Crack Development of Electroplated NiW Alloys and their Wettability and Tribological properties

This study investigates how sodium tungstate concentration (20–46 wt.%) and current density (40–60 A/dm²) affect the microstructure, wettability, mechanical properties, and tribological behavior of electrodeposited Ni-W coatings. Results show that increasing current density markedly raises crack density (from <100 to >400 cracks/cm²), while tungstate concentration has minimal effect. XRD confirms Ni-W solid solution formation, with higher tungsten content refining grains and increasing hardness—peaking at 900 HV at 50 A/dm² (an 80% rise from 500 HV at 40 A/dm²). However, excessive stress at 60 A/dm² leads to microcracking and hardness plateauing (~650–700 HV). Higher crack density improves wettability (contact angle ~17°), enhancing lubricant retention. Wear tests reveal that coatings with controlled microcrack networks perform better, with wear rates dropping by up to 60% in lubricated conditions. These findings highlight the potential of fine-tuning electroplating conditions to optimize Ni-W coatings as durable, high-performance, and environmentally friendly alternatives to chromium coatings, especially for aerospace, automotive, and industrial applications.