Some amorphous Fe-Cr-P-C coating films having high hardness and high corrosion resistance have been produced by a newly developed thermal spraying technique. In order to control the temperatures of the powder particles in the flame spray and the substrate, a newly developed cylindrical nozzle, with external cooling nitrogen gas, was mounted to the front end of the thermal spraying gun. Fe 70 Cr 10 P 13 C 7 films with various external cooling gas velocities between 20 m/s and 40 m/s exhibited entire amorphous structure without oxides and/or unmelted particles. Corrosion-resistance of the films was observed in immersion tests using various corrosive liquids. An amorphous film was formed on the surface of the shaft sleeve of the slurry pump by using the cylindrical nozzle. This shaft sleeve was installed in the slurry pump of chemical fertilizer maker's production line and the life test was done under the real operation condition for two months.

High chromium Fe-Cr-Mo-P-C amorphous coating films containing up to about 35 at% Cr having high hardness and high corrosion resistance have been produced by a newly developed thermal spraying technique. In order to control the temperatures of the powder particles in the flame spray and the substrate, a cylindrical nozzle, with external cooling nitrogen gas, was mounted to the front end of the thermal spraying gun. Fe 70 Cr 10 P 13 C 7 and Fe 38 Cr 35 Mo 7 P 13 C 7 films with various external cooling gas velocities between 20 m/s and 40 m/s exhibited entire amorphous structure without oxides and/or unmelted powder particles. High corrosion-resistance of the Fe 38 Cr 35 Mo 7 P 13 C 7 amorphous coating film was observed in immersion tests using 35% hydrochloric acid.

The influence of the substrate temperature on the structure, the pore distribution, and the adhesion strength of Fe-10Cr-based amorphous coating films has been examined. The amorphous coating films have been produced by a thermal spraying technique using our developed cylindrical nozzle on SS400 substrates. The splat morphology of the sprayed particles changed drastically from an irregular splash shape to a disk shape at a transition temperature of about 325°C. When the substrate temperature increased to the transition temperature region, between 325 and 350°C, the porosity in the boundary regions between the sprayed coating films and the substrates drastically decreased to about 6%, which may be due to the drastic increase in the wettability of the sprayed particles accompanied with the change of morphology from the splashed shape to the disk shape. When the substrate temperature increased from the transition temperature of 325°C up to 400°C, the porosity decreased gradually, and the volume fraction of the amorphous phase increased with increasing substrate temperature, resulting in an increase in the adhesion strength up to about 15 MPa.

The influence of the substrate temperature on the structure, pore distribution and cohesive/adhesive strength of FeCo-based metallic glass coating films has been examined. The metallic glass coating films have been produced by a thermal spraying technique using our developed cylindrical nozzle on SS400 substrates. The splat morphology of the sprayed particles changed from an irregular splash to a disk shape at a transition temperature of about 300°C. When the substrate temperature increased to the transition temperature region (300323°C), the porosity in the boundaries between the sprayed coating films and the substrates decreased. This can be produced by the strong increase in the wettability of the sprayed particles which is accompanied with a morphological change from splashed to disk-shaped particles. At temperatures ranging from 375 to 400°C, the porosity in both the boundary and inside regions decreased, and the volume fraction of the amorphous phase increased with temperature, resulting in a increase in the cohesive/adhesive strength up to about 27 MPa.

Some amorphous Fe-Cr-P-C coating films having high hardness and high corrosion resistance have been produced by a newly developed thermal spraying technique. In order to control the temperatures of the powder particles in the flame spray and the substrate, a newly developed cylindrical nozzle, with external cooling nitrogen gas, was mounted to the front end of the thermal spray gun. Fe70Cr10P13C7 films with various external cooling gas velocities between 20 m/s and 40 m/s exhibited entire amorphous structure without oxides and/or unmelted particles. Corrosion-resistance of the films was observed in immersion tests using various corrosive liquids.