the objective of this invention is to provide self - lubricating composites having sufficient high temperature strength to render them useful for the fabrication of gears , bearings , sleeves , etc ., to provide self - lubricating composites with outstanding thermal stability , to provide lubricative composites which are virtually void free and to provide moldable lubricative compositions which cure through an addition polymerization process to provide cured resin moldings which have superior lubricating characteristics when compared to prior art solid self - lubricating composites . in seeking to achieve the above stated objectives , polyimide oligomers prepared by the teachings of u . s . pat . nos . 3 , 845 , 018 and 3 , 879 , 349 , in which one of the instant inventors is also the coinventor , have been blended with molybdenum disulfide and other lubricating substances to form moldable lubricative composites which , when cured , exhibit exceptional properties exemplified by the properties presented in tables i and ii . the outstanding characteristics of composites prepared in accordance with this invention may be attributed to the following facts : they are essentially void free ; they are made from polyimides which are oxidatively , thermally and dimensionally stable to 700 °- 800 ° f ; they are made from polyimides of extremely high strength which retain their high strength at high temperatures ; and they contain lubricating additives which are stable to 700 ° f in air . the polyimides which are used in this invention are those derived from polyimide oligomers having the following structures . ## str1 ## where n usually is 1 - 3 . when n is 1 the resin is designated hr600 . when n is 2 , the resin is designated hr602 , etc . ## str2 ## other acetylene - terminated fully aromatic polyimide oligomers of the type defined in u . s . pat . nos . 3 , 845 , 018 and 3 , 879 , 349 have also been used . solid lubricative pigments such as mos 2 and ws 2 are preferred . however , higher thermal stability substitutes for these materials such as certain other chalcogenide ( e . g ., tungsten disulfide , tungsten diselenide , molybdenum diselenide ) may also be used . the invention may be made by forming a finely pulverized blend of the solid lubricative pigment ( 10 - 60 % by weight ) and the polyimide oligomer . this blend is then molded at about 485 ° ± 15 ° f for about 2 - 4 hours at pressures ranging from about 200 to about 2000 psi and postcured for periods of 4 + 1 / 2 hours each at temperatures of 450 °, 500 °, 550 °, and 600 ° f . following the cure sequence , the composite is allowed to cool and may be machined to form usable specimens , bearings , gears , and other items . other cure schedules may also be used . another way to make the invention is to form a mixture of approximately 85 % of polyimide oligomer ( finely powdered ) approximately 15 % lubricant pigment ( finely powdered ) in an inert suspension medium such as trichlorotrifluorethane ( freon tf ) and wet - blend with a high speed blender . following the mixing , or blending , the fluorocarbon is removed by air drying followed by vacuum drying . the dried mixture is then placed in a mold and preheated to approximately 485 ° f for 15 minutes at &# 34 ; contact pressure &# 34 ; ( 0 - 5 psi ) before molding pressures of up to 300 psi are applied for periods of up to 6 hours . post cures under pressure for periods of four hours each at temperatures of 485 °, 500 °, 550 ° and 600 ° f are employed as in the example above . in some cases , a 600 ° f cure for up to 50 hours is desirable . lubricative composites comprised of 15 % mos 2 and hr 600 ( polyimide of structure shown in fig1 ) prepared by the wet - blend method described above were compared to other self - lubricating composites in tables i , ii and iii . these tests were conducted on a lfw - 1 friction and wear tester utilizing the following test parameters : motion : oscillating ; arc : 90 °; speed : 95 cpm ( 17 fpm avg . ); normal load : 4 lbs . on 30 - 1 load lever system ; unit load : 800 psi ; ring material and surface finish : lfw - 1 alpha ring ( sae 4620 steel , r c 58 - 63 ) 11 . 0 ins o . d . ; and temperature , humidity : laboratory ambient . the test results were compared to those of dupont &# 39 ; s &# 34 ; vespel &# 34 ; sp - 3 a commercially available lubricative composite and an inorganic fluoride impregnated graphite . the results of this comparison are shown in table iii , where the invention is described as &# 34 ; hr 600 + 15 % mos 2 .&# 34 ; in tables i and ii the results are compared to another commercial composite designated wdc 140 . it is evident from the test results shown in table iii that graphite was the poorest of the 3 solid lubricants and wore away more than 27 times as fast as our composite . this is even more significant when it is recognized that the graphite failed to complete the test . furthermore , the vespel sp - 3 wore away 7 . 5 times more than our composite and exhibited a coefficient of friction 4 . 4 times higher than that of our composite , in spite of containing the same percentage of mos 2 . the characteristics of the invention , when compared to those of prior art self - lubricative composites , can be classified as outstanding . having fully disclosed our invention and provided teachings which enable others to make the use it , the scope of our claims may be understood to be as follows : table i__________________________________________________________________________load capability tests conditions : temperature - 600 ° f . speed - 43 . 2 fpm ( 120 rpm ) atmosphere - air time - 60 min . at each load * ( wt . ratio ) * ( wt . ratio ) hr600 / mos . sub . 2 ( 85 / 15 ) hr600 / mos . sub . 2 ( 60 / 40 ) wdc - 140 ** wear ( mil / hr ) wear wear ( mil / hr ) wear wear wear / hr ) pv total ter - factor total ter - factor total ter - factorload ( psi ) friction indi - minal ( 10 . sup .- 8 friction indi - minal ( 10 . sup .- 8 friction indi - minal ( 10 . sup .- 8 ( lb ) ( fpm ) coefficient cated value in / in ) coefficient cated value in / in ) coefficient cated value in / in ) __________________________________________________________________________ 25 8 , 640 0 . 72 - 0 . 34 - 0 . 23 2 . 0 0 . 54 1 . 74 0 . 43 - 0 . 35 2 . 6 2 . 6 8 . 36 0 . 23 39 36 . 8 118 50 17 , 280 0 . 17 2 . 0 2 . 0 6 . 43 0 . 26 - 0 . 23 3 . 3 2 . 6 8 . 36 0 . 11 . sup . a 55 . sup . b , d -- 178 . sup . b 75 25 , 920 0 . 18 - 0 . 16 - 0 . 18 3 . 6 2 . 7 8 . 68 0 . 20 - 0 . 17 3 . 6 2 . 0 6 . 43100 34 , 500 0 . 18 - 0 . 16 5 . 3 3 . 7 11 . 9 0 . 18 - 0 . 13 2 . 9 1 . 8 5 . 79125 42 , 200 0 . 12 - 0 . 10 4 . 8 1 . 6 5 . 14 0 . 18 - 0 . 11 4 . 7 2 . 4 7 . 72150 51 , 840 0 . 15 - 0 . 10 4 . 7 . sup . c 1 . 6 5 . 14 0 . 14 - 0 . 10 3 . 2 1 . 9 6 . 11175 60 , 480 0 . 12 - 0 . 09 - 0 . 10 4 . 9 3 . 5 11 . 3 0 . 09 3 . 4 1 . 9 6 . 11200 69 , 120 0 . 13 - 0 . 10 4 . 8 3 . 3 10 . 6 0 . 10 - 0 . 08 2 . 9 1 . 9 6 . 11225 77 , 760 0 . 08 - 0 . 13 - 0 . 09 4 . 7 3 . 7 11 . 9 0 . 10 - 0 . 08 5 . 7 2 . 1 6 . 75250 86 , 400 -- -- -- -- 0 . 10 - 0 . 08 4 . 9 2 . 3 7 . 40275 95 , 040 -- -- -- -- 0 . 08 14 0 . 06 5 . 5 2 . 5 8 . 04300 103 , 680 -- -- -- -- 0 . 09 - 0 . 08 7 . 6 . sup . c 5 . 3 17 . 0__________________________________________________________________________ . sup . a stabilization temperatures ( shaft ) with no heating or cooling . hr 600 / mos . sub . 2 ( 85 / 15 ) 270 ° f . hr 600 / mos . sub . 2 ( 60 / 40 ) 205 ° f . . sup . b test duration - 18 min . . sup . c cracks were observed at the rubbing interface , transverse to the sliding direction , after the test was completed . . sup . d deformation from flow of the resin was observed at the sliding interface in the direction of sliding after the test was completed . * hr 600 is the designation of the polyimide oligomer illustrated in fig1 . ** wdc - 140 is a commercial composition comprised of mos . sub . 2 and sb . sub . o . sub . 3 in a matrix polyphenylene sulfide resin . table ii speed capability tests conditions : temperature - 600 ° f . load - 100 lbs . atmosphere - air time - 60 min . at each speed ( wt . ratio ) ( wt . ratio ) hr 600 / mos . sub . 2 ( 85 / 15 ) hr 600 / mos . sub . 2 ( 60 / 40 ) wdc - 140 wear ( mil / hr ) wear wear ( mil / hr ) wear wear ( mil / hr ) wear speed pv friction total terminal factor friction total terminal factor friction total terminal factor ( fpm ) ( psi ) ( fpm ) coefficient indicated value ( 10 . sup .- 8 in / in ) coefficient indicated value ( 10 . sup .- 8 in / in ) coefficient indicated value ( 10 . sup .- 8 in / in ) 54 43 , 200 0 . 29 - 0 . 14 4 . 5 2 . 2 5 . 66 0 . 17 - 0 . 15 1 . 4 1 . 4 3 . 60 0 . 23 - 0 . 21 11 . 8 3 . 7 9 . 52 90 72 , 000 0 . 14 - 0 . 41 - 0 . 15 5 . 2 2 . 6 4 . 01 0 . 16 - 0 . 15 1 . 1 1 . 1 1 . 70 0 . 23 - 0 . 21 2 . 9 2 . 9 4 . 48 126 100 , 800 0 . 14 - 0 . 13 1 . 7 2 . 3 2 . 54 0 . 14 - 0 . 13 1 . 1 1 . 1 1 . 21 0 . 23 - 0 . 21 3 . 1 3 . 1 3 . 42 162 129 , 600 0 . 14 2 . 9 * 3 . 9 3 . 34 -- -- -- -- 0 . 17 28 . 8 . sup . c 20 . 8 * cracks were observed at the rubbing interface , transverse to the sliding direction , after the test was completed . table iii______________________________________results of room temperature lubricationtests on solid hr600 / mos . sub . 2 composites coefficient of friction after after 100 , 000 120 , 000 % wt . change after cycles cycles 120 , 000 cycles______________________________________hr 600 / mos . sub . 2 0 . 07 0 . 07 0 . 28 ( 1 . 0 ×)* polyimide / mos . sub . 2 0 . 31 0 . 31 2 . 09 ( 7 . 5 ×)*( vespel - sp - 3 ) graphite / lif 0 . 10 sample 7 . 58 ( 27 ×)* crumbled prior to completion of test______________________________________ * values in parentheses are the wt . change divided by 0 . 28