Friction hysteresis and subsequent wear mechanism of clay-based phenolic composites under cyclic load

Proceedings of the Institution of Mechanical Engineers, Part J:

2021

Self Cite

The stick–slip phenomena of various types (halloysite, montmorillonite and wollastonite) of clay-based composite friction materials were evaluated in terms of their velocity-dependent friction response. Scanning electron microscopy of the contact patches suggested breakage of contact plateaus in the composites with halloysite, whereas relatively small contact patches were developed in montmorillonite-based friction composites. The presence of relatively harder ingredients such as magnesium oxide and iron particles on the worn surface have contributed to the stick–slip phenomenon. The presence of wollastonite in the composites leads to the ploughing effect during sliding. The intensity of creep groan remained controlled by the shear strength of the interfacial junction involving asperity contact/welding whereas dynamic groan remains predominated by the stiffness of the composites.

Section: Fabrication and Composite Designationmentioning

confidence: 99%

Section: Fabrication and Composite Designationmentioning

confidence: 99%

Influence of various types of clays on velocity dependence of friction composites

Proceedings of the Institution of Mechanical Engineers, Part J:

2021

Self Cite

Tuning of Friction Oscillation Amplitude in Halloysite, Montmorillonite, and Wollastonite Filled Friction Composites: Load, Speed, and Temperature Sensitivity

2021

Journal of Tribology

The influence of clay mineral silicate types, such as halloysite, montmorillonite, and wollastonite with tubular, plate like, and acicular morphologies respectively, on frictional oscillation of composite materials have been evaluated on Chase type dynamometer and optimised following the combination of Taguchi's L9 design of experiment and regression analysis approaches. The coefficient of friction of ~0.35-0.45 and cumulative wear at < 10 % remained well within the acceptable range. The optimal tuning of friction oscillation to reduce braking induced noise and vibration propensity has been achieved by montmorillonite clay with platelet type morphology or by combination of MgO and wollastonite clay with acicular morphology. The extent of Fe- content in wear debris close to ~ 80 % on the composite surface led to an optimal level of friction oscillation amplitude (Aamp). The hierarchical ranking of the clay based composites by TOPSIS based operation research approach lead to the understanding of design ideology optimization for composites to ensure minimal friction oscillations.

Combinatorial effects of clay type silicate and MgO on friction braking performance of hybrid phenolic composites

2022

Journal of Tribology

Halloysite (tubular), montmorillonite (platy), and wollastonite (acicular) type clay silicate morphologies based magnesium oxide (MgO) filled compression molded hybrid friction composites were fabricated followed by their mechanical (compressive), thermal (onset of degradation), thermo-mechanical (loss modulus), and tribological performance (CoF, fade, recovery, wear) evaluation. The friction- fade and friction- recovery due to braking induced heating and cooling cycles vis-a-vis the instantaneous braking performances were evaluated following SAEJ661, on a Chase type friction tester. The combination of halloysite- MgO in the friction composite led to minimum fade (∼ 2.2%), whereas that of wollastonite- MgO showed maximum friction coefficient (∼ 0.47) with enhanced rotor friendliness as indicated from optical surface profilometry. Montmorillonite-MgO based composites showed maximum wear resistance along with greater extent of friction stabilization as supported by ID/IG data from Raman spectra. The performance attributes remained governed by the compressive stiffness of the friction composites, hardness, thermal stability, and morphological aspects of the clay type silicates, and their induced contact dynamics as evident from SEM-EDX studies. The heat dissipation mechanism, the disc temperature rise and friction coefficient under instantaneous braking condition were found to be controlled by MgO in the composites. The study demonstrates that clay- type silicate morphologies in combination with MgO as a mild abrasive may lead to synergistic fade- recovery performance without compromising the compressive stiffness response of the braking surface, enabling increased wear resistance.