Plasma spraying process was performed using a SG-100 torch
(Praxair S.T., Indianapolis, In, USA) installed on a 5-axis IRB-6 robot
of ABB (Zürich, Switzerland). The working gas mixture of Ar + H2
(45+5 slpm) and electric power of 40kWwere used. The experiments
were made using 2k (k=2) full factorial design, where the variable parameters
were robot scan speed (from 300 mm/s and 500 mm/s) and
spray distance (from 40 mm and 60 mm). The suspension feed rate
was of about 39 g/min. The suspension was introduced via internal injectionmode
using a continuous-stream injector (with an internal diameter
of 0.5 mm) installed inside the anode-nozzle of the plasma torch.
The suspension spraying was performed in order to obtain coatings
with a thickness up to 70 μm. The operational spray parameters are
collected in Table 1.