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1. A magnetic hard disk drive comprising a head along a suspension pivoted by a pivot bearing assembly, wherein the pivot bearing assembly utilizes a grease composition comprising an additive comprising:
a. at least one phosphite represented by Formula A: and/or b. at least one orthophosphoric acid ester represented by Formula B:wherein R1, R2, and R3 in each of Formula A and Formula B may be independently selected to be one of the following: an alkyl group; an aryl group; a hydrogen atom;and/or an OH group;and/or mixtures thereof, combinations thereof, derivatives thereof, and/or decomposition products thereof;with the proviso that the phosphite is not a compound selected from the group consisting of: trioctyl phosphite, triphenyl phosphite, tricresyl phosphite, bis-2-ethylhexyl phosphite, tridecyl phosphite, dibutyl hydrogen phosphite, tris(nonylphenyl) phosphite, dilauryl hydrogen phosphite, diphenyl monodecyl phosphite, and diphenyl hydrogen phosphite;and/or the orthophosphoric acid ester is not a compound selected from the group consisting of triphenyl phosphate, triethyl phosphate, tributyl phosphate, tris(2-ethylhexyl) phosphate, tris(2-ethylhexylyl) phosphate, tridecyl phosphate, diphenyl mono(2-ethylhexylyl) phosphate, tricresyl phosphate, trioctyl phosphate, and tristearyl phosphate;and/or
c. at least one functionally equivalent phosphite and/or orthophosphoric acid ester having a molecular weight of greater than about 369 g/mol., having low volatility, and having hydrolytic stability. |
