Single-wire arc spray apparatus and methods of using same

A wire arc thermal spray apparatus, comprising:

• a gas nozzle having a nozzle bore and a nozzle exit, the nozzle bore defining a nozzle axis;
• a first consumable wire electrode positionable within the nozzle bore, wherein the first consumable wire electrode has a first axis;
• and
• a second non-consumable electrode located proximate the nozzle exit, wherein at least a portion of the second non-consumable electrode defines a second axis substantially perpendicular to the nozzle axis, and further wherein the second non-consumable electrode is positioned outside of a gas jet produced by the gas nozzle.

A liquid material droplet generating system, comprising:

• a single-wire arc spray apparatus, comprising:
• a gas nozzle having a nozzle entrance, a nozzle exit, and a nozzle bore, the nozzle bore defining a nozzle axis;
• a first consumable electrode positionable within the nozzle bore, the first consumable electrode having a first electrode axis;
• and
• a second non-consumable electrode positionable outside the gas nozzle proximate the nozzle exit, wherein the second non-consumable electrode is positioned outside of a gas jet produced by the gas nozzle;
• a power supply apparatus adapted to connect to at least the first consumable electrode and the second non-consumable electrode and operable to permit arcing between the first consumable electrode and the second non-consumable electrode;
• a feeding apparatus adapted to feed the first consumable electrode through the nozzle bore;
• and
• a controller adapted to control one or more of the power supply apparatus and the feeding apparatus.

A method of generating a narrow beam thermal spray of liquid droplets, the method comprising:

• providing a gas nozzle having a nozzle entrance, a nozzle exit, and a nozzle bore, the nozzle bore defining a nozzle axis;
• positioning a first consumable electrode within the nozzle bore of the gas nozzle;
• positioning a second non-consumable electrode outside of the gas nozzle proximate the nozzle exit, the position of the second non-consumable electrode selected to avoid interference with a gas jet produced by the gas nozzle;
• and
• forming an electrical arc outside of the gas nozzle proximate the nozzle exit, the electrical arc formed between a terminal end of the first consumable electrode and a portion of the second non-consumable electrode.

A method for forming a high density microstructure, the method comprising:

• providing a gas nozzle having a nozzle entrance, a nozzle exit, and a nozzle bore, the nozzle bore defining a nozzle axis;
• positioning a first consumable electrode within the nozzle bore of the gas nozzle;
• positioning a second electrode outside of the gas nozzle and proximate the nozzle exit;
• accelerating a first arc gas through the gas nozzle to form a gas jet at the nozzle exit;
• forming an electrical arc outside of the gas nozzle proximate the nozzle exit, the electrical arc formed between a terminal end of the first consumable electrode and a portion of the second electrode, wherein the electrical arc causes a portion of the first consumable electrode to melt and form droplets near a center of the gas jet, forming a narrow beam thermal spray;
• and
• depositing the droplets on a substrate surface to form a coating, where the coating is defined by substantially indiscernible boundaries between the droplets that form the coating.

A wire arc thermal spray apparatus for generating a narrow beam thermal spray, the apparatus comprising:

• a gas nozzle having a nozzle bore and a nozzle exit, the nozzle bore defining a nozzle axis, the gas nozzle operable to produce a gas jet;
• a first consumable electrode positioned within the nozzle bore, wherein the first consumable electrode has a first axis that forms an angle with the nozzle axis of 5 degrees or less;
• and
• a second non-consumable electrode positioned outside the gas nozzle proximate the nozzle exit, wherein a terminal portion of the second non-consumable electrode is positioned outside of the gas jet such that an arc may form between the first consumable electrode and the second non-consumable electrode.

A method of generating a narrow beam thermal spray of liquid droplets, the method comprising:

• providing a gas nozzle having a nozzle entrance, a nozzle exit, and a nozzle bore, the nozzle bore defining a nozzle axis;
• positioning a first consumable electrode within the nozzle bore of the gas nozzle;
• positioning a second non-consumable electrode outside of the gas nozzle proximate the nozzle exit;
• accelerating a first arc gas through the gas nozzle to form a gas jet originating at the nozzle exit;
• forming an electrical arc outside of the gas nozzle proximate the nozzle exit, the electrical arc formed between a terminal end of the first consumable electrode and a portion of the second non-consumable electrode that is outside of the gas jet;
• detaching the droplets from the first consumable electrode with the gas jet;
• and
• carrying the droplets with the gas jet, wherein the droplets form the narrow beam thermal spray.

A liquid material droplet generator, comprising:

• a gas nozzle comprising a nozzle bore, the nozzle bore defining a nozzle axis;
• a first consumable electrode positionable within the nozzle bore, wherein the first consumable electrode comprises a first electrode axis which forms an angle with the nozzle axis of 1 degree to 3 degrees;
• and
• a second non-consumable electrode positionable outside the gas nozzle proximate the nozzle exit.

A wire arc thermal spray apparatus, comprising:

• a gas nozzle having a nozzle bore and a nozzle exit, the nozzle bore defining a nozzle axis;
• a first consumable wire electrode positionable within the nozzle bore, wherein the first consumable wire electrode has a first axis that forms an angle with the nozzle axis of 1 degree to 3 degrees;
• and
• a second non-consumable electrode proximate the nozzle exit, wherein the second non-consumable electrode defines a second axis substantially perpendicular to the nozzle axis.

A method of generating a narrow beam thermal spray of liquid droplets, the method comprising:

• providing a gas nozzle having a nozzle exit and a nozzle bore, the nozzle bore defining a nozzle axis;
• positioning a first consumable electrode within the nozzle bore of the gas nozzle such that a first electrode axis of the first consumable electrode forms an angle with the nozzle axis of 1 degree to 3 degrees;
• positioning a second non-consumable electrode outside of the gas nozzle proximate the nozzle exit;
• and
• forming an electrical arc outside of the gas nozzle proximate the nozzle exit, the electrical arc formed between the first consumable electrode and the second non-consumable electrode.