HVOF-GUN ATTACHMENT*

High velocity oxy-fuel process (HVOF) has been demonstrated to be one of the most efficient techniques to deposit high performance coatings at moderate cost. Although the HVOF process has shown to be technologically advanced to other thermal spray processes, the unique gun design makes a significant improvement on the final casting quality.
*US. Patent 6,845,929

HVOF-gun attachment configuration:(a) Diverging, (b) diverging-Converging

Simulent HVOF-Gun Attachment improves gun performance by:

• Reducing in-flight metal particle oxidation
• Reducing particle trajectory deviation

Experimental and numerical results performed at The Centre for Advanced Coating Technologies of the University of Toronto shows that the HVOF-gun attachment reduces or eliminates the shock diamonds associated with the standard HVOF nozzles so that the gas flow has a smoother transition from supersonic to subsonic flow.

The HVOF-gun attachment is able to prevent the penetration of the ambient air into the main spray flow and reduce in-flight oxidation of particles.

The attachment provides a favorable particle spatial distribution, as well as higher and more uniform particle velocity and temperature. These improvements enable us to spray dense Al2O3 coating with porosity less than 2%.

The pneumatic droplet generator can produce small, uniform droplets from a wide range of liquids and molten materials. It is simple to use, robust and particularly well suited for high- temperature applications requiring accurate dispensing or production of individual droplets on demand.
^{*US Patent 6446878}

TECHNOLOGY ADVANTAGES

• Controlled ejection of individual droplets on demand;
• Device is simple and easily operated;
• Wide range of drop sizes;
• No moving parts in contact with liquid;
• Easily cleaned;
• Multiple nozzle capability;
• No theoretical temperature limitations allows for use of high melting point materials and sterilization procedures

POTENTIAL APPLICATIONS

• Research
• Droplet dynamics
• Spray coating
• Droplet combustion
• Calibration of particle size measuring device
• Solder deposition on circuit boards
• Precise dispensing of adhesives, pharmaceuticals and other materials
• Manufacture of uniform sized metallic particles
• Specialized ink-jet printing