Influence of heat treatment temperature on structure and exothermic properties of electroless Ni–]P plating carbon fiber heating elements

In this work, the heating performances of electroless Ni–]P plated carbon fibers (MCF) at different heat treatment temperatures (300, 400, 500, and 700 °C) were investigated using an infrared thermal imaging camera. From the experimental results, we found that the MCF was a mixture of microcrystalline and amorphous phases, as indicated by XRD. In addition to the stable Ni, Ni ₃ P, and NiO phases, the metastable Ni ₅ P phase was also observed although the amount was small. A higher heat treatment temperature of 400 °C resulted in the growth of Ni and Ni ₃ P phases indicated by the stronger peak intensity. However, the specific resistance increased as the heat treatment temperature increased above 400 °C. Accordingly, the performance of heat-treated MCF as electrical heating elements was strongly dependent on the surface structure of the MCF as well as the heat treatment temperature. The MCF exhibited a low electrical heating temperature (31.0 °C), while MCF-H400 exhibited an excellent electrical heating temperature (102.0 °C) along with rapid temperature response and high heat output to maintain a maximum temperature at a given applied voltage.