Cold gas spray gun
A cold gas spray gun is disclosed. The spray gun includes a high-pressure gas heater which has a pressure vessel through which gas flows and a heating element situated in the pressure vessel, as well as a mixing chamber in which particles can be admixed with the gas through a particle feed. A Laval nozzle is arranged downstream in the direction of flow of the gas and consists of a convergent section, a nozzle throat and a divergent section. The high-pressure gas heater and/or the mixing chamber is/are at least partially insulated on the inside in the areas of contact with the gas.
1. A cold gas spray gun, comprising:
a high-pressure gas heater with a pressure vessel through which a gas flows and a heating element situated in the pressure vessel;
a mixing chamber in which particles are supplied to the gas through a particle feed; and
a Laval nozzle consisting of a convergent section, a nozzle throat, and a divergent section;
wherein the high-pressure gas heater, the mixing chamber, and the Laval nozzle are arranged in succession in a direction of flow of the gas in the cold gas spray gun and wherein the high-pressure gas heater and the mixing chamber are at least partially insulated on an inside in an area of contact with the gas.
2. The cold gas spray gun as claimed in claim 1 , wherein the pressure vessel of the high-pressure gas heater and/or the mixing chamber is/are lined with an insulation consisting of solid or flexible ceramic insulation material.
3. The cold gas spray gun as claimed in claim 1 , wherein the high-pressure gas heater, the mixing chamber and the Laval nozzle are aligned linearly and concentrically with one another.
4. The cold gas spray gun as claimed in claim 1 , wherein the direction of flow of the gas between the high-pressure gas heater and the mixing chamber is deflected by an angle of up to 60 ° in relation to one another.
5. The cold gas spray gun as claimed in claim 1 , wherein the mixing chamber forms the convergent section of the Laval nozzle.
6. The cold gas spray gun as claimed in claim 1 , wherein the convergent section of the Laval nozzle has a length between 50 and 250 mm and a conical, inside contour.
7. The cold gas spray gun as claimed in claim 1 , wherein the convergent nozzle section is insulated on an inside of the convergent nozzle or is made entirely of an insulating material.
8. The cold gas spray gun as claimed in claim 1 , wherein the pressure vessel and/or the mixing chamber and/or the convergent section and/or the divergent section is/are made entirely or partially of titanium, aluminum, or alloys thereof.
9. The cold gas spray gun as claimed in claim 1 , wherein a distance between a particle feed in the mixing chamber and the nozzle throat amounts to 40 mm to 400 mm.
10. The cold gas spray gun as claimed in claim 9 , wherein for at least 70% of the distance from the particle feed to the nozzle throat, a flow cross-section of the mixing chamber and/or the convergent section amounts to between 5 times and 50 times a nozzle throat cross-sectional area.
11. The cold gas spray gun as claimed in claim 1 , wherein the nozzle throat has a diameter of between 2 and 4 mm, the divergent section has a length corresponding to 30 to 90 times the diameter of the nozzle throat and an area ratio of a cross-section at an end of the divergent section to that of a nozzle throat cross-section is between 3 and 15.
12. The cold gas spray gun as claimed in claim 1 , wherein a particle feed consists of a tube supplied laterally at any angle.
13. The cold gas spray gun as claimed in claim 1 , wherein a heating power of the heating element, based on a flow cross-section in the nozzle throat, amounts to 1.5 to 7.5 kW/mm 2 .
14. The cold gas spray gun as claimed in claim 1 , wherein a power per unit of volume of the heating element amounts to 10 to 40 MW/m 3 .