It is well known that fluorosilicones are used as lubricant oils and base fluids for greases. They also show good rheological properties and resistance to degradation and oxidation. However, this lubricant behavior, which is satisfactory at relatively low temperatures (e.g., up to 100.degree. C.) tends to progressively worsen at higher temperatures (e.g., from 100.degree. to 200.degree. C. and higher). The prior art has taught the use of various additives, such as antioxidants and/or antiwear agents, in an attempt to extend the practical application temperature range of fluorosilicones. But, e.g., Braun et al., in an article entitled "Silicone Lubrication of Porous Bronze Bearings" (Lub. Eng., 32, 176-182, 1975) found some antioxidants to be ineffective. Further, some fatty ester antiwear agents were found to give similar unsatisfactory results.
Kim et al. (U.S. Pat. No. 3,629,115) suggested the use of fluorinated phenylphosphine as both an antioxidant and an antiwear additive in fluorosilicones. However, the antiwear properties of these compositions are not satisfactory in practice.
Kobzova et al., in an article entitled "Efficiency of Antioxidants in Phthalocyanine Greases" (Khim. i Tekhn. Topliv i Masel, No. 10, pp 59-61, 1971) showed that conventional antioxidants, such as N-phenyl-.alpha.-naphthylamine, are nearly ineffective in fluorosilicone-based greases.
Therefore, from an application standpoint, there is still a need for agents which, when added to fluorosilicones, result in effective lubricants for use in air at temperatures higher than 100.degree. C., particularly at 125.degree. C. to 200.degree. C., and higher.