Prakt. Met. Sonderband 30 (1999) 373 
“ation of 
the tg 
Wer 
g 
Ay: 
lc valugs, 
of the 
1 Substrate 
eed sel, AT 
po Fig. 6: SEM, BSE image of Ti(C,N) coating perforation on 9-2-2+Si+Ti 
srligt high - speed steel due to erosion test after 48 s of test performance 
k mission Ti(C,N) coatings the failure process begins selectively, e.g., in pits from where the drop shaped Ti 
the costing, microparticles fell out (Fig. 5). This process commences in many locations simultaneously, developing 
is. obtained later on into failure isles, which join forming larger zones, to develop finally an entire crater getting 
de on the uniformly deeper only after total perforation of the coating. Such mechanism decides mostly the 
oop to significant increase of the erosion resistance of the surface of the high-speed steels coated in the PVD 
the failure process. Erosion resistance of the steel with the PVD coatings is about three times higher than of the 
the increase high-speed steel heat treated in conditions ensuring their maximum secondary hardness. Coating type 
herence 0° decides this increase value. To evaluate the erosion failure newly developed method was employed 
s good. This employing the computer image analysis on the scanning electron microscope, consisting in 
25 and about SI measurement of the fraction of the damaged coating area 
load begs Ol during the erosion test in the appropriately selected 
ottom of the = 9-2-2+Si+Ti measurement field (Fig. 6, 7). This makes it possible to 
. sometimes 0 eliminate the incorrect evaluation of the erosion rate 
with coat” consisting in measurement of the mass loss, these 
MT 1 40f yey) | Measurements conform to the test results based on 
nce of ws 30} measurement of the mass loss. Experiments carried out 
of coats confirm the practical usefulness of the new methodology 
need steel 20} employing the computer image analysis on the scanning 
; o} electron microscope for evaluation of the erosion 
resistance. 
SL _ 
0 6 12 18 24 30 36 42 48 
EXPOSURE TIME, s 4. Final remarks 
Fig. 7: Comparison of erosion resistance 1. The investigated TiN and Ti(C,N) coatings 
of TiN and Ti(C,N) coatings deposited demonstrate the columnar structure with a clear axial 
on 2-2-2+Si+Ti high-speed steel texture {111} and chemical composition indicating to 
occurrences of the secondary solid solutions. Surface of 
the coatings is rough, with the solidified drops of 
titanium deposited directly onto the substrate or on the previously originated coating fragments. 
Some pits were observed that originated due to falling out of some of the titanium drops 
immediately after ending the PVD process. 
2. TiN and Ti(C,N) coatings demonstrate good adherence to substrates from high-speed steels, 
which is decided not only by adhesion, but also by mixing of elements in the transition zone 
between the coating and substrate, caused by diffusion or connected with ion implantation, and the