Electrical and mechanical properties of nano-structured TiN coatings deposited by vacuum cold spray

Abstract

Titanium nitride (TiN) coatings were fabricated by vacuum cold spray (VCS) process at room temperature with nano-sized starting powder (about 20 nm in size). The microstructure of the powder and coating was examined by scanning electron microscope and X-ray diffraction. The porosity and pore distribution of the VCS TiN coatings were measured by the N2 adsorption-desorption method. The microhardness and fracture toughness of the coatings were evaluated by using the micro-indentation technique. The sheet resistance and electrical resistivity of the coatings were characterized by the four-point probe method. The results show that the sheet resistance of coatings is significantly reduced from 13565 to 127 Ω with increasing the coating thickness. A minimum electrical resistivity of 1.8 × 10−3 Ω m is achieved. The VCS TiN coatings with high porosity ranging from 58.3 to 67.6% exhibit low hardness of 279–490 HV and relatively good fracture toughness of about 3.12 MPa m1/2.