfides. These compounds have the general structural formula:

(R)! l i )XJI (R):

wherein R is an alkyl having from 5 to 24 carbons, x is an integer from 1 to 3;

y is an integer from 1 m5; and

z is an integer from 0 to 5. Compounds having the above formula are prepared by contacting an alkylated phenol with sulfur mono or dichloride in the proper portions under elevated temperatures. These compounds can be thereafter reacted with phosphorus pentoxide, 'an alkali or alkaline earth metal base or an amine.

A particularly useful sulfurized compound because of its multifunctional properties is a sulfurized metal phenate. These compound are prepared by reacting an alkyl phenol with sulfur and an alkaline earth metal base (e'.g., calcium hydroxide, barium hydroxide, calcium oxide, etc.) in the presence of a mutual solvent. The resulting compounds have a generalized structural formula as follows:

CY 01 OY olQ I i, R 2i, R

wherein R is an alkyl group having from 8 to 35 carbons;-

y is an integer from 1 to 5;

z is an integer from 0 to 15;

Y is the same or different constituent selected from H or /2 M where the ratio of H to k M is proportional to the ratio of M to alkyl phenol reacted; and

M is an alkaline earth metal.

The above formula represents a broad and simplified version of the sulfurized compounds and it should be recognized that minor amounts of compounds not defined by the above equation may be present in the reaction p'roduct mixture. The mutual solvent employed in the above reaction can comprise any stable organic liquid having appreciable solubility for both the alkaline earth metal base and alkylphenol. Exemplary solvents include ethylene glycol, 1,4-butanediol, etc.

Sulfurized alkaline earth metal phenates prepared by reacting an alkylated phenol with an alkaline earth metal base to form an intermediate metal phenate which is then sulfurized may be successfully employed.

These compounds are more specifically described in U.S. Pat. No. 2,360,302.

The Bisphosphoramide wherein X is the same or different element selected from nitrogen or oxygen;

Y is the same or different element selected from oxygen, sulfur or nitrogen when X is nitrogen or nitrogen when both Xs are oxygen;

n is an integer equal to 1 when' Y is oxygen or sulfur and 2 when Y is nitrogen;

m is an integer equal to 11-1, i.e., 0 when X is oxygen and 1 when X is nitrogen;

R is a hydrocarbylene or dihydrocarbylene having from 2 to 18 carbons and preferably from 2 to 8 carbons or the halo, keto, t-amino, amido, mononitro, or alkoxy derivative thereof;

R is the same or different constituent selected from hydrogen when Y is nitrogen or a hydrocarbyl having from 1 to 24 carbons and preferably from 6 to 20 carbons or the halo, keto, t-amino, amido, mono-nitro or alkoxy derivative thereof; and

R is the same or different hydrocarbyl having 1 to 24 carbons or a hydrocarbylene having from 2 to 18 carbons and preferably from 2 to 8 carbons with one end of each R bonding to the other R or to said R when R is a dihydrocarbylene or the halo, keto, t-amino, amido, mono-nitro or alkoxy derivative of either of the above.

As referred to herein, hydrocarbyl is a monovalent organic radical composed essentially of hydrogen and carbon and may be aliphatic, aromatic, or alicyclic or combinations thereof; e.g., aralkyl, alkyl, aryl, cycloalkyl, alkylcycloalkyl, etc., and may be saturated or ethylenically unsaturated (one or more double bonded carbons, conjugated or nonconjugated). The preferred hydrocarbyl is an alkyl. The hydrocarbylene, as defined herein, is a divalent hydrocarbon radical which may be aliphatic, alicyclic, aromatic or combinations thereof; e.g., alkylene, arylene, alkylarylene, aralkylene, alkylcycloalkylene, cycloalkylarylene, etc., having its two free valences on different carbon atoms. The preferred hydrocarbylene is an alkylene. The dihydrocarbylene, as defined herein is a quadruple valent hydrocarbon radical which may be aliphatic, alicyclic, aromatic or combinations thereof; e.g., dialkylene, diarylene, dialkylarylene, diaralkylene, dicycloalkylene, etc., having less than three of its free valences on a single carbon atom and preferably having its four free valences on different carbon atoms.

The various derivatives of the R, R and R groups as referred to herein'mean the substitution of the functional group (halo, keto, etc.) on or within the R, R or R chain with less than percent and preferably less than 5 percent of the available sites substituted.

The above structural formula represents a simplified version of the reaction product. The reaction product is not a pure compound having only one single structure, but, rather, is a mixture of numerous amidophosphorous compounds. The above formula indicates that there are two phosphorus atoms in each molecule.

However, because the composition is a mixture of compounds, it is recognized that some molecules may have more than two phosphorus atoms such as polyphosphoramides and at the same time some molecules may have only one phosphorus atom as in monophosphoramide. Thus, it is apparent that while the above chemiyldicyclohexylphosphorothioamide); trimethylene dipiperazine bis (tetracocophosphoramide); diethylene glycol bis(tetracocophosphoramide); N,N-diethyl-l ,3- propane diamine bis (tetracocophosphoramide); piperazine bis (dilaurylphosphorthioamide); etc.

The bisphosphoramides are prepared by reacting phosphorus oxychloride with a difunctional secondary amine or glycol and a monofunctional amine, alcohol or mercaptan. The reaction can be conducted noncatalytically by merely contacting the three reactants within a suitable reaction vessel at a temperature from 0 to 200C and preferablyfrom 20 to C. The reaction pressure is not critical except that it is preferred to apply sufficient pressure on the system to maintain liquid phase conditions. Generally, the pressure will range from 10 to 50 0 psia and preferably from 14 to 35 psia. l

The difunctional amine or alcohol forms the bridging group between the two phosphorus atoms as shown in the structural formular supra. The monfunctional amine, alcohol or mercaptan, on the other hand, reacts with remaining halogens on the phosphorus oxychloride molecules to form the four terminal groups extending from the phosphorus atoms.

The difunctional compounds which may be employed in the practice of this invention have the following general structure:

The definition of X, R, R and m ispresented supra under the description of the bisphosphoramide general formula. The dotted lines above illustrate the possible heterocyclic bonding of the R and R groups when X is nitrogen. For example, when R is a .dihydrocarbylene or substituted dihydrocarbylene, the two R groups bond to the center R group along path (1). Exemplary compounds of this structure include methylene dipiperazine, dimethylene dipiperazine, trimethylene dipiperazine, tetramethylene dipiperazine, diethyleneoxydipiperazine, bis(diethyleneoxy) dipiperazine, etc. When R is a hydrocarbylene, one R group along path (2) forms a heterocyclic ring encompassing the two X atoms. Exemplary compounds of this structure include piperazine, 2,5dichloropiperazine, 2,5 dimethylpiperazine,

etc.

Secondary diamines other than heterocyclic diamines may also be employed in the practice of this invention. In this embodiment, the R groups are hydrocarbyl or substituted hydrocarbyl radicals and R is a hydrocarbylene or substituted hydrocarbylene. Exemplary compounds of this type include N,N'diphenylethylenediamine, N,N'-diethyl-o-tolidine; N,N'-diethylo-dianisidine, N,N-diethyl-l,3-propanediamine, N,N'- di(p-chlorophenyl)ethylenediamine, N,N'-diethylcyclohexylenediamine, etc.

Difunctional compounds having two hydroxy groups (X in the above formula is oxygen) include C to C primary diols such as trimethylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tetramethylene glycol, npropane-1,3-diol, 2-butene-1,4-diol, 2,2'thiodiethanol, neopentyl glycol, hydroquinone, chlorohydroquinone, naphthohydroquinone, phenyl-l,2-ethanediol, 2-

anilino-l ,4-naphthohydroquinone, 2,7-dihydroxynaphthalene, etc. The preferred difunctional hydroxy reactants have from 2 to 12 carbons.

Difunctional compounds having one hydroxy group and one secondary amine groupmay also be employed. In this embodiment one of the Xs in the above formula is oxygen and the other X is nitrogen. Exemplary com- The mono functional compounds which may be employed in the practice of this invention have the following general formulai 0,! Y e H wherein R n and Y are defined supra under the description of the'bisphosphoramide general formula. Exemplary monofunctional compounds include C to C monohydroxy alcohols, monomercaptans and primary or secondary monoamines. Exemplary monohydroxy alcohols include, methanol, propanol, butanol, pentanol, hexanol, octanol, cyclohexanol, 2-methyl cyclohexanol, phenol, cresol, naphthol, p-chlorophenol, pmethylphenol, etc. Exemplary mercaptans include methyl mercaptan, propyl mercaptan, butyl mercaptan, hexyl mercaptan, cyclohexyl mercaptan, naphthyl mercaptan, p-butylphenyl mercaptan, B naphthyl mercaptan, etc. Exemplary monoamines include primary alkyl-, amines such as heptylamine, octylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, etc; secondary alkylamines such as, diheptylamine, N-ethyl-N-hexylamine, N-hexyl-N-octylamine, N,N-dioctylamine, and N-butyl-N-hexylamine, etc.; primary and secondary cycloalkyl and alkylcycloalkylamines such as 2-ethylcyclohexylamine, N-ethyl-N- cyclohexylamine, N-methyl-N-cyclohexylamine, N-propyl-N-cyclohexylamine, N,N-dicyclohexylamine, N-ethyl-N-cyclopentylamine, 2-propyl-3-ethylcyclohexylamine, etc.,; and primary and secondary aryl and alkylarylamines such as methylaniline, toluidine, N-ethyl-N-phenylamine, p-anisidine, nitroaniline, diphenylamines, N/,N-propylphenylamine, 2,4,6 trichloroaniline, N-octyl-N-phenylamine, p-phenetidine, etc.

Particularly preferred monohydroxy alcohols, mono mercaptans and monamines are prepared from animal and vegetable oils and fats. Typical natural oils and fats which may be employed in preparing the monofunctional compounds include coconut oil, corn oil, rape oil, castor oil, peanut oil, cottonseed oil, linseed oil, olive oil, palm oil, safflower oil, soybean oil, tall oil, sperm oil, tallow, lard, etc. These oils are generally comprised of a mixture of saturated and unsaturated fatty acids such as caprylic, capric, lauric, myristic, pal-' mitic, stearic,'arachidic, palmitoleic, oleic, ricinoleic, linoleic, eleostearic, etc. The fatty acids are converted into the corresponding primary or secondary amine, alcohol or mercaptan by conventional processing means.

The preferred monofunctional compounds are the C -C primary and secondary vegetable oil amines such as caprylamine, dicaprylamine, laurylamine, dilaurylamine, myristylamine, dimyristylamine, palmitylamine, dipalmitylamine, etc. and mixtures thereof.

The preferred bisphosphoramides of this invention are prepared by reacting a primary or secondary'monoamine having from 2 to 40 carbons with piperazine and phosphorus oxychloride. The compounds have the following general structure:

wherein R is hydrogen or preferably a hydrocarbyl having from 2 to 20 carbons; and

R is a hydrocarbyl having from 2 to 20 carbons.

The bisphosphoramides may be prepared by either a batch or continuous processing scheme. In a typical batch process, a reaction vessel, preferably constructed or lined with a corrosive resistant material such as glass, teflon, etc., is charged with a suitable inert reaction solvent and the difunctional and monofunctional compounds. The contents of the reactor are stirred to disperse the reactants within the reaction solvent. The

phosphorus oxychloride is then introduced into the reaction vessel in contact with the other reactants. The reaction takes place spontaneously upon the contacting of these reactants to produce the bisphosphoramide. Since the reaction is also exothermic, care must be taken in the introduction of the reactants in order to avoid rapid increases in localized temperatures. Preferably, the phosphorus reactant is introduced into the vessel at a rate of 5 to 25 mols per 50 mols of difunctional and monofunctional compounds per hour. This addition rate is not critical to the practice of this invention and only provides a convenient method of introducing the phosphorus reactant into the system without the problems of spontaneous boiling. For example, the phosphorus oxychloride may be charged to the reaction vessel before either the difunctional or monofunctional reactant, or in another alternative embodiment, the reactants may be charged to the vessel in an intermittent manner. The reaction can also be conducted adiabatically with the heat of reaction effecting the necessary temperature increase in the system.

In preferred embodiments, when a mercaptan or alcohol monofunctional reactant is employed, these compounds are contacted with the phosphorus oxychloride prior to the introduction of the difunctional amine or at least before the stoichiometric amounts of difunctional amine is introduced into the reaction medium. In this manner, the less reactive mercaptan or alcohol is allowed to partially react with the phosphorus oxychloride prior to the introduction of the more reactive difunctional amine. When a dihydroxy difunctional reactant and amine monofunctional reactants are employed, it is, likewise, preferred to introduce the less reactive dihydroxy reactant into contact with the phosphorus oxychloride prior to the addition of the amine reactant.

During the course of the reaction, hydrogen chloride is released as a by-product. This by-product can be stripped from the reaction medium during or after the completion of the reaction. While stripping may be a convenient method for removing the material, the conditions employed during the stripping steps in many instances have an adverse effect on the product bisphosphoramide. Therefore, it is preferred to complex or neutralize the hydrogen chloide within the reaction medium concomitant with its formation. I have found that the complexing or neutralization step can be accomplished by admixing a stable basic compound or acid acceptor within the reaction medium. Exemplary acid acceptors include C to C trialkyl amines such as trimethylamine, triethylamine, tripropylamine, triisopropylamine, tributylamine, etc., basic hetarenes, such as pyridine, quinoline, picoline, pyrazine, etc., as well as basic metal compounds such as magnesium oxide, calcium oxide, calcium carbonate, magnesium carbonate, alkaline earth metal hydroxides such as magnesium hydroxide, calcium hydroxide, barium hydroxide, etc., and alkali hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide or alkali carbonate or bicarbonate.

The preferred acid acceptors are the trialkylamines and hetarenes since water is not produced in the neutralization of the hydrogen chloride by-product. The presence of water is the system is to be avoided since it may react with the phosphorus oxychloride reactant.

The crude bisphosphoramide can then be filtered to remove the liquid reaction medium and unreacted reactants. Although filtering is preferred, it is recognized that alternative purification steps can be performed such as extraction, stripping, etc.

As discussed supra, the 'reaction is preferably conducted in the presence of an inert stable reaction solvent. Exemplary reaction solvents which may be employed in the practice of this invention include C to C aliphatic or aromatic hydrocarbons such as hexane, octane, nonane, benzene, toluene, naphthalene, ethylcyclohexane, etc., halogenated hydrocarbons, hydrocarbon esters, hydrocarbon ethers, etc., may be employed.

The concentration of the various reactants within the reaction medium can vary over a wide range depending upon the reactants chosen, the reaction conditions, vessel construction, processing scheme, etc. Generally, however, the reactants will be present in the amounts shown in the following Table 1.

(1) Based on the amount introduced into the reaction medium.

The molar ratio of the reactants introduced into the reaction medium will generally vary from 3 to 5 mols of monofunctional compound and 0.4 to 0.6 mols of difunctional compound per mo] of phosphorus compound. Preferably the reactants are present in substantially stoichiometric amounts.

The lubricant composition is prepared by simply admixing through conventional dispersing techniques, the

appropriate amount of organic sulfur compound and bisphosphoramide within a suitable lubricating oil. The selection of the particular base oil, organic sulfur compound and bisphosphoramide, as well as the amounts and ratios each, depends upon the contemplated appli cation of the lubricant and the presence of other additives. Generally, however, the amount of organic sulfur compound in the lubricating oil will vary from 0.5 to 10 and usually from 1 to 6 weight percent in most applications and the bisphosphoramide will range from 0.05 to 5 and usually from 0.1 to 1 weight percent based on the weight of the final composition. The ratio of organic sulfur compound to bisphosphoramide will generally vary from 2 to 30:1 and usually from 5 to 20:1.

The lubricating oil which may be employed in the practice of this invention includes a wide variety of hydrocarbon oils. Other oils include lubricating oils derived from coal products and synthetic oils, e.g., alkylene polymers (such as, polypropylene, butylene, etc. and mixtures thereof) alkylene oxide-type polymers (e.g. alkylene oxide polymers prepared by polymerizing alkylene oxide such as ethylene oxide, propylene oxide etc., in the presence of water or alcohol, e.g. ethyl alcohol), carboxylic acid esters (e.g. those which wereprepared by esterifying carboxylic acids such as adipic acid, azelaic acid, suberic acid, sebacic acid, alkenylsuccinic acid, fumaric acid, maleic acid, etc., with the alcohol such as butyl alcohol, hexyl alcohol, 2- ethylhexyl alcohol, pentaerythritol, etc., liquid esters of phosphorus, such as trialkyl phosphate (tributyl phosphate), dialkylaryl phosphate, triaryl phosphate (tricresyl phosphate) etc. alkylbenzenes, polyphenyls (e.g., biphenyls and terphenyls), alkylbiphenyl/ethers, esters and polymers of silicon, e.g., tetraethyl. silicate, tetraisopropyl silicate, hexyl(4-methyl-2-pentoxy) disilica'te, poly(methyl)siloxane and poly(methylphenyl) siloxane, etc. The lubricating oils may be used individually or in combinations whenever miscible or whenever made so by use of mutual solvents. Thelubricating oils generally have a viscosity which ranges from 50 to 5000 SUS (Saybolt Universal Seconds) and usually from to 1500. SUS at 100F.

In addition to the sulfurized organic compound and the bisphosphoramide, other additives may be successfully employed within the lubricating composition of this invention without affecting its high stability and performance over a wide temperature scale. One type of additive which may be employed is a rust inhibitor. The rust inhibitor is employed in all types of lubricants to suppress the formation of rust on the surface of metallic parts. Exemplary rust inhibitors include, sodium nitrite, alkenylsuccinic acids and derivatives thereof, alkylthio-acetic acid and derivatives thereof, substituted imidazoles, amine phosphates, etc.

Other types of lubricating oil additives which may be employed in the practice of this invention include antifoam agents (e.g., silicones, organic copolymers), stabilizers, anti-stain agents, tackiness agents, anti-chatter agents, dropping point improvers, anti-Squawk agents, lubricant color correctors, extreme pressure agents, odor control agents, dispersants, detergents, anti-wear agents, such as tricrescyl phosphate and zinc dithiophosphate esters, etc.

In many instances it may be advantageous to form concentrates of the organic sulfur compound and the bisphosphoramide with or without a carrier liquid. The employment of concentrates provides a .convenient method of handling and transporting the compounds for their subsequent dilution and use. The concentration of the two components within the concentrates may vary from 50 to 98 weight percent of sulfurized organic compound, 1 to weight percent bisphosphoramide and O to 45 percent diluent oil, although it is preferred to maintain the concentration between about 75 and 95 weight percent organic sulfur compound, 4 to 15 weight percent bisphosphoramide and O to 21 weight percentdiluent oil.

LUBRICANT PERFORMANCE The presence of the bisphosphoramide within the lubricant composition promotes the extreme pressure and anti-oxidation properties of the sulfurized organic compound. With this combination, less of the sulfurized compound is necessary in the lubricant to realize the desired anti-oxidant and extreme pressure properties.

In addition to promoting the anti-oxidation and extreme pressure properties of the organic sulfur com-,

pounds, the bisphosphoramides impart substantial antiwear properties to the lubricant and in many instance surpass the anti-wear properties imparted by tricresyl phosphate and zine dihydrocarbyldithiophosphate.

It should be well recognized that the organic sulfur compound and bisphosphoramide mixture may be successfully employed in lubricant applications wherein oxidation, extreme pressures or metal wear is a problem. Thus, the mixture may be employed in lubricating oil such as motor oils, turbine oils, gear oils, railroad diesel engine oils, tractor and truck diesel engine oils, two cycle gasoline engine oil, cutting oils, drilling oils, lapping, grinding and honing oils, lubricating oils for pneumatic devices such as jackhammers, sinkers, stoppers, drifters and down hole drills.

The organic sulfur compound and bisphosphoramide mixture may also be useful in mist lubricants. In a mist lubricating system the lubricant is atomized in a mist generator and carried through conduits by an air stream. The lubricant droplets are coalesced and collected at the lubricant site. Such systems permit simultaneous lubrication of several remote lubrication points from a central lubricant reservoir.

The following examples are presented to illustrate the practice of specific embodiments of this invention and should not be interpreted as limitations upon the scope of this invention.

EXAMPLE 1 I This example is presented to illustrate the preparation of a representative bisphosphoramide of this invention. A two-liter resin flask equipped with a dropping funnel, gas tube, stirrer and thermometer is charged with 315 g. of toluene, 303 g. of triethylamine, 754 g. of dicocoamine and 43 g. of piperazine. The contents of the flask are stirred and heated to a temperature of 50C to uniformly disperse the dicocoamine and piperazine within the toluene solution. The contents are cooled to 29C and 155 g. of phosphorus oxychloride are slowly added to the mixture through the dropping funnel for a period of approximately 1 hour.

A stream of nitrogen gas is passed through the reaction medium at a rate of about 200 milliliters per minute.

After the phosphorus oxychloride has been charged to the reactor, the contents are heated to reflux at a temperature of approximately l20F for a period of about 1.5 hours. At the end of the reaction period the reactor contents are cooled and filtered to recover the filtrate. The filtrate is then washed with 700 ml. of water until the filtrate is free of chloride. The filtrate is stripped of toluene and the remaining waxy residue is calculated to have the following structural formula:

where Coco is a mixture of alkyl groups derived from coconut oil fatty acids.

An analysis of the product reveals the following:

This example is presented to demonstrate the preparation of piperazine bis (N,N'-diethyl-N,N'-dicyclohexylphosphoramide). In the preparation, a 2-liter resin flask equipped with a dropping funnel, gas tube, stirrer and a thermometer is charged with 380 g. of toluene, 606 g. of triethylamine, 510 g. of ethylcyclohexylamine and 84 g. of piperazine. The mixture is heated to a temperature of C and stirred to disperse the amine reactants within the toluene. Phosphorus oxychloride is then slowly introduced into the reaction medium at a rate of 300 g. per hour. During the addition of the phosphorus oxychloride the mixture is maintained in dry state by passing 200 ml. per minute of nitrogen gas through the reaction medium. After 310 g. of phosphorus oxychloride have been introduced into the vessel, further addition is terminated and the reactor contents are heated to a temperature of approximately 120'C under refluxing conditions. The mixture is refluxed for a period of 2 hours. The flask is then cooled and the contents filtered. The filtrate is washed with water to remove the chloride and thereafter stripped of toluene. The bisphosphoramide product is calculated to have the following structure:

In this example, diethylene glycol bis(tetracocophosphoramide) is prepared. A 1 liter resin flask equipped with a stirrer, turned down condenser, thermometer, dropping funnel and a nitrogen gas inlet tube is charged with 64 grams of triethylamine, 10.6 grams of diethylene glycol, 600 milliliters of toluene and 151 grams of phosphorus oxychlmide di(hydrogenated coco) amine (mol wt. 377). The mixture is heated to about 50C and stirred to dissolve its reactants within the toluene. Phosphorus oxychloride is then slowly introduced into the vessel, further addition is terminated and the flask is heated to a temperature of 100-110C under refluxing conditions for a period of about 7 /2 hours. The flask is washed with water to remove the chloride ions and thereafter stripped of toluene. The bisphosphoramide product is calculated to have the following structure.

wherein Coco is the coconut oil fatty radical.

An analysis of the bisphosphoramide reveals the following:

Calculated Found (weight (weight Nitrogen 3.3 3.16 Phosphorus 3.6 3.8

EXAMPLE 4 An analysis of the bisphosphoramide reveals the following:

Calculated Found (weight (weight Nitrogen 4.9 3.5 Phosphorus 3.6 3.7

EXAMPLE 5 The procedure of Example 1 is repeated except that trimethylene dipiperidine is substituted for the piperazine and the following amounts employed.

Moles Grams Trimethylene 4,4' dipiperidine 42 0.2 Triethylamine 111 1.1 Toluene 500 -Continued Grams Moles Dicocoamine 302 0.8 62 0.4

The resulting bisphosphoramide is calculated to have the following structure:

An analysis of the compound reveals the following:

Calculated Found 9 (weight 7:) (weight i Nitrogen 4.6 I 4.0 Phosphorus 3.4 4.8

EXAMPLE 6 EXAMPLE 7 The preparation of a sulfurized calcium phenate which may be employed in the practice of this invention is illustrated by this example. A 3 liter reaction vessel equipped with a stirrer, thermometer, condenser and dropping funnel is charged with 661 grams of neutral oil, 747 grams of tetrapropylene phenol, 197 grams of sulfur and 144 grams of calcium hydroxide. The mixture is heated to 260F under a vacuum of 10 mm Hg and vigorously agitated. Thereafter 0.346 grams of ethylene glycol are added to the mixture over a 20 minute period and the temperature allowed to increase to about 300F. The temperature is maintained at 300F under a 10 inch Hg vacuum for a period of 2 hours. Thereafter, the temperature is increased to 386F over a 2% hours period while simultaneously reducing the pressure to 11 mm Hg. The contents are maintained at a temperature of 386F and a pressure of 1 1 mm Hg for 15 minutes and thereafter cooled and filtered.

A sample of the crude sulfurized metal phenate is filtered through diatomaceous earth and found to contain 5.54 wt. percent sulfurand 4.4 wt. percent calcium. The product had an alkalinity value of 1 14.3 mg KOH/gm.

EXAMPLE 8 This example is presented to illustrate the'effectiveness of the combination of a sulfurized organic compound and a bisphosphoramide in suppressing oxidation over the use of either component individually. The oxidation test as employed herein measures the resistence of the test sample to oxidation from pure oxygen with a Dornte-type oxygen absorption apparatus (R.W. Dornte, Oxidation of White Oils, Industrial and Engineering Chemistry, Vol. 28, p. 26, 2936). The conditions are atmosphere of pure oxygen exposed to the test oil maintained at a temperature of 340F. The time required for 100 grams of the test sample to remove 1000 ml. of oxygen is observed and reported in the follwoing Table 2.

In order to simulate the oxidation occurring in an internal combustion engine, a mixture of various soluble metal-naphthenates, typifying the metal analysis frequently encountered in crankcase oils, is mixed with the test oil.

The experimental samples subjected to the above oxidation test consist of the following: Sample A contains 98 weight percent of a neutral oil having a viscosity of 480 SUS at 100F., 1.8 weight percent of a-sulfurized alkyl tallate ester containing about 10 percent sulfur and 0.2 weight percent of a bisphosphoramide .prepared by the method of Example 1. This sample is designated as containing the combination of additives. Sample B contains 98 weight percent of an identical neutral oil as used in Sample A, 1.9 weight percent of an identical sulfurized tallate as used in Sample A and 0.1 weight percent of tricresyl phosphate. The sample is designated as containing the sulfurized compound only. Sample C contains 99.8 weight percent of the idential base oil as used in Sample A and 0.2 weight percent of an identical bisphosphoramide as used in Sample A. This sample is designated as containing the bisphosphoramide only. Sample D is 100 percent of the base oil employed in the above samples and is designated as containing no additive". The results of the oxidation test with the above sample are reported in the following Table 2.

TABLE 2 OXIDATION TEST Sample Additive Package Oxidation Life (hr.)

A Combination 5.7 B Sulfurized Compound only 3.3 C Bisphosphoramide only 0.5 D No additive 0.5

EXAMPLE 9 The effectiveness of the instant combination in improving the extreme pressure properties of a lubricant over any of the components individually is illustrated in this example. In this test a sample of the composition is subjected to a Timken Test (ASTM 2782-69T) to determine the load carrying capacity of the lubricant. This test measure the maximum load or pressure which containing a combination of additives. Sample B is identical to Sample A except that no bisphosphoramide is present. This sample is designated as containing the sulfurized compound only. Sample C isv the same as Sample A except that no sulfurized compound is present. This sample is designated as containing the bisphosphoramide only. The results of the Timken test with the above samples is repeated in the following Table 3.

TABLE 3 TIMKEN TEST Sample Additive Package Load Passing (lb) A Combination B Sulfurized Compound only 45 C Bisphosphoramide only 10 The above table illustrates the effectivenessof teh combination of sulfurized compound and bisphosphoramide in effecting superior passing loads over either component individually. The Timken load is indicative of the extreme pressure properties of the lubricant with a higher load connoting superior E.P.

EXAMPLE 10 This example is presented to illustrate the effectiveness of the bisphosphoramides in promoting the extreme pressure properties of railroad oils containing sulfurized alkaline earth metal phenates. In this example several samples are subjected to a silver thrust washer test. The apparatus of this test is prepared by soldering to a back of soft steel washer, a silver test washer composed of 99.9percent pure silver. Both the silver and the steel backing are nominally /8 inch in thickness, 1.3 inches OD. and 1.0 inch ID. The silver surface is grooved by three equally spaced 5 inch slots. A 0.0l-inch-deep and 1/32 inch-wide slit is cut across the center of each of the three raised silver surfaces.

The silver washer is annealed after machining and after each use to remove any work hardening in the silver. The annealing is carried out at 650F for one half hour and allowed to cool to room temperature. Following annealing, both sides are surface lapped to obtain a smooth flat surface of approximately 9-12 micro inches finish.

The steel test specimen is made to duplicate the metallurgy of the wrist pin steel in the EMD locomotive engine. The material is AISI Steel No. 862011. Heat treatment to a minimum hardness of 58 Rockwell C is achieved by carburizing for 0.04-0.05 finish case depth, pit cool; reheating to 1,475F. and oil quenching; followed by tempering at 400F. for 8 hours. Both sides are finished-lapped to a finish of 3-5 microinches. Nominal dimensions are 1% inches OD, 0.9 inch ID, and 0.2 inch thick.

A motor-driven mechanism is used to obtain oscillatory motion at the test surfaces. A 20 cc. sample of test oil is employed in the oil cup, the apparatus assembled and the oscillatory motion begun. The apparatus is run for'lO minutes without heating. At the end of the minutes, there is a 35 minute heatup as the temperature is raised to 350F., followed by 45 minutes of constant temperature operation at 350F. The load during the test is maintained contiuously at 4280 psi at the bearing surfaces by means of a calibrated spring.

The power, as measured in watts, required to maintain the oscillatory motion at the test surface is measured and reported in the following Table 4. The power requirement of the motor is indicative of extreme pressure properties of the lubricant with a lower power requirement connoting a superior E.P. lubricant.

Four test lubricants are subjected to the above silver thrust washer test. Test sample A comprises (1) 99 weight percent of a 40 grade lubricating oil having a viscosity index of 73 and containing a conventional succinimide dispersant and 79 millimole per kilogram of oil ofa carbonated sulfurized calcium polypropylene phenate containing 9.25 weight percent calcium, 3.73 weight percent sulfur and 4.6 weight percent equivalent CO and (2 1 weight percent of a cross-sulfurized alkyltallate and cracked wax olefin. This sample is referred to as containing a sulfurized calcium phenate and a sulfurized ester only. Test sample B comprises (1 98.8 weight percent of the lubricating oil containing a succinimide dispersant employed in test oil A, and 79 millimoles per kilogram of the sulfurized calcium phenate as employed in test oil A, (2 1 weight percent of the sulfurized ester as employed in test oil A, and (4) 0.2 weight percent of a bisphosphoramide of the type prepared by the method of example 1. Test oil C comprises 100percent of the test oil as employed in sample A and 34 millimoles per kilogram of oil of a sulfurized calcium polypropylene phenate containing about 4.5 wt. percent calcium and 4.9 wt. percent sulfur. This test oil is referred to herein as containing a sulfurized calcium phenate only. Test sample D comprises 99.8

weight percent of test oil C plus 0.2 weight percent of a bisphosphoramide prepared by the method of example 1. This test sample is referred to as containing a sulfurized calciumphenate and a bisphosphoramide.

The above test samples are subjected to the silver thrust washer test as defined above with the results being reported in the following Table 4.

TABLE 4 SILVER THRUST WASHER TEST Sample Additives Power (watts) A Sulfurized calcium phenate Sulfurized ester 250 B Sulfurized calcium phenate sulfurized ester Bisphosphoramide 185 C Sulfurized calcium phenate 230 D sulfurized calcium phenate Bisphosphoramide 177 I claim:

1. A concentrate comprising (a) from 50 to 98 weight percent of an oleophilic organic sulfur compound or mixture thereof containing from 3 to 40 weight percent-sulfur and selected from the group consisting of sulfurized esters, sulfurized terpenes, sulfurized olefms, aromatic sulfides, alkyl sulfides, amidosubstituted dithiazole-thiones, sulfurized hydroxy esters, polyalkylphenol sulfides and sulfurized alkaline earth metal phenates, (b) from 1 to 20 weight percent of a bisphosphoramide prepared by contacting within a liquid phase reaction medium (1 phosphorus oxychloride (2 a difunctional compound having the structure:

nx n xrr om-4R2)...

wherein X is the same of different element selected from nitrogen or oxygen, R is a hydrocarbylene having from 2 to 18 carbons or a dihydrocarbylene having from 2 to 18 carbons; m is an integer equal to 1 when X is nitrogen and 0 when X is oxygen; R is (a) the same or different hydrocarbyl having from 1 to 24 carbons or (b) a hydrocarbylene having from 1 to 18 carbons with one end of each R hydrocarbylene bonding to the other R hydrocarbylene or to said R when R is a dihydrocarbylene; and (3 a monofunctional compound having the formula:

wherein Y is the same of different element selected from (i) oxygen, sulfur or nitrogen when X is nitrogen or (ii) nitrogen when both Xs are oxygen; n is an integer equal to 1 when Y is oxygen or sulfur and 2 when Y is nitrogen; and R, is the same or different constitutent selected from (i) hydrogen when Y is nitrogen or (ii) a hydrocarbyl; said contacting being conducted at a temperature of about 20 to C and at apressure sufficient to maintain a liquid reaction medium, and (c) from 0 to 45 weight percent of a diluent oil.

2. The composition defined in claim 1 wherein said difunctional compound is selected from piperazine, methylene-dipiperazine, dimethylenepiperazine and trimethylenedipiperazine.

3. The composition defined in claim 1 wherein said oleophilic organic sulfur compound is selected from the group consisting of sulfurized C to C alkyl esters of C to C fatty acids, sulfurized C to C unsaturated aliphatic hydrocarbons, C to C sulfurized hydroxyesters, polyalkylphenol sulfides, and sulfurized metal phenates.

4. The composition defined in claim 3 wherein said bisphosphoramide is the reaction product of dicocomaine with piperazine and phosphorus oxychloride.

5. A lubricating composition comprising (1 a major amount of an oil of lubricating viscosity, (2 from 0.5 to 10 weight percent of an oleophilic organic sulfur compound or mixture thereof containing from 3 to 40 weight percent sulfur and selected from the group consisting of sulfurized esters, sulfurized terpenes, sulfurized olefms, aromatic sulfides, alkyl sulfides,- amidosubstituted dithiazole-thiones, sulfurized hydroxy esters, polyalkylphenol sulfides and sulfurized alkaline earth metal phenates, and (3 from about 0.05 to 5 weight percent of a bisphosphoramide prepared by reacting (a) phosphorus oxychloride (b) a difunctional compound 'of the formula:

ma n-x11 (Rimom wherein X is the same or different element selected from nitrogen or oxygen;

R is a hydrocarbylene having from 2 to 18 carbons or a dihydrocarbylene having from 2 to 18 carbons; m is an integer equal to 1 when X is nitrogen and when X is oxygen; R is the same or different hydrocarbyl having from 1 to 24 carbons or a hydrocarbylene having from I to 18 carbons with one end of each R hydrocarbylene bonding to the other R hydrocarbylene or to-said R when R is a dihydrocarbylene; and (c) a monofunctional compound having the formula:

oxygen, sulfur or nitrogen when X is nitrogen or 8. The composition defined in claim 5 wherein said oil of lubricating viscosity is present in major amounts, said organic sulfur compound is present at a concentration of l to 6 weight percent and said bisphosphoramide is present at a concentration of 0.1 to 1 weight percent.

9. The composition defined in claim 5 wherein said organic sulfur compound is a sulfurized C, to C alkyl ester of an unsaturated C to C fatty acid.

10. The composition defined in claim 9 wherein said oil has a viscosity of 50 to 5000 SUS at a temperature of F.

11. A composition of matter comprising a major portion of an oil of lubricating viscosity containing 1. from 0.5 to 10 weight percent of an oleophilic organic sulfur compound containing from 3 to 40 weight percent of sulfur present as organic sulfides or polysulfides or mixtures thereof and selected from a C to C alkyl ester of a C to C unsaturated fatty acid or a sulfurized alkaline earth metal phenate; and I 2. from 0.05 to 5 weight percent of a bisphosphoramide having the formula:

(NRsRDa wherein R is hydrogen or a hydrocarbyl having from 2 to 20 carbons; and

R is a hydrocarbyl having from 2 to 20 carbons.

@33 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 38592l9 Dated January 7, 9 5

I BRUCE W. HOTTEN It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Title page, Col. 1, line 6, 7 and 8, should read --Notice:

The portion of the term of this patent subsequent to March 5, 1991 has been disclaimed.--

Col. 2, line 1. 1, "properites" should read --prop erties--.

Co 5, line 13, "having from 2 to 18" should read having from 1 to l8--;

Col. 5, line 15, "to the other R should read -to the other 13 Col. 6, line 20, "monfunctional" should read --monofunctional--.

' Col. 7, line 8, "Bhydroxyethy1e" should read ---B-hydroxyethyl-- Col. 9, line 19, "is the system" should read --i n the system-- Col. 15, line 7, 26, 2936" should read --p. 26, 1936- Col. 16, line 28, "teh" should read --the- Col. 17, line 7, "contiuously" should read --continuously-. Col 1.7, line 6 1, "repersent" should read --represent-- Col. 18, line 18, "of different" should read ordifferent-- Col'. 18, line 31 "of different" should read --or different- Col. 19, lines 31 and 32, "hydro-carylene" should read -hydro-carbylene-.

Signed and sealed this 1st day of April 1975.

Attest:

R' TEI C. 22x80? Commissioner of Patents fittest-tin; Officer and Trademarks

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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3968157 *Apr 24, 1975Jul 6, 1976Chevron Research CompanyBisphosphoramides
US3992307 *Nov 4, 1974Nov 16, 1976Chevron Research CompanyLubricant composition of improved antioxidant properties
US4142979 *Nov 18, 1977Mar 6, 1979S.A. Texaco Belgium N.V.Lubricating compositions containing bispiperazido phosphorus and trispiperazido phosphorus compounds
US6227285 *Jun 20, 1997May 8, 2001Schümann Sasol Gmbh & Co. KgHeat storage medium
US6921885 *Nov 20, 2001Jul 26, 2005Sandvik AbMethod of increasing the useful life of a molybdenum silicide heating element