Friction Coefficient Of Steel Research Articles

Tribological properties of liquid crystals as lubricant additives

Several families of liquid crystals, 4,4′-dialkyl- and dialkoxyazobenzenes, 4,4′-dialkylazoxybenzenes and cyanoaryls, have been studied as commercial oils additives. Tribological studies have been carried out on a real time pin-on-disk machine at variable temperature and concentration. Variations in viscosity and transition temperature have no significant effect on friction values. Friction values for increasing concentration solutions of liquid crystals in base oil are very similar. A 1% weight addition of liquid crystals to two different base oils lowers friction coefficients of steel for all 14 liquid crystals studied. Wear rates of steel-steel and steel-aluminium contacts are significantly lowered by addition of liquid crystals to base oil.

Friction and wear behavior of TiN in air: The chemistry of transfer films and debris formation

Friction tests were performed on TiN-coated substrates at low speed (less than 0.1 m s −1) in air. Optical (Nomarski) and scanning electron microscopy, Auger electron spectroscopy and transmission electron microscopy (TEM) were used to characterize the transfer films and debris generated during sliding against steel and sapphire balls. Friction coefficients of steel against rougher ( R a ≈60–100 nm) TiN coatings started and remained relatively high (0.5–0.7) owing to wear and transfer of the steel. After the TiN coating was polished ( R a ≈4 nm), transfer was reduced and initial friction coefficients ranged from 0.15 to 0.2. Initial friction coefficients with sapphire balls sliding against polished TiN were even lower (0.05). However, friction coefficients with both balls increased as debris formed and transferred to the wear track. Auger analysis showed that steel balls accumulated metallic iron and/ or iron oxide as well as titanium oxide layers and debris, whereas sapphire balls acquired only titanium oxide transfer layers. TEM of debris stripped from contact areas of steel and sapphire balls identified the phases of debris as a rhombohedral ternary oxide (FeTiO 3/ α-Fe 2O 3) and rutile (TiO 2) respectively; morphologies were either thin, uniform flakes — prevalent in low friction sliding — or spherical clusters. A thermochemical basis for oxide debris formation is given and the friction behavior is interpreted in terms of an oxide wear mechanism.

Coefficient of Friction for Steel on Concrete at High Normal Stress

Experiments were performed to determine the coefficient of friction between concrete and steel. The nominal normal stress varied from 1 P.S.I. to 68,000 P.S.I. The coefficient of friction was found to be nearly constant with an average value of 0.47.

Friction Coefficient of Steel on Concrete or Grout

An experimental investigation was conducted to determine the coefficient of static friction between rolled steel plate and cast‐in‐place concrete or grout. Fifteen tests were performed under conditions that represented the interior and exterior bearing surfaces of a containment vessel. Test parameters included concrete blocks or grout blocks, wet or dry interface, and level of normal compressive stress. For conditions tested, the average effective coefficient of static friction varied between 0.57 and 0.70. It is recommended that the coefficient of static friction for concrete cast on steel plate and grout cast below steel plate should be taken as 0.65 for a wet interface with normal compressive stress levels between 20 and 100 psi (0.14 and 0.6 MPa). For dry interface, the coefficient of static friction should be taken as 0.57.