Insights into arc-assisted self-propagating high temperature synthesis of TiB2-TiC ceramic coating via wire-arc deposition

TiB₂-TiC ceramic coating was fabricated by wire-arc deposition of Ti-B₄C cored wire in conjunction with self-propagating high temperature synthesis (SHS) technology, to enhance the hardness and wear resistance of Ti. Results showed that a periodic combustion reaction, triggered by the capillary infiltration of molten Ti sheath into the inside B₄C particles, occurred as the wire entered the arc zone. During combustion reaction, B₄C experienced the course of dissolution as well as the transformation of decarbonization expressed as B₄C→B₁₃C₂→B₁₃C_{x(1.27. In particular, the loss of C was more notable at combustion front region. The as-synthesized coating exhibited ultralow porosity thanks to the elevated adiabatic temperature, and possessed gradient microstructures formed due to the dissolution-precipitation mechanism. Mechanical and tribological tests showed that the coating had ultrahigh microhardness (2140 HV0.5, close to theorical value) and low wear rate (5.5×10⁻³ mm⁻³ min^-1·N^-1). The superior performance was attributed to ultralow porosity and high-strength coherent TiB2/TiC interface.}