Effect of pressure in the transition between moderate and severe wear regimes in brake friction materials

Barros, L.Y.; Poletto, Jean Carlos; Buneder, Diogo; Neis, Patric Daniel; Ferreira, Ney Francisco; Pavlak, Rafael Paini; Matozo, Luciano Tedesco

doi:10.1016/j.wear.2019.203112

Cited by 11 publications

(15 citation statements)

References 23 publications

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“…Some studies have focused on metal-matrix brake pads (such as [ 23 ]), designed for high-speed trains or heavy-duty vehicles. Regarding organic matrix brake materials, Barros et al [ 24 ] highlighted the role of contact pressure in the transition to severe wear. Laguna-Camacho et al [ 25 ] studied drum shoes used in real service for eight months in a warm environment and found major cracks that they attributed to fatigue from repeated impacts of the shoe against the drum.…”

Section: Introductionmentioning

confidence: 99%

Differences in Wear and Material Integrity of NAO and Low-Steel Brake Pads under Severe Conditions

et al. 2021

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In this study, through severe reduced-scale braking tests, we investigate the wear and integrity of organic matrix brake pads against gray cast iron (GCI) discs. Two prototype pad materials are designed with the aim of representing a typical non-metal NAO and a low-steel (LS) formulation. The worn surfaces are observed with SEM. The toughness of the pad materials is tested at the raw state and after a heat treatment. During braking, the LS-GCI disc configuration produces heavy wear. The friction parts both keep their macroscopic integrity and wear appears to be homogeneous. The LS pad is mostly covered by a layer of solid oxidized steel. The NAO-GCI disc configuration wears dramatically and cannot reach the end of the test program. The NAO pad suffers many deep cracks. Compacted third body plateaus are scarce and the corresponding disc surface appears to be very heterogeneous. The pad materials both show similar strength at the raw state and similar weakening after heat treatment. However, the NAO material is much more brittle than the LS material in both states, which seems to favor the growth of cracks. The observations of crack faces suggest that long steel fibers in the LS material palliate the brittleness of the matrix, even after heat damage.

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Section: Introductionmentioning

confidence: 99%

Differences in Wear and Material Integrity of NAO and Low-Steel Brake Pads under Severe Conditions

et al. 2021

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“…As mentioned by Sugozo, Mutlu, and Sugozo [ 28 ], the secondary plateaus of the third body are formed on the surface of the brake pads through the accumulation of wear residues of the pad material constituents that are compacted under the effect of normal pressure, tangential stress and heat from friction. As described by Barros et al [ 29 ], tribofilm (friction layer or friction film) forms on the surface of the brake disc. The friction film originates from wear particles generated on the contact surface of the pad with the brake disc.…”

Section: Resultsmentioning

confidence: 99%

Influence of Contact Plateaus Characteristics Formed on the Surface of Brake Friction Materials in Braking Performance through Experimental Tests

et al. 2021

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This work applies a procedure for analysis and characterization of the surface of brake friction materials, correlating them with the tribological and thermal properties achieved in different vehicle braking conditions. Experiments were performed in a vehicle under two real conditions of braking operation, simulated flat track descent and emergency braking. Characteristics of the plates formed on the surfaces of the friction materials were analyzed by scanning electron microscopy (SEM) and correlated with the performance during braking, as measured by the coefficient of friction at the interface of the friction pair and temperature. As a result, the formation of the primary and secondary plateaus in these two different braking operating conditions was observed, and the relationship between the characteristics of the plateaus formed on the surface and the surface roughness parameters and performance measurements during braking.

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“…This BFM has the same composition (Table 1) of the BFM used in an earlier experiment carried out by the current research group. [ 21 ]…”

Section: Methodsmentioning

confidence: 99%

“…More details about this code can found in an earlier study published by the present research group. [21] Besides the quantification of the tribofilm on the disc's surface, the radial homogeneity of the tribofilm along the braking operations was measured. In order to do that, a radial line (Figure 2C) was selected in the image of the friction track.…”

Section: Tribofilm Analysismentioning

confidence: 99%

“…An earlier investigation of the current research group [ 21 ] examined the effects of increasing steps of contact pressure on the transition in wear regime. It was found that a limit pressure (called “LP”) marks a sudden remotion of tribofilm over the disc's surface, and then, leads to the transition in wear regime from moderate to severe.…”

Section: Introductionmentioning

confidence: 99%

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An experimental study of the transition in the wear regime of brake friction materials

et al. 2021

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Brake friction materials (BFMs) are designed to have low wear rate under different conditions of contact pressure, temperature, and sliding velocity. The conditions to ensure a low wear rate (i.e., a moderate wear regime) between the disc and the BFM are not well established. The present article aims to enhance the comprehension about the wear regimes for BFMs. For this purpose, a commercial BFM was slid against a gray cast iron rotor (disc). Tests were performed under different sliding velocities and with both increasing and decreasing steps of pressure levels. Tribofilm formed on the disc's surface and BFM's wear were monitored during the tests. It was possible to conclude that the previous condition of the surface of the disc, with respect to the presence or absence of tribofilm, affects the required conditions for the transition in the wear regime. The removal of tribofilm on the surface of the disc was affected by high contact pressures and high sliding velocities. Those conditions led to a severe wear regime with a destruction of contact plateaus and an increase in friction and BFM's wear.

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Effect of pressure in the transition between moderate and severe wear regimes in brake friction materials

Cited by 11 publications

References 23 publications

Differences in Wear and Material Integrity of NAO and Low-Steel Brake Pads under Severe Conditions

Differences in Wear and Material Integrity of NAO and Low-Steel Brake Pads under Severe Conditions

Influence of Contact Plateaus Characteristics Formed on the Surface of Brake Friction Materials in Braking Performance through Experimental Tests

An experimental study of the transition in the wear regime of brake friction materials

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