Influence of Deposition Temperature on the Microstructures and Properties of Plasma-Sprayed Al2O3 Coatings

Abstract

Al 2 O 3 coatings were deposited on 1Cr13 substrates by atmospheric plasma spraying at different deposition temperatures of 140, 275, 375, 480, 530, and 660°C to investigate the effect of coating surface temperature on the lamellar bonding formation. The fractured cross section morphology was characterized by scanning electron microscopy to reveal the lamellar interface bonding. X-ray diffraction was used to characterize the phase contents in the coating. Micro-hardness, YoungÕs modulus, and thermal conductivity of the deposits were measured for examining the dependency of coating properties on its microstructure. The results show that the interface area bonded through columnar grain growth across splat-splat interfaces was increased with increasing deposition temperature. Moreover, micro-hardness, YoungÕs modulus and thermal conductivity were increased with the increase of deposition temperature. However, the phase structure of the coating changed little with deposition temperature. The results evidently indicate that the apparent bonding ratio and properties of deposits can be significantly changed in a wider range through controlling the deposition temperature.

Residual Strain and Fracture Response of Al2O3 Coatings Deposited via APS and HVOF Techniques

“…12). A columnar grain structure was also observed in much of the individual lamellae, which was consistent with previously reported results for plasma-sprayed Al 2 O 3 coatings ( Ref 5,10,35,36). The columnar structure occurs as the crystallization of lamella occurs in strongly nonequilibrium conditions and the molten material loses heat mainly by conduction to the underlying material in a direction perpendicular to the plane of the underlying material, as indicated previously by Forcey and Iordanova (Ref 37).…”

Atmospheric plasma-sprayed La0.8Sr0.2Ga0.8Mg0.2O3 electrolyte membranes for intermediate-temperature solid oxide fuel cells

“…46,47 When the deposition temperature is higher than the critical bonding temperature, the lamellar interface bonding ratio is signicantly increased with the increase of the deposition temperature. 46,47 For Al 2 O 3 coatings which have a lower critical bonding temperature of about 300 C, the mean lamellar interface bonding ratio increased from 32% to 59% when the deposition temperature was increased from near-room temperature to 660 C. 45 Since the LSGM deposits were prepared at a deposition temperature of $300 to 350 C, being higher than the critical deposition temperature, they have a high interface bonding ratio.…”

Epitaxial grain growth during 8YSZ splat formation on polycrystalline YSZ substrates by plasma spraying

“…The recent study has clearly revealed that the lamellar interface bonding of plasmasprayed YSZ coating can be remarkably increased by a factor of three when the substrate temperature was increased to 880°C during coating deposition as compared with the counterpart deposited in the conventional routine [16,17]. Similar phenomenon was also found in plasma-sprayed Al 2 O 3 [18,19]. Pershin et al [20] confirmed that the adhesion strength of nickel coating on stainless steel prepared by plasma spray increases from 10 to 74 MPa, when the substrate temperature was raised from 25 to 650°C.…”