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Halogen-Based FRs
Published in Asim Kumar Roy Choudhury, Flame Retardants for Textile Materials, 2020
Fluorine plays an important role in flame retardancy. Two important FR fluorine-based FR compounds are polytetrafluoroethylene (PTFE) and fluorinated ethylene propylene (FEP). Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. The well-known brand name of PTFE-based formulas is Teflon (Teflon, 2019).
Applications of Electroless Nickel and Practical Aspects
Published in Fabienne Delaunois, Véronique Vitry, Luiza Bonin, Electroless Nickel Plating, 2019
NiP-polytetrafluoroethylene (PTFE) has been recently found to provide nonstick, non-galling, high dry-lubricity, low friction, good wear, and corrosion-resistant surfaces. Although these composite coatings also provide wear-resistance benefits, they are considered in a separate category based on the unique characteristics they embody: dry lubrication, improved release properties, and repellence of contaminants, such as water and oil. They are applied to pumps and valves butterfly valves (Figure 9.2e) in the oil and gas industry (Mallory & Hajdu, 1991). It cuts the leak rate and permits safe operation of the valve for cryogenic applications (Feldstein, 2019).
Organic Low-Dielectric Constant Materials for Microelectronics
Published in Sam-Shajing Sun, Larry R. Dalton, Introduction to Organic Electronic and Optoelectronic Materials and Devices, 2016
Perfluorinated aliphatic polymers incorporate C–F bonds of the lowest polarizability, leading to the lowest dielectric constants (1.9–2.1) reported for any nonporous materials. The base polymer, polytetrafluoroethylene (PTFE), is a highly crystalline material that lacks solution processibility by traditional methods. In addition, the flexible and uncross-linked chain structure limits its thermomechanical stability. However, W.L. Gore and Associates has developed a PTFE nano-emulsion material, SPEEDFILM, which is an aqueous emulsion containing sub-20 nm PTFE particles and surfactant. The resultant material is nonporous with gap fill of 0.35 μm. The film demonstrates good thermal stability up to 400°C and has a 460°C decomposition temperature [24]. SPEEDFILM is nonetheless susceptible to the potential release of fluorine atoms and consequent interconnect metal corrosion, which is displayed by all fluorine-containing materials.
Investigation of Dry Sliding Friction Wear Behavior of CuSn11 Bronze Plain Bearing Applying Impregnated Graphite-Filled PTFE
Published in Tribology Transactions, 2022
Tin bronze and polymers are commonly used as plain bearing material in the industry. Copper-based tin bronzes (Cu + 10–15% Sn) are preferred due to their high abrasion resistance and embedding of foreign particles, good electrical conductivity, strong corrosion resistance, and thermal conductivity (3). Polytetrafluoroethylene (PTFE), which is a polymer material, is also preferred due to its wide operating temperature range (from –260 °C to +270 °C), high chemical strength, the lower static and dynamic friction coefficient, self-lubricating property, high resistance to corrosion, and sufficient mechanical strength (4, 5). Due to developments in technology, self-lubricating bearings have been produced by using the superior properties of both bronze and PTFE, especially for systems that do not allow continuous lubrication.
Tribological Performance of Si3N4-PTFE Composites Prepared by High-Pressure Compression Molding
Published in Tribology Transactions, 2020
Dapeng Gu, Shouyao Liu, Suwen Chen, Kefeng Song, Bingchao Yang, Deng Pan
Polytetrafluoroethylene (PTFE) is well known for its low friction coefficient, excellent high-temperature resistance, and chemical stability. Despite these benefits, the application of pure PTFE in tribology was rare due to its poor wear resistance. Therefore, inorganic and organic fillers were introduced into PTFE-based composites. Inorganic fillers, such as glass and carbon fibers (7, 8), graphite (9), bronze powder (10), and oxides (11–13), have been researched. Sawyer et al. (14) filled 20 wt% alumina (Al2O3) nanoparticles in the PTFE matrix and found that the friction coefficient increased slightly but the wear rate decreased by two orders of magnitude. Wang et al. (15) found that the wear rate of PTFE-based composites reached 10−5 mm3 (Nm)−1 when filled with 20 wt% poly (p-hydroxybenzoic acid) and 20 wt% h-BN. Although the wear resistance could be improved, most inorganic fillers dispersed in a polymer matrix with a percolation limit of the mass fraction (16). Therefore, the maximum mass fraction of inorganic filler limited the further decrease in wear, because the wear resistance was related to the hardness (17, 18).
Effect of Graphite and Bronze Fillers on PTFE Tribological Behavior: A Commercial Materials Evaluation
Published in Tribology Transactions, 2020
Caio Augusto Garcia Sampaio Valente, Felipe Fernando Boutin, Lucas Prado Caetano Rocha, João Luiz do Vale, Carlos Henrique da Silva
Polymeric materials and their composites have been increasingly used in tribological applications due to their unique characteristics, such as low density, self-lubrication, processability, and low cost (Song, et al. (1)). Polytetrafluoroethylene (PTFE), in particular, is well known to have low chemical interaction with the environment, good mechanical strength at high temperatures, high impermeability, and a lower coefficient of friction (COF) compared to other engineering polymers (Makowiec and Blanchet (2); Mazza, et al. (3)). Therefore, PTFE is attractive in several areas of industry, such as aerospace and automotive (Freudenberg Sealing Technologies (4)), nuclear (Wyszkowska, et al. (5)), biomedical (Furuta, et al. (6)), and petrochemical (Jin, et al. (7)) industries, among many others.