Spray Forming of al Alloys: experiment and theory

Abstract

Close coupled gas atomization has been studied. Pitot tube gas flow measurements support a postulate of transition from an initial sonic to a supersonic and a final sonic state along the convergence region of the jets. Predictions of the d 50 median diameter utilizing a two phase model for primary and secondary break up correlate strongly with experimental results from He-atomized Al alloys by a factor of 0.8216.

Plasma-spray synthesis and characterization of ti-based nitride and oxide nanogranules

“…The distribution of particle sizes for the case of the Ti-N system is presented in Figure 5b, as measured by the size analyser. Dverall, the effect of the radial injection point of the gas upon the nanocrystalline particle diameter followed the gas density and was on par with gas compressibility as previously calculated in the case of two-phase flows [17][18][19]21 . When argon was used as the working gas and oxygen as the reaction gas, an oxygendeficient oxide nanocrystal was formed, as detected by X-ray diffraction (see Figure 1a), while sub-stoichiometric material required further processing for complete oxidation; such post processing involved annealing of the powders in ambient conditions.…”

“…The consumable precursor material is in the form of a rod, typically with a diameter up to 5 cm, fed horizontally or vertically relative to the non-consumable electrode; it is also electrically grounded and cooled by a copper anode and able of both translational and rotational motion. Homogeneous gas injection is achieved by the use of closecoupled gas injection nozzles [17][18][19] . However, with increasing production rates (and, hence, with increasing vapour density 19 ), both the gas flow rate and location of injection become important.…”

Gas Atomization of Aluminium Melts: Comparison of Analytical Models

“…The models have been applied to the atomization of Al melts. In a previous study of He atomized Al alloys [28] the mean powder size appeared largely uninfluenced by secondary alloying elements, effectively behaving as bulk Al. Accordingly, the current study considers Al as the melt phase and results of the radial distribution of powder sizes are presented for a variety of atomization conditions, in a close coupled atomizer assembly.…”

Studying the Erosion Corrosion Behavior of NiCrAlY Coating Layer Applied on AISI 446 Stainless Steel Using Thermal Spray Technique

“…A coating may be defined as a near surface region, having properties different from the bulk material it is deposited on. Coatings may be applied to the surface of materials in order to protect the surface from the environment that may produce corrosion or other deteriorative reactions and to improve the surface's appearance [11]. There are many techniques available, e.g.…”