This study deals with experimental and theoretical investigations of prehea
ting of the particles injected into a flame during the process of atmospher
ic plasma spraying (APS). Prior to the injection in the flame, the particle
s, delivered from the powder feeder, were heated in a carrier gas. The expe
rimental devices to preheat the carrier gas, based on a principle of linear
, superficial, and volume heating are discussed. The particle velocity and
temperature in the pipeline connected to a preheating device were estimated
theoretically using a simple analytical model. Two types of preheating dev
ices were submitted to preliminary tests. The temperature of the carrier ga
s was measured using a thermocouple for a volumetric device working with a
gliding are discharge. The microstructure and properties of chromium oxide
coatings plasma sprayed with the aid of a superficial preheating device are
also presented and discussed.