Re: Proper way to lube a AR15
In a word NO to graphite. See below:
This information is taken from PREVENTION OF MATERIAL DETERIORATION: CORROSION CONTROL COURSE, LOGISTICS ENGINEERING DIRECTORATE, JUNE 1985
This course was presented by U.S. Army Armament Munitions and Chemicals Command
Rock Island Arsenal, Illinois (Note this command name has changed and is unknown at this time. I am told there is no update to this course book. It is considered by many as the finest course ever conducted by the Army.)
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GRAPHITE
Graphite, a natural occurring mineral is singularly one of the most insidious causes of corrosion in military equipment. It is an electrical conductor and is cathodic to all of the common metals with the exception of gold and platinum. It is this property that results in galvanic corrosion of metal structures to which it has been applied when an electrolyte is present. The voltage generated is sufficient to cause a rapid corrosive reaction. An example of this reaction is seen in the common dry cell where graphite and zinc develop a potential of approximately 1.5 volts. The voltage is produced by the corrosion reaction within the battery.
When applied on bearing surfaces the galvanic corrosion action destroys the very surface requiring lubrication and forms abrasive corrosion products which further hasten wear or seizure of mating parts. While graphite is generally considered .to be a lubricant it is a lubricant only in the presence of absorbed moisture or certain gases. Under conditions of vacuum or at subzero temperatures it is actually an abrasive. It is therefore unsuited for lubrication in space applications or high altitude aircraft unless combined with other materials capable of supplying the needed gas.
The graphite problem is compounded by the fact that many commercial solid film lubricants contain graphite in a mixture of powdered heavy metals, molybdenum disulfide or other lubricative solids. Many of these products qualify under a number of military specifications written primarily to obtain lubricant properties with little or cursory regard for the corrosivity of the product. Typical specifications are MIL-L-8937 or MIL-L-23398. The problem is made more complex by the fact that many nongraphite products qualify but the specification is not sufficiently stringent in respect to corrosion tests. A list of corrosive graphite lubricant specifications is found in Incl. 1.
Serious problems involving potential loss of human life as well as equipment are accelerated by the use of graphite lubrication hinge pins for critical control surfaces for aircraft. Graphite has been applied by mechanics to aid in installation of these long thin pins through multiple hinge tabs. Pitting, stress corrosion cracking, and ultimate seizing and breaking of the high strength aluminum hinge tabs results.
Major corrosion problems have been encountered when graphite-petrolatum compound was used in the “Lube-torque” wheel lug bolt torquing procedure on aircraft landing gear wheels, particularly with magnesium wheels.
A high incidence of corrosion is invariably found in wheel-well areas of aircraft where graphite from the brake lining combines with dirt and water and contacts critical structural members. There is no known qualified brake lining that does not contain graphite. Therefore, the solution of this problem is “cleansing” maintenance.
Problems of graphite induced corrosion were encountered in the M28 Armament Subsystem for Helicopters. In this equipment graphite containing qualified solid film lubricant meeting requirement of MIL-L-8937 was designated as the lubricant to be applied to a 7075T6 cam ring. After a brief period of exposure in field operation, severe stress corrosion cracking was encountered which required replacement of a number of the cam rings.
Layout pencils containing graphite were used in sheet metal fabrication for aircraft caused corrosion of aircraft in service and resulted in issuance of a US Air Force Specification for layout pencils with no graphite or conductive carbon content.
Corrosion problems were encountered on aluminum deck structures aboard naval ships in England and on launch facilities at Cape Kenney where graphite “lead” pencils were used for extraneous marking on the surfaces.
Graphite added to wheel-bearing grease used on the F-4 Phantom aircraft main landing gear caused severe corrosion of the bearings in as little as three months of service.
Graphite grease used in lubricating arresting cables aboard aircraft carriers contributes to the severity of corrosion of carrier based aircraft when landing gear wheels pick up graphite form the deck surface during rainy weather and spray it into wheel well areas and other surfaces of the rear of the wheels. “Cleansing”: maintenance will reduce the severity of the problem.
Solid film lubricants which meet the lubricant requirement s without graphite are available for most applications (see Incl. 1). Use of the corrosive graphite types is justified only in certain high temperature applications.
TABLE 1
GRAPHITIC (CORROSIVE) NON-CORROSIVE
LUBRICANTS USE REPLACEMENT
TT-A-580 Antiseize MIL-L25681 (Note 4)
SS-G-659 Dry Lubricant MIL-M-7866
JAN-A-669 Antiseize MIL-L-25681 (Note 4)
VV-G-671 Dry Lubricant MIL-M-7866
MIL-A-907 Antiseize MIL-L-25681 (note 4)
MIL-T-5544 Antiseize MIL-L-25681
MIL-T-5544 General Lubricant MIL-L-21164 (note 1)
MIL-G-13912 Antiseize MIL-L-25681 (note 4)
MIL-L-3572 Oil Lubricant MIL-M-7866
CANCELLED SPECIFICATIONS
MIL-G-6711 Dry Lubricant MIL-M-77866
(Cancelled 4 Mar 71)
MIL-G-7187 General Lubricant MIL-G-211164(Note 1)
(Cancelled 12 Nov 65)
SOLID FILM LUBRICANTS
MIL-L-8937 Heat Cure MIL-L-46010 (Note2)
MIL-L-23398 Air Dry MIL-L-46147 (Note 2)
MISCELLANEOUS SPECIFICATIONS
MIL-L-24131 Dry Lubricant Note 3
MIL-L-81329 Solid Film Lubricant Note 3
MIL-L-5542 Antiseize Note 3
MIL-L-17745 General Lubricant Note 3
TABLE 1 NOTES
Note 1: Where there are problems with noncompatibility of elastomers and this synthetic lubricant, use MIL-G-23549.
Note 2: Requests have been made for standardization action removing graphite from MIL-L-8937 and MIL-L-23398. Until this action is accomplished;, Air Force use of these specifications shall be withdrawn. Wide use of MIL-L-8937 and MIL-L-23398 has been made on supplier lubricated parts. We have found much corrosion/galling of the MIL-L-8937 or MIL-L-23398 types should be changed out under TCTO directives. Where this is impractical, its hold be made positive that replacement parts be solid film lubricated by non graphitic lubricants.
NOTE 3: In order to select a suitable substitute for these miscellaneous materials, the specific application just be known. Each specific use of these materials should be checked through San Antonio ALC/SFQTE, Autovon 945-7613.
NOTE 4: Do not use this silicone lubricant in fuel tank areas where sealing of fasteners is critical or in areas where paint adhesion is critical. Where sealing, paint adhesion, or torque values are involved, contact Warner Robins ALC/MMEETC, Autovon 468-3284, for substitute.
Note 5: Where use of a silicone oil base lubricant is impractical, (see Note 4), MIL-G_81322 also may be substituted for MIL-L-3572, except where use of an oil is mandatory, i.e., poor access, configuration, etc. Checked these instances with the ALC prime on the equipment.
Note 6: Rock Island Arsenal Purchase Description 703 air dry solid film will be furnished when MIL-L-46147 is ordered. There is no QPL for MIL-L-46147. Until a QPL is issued, specify RIA PD 703. This product is available in 12 oz aerosol containers (9150-00-142-9309) and one gal bulk containers (9150-00-142-9361).
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Below is a list of metals that react with each other in the presence of water. Sea water is generally the worst scenario. The metals are listed from one end of the potential the other. To put it simply the worst is at the top and the further down the list the contact metal is the more problems you get. Metals that are next to each other in the ladder will have the least amount of reaction in the presence of moisture. Metals that are further apart will have the most reaction. The metals highest on the list attract to those lower and interact trying to go to the lower metal.
You will note GRAPHITE always wins. Graphite will be the last thing left as everything else is below it. You may have noticed aluminum pots that have had water left in them long term will show pitting. The aluminum in the presence of water is attracted by the copper in the mixture and when the aluminum breaks away heading for the copper it floats away leaving pitting.
Magnesium
Zinc
Beryllium
Aluminum Alloys
Cadmium
Mild Steel, Cast Iron
Low Alloy Steel
Austenitic Nickel Cast Iron
Aluminum Bronze
Naval Brass, Yellow Brass, Red Brass,
Tin
Copper
Pb-Sn Solder (50/50)
Admiralty Bras, Aluminum Brass
Manganese Bronze
Silicon Bronze
Tin Bronzes (G&M)
Stainless Steel Types 410, 416 Note: 1
Nickel Silver
90-10 Copper – Nickel
80-20 Copper –Nickel
Stainless Steel Type 430 Note 1
Lead
70-30 Copper-Nickel
Nickel-Aluminum Bronze
Nickel-Chromium alloy 600 Note 1
Silver Braze alloys
Nickel 200
Silver
Stainless Steel Types 302, 304, 321, 347 Note 1
Nickel-Copper Alloys 400, K-500
Stainless Steel Types 316, 317 Note 1
Alloy “20” Stainless steels, cast and wrought
Nickel-Iron-Chromium alloy 825
Ni-Cr-Mo-Cu-Si alloy B
Titanium
Ni-Cr-MO alloy C
Platinum
GRAPHITE
Note 1: IN LOW-VELOCITY OR POORLY AERATED WATER, AND AT SHIELDED AREAS MAY BECOME ACTIVE AND EXHIBIT A POTENTIAL NEAR -0.5 VOLTS.
