Harry M Schiefer

Boundary Lubricating Properties of Fluoroalkyl Silicones in Bench and Pump Tests

As technological advances are being made, the need for lubricants with higher load carrying capacities and stability to various environmental conditions are required. Nonadditive silicone fluids have approached the stability and temperature range required but have fallen short in their antiwear and load carrying ability for ferrous metals. The advent of fluoroalkylsiloxanes has brought about the much sought for boundary lubrication for steel sliding against steel as well as for other metal combinations. The trifluoropropylmethylpolysiloxanes exhibited the best combination of physical and lubricity properties. Laboratory data are presented which describe the physical properties and improved boundary lubrication of the fluids. To complement the bench testing, results of application tests with a vane pump, piston pump, mechanical vacuum pump (vane type), and a reciprocating compressor are described. Solvent resistance, liquid oxygen compatibility, and resistance to chemical attack are also discussed. Present...

Trifluoropropyl Halophenyl Substituted Silicone Copolymers—A New Class of Wide Temperature Range Lubricants

Chlorophenyl substituted silicones have better lubricating properties than lightly phenylated methyl silicones with similar physical properties. The best load-carrying and anti-wear properties are obtained with fluorosilicones at some loss in low-temperature properties. This paper describes a new class of silicone copolymers containing both trifluoropropyl and halophenyl substitution which can cover a temperature span of −100 F to 650 F. Data are included showing that this combination improves both low and heavy load anti-wear properties for steel. Physical, friction and wear, and stability data are given describing these properties as a function of the type, and amount of halogen on the phenyl as well as with varying ratios of trifluoropropyl to halophenyl substitution. Differences in lubricating performances and mechanisms for various halogenated groups are discussed to explain the improvements noted for the combination of halophenyl with trifluoropropyl groups. Final formulation of a potential wide tem...

Controlled Friction Additives for Brake Pads and Clutches

The elimination of asbestos in brake and clutch compositions, as well as the use of smaller brake pads for down-sized and compact cars, has produced new requirements for friction lining materials. The emerging semi-metallic compositions generally need some friction modifiers to reduce squeal and wear and to produce friction characteristics that are less dependent on temperature. In Europe MoS//2 has been utilized as a friction modifier for harder brake pad compositions for many years, but provided only limited improvements. Research on solid friction control additives at Dow Corning has produced new technology by which friction and wear properties can be tailored to specific requirements of the friction lining industry. This material has been evaluated in a number of brake and clutch compositions at a level of from one to six weight percent.