Development and Performance Evaluation of Dual Microcapsule-based Self-healing Polymeric–Carbon Composites for DC Motor Brushes
Keywords:
Autonomous repair materials, Carbon nanotubes (CNTs), Conductive composites, DC motor brushes, Dual microcapsule system, Electrical conductivity recovery, Electrical contact materials, Epoxy-amine healing mechanism, Microcapsule-based healing, Polymeric–carbon composite, Self-healing composites, Wear resistanceAbstract
The durability and performance of DC motor brushes are critically limited by friction-induced wear, electrical degradation, and microstructural damage during operation. This study presents the development and performance evaluation of a dual microcapsule-based self-healing polymeric-carbon composite designed to enhance the operational lifespan and reliability of DC motor brushes. The composite integrates conductive carbon fillers, including graphite, carbon black, and carbon nanotubes (CNTs), within an epoxy polymer matrix embedded with two distinct types of microcapsules containing epoxy resin and amine hardener, respectively. Upon mechanical damage, the rupture of microcapsules enables in-situ mixing and polymerization, resulting in autonomous crack repair and restoration of conductive pathways. Experimental investigations were conducted under varying load conditions to evaluate electrical resistivity, contact voltage drop, wear rate, and healing efficiency. The results demonstrate a significant reduction in wear rate (up to ~45%), improved electrical stability, and recovery of up to 88% of initial conductivity after damage. Scanning electron microscopy (SEM) analysis confirms effective crack closure and microstructural restoration. The proposed dual microcapsule system exhibits superior healing performance compared to conventional single-capsule approaches, providing a promising solution for advanced self-healing electrical contact materials in DC motor applications.
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