Titanates are currently used in friction materials worldwide. This study investigates the effects of titanates in friction materials with Low Steel (LS) formulations.
A kind of titanate compound is examined with a LS formulation. Test pieces both with and without the titanate are examined using small rotors of gray cast iron. The frictional performance tests use a 1/7 scale dynamometer. The surfaces and the cross-sections are closely observed using a Scanning Electron Microscopic analyzer.
Results of the testing on samples without the titanate suggest that frictional effectiveness is sensitive to the load value especially in high speed braking conditions. A Metal Pick Up (MPU) phenomenon, which is one of the significant problems of friction materials, also occurs. The millimeter-sized picked-up metals consist of micron-sized wear debris of iron. The crystalline transformation of the steel fibers around the picked up metals is investigated. Results show that the crystalline structure of the steel fibers changes from ferrite to martensite. This results in hardening of the steel fibers. The frictional effectiveness may become unstable due to these changes.
On the other hand, frictional effectiveness in high speed braking conditions is stabilized in the samples containing the titanate. The MPU phenomenon and the hardening of steel fibers are not found. Titanates seem to have the effect of stabilizing frictional effectiveness by preventing the MPU phenomenon in high speed braking conditions. There is a reason to suggest that titanates might be better classified as “modifiers” rather than lubricants or abrasives in LS formulations.