THE STABILIZATION OF SILICONE LUBRICATING LIQUIDS ABOVE 200 C PART 2 - IRON.COPPER, CERIUM, AND OTHER METAL COMPOUNDS

摘要

Silicone liquids have been stabilized against oxidation and gelatin so that the useful life at 325°C or below is lengthened 30- to 500-fold over the original oil. The stabilization is accomplished by treating the silicone oil with a cerium soap in the presence of disalicylalpropylene-diamine, or a related chelating compound, at 285°C. Similar but less effective stabilization occurs when the cerium soap is replaced by suit¬able iron, copper, chromium, praseodymium, or europium compounds. This treatment is effective with diethyl silicones and also with phenyl -substituted types. The percentage improvement obtainable with the phenyl-ated oils decreases with increasing aromatic content; after inhibition the lightly phenyl-ated oils, which have excellent viscosity-temperature characteristics, have as long a life as the highly phenylated oils, here¬tofore found most stable in high-temperature service. Also, the volatile products of silicone oxidation at 300°C promote premature gelatin if they are returned to the liquid under test.