PLASMA SPRAY

The plasma spray process uses inert gas — usually nitrogen or argon — excited by a pulsed DC arc to ionize the gas and produce a state of matter called plasma. Other gasses — mainly hydrogen and helium — are often introduced in small quantity in order to increase the ionization. The plasma gasses are introduced at high volume and high velocity, and are ionized to produce a plume that ranges in temperature from about 12,000° to 30,000° F. Powder feedstock is then injected into this hot gas stream (called a plume), heated very quickly, and deposited onto the work piece.

Characteristics
Plasma is the most versatile of the processes with the ability to spray almost any feedstock in powder form. Extensive experience with this process makes it the one most used at CTS. We spray thousands of pounds of a broad range of materials through our plasma systems. Almost all of these applications are sprayed robotically.

Materials
Materials that are very difficult to melt, such as virtually any ceramic or refractory metal can be used to produce serviceable coatings using the plasma spray process. Plasma coatings are very dense, well bonded structures.

Plasma spray is the most versatile of the thermal spray processes. Excellent coatings of metals, ceramics, cermets, refractory metals, plastics, all can be produced using the plasma process. Of all the potential coating choices, plasma is best suited to apply ceramic coatings because of their high melting temperature.

Plasma spray is especially effective in applying hard to melt materials like refractory metals and ceramics although it is certainly possible to apply the other classes of materials such as metals, alloys, and plastics using plasma. The extremely high temperatures and gas velocities second only to HVOF produce well bonded dense coatings of the broadest range of materials of any of the processes.