Effect of duty ratio on the performance of pulsed electrodeposition Ni–P–Al2O3–PTFE nanocomposite coatings

Influence of Duty Cycle on the Phosphorus Content and Hardness of the Ni-P Coatings Produced by Pulse-Current Electroplating

“…At lower duty cycles, the off-time duration becomes longer than the on-time duration, potentially allowing for an accumulation of phosphorus to occur. Our findings are consistent with reports by Y. Li et al [9] and K.-H. Hou et al [10]. Figure 4 illustrates the influence of the duty cycle on the phosphorus content and the hardness of the Ni-P coating layers.…”

“…In this high P regime, diffuse hardening diminishes, resulting in decreased hardness [12][13][14]. This work is consistent with reports by Y. Li et al [9], K.-H. Hou et al [10], and H.-H. Sheu et al [15], which demonstrate the decrease in microhardness of Ni-P coatings as the phosphorus content increases. Table 1 summarizes the thickness, phosphorus content, and hardness of Ni-P coatings produced at different duty cycles.…”

“…The phosphorus content ranging from approximately 13 wt.% to 18 wt.% observed in this study is considered to be in the high phosphorus regime. According to Y. Li et al [9], Ni-P coatings with P content higher than 8 wt.% might exhibit reduced hardness values due to the reverse Hall-Petch effect, where smaller grains result in lower hardness. P is typically regarded as a "grain refiner" in the Ni-P system, leading to excessively small grain sizes at high P content.…”