Plasma technology has been applied in the dissociation of raw zircon since the mid-1960s [1, 2]. When zircon is passed through the plasma flame, dissociation of the feedstock into ZrO2 crystals and SiO2 glass takes place. Plasma-dissociated zircon (PDZ) has attractive applications in ceramic colouring, refractory as well as the preparation of fine ZrO2 crystals [3, 4]. Previous studies have shown that quenching rates and particle size of the zircon feedstock affect the microstructure and phase composition of PDZ [5, 6]. The proportion of tetragonal ZrO2 in PDZ increases with decreasing initial zircon particle size and increasing cooling rate. This letter reports the preparation of fine dissociated zircon powders (average particle size ,10 im) by the plasma-spray atomization process. The plasma-spray atomization process involves primarily the melting of a coarse feedstock (metal and=or ceramic) in the plasma flame and the rapid projection of the liquid droplets towards a solid rotating substrate. Fragmentation of the molten droplets at the surface of the solid rotating substrate yields fine particles with rapid solidification (RS) microstructures. This method has been applied to the production of fine stainless steel (AISI 316), yttriastabilized zirconia (ZrO2 –7 wt % Y2O3), Al–Si, Al– Ni and metal matrix composite powder [7–9]. The PSA system consists of a 40 kW direct current (d.c.) plasma-spray torch and a double-wall stainless steel chamber that houses the rotating substrate (Fig. 1). The plasma-spray gun is the SG100 from Miller Thermal Inc., USA. It features interchangeable water-cooled, self-aligning electrodes. The primary arc gas is argon while the secondary gas is helium. A closed-loop computerized rotor wheel powder feeder aids the introduction of the powders to plasma torch. The powder hopper is mounted on an electronic scale where the weight of the powder is continuously weighed. The feed rate is calculated from the weight loss with time. The driving mechanism for the rotating substrate is mounted on top of the chamber while the plasma gun is fixed on to a steel bar holder that is welded to the bottom of the base-plate of the chamber. The speed of the motor is controlled by a frequency inverter. A pulse width modulation (PWM) variablespeed controller is used to adjust the speed of the motor. The operating speed ranges from 0–3000 r.p.m. A more detailed description of the powder production system was reported in an earlier work [10]. Table I lists a set of typical process parameters in a PSA operation. The raw zircon sand from India was sieved into three groups: ,106 im, ,75 im and 50–75 im. Table II lists the mean particle size of the powders. Some samples were plasma sprayed directly into distilled water to examine the as-sprayed morphology and structure. Table III specifies the changes made in the process parameters. This includes changes in powder feed rate and the distance between the plasma torch and the rotating substrate. Phase analysis of the processed powders was performed by an X-ray diffractometer (Philips MPD 1880) using CuKAE radiation. The relative proportion of tetraganol ZrO2 in dissociated zircon was determined from the formula based on the work by Garvie and Nicholson [11]