PTA Description
The Plasma Transferred Arc (PTA) process employs the plasma principle hence it may be considered an evolution of the Gas Tungsten Arc Welding (GTAW) process, where the high-energy concentration is due to the use of a constrictor nose, which restrains the column diameter of an electric arc established between a tungsten electrode and the workpiece in an inert gas atmosphere, usually argon.
The feeding material is carried to the plasma jet by a gas stream, which might be inert, active, or a mixture of active and inert gases. A third gas flow is employed to protect the metal pool from atmospheric contamination. Even though there is the possibility of using mixtures of active and inert gases, argon is typically employed for all three-gas systems.
PTA Applications
- Hard Surfacing: PTAW is well suited to apply hard alloys for wear resistance. Stellite, Colmonoy, Hastelloy, and Tungsten Carbide can all be successfully applied with PTAW.
- Corrosion Resistant Overlays: The localized heat input characteristics of PTAW allow corrosion-resistant alloys to be applied with very little dilution into the base material. PTAW can achieve subsea chemistry requirements of <5% Fe in as little as 0.040” of overlay thickness.
- Industries / Components:
- Non-Mag Down Hole Tools: Drill Collars, Wear Bands for MWDs, Flex Ponies, etc.
- Down Hole Components: Mud Motor Bearings, Stabilizers, Topsubs, Piston SubsFlow Restrictors, Drill Bits, etc.
- Flow Control: Valve Bores, Gates, Seats, Seat Pockets, Ring Grooves, Valve Stems, etc...
- Power Generation: Turbine Blades, Shafts, Bearing Surfaces, etc.
- Riser Equipment o Pins, Boxes, etc.
Laser Cladding Description
Laser Cladding is a weld build-up process and complementing coating technology to thermal spray. It is increasingly used instead of PTA (Plasma Transferred Arc) welding and easily outperforms conventional welding methods like TIG (Tungsten Inert Gas) for advanced weld repair applications.
In laser cladding, the laser beam is defocused on the workpiece with the selected spot size. The powder coating material is carried by an inert gas through a powder nozzle into the melt pool. The laser optics and powder nozzle are moved across the workpiece surface to deposit single tracks, complete layers, or even high-volume build-ups.
Laser Cladding Applications
Laser cladding has recently gained increased importance in a variety of industrial sectors such as automotive, aerospace, navy, defense, and many others. Similar to overlay welding, laser cladding is a coating technique where a laser heat source is utilized to fuse and deposit a layer of a selected material on a substrate in order to form a defect-free protective coating, fusion bonded to the base material, with maximum coating material efficiency and minimum dilution (i.e. contamination due to the substrate material that has been melted and has mixed with the cladding). The additive material can be deposited to the substrate by several methods: in form of powder or paste, which can be either injected during the process or pre-placed or by wire/strip feeding.
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Products
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Iron base alloy
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Nickel base alloy
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Cobalt base alloy
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Cast/Fused WC
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Spherical Cast WC
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Macro-Crystalline
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Reference
A.S.C.M.D’Oliviera, R.S.C.Paredes, R.L.C. Santos: Pulsed current plasma transferres arc hardfaccing, Journal of Materials Processing Technology 171, 2006, p.167–174;
V.V.Diaz, J.C.Dutra, A.S.C.D’Oliveira: Hardfacing by Plasma Transferred Arc Process, INTECH, Ed.W.Sudnik, 2011, ISBN 978-953-307-642-3;
P.V. Senthill, A.Shirrushti: Finite Element Simulation of Plasma Transferred Arc Welding [PTAW} of structural steel, PV Senthiil Int. Journal of Engineering Research and Applications www.ijera.com ISSN : 2248-9622, Vol. 4, Issue 10(Part - 4), October 2014, p.06-11;
What is Plasma Transferred Arc Welding [PTAW], 1/12/15, js, Accessed Oct 2015;
Simone Zanzarin: Laser cladding with metallic powder. https://core.ac.uk/download/pdf/35317589.pdf
