Effect of Gas Pressure and Temperature on Stereometric Properties of Al+Al2O3 Composite Coatings Deposited by LPCS Method

Abstract The paper deals with effect of working gas pressure and temperature on surface stereometry of coatings deposited by low-pressure cold spray method. Examinations were focused on aluminium coatings which are commonly used to protect substrate against corrosion. A commercial Al spherical feedstock powder with admixture of Al2O3 (Al + 60vol.-% Al2O3), granulation -50+10 µm, was used to coat steel, grade S235JR. Thedeposited coatings were studied to determine their stereometry, i.e. roughness, transverse and longitudinal waviness, topography of surface and thickness as the functions of gas pressure and temperature. A profilometer and focal microscope were used to evaluate the stereometric properties. In order to reduce the number of variables, the remaining process parameters, i.e. shape and size of de Laval nozzle, nozzle-to-substrate distance, powder mass flow rate, linear velocity of spraying gun, were kept unchanged. The investigation confirmed influence of temperature and pressure on coating thickness as well as on the surface seterometry.

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Characterisation of Cold Spray Titanium Coatings

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.898 ◽

2010 ◽

Vol 654-656 ◽

pp. 898-901 ◽

Cited By ~ 14

Author(s):

Stefan Gulizia ◽

A. Trentin ◽

S. Vezzù ◽

Silvano Rech ◽

Peter King ◽

...

Keyword(s):

Cold Spray ◽

Laval Nozzle ◽

Fine Particles ◽

Spray Deposition ◽

Deposition Process ◽

Gas Temperature ◽

Nitrogen Gas ◽

De Laval Nozzle ◽

Titanium Coatings ◽

Temperature And Pressure

Cold spray is a solid state spray deposition process utilizing a supersonic De Laval nozzle to accelerate fine particles to high velocities. Particles plastically deform on impact to the substrate and to each other to create dense well adhered structures. In this study, the microstructure and mechanical properties of cold spray Titanium coatings deposited using nitrogen gas at different gas temperature and pressure were examined. In general, it was found that gas-atomised CP-titanium powder is capable of producing dense coating structures on aluminium alloy (Al6061) substrates. The micro-hardness, oxygen and nitrogen content of the coatings were found to be slightly higher than powder in the as-received condition. It was also found the coating residual stress was purely compressive when cold spray is conducted at high gas pressure and temperature.

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An improved de Laval nozzle experiment

International Journal of Mechanical Engineering Education ◽

10.1177/03064190211034165 ◽

2021 ◽

pp. 030641902110341

Author(s):

Nicholas Goodman ◽

Brian J Leege ◽

Peter E Johnson

Keyword(s):

Data Acquisition ◽

Laval Nozzle ◽

Flow Characteristics ◽

Data Acquisition System ◽

Isentropic Flow ◽

Hands On ◽

De Laval Nozzle ◽

Physical Phenomena ◽

The Impact ◽

The Relationship

Exposing students to hands-on experiments has been a common approach to illustrating complex physical phenomena that have been otherwise modelled solely mathematically. Compressible, isentropic flow in a duct is an example of such a phenomenon, and it is often demonstrated via a de Laval nozzle experiment. We have improved an existing converging/diverging nozzle experiment so that students can modify the location of the normal shock that develops in the diverging portion to better understand the relationship between the shock and the pressure. We have also improved the data acquisition system for this experiment and explained how visualisation of the standing shock is now possible. The results of the updated system demonstrate that the accuracy of the isentropic flow characteristics has not been lost. Through pre- and post-laboratory quizzes, we show the impact on student learning as well.

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