Silica coated titanium using Laser Engineered Net Shaping for enhanced wear resistance

Abstract

Laser Engineered Net Shaping (LENS™) was utilized to create novel silica (SiO2) coatings onto commercially-pure titanium (Cp-Ti). It was hypothesized that if silica could be deposited as a coating via laser surface engineering, high hardness and wear resistance could be added to existing Cp-Ti material. Post-deposition heat-treatments in the form of laser passes (LP) and a furnace residual-stress relief were completed on the coatings and mechanical/material properties were subsequently evaluated. Titanium silicide (Ti5Si3) formation and related dendritic microstructures were identified throughout the coating by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopic (SEM) analysis, and appeared more ordered after stress-relief heat treatment. High hardness values of approximately 1500 HV were measured at the coating’s topmost surface while specific wear rates showed a maximum 98% reduction from 346.2 × 10−6 mm3/N-m in the Cp-Ti substrate to 7.1 × 10−6 mm3/N-m in the heat treated 1 LP coating. In situ tribofilm formation was observed during wear, which indicated self-healing properties from the material and likely aided further in wear reduction. Our results show that silica coating on titanium via laser surface engineering could be used as a suitable manufacturing practice to create hard, Ti5Si3-reinforced ceramic coatings with high wear resistance and self-healing properties for applications ranging from biomedical to aerospace.