Porosity in Spray-Formed Materials

Volker Uhlenwinkel; N. Ellendt

doi:10.4028/www.scientific.net/MSF.534-536.429

Paper Titles

Effect of Gun Nozzle Geometry, Increase in the Entrance Convergent Section Length and Powder Injection Position on Cold Sprayed Titanium Coatings
p.413

Experimental Investigation and Modeling of the Specific Enthalpy Distribution in a Spray Cone
p.417

Fabrication of Ti(Al,O)-Al₂O₃ Powder Feedstock for Thermal Spraying and Evaluation of Composite Coating
p.421

Microstructure and Bonding Strength of Tungsten Coating Deposited on Copper by Plasma Spraying
p.425

Porosity in Spray-Formed Materials
p.429

Present Status and Future Prospects of Cold Spraying
p.433

Spray Forming of Mg₂Si Rich Aluminum Alloys
p.437

Study on Metal/Diamond Binary Composite Coatings by Cold Spray
p.441

The Effect of In-Flight Bulk Metallic Glass Particle Temperature on Impact Behavior and Crystallization
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HomeMaterials Science ForumMaterials Science Forum Vols. 534-536Porosity in Spray-Formed Materials

Porosity in Spray-Formed Materials

Abstract:

Porosity in spray-formed materials is an important issue, but the formation of porosity is not completely understood. Many experimental results and some theoretical models have been presented in the past. Nevertheless, the prediction of porosity in a deposit is still not possible today. The paper will give some examples picked from literature, which show some general correlations between process parameters and porosity. These correlations can be helpful to form a basic understanding of the process. Finally it is necessary to know more about the conditions of the droplets and the deposit at the point of impingement. These impacting conditions have to be correlated to the porosity to improve the understanding of the process and to make a prediction possible. Determining the impact conditions is a challenge because usually they are not constant with time and some values are difficult to measure. Our experiments show a strong correlation between the surface temperature of the deposit and the porosity. For IN718 and U720 as-sprayed porosities below 1 vol.% were achieved if the deposit surface temperature is app. 1250 °C. The average impact angle weighted by the local particle mass flux is also an important parameter. The probability of low as-sprayed porosity is high if the average weighted impact angle is below 25° but decreases dramatically for higher impact angles.

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Periodical:

Materials Science Forum (Volumes 534-536)

Pages:

429-432

DOI:

https://doi.org/10.4028/www.scientific.net/MSF.534-536.429

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Online since:

January 2007

Authors:

Volker Uhlenwinkel, N. Ellendt

Keywords:

Billet, Impact Angle, Porosity, Spray Forming, Surface Temperature, Tube

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