Structure and phase formation of ion-plasma vacuum-arc Zr-B-Si-C-Ti-(N) coatings during deposition

Zr-B-Si-C-Ti-N and Zr-B-Si-C-Ti coating systems were produced by arc-PVD technique. For their deposition, a combined titanium cathode with a ZrB2-SiC insert was used. Deposition was carried out in a residual atmosphere of N2 and Ar. Coatings structure and composition were investigated. The Zr-B-Si-C-Ti coating is characterized by an amorphous-nanocrystalline structure. In this case, nanocrystallites were formed from complex (Zr, Ti) C, and the amorphous structure fraction is formed mainly by phases based on zirconium and silicon. The second system, deposited in a nitrogen residual atmosphere, Zr-B-Si-C-Ti-N, has a predominantly amorphous structure. Such a structure is formed mainly from borides, nitrides, carbides and complex compounds of zirconium, silicon and titanium.

Effect of Iron Content on Corrosion Properties of Pure Titanium as Grain Refiner

Microstructures and corrosion properties of pure titanium were characterized when iron was used as a grain refiner. The added Fe element acted as a strong grain refiner for pure titanium by forming β Ti phase at grain boundaries, and 0.15 wt% Fe was revealed to be a sufficient amount to make the grain size of pure titanium below 20 μm, which was the requirement for the desired titanium cathode. However, corrosion resistance was decreased with the Fe amount added. From the open circuit potential (OCP) results, it was obvious that the TiO2 stability against the reducing acid environment was deteriorated with the Fe amount, which seemed to be the main reason for the decreased corrosion resistance. Electrochemical impedance spectroscopy (EIS) results showed that both the decrease in the compact oxide film’s resistance (Rb) and the appearance of the outer porous film occurred as a result of the dissolution of the TiO2 layer, whose phenomena became more apparent as more Fe was added.