Abstract: Described herein is a method for providing a clean edge at the interface of a portion of a substrate coated with a coating system and an adjacent portion of the substrate which is uncoated. The method includes the step of forming a zone of non-adherence on the substrate portion which is to be uncoated, prior to application of the coating system. The zone of non-adherence is adjacent the interface, so that the coating system will not adhere to the zone of non-adherence, but will adhere to the portion of the substrate which is to be coated with the coating system.

Abstract: A local environmental cell for a welding spray gun includes an annular ring having a top surface and a bottom surface, wherein the annular ring is adapted for attachment to an outer perimeter of the spray gun; and a plurality of fluid passageways radially disposed about the annular ring having a plurality of openings in the bottom surface of the ring in fluid communication with a vacuum source for providing a vacuum thereto. The use of the local environmental cell permits deposition of local bond coats as well as minimizes the number of steps associated with welding repair processes. For example, the use of the local environmental cell permits welding and formation of a low oxide bond coat during the welding process, thereby eliminating the need for placing the substrate subsequent to a welding process in a separate spray cell to deposit the bond coating.

Abstract: Method of producing a profiled abradable coating on a substrate in which an abradable ceramic coating composition is applied to a substrate using direct-write technology, or plasma sprayed onto the substrate through a mask or by use of a narrow foot-print plasma gun. These methods of producing abradable coatings are performed in the absence of a grid.

Abstract: Method of producing a profiled abradable coating on a substrate in which an abradable ceramic coating composition is applied to a substrate using direct-write technology, or plasma sprayed onto the substrate through a mask or by use of a narrow foot-print plasma gun. These methods of producing abradable coatings are performed in the absence of a grid.

Abstract: A method for protecting an article from degradation, and a method for in-situ repair of a component of an assembly are presented, wherein the method for protecting comprises providing a substrate; providing a Plasma Transferred Arc (PTA) apparatus; setting the PTA apparatus to operate in a non-transferred arc mode; and disposing at least one coating on the substrate using the PTA apparatus in the non-transferred arc mode. The method for in-situ repair comprises providing a substrate, the substrate comprising a component of an assembly and coupled to the assembly; providing a PTA apparatus; welding the substrate using the PTA apparatus in a transferred arc mode to form a welded region on the substrate; setting the PTA apparatus to operate in a non-transferred arc mode; and disposing at least one coating on the welded region of the substrate using the PTA apparatus in the non-transferred arc mode, wherein the PTA apparatus is operated using a pilot arc power supply to dispose the at least one coating.

Abstract: Described herein is a method for providing a clean edge at the interface of a portion of a substrate coated with a coating system and an adjacent portion of the substrate which is uncoated. The method includes the step of forming a zone of non-adherence on the substrate portion which is to be uncoated, prior to application of the coating system. The zone of non-adherence is adjacent the interface, so that the coating system will not adhere to the zone of non-adherence, but will adhere to the portion of the substrate which is to be coated with the coating system.

Abstract: Described herein is a method for providing a clean edge at the interface of a portion of a substrate coated with a coating system and an adjacent portion of the substrate which is uncoated. The method includes the step of forming a zone of non-adherence on the substrate portion which is to be uncoated, prior to application of the coating system. The zone of non-adherence is adjacent the interface, so that the coating system will not adhere to the zone of non-adherence, but will adhere to the portion of the substrate which is to be coated with the coating system.

Abstract: Described herein is a method for providing a clean edge at the interface of a portion of a substrate coated with a coating system and an adjacent portion of the substrate which is uncoated. The method includes the step of forming a zone of non-adherence on the substrate portion which is to be uncoated, prior to application of the coating system. The zone of non-adherence is adjacent the interface, so that the coating system will not adhere to the zone of non-adherence, but will adhere to the portion of the substrate which is to be coated with the coating system.

Abstract: A shroud for a welding torch includes a hydrophilic skirt supported by a frame. The skirt is soft and pliable when wet and is self protected from the heat of welding by the water absorbed therein. The frame supports the skirt around the weld site and permits a good seal with the workpiece for excluding water during the welding process.

Abstract: A shroud for a welding torch includes a hydrophilic skirt supported by a frame. The skirt is soft and pliable when wet and is self protected from the heat of welding by the water absorbed therein. The frame supports the skirt around the weld site and permits a good seal with the workpiece for excluding water during the welding process.

Abstract: A robotic machine includes a robotic arm with a machine tool mounted thereto. A powder injector is mounted near the tool. A local powder feeder is mounted to the arm and includes a local conduit for supplying powder to the injector, and a load cell for measuring powder weight therein to control feedrate. A remote powder feeder is spaced from the arm, and includes a remote conduit joined to the local feeder for supplying powder thereto. A process computer controls the arm, and two feeders and effects staged delivery of the powder from the remote feeder to the local feeder for improving powder delivery response time.

Abstract: A robotic machine includes a machine tool removably supported in a mount for following a programmable path over a workpiece. A calibration pointer includes a housing configured like the tool for being supported in the mount, and a laser is affixed in the housing for emitting a laser beam at the workpiece. In a method of operation, the laser beam is projected from the laser in a focused spot at the workpiece at an offset therefrom. The spot permits accurate programming of the machine without contacting the workpiece.

Abstract: A plasma arc torch includes a housing having a nozzle at one end with a central orifice. An electrode extends into the orifice for producing a plasma arc. A port is disposed in the nozzle adjacent the orifice for injecting powder into the arc. The port includes an outlet, an inlet, and a reniform manifold extending therebetween for laterally distributing the powder about the nozzle orifice. In this way, the powder may be carried to the torch underwater and is distributed circumferentially about the plasma arc while simultaneously diffusing its carrier gas.

Abstract: A plasma arc torch includes a housing having a nozzle at one end with a central orifice. An electrode extends into the orifice for producing a plasma arc. A port is disposed in the nozzle adjacent the orifice for injecting powder into the arc. The port includes an outlet, an inlet, and a reniform manifold extending therebetween for laterally distributing the powder about the nozzle orifice. In this way, the powder may be carried to the torch underwater and is distributed circumferentially about the plasma arc while simultaneously diffusing its carrier gas.

Abstract: A hopper feeds powder underwater to a welding torch. The hopper includes a housing having a lower chamber and an integral upper chamber. An inlet joins the upper chamber for receiving powder and a pressurized carrier gas. A powder outlet joins the lower chamber for discharging the powder to the torch. A gas outlet joins the upper chamber for releasing the carrier gas. And, a control valve joins the gas outlet for selectively controlling pressure internal the housing.

Abstract: Stress corrosion cracking damage to stainless steels and nickel base superalloys is repaired by underwater plasma transferred arc welding which under conditions which reduce residual tensile stresses in the weld and adjacent portions of the repaired structure.

Abstract: Compressive residual stresses can be developed by underwater plasma transferred arc welding. The development of these compressive stresses act to prevent hot cracking and He embrittlement that can develop during welding or stress corrosion cracking that can develop subsequent to the welding operation.

Abstract: Persistent compressive stresses sufficient to suppress hot cracking, reheat cracking and stress corrosion cracking are developed in welds containing alloys of plural materials by quenching of the weld after onset of solidification but while the weld remains soft or "mushy" at a temperature above the melting point of eutectic alloys which may form. Control of the time of quenching is preferably established during submerged welding by a cup-shaped exclusion fitting which is sized relative to the dimensions of a molten weld pool and the speed of travel of a welding heat source such as a plasma transfer arc torch. The cup-shaped exclusion fitting provides improved protection of the weld and heat source with inert gas supplied thereto while also permitting submerged welding at higher hydrostatic pressures than has heretofore been possible.

Abstract: An apparatus and method feeds weld material to an underwater plasma transferred arc welding torch. The weld material comprises a powder, which can be entrained in a fluidizing gas flow. The weld material is fed by the apparatus from a first supply through at least one conduit to a supply container. The apparatus comprises a first powder supply pressurized with a powder carrier gas positioned above the surface of the body of water; a second powder supply container positioned below the surface of the body of water and the second powder supply container comprising at least one powder outlet port and a gas vent open to the above surface atmosphere; at least one powder conduit connecting the first container with the second container; an underwater welding torch positioned near the second container and having at least one powder inlet; and at least one powder conduit connecting the second powder supply container to the at least one powder inlet of the torch.