Nozzle-substrate Distance Research Articles

Reaction kinetics of the formation of indium tin oxide films grown by spray pyrolysis

The electrical and optical properties of sprayed indium tin oxide (ITO) films have been reported as a function of tin concentration, substrate temperature T s and the substrate-nozzle distance D sn · D sn and T s seem to be interrelated for the optimization of good quality ITO films. Highly conduction (3 × 10 5 ohm −1m −1) and transparent (90% in visible region) ITO films were obtained when D sn = 0.3 m, T s = 693 K with 5% by weight of SnCl 4 in the starting material. These data are discussed in the light of reaction kinetics.

Electrical and optical properties of pyrolytically sprayed SnO 2 film—Dependence on substrate temperature and substrate-nozzle distance

The dependence of electrical and optical properties of SnO 2 films, prepared using the spray pyrolysis technique, on the substrate temperature and substrate-nozzle distance was studied. A 0.05 cm diameter spray nozzle was employed ( 1 4 JAU, Spraying Systems Inc., U.S.A.). Films of about 10 −3 Ω cm resistivity and high visible transparency of about 90% were obtained at a substrate temperature of 400°C and a substrate-nozzle distance of 30 cm. It has been observed that substrate-nozzle distance plays an important role in the reaction kinetics of SnO 2 films. At a substrate-nozzle distance greater than 30 cm, the homogeneous reaction enhances and hence impedes the growth rate, resulting in inferior electrical and optical properties of the films.

The influence of surface preparation on the bond strength of flame-sprayed aluminium coatings on mild steel

The bond strength of sprayed-aluminium coatings on grit blasted steel substrates was shown to be highly dependent on surface preparation. Type and condition of the grit and the angle of blasting markedly influenced bond strength but variations of blasting pressure, blasting speed, and nozzle–substrate distance had no effect. With chilled iron angular grit, failure occurred mainly at the sprayed metal–substrate interface. The level of bond strength was reduced when blunted grit or low blasting angles were used. With alumina grit the bond strength was increased and the failure location moved from the interface to within the spray coating. Examination of grit blasted surfaces with the scanning-electron microscope gave an indication of the cause of the above behavior in terms of surface roughness and surface debris. The work indicates that bonding between flame-sprayed aluminium and steel substrates is of a mechanical rather than metallurgical nature. From the technological viewpoint, the importance of grit condition and blasting angle can be seen and simple rules of surface preparation formulated.