On the gas dynamics of HVOF thermal sprays. [HVOF (High-Velocity Oxy-Fuel)]

Conference · Fri Jan 01 04:00:00 EST 1993

OSTI ID:6402621

Hackett, C M; Settles, G S; Miller, J D

An experimental study has been performed on the gas dynamic aspects of the HVOF thermal spray process. A commercially-available HVOF gun (Hobart Tafa JP-5000) is used in this study. Optical diagnostic techniques including microsecond-exposure schlieren and shadowgraph imaging are applied to visualize the hot supersonic jet produced by this equipment without any particle injection. Rapid turbulent mixing of the jet with the surrounding atmosphere is observed, which is an issue of concern in coating quality because of the possibility of oxidation of the sprayed particles. This mixing appears principally to be a function of the density ratio between the hot jet and the cold atmosphere, rather than depending upon the combustion-chamber pressure or barrel length. The supersonic core of the HVOF jet dissipates rapidly due to the, mixing, so that the jet is no longer supersonic when it impinges upon the target surface being sprayed. Secondary issues also observed in this study include strong jet-noise radiation from the HVOF plume and the entrainment and induced bulk motion of the surrounding air. All these issues have a background in the field of gas dynamics which has not been previously applied to thermal spray technology.

• Research Organization: Pennsylvania State Univ., University Park, PA (United States). Gas Dynamics Lab.
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: FG02-92ER14302
• OSTI ID: 6402621
• Report Number(s): CONF-9306130-3; ON: DE93013803
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101* -- Metals & Alloys-- Preparation & Fabrication
360201 -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360601 -- Other Materials-- Preparation & Manufacture
CHEMICAL REACTIONS
DATA
DEPOSITION
DIAGNOSTIC TECHNIQUES
DYNAMICS
EXPERIMENTAL DATA
FLUID FLOW
GAS FLOW
IMAGES
INFORMATION
JETS
MECHANICS
MIXING
NUMERICAL DATA
OXIDATION
PHOTOGRAPHY
SCHLIEREN METHOD
SPRAY COATING
SPRAYS
SURFACE COATING
TURBULENT FLOW