Radio frequency inductively coupled plasma (RF-ICP) torch

A method of making processed particles, characterizes as solid, smooth, spherical and dense particles from unprocessed solid particles, characterized as irregularly shaped particles, comprising the steps of:

• a) generating a plasma by a conical inductively coupled plasma torch, having a torch tube that has a first end and a second end and an internal surface comprising of a cylindrical section extending from the first end, and a conical section extending from an end of the cylindrical section to the second end;
• the conical torch further has an injector tube having an inner diameter to form an inner gas flow path and a conical end with an outer surface having a cone angle α to form an annular gap with a gap size d, with the conical section of the torch tube to form an outer gas flow path, wherein the conical torch generates a plasma with high power density having a rapidly increasing temperature zone;
• b) injecting unprocessed solid particles into the inner gas flow path together with a carrier plasma gas, wherein the unprocessed solid particles are carried and injected into the plasma;
• c) rapidly melting unprocessed solid particles inside the plasma and generating spherical molten particles by capillary and surface tension forces of the molten particles, and
• d) cooling the spherical molten particles to form the solid, smooth, spherical and dense particles.

A plasma spray method for turning a given material into a partially or fully molten drops and depositing them on a given substrate, comprising the steps of:

• a) generating an inductively coupled plasma discharge by means of a conical torch having a torch tube that has a first end and a second end and an internal surface comprising of a cylindrical section extending from the first end, and a conical section extending from an end of the cylindrical section to the second end;
• the conical torch further has an injector tube having an inner diameter to form an inner gas flow path and a conical end with an outer surface having a cone angle α to form an annular gap with a gap size, d, with the conical section of the torch tube to form an outer gas flow path wherein the conical torch generates a plasma with high power density having a rapidly increasing temperature zone;
• b) injecting the given material into the plasma discharge, by way of suspending the given material in particle form in a liquid carrier creating a suspension;
• c) evaporating the liquid carrier liquid and desolvating the suspension by means of said plasma discharge and agglomerating the given material particles into the partially or fully molten drops, or injecting the given material into the plasma discharge in the form of a powder, a rod, or a wire, and
• d) turning the injected powder, rod, or wire material into partially or fully molten drops by means of the plasma discharge,
• whereby a higher power density of the plasma discharge due to the conical geometry melts a greater portion of the injected material and leads to a denser, more uniform coating with improved mechanical properties.

A powder production process by atomization and melting of a given material, comprising:

• a) generating an inductively coupled plasma discharge by means of a conical torch having a torch tube that has a first end and a second end and an internal surface comprising of a cylindrical section extending from the first end, and a conical section extending from an end of the cylindrical section to the second end;
• the conical torch further has an injector tube having an inner diameter to form an inner gas flow path and a conical end with an outer surface having a cone angle α to form an annular gap with a gap size, d, with the conical section of the torch tube to form an outer gas flow path wherein the conical torch generates a plasma with high power density having a rapidly increasing temperature zone;
• b) feeding the given material in the form of wire, rod, raw powder, or suspension into the plasma discharge to be melted or evaporated by the heat generated by the plasma;
• c) atomizing the molten material by the plasma discharge to form small droplets which then exit the second portion of the tubular component, followed by a process to cool down the droplets, solidify them into power particles, and
• d) collecting the cooled, solidified powder particles by a powder collector placed in front of the second portion of the tubular component,
• whereby a higher power density of the plasma discharge due to the conical geometry melts a greater portion of the injected material and leads to higher powder output, and whereby the higher power density of the plasma discharge allows for reduction of plasma power, without affecting the performance of the torch, to save electrical energy and reduce operation costs.

A powder spheroidization method, comprising:

• a) generating an inductively coupled plasma discharge by means of a conical torch having a torch tube that has a first end and a second end and an internal surface comprising of a cylindrical section extending from the first end, and a conical section extending from an end of the cylindrical section to the second end;
• the conical torch further has an injector tube having an inner diameter to form an inner gas flow path and a conical end with an outer surface having a cone angle α to form an annular gap with a gap size d, with the conical section of the torch tube to form an outer gas flow path wherein the conical torch generates a plasma with high power density having a rapidly increasing temperature zone;
• b) injecting powder of a given material having crushed, non-spherical, or non-uniform particles into the said plasma discharge to be at least partially molten or fully molten by the plasma discharge, wherein the molten particles then assuming a spherical shape due to surface tension forces, and
• c) cooling the said spherical molten particles to re-solidify and collecting the solidified particles,
• whereby a higher power density of the plasma discharge due to the conical geometry melts a greater portion of the injected material and leads to higher throughput, and whereby the higher power density of the plasma discharge allows for reduction of plasma power, without affecting the performance of the torch, to save electrical energy and reduce operation costs.