Low Friction Elastomeric Compounds (Slippery Elastomeric Compositions)
(Elastomeric compounds with a dynamic friction coefficient of less than 0,2 against hard
surfaces without any lubricant)
Low friction and wear resistant elastomeric compounds are recommended when application suggests harsh wear conditions and minimum breakout torque. REAM-RTI commercialized a range of wear and abrasion resistant elastomeric compounds RS-26ch-5/-65 and developed a new elastomeric compound K-38. The dry friction coefficient of the compounds against hardened carbon steel is below 0,2. The compounds are able to sustain dry friction conditions under severe mechanical load for at least 40 minutes.
The use of the low friction elastomeric compounds as the materials for impeller thrust washers resulted in significant (tens times) decrease of total wear. Testing of low friction elastomers performed by ZAO "NOVOMET-Perm" (a test bench for ESP units) revealed advantages of REAM's low friction elastomers over traditional materials textolite, flubon and the latest wear resistant material carbonite used for production of impeller thrust washers.
Being a promising alternative for such traditional materials as textolite, novolone (PTFE + carbon) and carbonite the low friction elastomeric compounds are used for production of marine bearings. Low friction elastomeric compounds are also recommended for application in PCP pump and drill motor stators. For harsh operation conditions a number of specialist HNBR-/HSN- and FEP- based low friction elastomeric compounds are formulated.
Elastomeric compounds RS-26ch-5/-65 correspond to the 1 st class of ED resistance in accordance with NACE TM 0192-98 "Evaluating Elastomeric Materials in Carbon Dioxide Decompression Environments".
Comparison of Methods to Reduce Dry Friction of Technical Rubber Products
Elastomeric compounds used for production of seals, marine bearings, PCP pump/drill motor stators and other heavy duty components that are exposed to sliding friction against smooth metal surfaces must have high resistance and exhibit low friction coefficient and minimal breakout torque. Improving the features of widelyused elasomeric compositions is possible by modifying (treating) working characteristics of the existing elastomeric materials. A number of different treatment methods can be used: the volume treatment -modifiers are added at the elastomer formulation stage, the surface treatment - treatment of the finished product surface by modifiers and the combined treatment - combination of volume and surface treatments.
REAM-RTI specialists invented and patented a method of adsorptive-absorptive treatment (AAT) that uses nonionic surfactants as modifiers. The AAT requires the finished products to be dipped into the modifier medium and this results in the modifier being absorbed on the product surface and then it penetrates into the material matrix. The modifier migrates on to the surface of the modifier and creates a functional layer, e.g. a low friction layer or/and anticorrosive highly resistant layer.
This technology is successfully used for cured products as it does not change their geometry.
AAT application is sometimes restricted. Care is needed in selecting media and AAT regimes for products which operate in vacuum and at high temperatures.
This method of product treatment is applied in the production of reliable, heavy duty oil production equipment seals and can improve efficiency as it increases the operation of PCP pump and drill motor stator elastomeric coatings.
Comparison of "dry" friction reduction methods of technical rubber products
made from NBR- and HNBR-basуd elastomers
|"Dry" friction reduction method||Restrictions for the use of friction reduction method||
Minimum dynamic friction
Wear of the treated reduced friction layer in the
|Volume treatment||Technical problems due to compound mix and product combination. Non compatibility or agglomeration of antifriction additive agents||0,15…0,25|
Evaporation or outwashing of the modifier in the
medium and/or in the operating conditions
Friction coefficient f versus test duration t for elastomeric compounds treated by different methods. Friction couple: elastomer thrust washer/carbon steel ring test samples (high_carbon steel), Rz = 0,5...0,65 μm
The results of bench tests of untreated and treated leap seals in the liquid mediu (the material _ HNBR compound, 87 Shore A)
Examples of elastomer products with low dry friction coefficient