Improvement of erosion resistance of titanium with different surface treatments

To improve the erosion resistance of titanium, several surface treatment me thods were applied: (1) duplex treatment with carbon nitride film deposited on a plasma-nitrided layer, (2) diamond coating, and (3) laser alloying, D uplex treatment could improve the erosion resistance of titanium under a lo w impact velocity of erosion particles. However, under a high velocity of e rosion particles, because of the shallow depth of the plasma-nitrided layer and low load-bearing capacity of carbon nitride layer on the plasma-nitrid ed specimen, the improvement of erosion resistance was not significant. Dia mond coatings with a thickness of 15 mum made no significant improvement on the erosion resistance of the titanium substrate. The large-area spallatio n of diamond coating during erasion was observed, probably due to the high residual stresses, poor load-bearing capacity, and brittle nature of diamon d coatings. Compared with untreated Ti substrate, the erosion resistance of the laser-alloyed (nitrided) specimen was improved significantly. The eros ion mechanisms for laser-nitrided titanium were characterized by chipping, brittle fracture, and formation of large flakes in the laser-nitrided layer s.