Abstract: A plasma spray nozzle system for uniform injection of feedstock into a plasma stream. A plasma nozzle is provided, having a bore with an axis, the bore shaped for the passage of a plasma stream. An annular plenum chamber is provided coaxial with and substantially surrounding the bore. A plurality of feedstock injection passages extend from the plenum chamber and converge towards the plasma stream. The plenum chamber is supplied continuously with feedstock material from an outside source. The feedstock is distributed throughout the plenum chamber volume and is exhausted into the plasma stream via the plurality of feedstock injection passages. By selecting an appropriate number of feedstock injection passages a more uniform and symmetrical loading with feedstock of the plasma stream is achieved.

Abstract: A feedstock injector for connection to a source of heated gas comprises a converging channel extending from the upstream end to the downstream end of the injector. A splitting arm extends diagonally within the converging channel, the splitting arm comprising two symmetrically opposed surfaces extending from the inlet to the outlet ends of the converging channel. A feedstock injection passage opens axially at the downstream end of the splitting arm. The gas stream discharged by the injector contacts and entrains the feedstock with improved uniformity.

Abstract: A feedstock injector for connection to a source of heated gas comprises a converging channel extending from the upstream end to the downstream end of the injector. A splitting arm extends diagonally within the converging channel, the splitting arm comprising two symmetrically opposed surfaces extending from the inlet to the outlet ends of the converging channel. A feedstock injection passage opens axially at the downstream end of the splitting arm. The gas stream discharged by the injector contacts and entrains the feedstock with improved uniformity.

Abstract: A feedstock injector for connection to a source of heated gas comprises a first plurality of channels arranged symmetrically about a longitudinal axis, the channels leading from the upstream end to an intermediate region of the injector. A second plurality of channels, coaxial with the first plurality of channels and arranged symmetrically about the same longitudinal axis, extend from the outlet ends of the first plurality of channels towards the downstream end of the injector and converge at a convergence angle towards a common region of convergence located downstream on the longitudinal axis. Feedstock material is injected axially towards the common region of convergence.

Abstract: A feedstock injector for connection to a plasmatron or to a fuel combustion chamber comprises a plurality of major channels arranged symmetrically about a core member, the channels leading from the upstream end of the injector towards a downstream region of convergence. In a preferred embodiment of the core member, a plurality of minor channels are provided, each minor channel leading from the inner wall of a major channel towards a minor region of convergence located inside the core. A feedstock-input passage is located axially inside the core, the passage communicating at its upstream end with the minor region of convergence and opening at its lower end through the tip of the core and a feedstock-supply passage opens into the side of the feedstock-input passage. In an alternate preferred embodiment of the core member, a minor channel extends axially from the upstream end to the downstream end of the core and feedstock-supply passage opens into the side of the minor channel.

Abstract: A plasmatron operating efficiently within a wider range of gas flows and capable of sustaining a stable arc voltage. The plasmatron generates an electric arc at the tip of a cathode electrode and transfers the arc along an arc chamber and into the bore of an anode electrode located at the downstream end of the arc chamber. A plurality of arc root attachment surfaces are defined on an inner surface of the anode by a plurality of ring members, causing the electric arc to attach with its root to the arc root attachment surfaces and therefore the axial movement of the arc root is confined substantially to the anode electrode. The arc voltage variations are limited and controlled substantially by the arc root movement between two adjacent arc root attachment surfaces. When used within a plasma-spraying torch, the plasma stream generated by the plasmatron has improved characteristics and induces improved plasma spray coatings.