INDUSTRIAL AND ENGINEERING CHEMISTRY
632
Vol. 34, No. 5
solution probably gives little corrosive effect but acidity develops with use. Polarity of the liquids seems to be Day examined 1st 2nd 3rd 4th 5th Temp., F. - 23 - 36 - 29 -29 -33 an important factor in corrosion in organic solutions. Good castor oil solSample No. a Solid Solid Solid Good 70 vents are necessarily polar, especially a Thick, cloudy Solid Solid Good 70 those suitable for use with gaskets. ConGood Good Good Good Good 72 ductivity measurements are probably Good Good Good Good Good 73 a more important than total acidity. KO Solid Solid Thick 76 Good Solid Thick Thick, cloudy Good 77 work has been done in this direction as Good Good Good Good Good 78 yet; p H measurements in media differGood Good Good Good Good 79 ent from the fluid are of little signifiGood Good Good 80 Good Good cance. Good Good Good Good Good 81 , l Solid Very cloudy Good 82 The best solution for controlling Good Good Good Good Good 83 corrosion in hydraulic fluids suggested Good Good Good Good Good 85 by the investigation is to leave the fluid Good Good Good Good Good 86 acid and use a good inhibitor. The *.. .. 3586A (light) Cloudy, pours Cloudy, 0. K. Crystals, pours easily well aliphatic amine phosphates are very Good Thick, pours Good Good B Good effective in reducing corrosion of copper, Cloudy Some crystals, pours Same Same D Good lead, and steel. easily Hydroquinone was used in blend 91A Thick Thick 0. K., cloudy Thick Thick A to inhibit oxidation of the castor oil. Test discontinued. Hydroquinone1 and similar compounds have been shown to reduce such oxidation. As a result of the investigation Air Corps Specification 3586 is nom being revised2 around I n all of the experimental fluids described except 91A a formula 91a. The material is to be purchased on a formula commercial amine was used as the corrosion inhibitor. Howbasis. Two grades (viscosities) will be used instead of the ever, the fluids thus treated were not so satisfactory as the present three. Viscosities a t 100" F. are 180-220 and 70-80. specification fluid in the endurance tests. Considerable inVariation in viscosity is achieved b y changing the proporvestigation has been carried out by the Materials Laboratory tions of castor oil and alcohol. The diamylamine phosphate on the use of amine phosphates as corrosion inhibitors with and an oxidation inhibitor are required. The finished fluid favorable results. Mono-, di- and triethanolamine phosis to be slightly acid. phates were found to be insoluble in the fluids. The aliphatic amine phosphates were soluble, diamylamine phosphate being Conclusions TABLEIX. RESULTSOF COLDROOMTESTS
O
0
(L
OF COLD Roox TESTS TABLEX. RESULTS
Day examined Temp., O F. Sample No. 93 92 91 95 E-1 A-1 O
1st
-24
Solid Solid 0. K. 0. K. Murky, pours easily Murky, crystals, pours easily
2nd
- 36 0
3rd
- 50 a
G
0. I
