Solid and Dry Film Lubricants

Solid and dry film lubricants form a dry layer or coating that excludes moisture and reduces friction, binding, and wear. They often contain additives such as corrosion, oxidation, and rust inhibitors. Extra pressure (EP) additives include chemically active agents such as sulfur, phosphorous, or chlorinated compounds that form a film to prevent seizure, sticking or surface adhesion under high pressure conditions. Solid and dry film lubricants are also used to provide shock or vibration dampening functions. Fire resistant, biodegradable, and microbe inhibiting products are available. Release agents that prevent materials from sticking or adhering to an underlying surface require periodic replenishment. Important specifications to consider include density, specific gravity, thermal conductivity, and dielectric strength.

Solid and dry film lubricants vary widely in terms of chemical composition. Some products contain boron nitride (BN) or “white graphite”, a chemically inert compound that provides high thermal conductivity and low thermal expansion. Hexagonal or flake graphite, molybdenum, and metal sulphide are solid lubricants that maintain a low coefficient of friction up to 400° C (752° F) and are available in powder, sprayable coating, and solid machinable forms. Products that are based on halogenated hydrocarbons include chlorofluorcarbon (CFC), halogenated fluorocarbon (HFC), halogenated chlorofluorocarbon (HCFC), and perfluorocarbon (PFC). Wax, paraffin and stearate compounds are suitable for some lubrication, anti-corrosive and anti-static applications. Fluoropolymer-based compounds include polytetrafluoroethylene (PTFE).

Important specifications to consider when selecting solid and dry film lubricants include density, specific gravity, thermal conductivity, and dielectric strength. Density is the mass per unit volume of a material. Specific gravity is density normalized to water or another standard. Thermal conductivity is a measure of a fluid's ability to transfer heat. Dielectric strength is the maximum voltage field that a material can withstand before electrical breakdown occurs. Operating temperature, another important consideration, is the full ambient operating range for solid and dry film lubricants.

There are a variety of applications for solid and dry film lubricants. Some are designed for use in the automotive, transportation or aerospace industries. Others are suitable for bearings, combustion engines, compressors, pistons, machines, and gears. Products that meet military specifications (MIL-SPEC) or the regulatory requirements of the U.S. Food and Drug Administration are also available. Solid and dry film lubricants are also used in processing equipment, metal working, and metal forming applications.

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