Cold spray

A pressurizer operating within the range of approximately 2,450 to 2,750 psig maintains pressure within the closed-loop circuit. The pressurizer contains the cold spray water system, which is typically supplied at around 550 °F (288 °C), and the electric heater-bank system. These systems maintain and control primary-coolant water pressure and temperature. The high-temperature water produced in the primary... 

Although the quality of the springs over the years has improved tremendously, they are subject to corrosion and it is important that their material selection is done properly for the process or that they are coated or treated correctly. Do not confuse, for example, aluminium paint with the higher specification (for NACE-level 2) six layers of cold-sprayed aluminium (called aluminized springs). 

A visualization study of fuel atomization using a pulsed laser holography/photography technique indicates that basic spray formation processes are the same for both a coal-derived synthetic fuel (SRC-II) and comparable petroleum fuels (No. 2 and No. 6 grade). Measurements were made on both pressure swirl and air assisted atomizers in a cold spray facility having well controlled fuel temperature. Quality of the sprays formed with SRC-II was between that of the No. 2 and No. 6 fuel sprays and was consistent with measured fuel viscosity. Sauter mean droplet diameter (SMD) was found to correlate with fuel viscosity, atomization pressure, and fuel flow rate. For all three fuels, a smaller SMD could be obtained with the air assisted than with the pressure swirl atomizer. 

Monde K. Direct observation of sugar-protein, sugar-sugar, and sugar-water complexes by cold-spray ionization time-of-flight... 

Path The entering liquid temperature is below the dew point of the entering air. The temperature of the air contacted by the cold spray drops below the dew point (the path again moves to the left), and water vapor condenses out of the air (the path moves down). 

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). 

Figure 5.38 Role of critical particle velocity during formation of cold sprayed coatings abrasion vs. deposition. (Adapted from Gartner et al. (2006).)...

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). 

Karthikeyan, J. (2009) Bioceramic composite coatings by cold spray, in Thermal Spray 2009 Expanding Thermal Spray Performance to New Markets and Applications, ASM International, pp. 391 -396. 

Cizek, J., Kovarik, O., Siegl, J., Khor, K.A., and Dlouhy, I. (2013) Influence of plasma and cold spray deposited Ti layers on high-cycle fatigue properties of Ti6A14V substrates. Surf. Coat. Technol., 217, 23-33. 

Gartner, F., Schmidt, T., Stoltenhoff, T., and Kreye, H. (2006) Recent developments and potential applications of cold spraying. 

Ghelichi, R., Bagherifard, S., Guagliano, M., and Verani, M. (2011) Numerical simulation of cold spray coating. Surf. Coat. Technol., 205 (23-24), 5294-5301. 

Ghelichi, R. and Guagliano, M. (2009) Coating by the cold spray process a state of the art. Fratt. Integrity Strutturale, 8, 30-44. 

Irissou, E., Legoux, J.G., Arsenault, B., and Moreau, C. (2007) Investigation of Al-AljOj cold spray coating formation and properties. J Therm. Spray Technol., 16 (5-6), 661-668. 

Jodoin, B., Raletz, F., and Vardelle, M. (2006) Cold spray modelling and validation using an optical method. Surf. Coat. Technol.,... 

H.K. (2013a) In vitro and in vivo evaluation of the bioactivity of hydroxyapatite-coated polyetheretherketone biocomposites created by cold spray technology. Acta Biomater., 9 (4), 6177-6187. 

Huang, J., and Li, H. (2014) Hydroxyapatite/graphene-nanosheet composite coatings deposited by vacuum cold spray for biomedical applications inherited nanostructure and enhanced properties. Carbon, 67, 250-259. 

Aishvarya, V., and Dhindaw, B.K. (2013) Hydroxyapatite-coated magnesium-based biodegradable alloy cold spray deposition and simulated body fluid studies. /. Mater. Eng. Perform., 22 (10), 2997-3004. 

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