• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.330-336
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• 1998

The friction and wear characteristics of automotive friction materials reinforced with carbon fibers were studied using a direct drive brake dynamometer. Two types of model friction materials, a low-metallic and an NAO type, were prepared and each of the materials was modified by substituting 5 vol% of carbon fibers with other reinforcing fiber used in the model formulations. Drag tests were carried out to investigate the friction properties of these materials at various braking conditions. Results showed that the modified friction materials were improved in the friction stability and the wear resistance.

• Particle and aerosol research
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• v.19 no.2
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• pp.31-42
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• 2023

The charge and magnetic characteristics of LM (Low-metallic) and NAO (Non-asbestos-organic) brake wear particles were analyzed. The ratio of charged particles from total particles is about 86% of the LM pad and about 92% of the NAO pad. Number of charge per particle from the NAO pad is also higher than that of the LM pad. The ratio of magnetic particles from total particles increases with the particle size. The ratio of magnetic particles from the LM pad is about 15% for the particles with the size of 1 ㎛, and about 74% for ones with 5 ㎛. The ratio from the NAO pad is about 5% for the particles with the size from 0.5 ㎛ to 2 ㎛, and about 80% for the particles with 5 ㎛. Through the analysis of the components of the two pads with SEM-EDS (Scanning Electron Microscopy - Energy Dispersive X-ray Spectroscopy), it was found that the LM pad was occupied with more iron fraction than the NAO pad and that PM_2.5-10 was occupied with more iron fraction than PM_2.5. The particles smaller than 10 ㎛ (i.e. PM₁₀) from the LM pad contained about 83% of charged particles, about 43% of magnetic particles, and about 93% of charged or magnetic particles. PM₁₀ from the NAO pad contained about 88% of charged particles, about 15% of magnetic particles, and about 89% of charged or magnetic particles.

• Tribology and Lubricants
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• v.17 no.4
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• pp.267-275
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• 2001

Friction and wear properties of brake friction materials containing different metal fibers (Al, Cu or Steel fibers) were investigated. Based on a simple experimental formulation, friction materials with the same amount of metal fibers were tested using a pad-on-disk type friction tester. Two different materials (gray cast iron and aluminum metal matrix composite (MMC)) were used for disks rubbing against the friction materials. Results front ambient temperature tests revealed that the friction material containing Cu fibers sliding against gray cast iron disk showed a distinct negative $\mu$-v (friction coefficient vs. sliding velocity) relation implying possible stick-slip generation at low speeds. The negative $\mu$- v relation was not observed when the Cu-containing friction materials were rubbed against the Al-MMC counter surface. Elevated temperature tests showed that the friction level and the intensity of friction force oscillation were strongly affected by the thermal conductivity and melting temperature of metallic ingredients of the friction couple. Friction materials slid against cast iron disks exhibited higher friction coefficients than Al-MMC (metal matrix composite) disks during high temperature tests. On the other hand, high temperature test results suggested that copper fibers in the friction material improved fade resistance and that steel fibers were not compatible with Al-MMC disks showing severe material transfer and erratic friction behavior during sliding at elevated temperatures.