Patent GB-784793-A (GB)
Title: Improvements in or relating to lubricants resistant to atomic radiation
Filed: 1954-12-14
Abstract: A lubricating composition, suitable for use in equipment exposed to neutron and/or gamma radiation, comprises a lubricating oil and sufficient of (1) an element or compound having a gamma ray absorption coefficient of at least 3, and (2) an element or compound having a capture cross-section for thermal neutrons of at least 2500 borus, to stabilize the oil against atomic radiation. The lubricating oil may be mineral or synthetic, and examples of suitable synthetic oils are Fischer-Tropsch synthesis products, hydrocarbon polymers, formals, acetals, glycols, ethers including glycol and polyglycol ethers, carbonates, silicanes, silicones, silicates and fluorocarbons.  Ingredient (1) may be titanium, molybdenum, mercury, lead, bismuth, thorium or platinum, or a compound thereof.  Suitable metal compounds are oxides, sulphides, naphthenates, stearates, sulphonates, organic thiophosphorus acid salts and phosphides. Graphite, mica, asbestos and talc are also suitable as ingredient (1).  Ingredient (2) may be cadmium, samarium or gadolinium or a compound thereof.  Suitable compounds of these elements are oxides, sulphides, phosphides, phosphorus acid salts, naphthenates, petroleum sulphonates, fatty acid soaps, soap-salt complexes, chelates and porphyrin derivatives.  The lubricating composition may be thickened to a grease structure by the addition of a thickener such as a metal soap of a fatty acid, a metal salt of a hydrocarbon sulphonic acid, carbon black, calcium silicate, bentonite, attapulgus clay, onium clays, oxides of silicon, aluminium, iron, bismuth or tin, N-stearoyl-p-amino-phenol and urea adducts of benzene or biphenyl. The soap or sulphonate thickeners may be derived from alkali or alkaline earth metals, magnesium, aluminium or lead and may be employed in the form of complexes with metal salts of C1-C5 carboxylic acids.  Alternatively ingredient (1) or (2) may be a thickener of the soap or soapsalt complex type. Thus, ingredient (2) may be cadmium stearate or a cadmium stearatecadmium acetate complex. The lubricating composition may contain additional ingredients such as calcium sulphonates, antioxidants (e.g. phenyl alphanaphthylamine), corrosion inhibitors (e.g. sorbitan mono-oleate), extreme pressure agents (e.g. tricresyl phosphate and chlorinated hydrocarbons) viscosity index improvers (e.g. polybutenes and polymethacrylates), pourpoint depressors (e.g. naphthalene alkylated with chlorinated paraffin wax and lauryl fumarate-vinyl acetate copolymers) and tackiness or stringiness agents (e.g. polyisobutylenes).  In an example, a lubricating grease is prepared from a formal of C13 oxo alcohol, cadmium stearate, calcium acetate, molybdenum disulphide and phenyl alpha-naphthylamine.  In further examples, lubricating oils are prepared from (a) mineral oil, gadolinium naphthenate, bismuth stearate, salicylalpropylene diamine condensation product and phenyl alpha-naphthylamine; or (b) polyethylene glycol, gadolinium oleate, mercury naphthenate, salicylal-propylene diamine condensation product and phenyl alpha-naphthylamine.