Effect of the degree of melting of zirconium dioxide on its adhesion in plasma spraying

Conclusions

• 1. The adhesion of sprayed coatings depends to a large extent on the degree of particle fusion.

• 2. An indirect, qualitative evaluation of the degree of particle fusion can be made by examining the appearance of particles collected in water and the character of deformation of particles sprayed onto glass. The greater the number of spherical particles in a sample sprayed into water and the more developed the surface of particles sprayed onto glass, the higher is the degree of particle fusion and, consequently, the stronger is the adhesion to the substrate.

• 3. The adhesion and thermal-shock resistance of a deposit increase with increasing size of the heat-exchange zone in the torch nozzle with increasing arc power, and with decreasing distance from the substrate. For 1Kh18N9T steel substrates, the minimum distance from the nozzle orifice is 70 and 45 mm for uncooled and cooled surfaces, respectively.