An integrated model for interaction between melt flow and non-equilibrium solidification in thermal spraying

Characterisation of plasma-sprayed SrFe12O19 coatings for electromagnetic wave absorption

“…Previous studies on plasma-and HVOF-sprayed Bahexaferrites clearly showed that, when such extensive melting of the sprayed agglomerates occurred, no hexaferrite phase could ever be retained in the coatings, [20][21][22] because the time required to complete the crystallisation process of Ba-hexaferrite, which involves various peritectic reactions, 29 is definitely too long, compared to the very short solidification times (of the order of few microseconds, with cooling rates of ∼10 6 K/s) of impactquenched molten lamellae. 30,31 A similar phenomenon can be expected for Sr-hexaferrite as well; indeed, according to the most recent phase diagram published on the SrO-Fe 2 O 3 system, 32 the Sr-hexaferrite compound exhibits incongruent melting: as temperature increases, the stoichiometric hexagonal ferrite compound is progressively altered by three peritectic reactions, each involving loss of oxygen and partial reduction of some Fe 3+ to Fe 2+ . After the last peritectic reaction, magnetite is formed in equilibrium with a Sr-rich liquid phase.…”

Numerical simulation of nucleation, solidification, and microstructure formation in thermal spraying

“…Since the thickness of the splat is usually about two orders of magnitude smaller than the diameter of the splat [8,9], a one-dimensional heat conduction analysis is usually appropriate. Based on one-dimensional heat conduction, the problem can be described as follows…”

“…Note that the interfacial heat transfer coefficient is a complex function of the processing conditions and surface characteristics, and only limited quantitative data are available. In this paper, h c ¼ 10 6 -10 8 W/m 2 K is used [8][9][10], and its value is assumed to remain unchanged during solidification. The substrate temperature far away from the splat, T sub , is assumed to be constant.…”

“…The interface elevation can then be estimated as Table 1 Thermophysical properties used in calculations [8,9] Parameter Mo Steel Glass 3.9 · 10 À6 a s , m 2 /s 2.43 · 10 À5 5.2 · 10 À6 6.5 · 10 À7 l k , m/s K 0.26 0.01 m, m 2 /s 6.78 · 10 À7 a 0 , m 2.7 · 10 À10 r E , J/m 2 0.33 X, m 3 /mol 1.04 · 10 À5 DG a , J/molecule 6.4 · 10 À20 As a first order approximation, T ss can be replaced by T sub . Based on Eq.…”

Numerical and Experimental Studies of Substrate Melting During Thermal Spraying

“…Zhang (1999) developed a theoretical model for the splat-flattening ratio accounting for the wetting and solidification of the droplet. Zhang et al (2001) and Wang et al (2002) have investigated the interaction between the melt flow and rapid solidification of the splat. Substrate melting and droplet splashing have also been considered in their papers.…”