Gas dynamic cold spray
Encyclopedia
Gas dynamic cold spray is a coating deposition method developed in the mid-1980s in the Soviet Union
in The Institute of Theoretical and Applied Mechanics by Papyrin and his team. The solid powders (1 to 50 micrometer
s in diameter) are accelerated in supersonic
gas jets to velocities up to 500–1000 m/s
. During impact with the substrate, particles undergo plastic deformation and adhere to the surface. To achieve a uniform thickness the spraying nozzle is scanned along the substrate. Metal
s, polymer
s, and composite material
s can be deposited using cold spraying. The kinetic energy of the particles, supplied by the expansion of the gas, is converted to plastic deformation energy during bonding. Unlike thermal spraying
techniques e.g, plasma spraying, arc spraying, flame spraying, high velocity oxygen fuel (HVOF) the powders are not melted during the spraying process.
" which occurs at the particle substrate interface at or beyond a certain velocity called critical velocity. When a spherical particle travelling at critical velocity impacts a substrate, a strong pressure field propagates spherically into the particle and substrate from the point of contact. As a result of this pressure field, a shear load is generated which accelerates the material laterally and causes localized shear straining. The shear loading under critical conditions leads to adiabatic shear instability where thermal softening is locally dominant over work strain and strain rate hardening, which leads to a discontinuous jump in strain and temperature and breakdown of flow stresses. This adiabatic shear instability phenomena results in viscous flow of material at an outward flowing direction with temperatures close to melting temperature
of the material. This material jetting is also a known phenomenon in explosive welding of materials.
Other companies involved in the research and development of cold spraying:
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
in The Institute of Theoretical and Applied Mechanics by Papyrin and his team. The solid powders (1 to 50 micrometer
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...
s in diameter) are accelerated in supersonic
Supersonic
Supersonic speed is a rate of travel of an object that exceeds the speed of sound . For objects traveling in dry air of a temperature of 20 °C this speed is approximately 343 m/s, 1,125 ft/s, 768 mph or 1,235 km/h. Speeds greater than five times the speed of sound are often...
gas jets to velocities up to 500–1000 m/s
Metre per second
Metre per second is an SI derived unit of both speed and velocity , defined by distance in metres divided by time in seconds....
. During impact with the substrate, particles undergo plastic deformation and adhere to the surface. To achieve a uniform thickness the spraying nozzle is scanned along the substrate. Metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
s, polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
s, and composite material
Composite material
Composite materials, often shortened to composites or called composition materials, are engineered or naturally occurring materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct at the macroscopic or...
s can be deposited using cold spraying. The kinetic energy of the particles, supplied by the expansion of the gas, is converted to plastic deformation energy during bonding. Unlike thermal spraying
Thermal spraying
Thermal spraying techniques are coating processes in which melted materials are sprayed onto a surface. The "feedstock" is heated by electrical or chemical means ....
techniques e.g, plasma spraying, arc spraying, flame spraying, high velocity oxygen fuel (HVOF) the powders are not melted during the spraying process.
Basic principles
The most prevailing bonding theory in cold spraying is attributed to "adiabatic shear instabilityAdiabatic shear band
Adiabatic shear band is a term used in physics, mechanics and engineering.Since the 1960s adiabatic shear bands have been studied extensively because of their importance as a failure mode in areas such as metal forming and cutting, various types of ballistic impact, as well as vehicle crashes.An...
" which occurs at the particle substrate interface at or beyond a certain velocity called critical velocity. When a spherical particle travelling at critical velocity impacts a substrate, a strong pressure field propagates spherically into the particle and substrate from the point of contact. As a result of this pressure field, a shear load is generated which accelerates the material laterally and causes localized shear straining. The shear loading under critical conditions leads to adiabatic shear instability where thermal softening is locally dominant over work strain and strain rate hardening, which leads to a discontinuous jump in strain and temperature and breakdown of flow stresses. This adiabatic shear instability phenomena results in viscous flow of material at an outward flowing direction with temperatures close to melting temperature
Melting temperature
Melting temperature may refer to:* Melting point, the temperature at which a substance changes from solid to liquid state.* DNA melting temperature, the temperature at which a DNA double helix dissociates into single strands....
of the material. This material jetting is also a known phenomenon in explosive welding of materials.
Industry
Today, cold spray technology is used in a wide range of surfacing applications. In addition to repair and remanufacturing for aerospace and industrial components, the latest applications include rapid manufacturing and microsystems. A list of original cold spraying equipment manufacturers includes :- Supersonic Spray Technologies (CanadaCanadaCanada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
) - Obninsk Center for Powder Spraying (RussiaRussiaRussia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
) - Inovati (USA)
- CGT (GermanyGermanyGermany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
) - ASB-Industries (USA)
Other companies involved in the research and development of cold spraying:
- University of Ottawa (CanadaCanadaCanada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
) - Linde AG (GermanyGermanyGermany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
) - Linde AG(USA)
- HC Starck (GermanyGermanyGermany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
) - Praxair LOXPlate (GermanyGermanyGermany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
) - Praxair(USA)
- FNE-Freiberg (GermanyGermanyGermany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
) - OBZ GmbH (GermanyGermanyGermany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
) - Dycomet Europe (The Netherlands)
External links
- DYMET, Apparatus for gas-dynamic coating. US patent 6402050, 1999
- Helmut-Schmidt-Universität, Hamburg
- Parameter window for cold spray deposition
- DIPI France
- Cold Gas Spray in Australia
- International Status Report 2004
- New developments in cold spraying 2006
- Bonding mechanisms in cold spraying
- Rus Sonic Technology, Inc. United States Patent - Method and Apparatus for Applying a Powder Coating
- Particle Consolidation by Low Pressure Cold Spray: Modelling, Experiments and Applications
- Kinetic Metallization - Low pressure particle impact consolidation coating process