Cold Gas Dynamic Spraying CGDS

Numerical simulation of the cold spray process was reported by Ghelichi et al. (2011) using a 3D-finite element model to calculate the critical velocity. The results obtained from the software are converted to Wavelet parameters allowing to calculate the second derivative of the physical parameters in Sobolev space. The authors concluded that their approach is a useful tool to improve the experimental setup as well as the sensitivity and accuracy of the described method. It may help to survey the cold spray process and its qualification with the aim to increase the properties and performance of the coating material deposited under optimum conditions (see also Jodoin, Raletz and Vardelle, 2006). 

Work performed on depositing bioceramic materials, in particular, hydroxyapatite by CGDS is still few and far between. This is mainly caused by the fact that hydroxyapatite in its pure form cannot be sprayed by CGDS but requires the presence of a ductile, that is metallic matrix that provides adhesion to the substrate by deformation during impact. 

The antibacterial behaviour of cold sprayed HAp-Ag (silver-doped hydrox-yapatite)/PEEK composite coatings were investigated against Escherichia coli (DH5a) by Sanpo et al. (2009). The antibacterial activity was found to increase with increasing concentration of HAp-Ag nanoparticles. The precursor nanocomposite powders were deposited using rather mild cold spraying parameters (11-12 bars, preheated air temperature between 150 and 160 °C). 

The CGDS deposition process of pure titanium powder was studied by Shukla et al. (2001) to establish conditions for the build-up of dense and porous Ti coatings on Ti substrates. A detailed study was undertaken of the first stages of coating 

A novel low temperature variant of dynamic spraying is CoBlast microblast technique (Barry and Dowling, 2011). Hydroxyapatite coatings are deposited by 

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Figure 5.37 Schematic of a cold gas dynamic spraying (CGDS) apparatus.

Ballhom, R., and Heimann, R.B. (2007) Cold gas dynamic spraying (CGDS) of Ti02 (anatase) coatings on polymer substrates microstructural characterisation and photocatalytic efficiency. /. Photochem. Photobid. A, 187 (2-3), 285-292. 

Physical functionalization by the application of surface coatings, including APS (atmospheric plasma spraying), CVD (chemical vapor deposition), CGDS (cold gas dynamic spraying), PLD (pulsed laser deposition), MAO (micro-arc oxidation) or plasma electrolytic oxidation (PEO), sol-gel, and polyelectrolyte coatings and films. 

Heimann, R.B., Kleiman, J.I., Litovsky, E., Marx, S., Ng, R., Petrov, S., Shagalov, M., Sodhi, R.N.S., and Tang, A. (2014) High-pressure cold gas dynamic (CGD)-sprayed alumina-reinforced aluminum coatings for potential application as space construction material. Surf. Coat. Technol., 252, 113-119. 

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