Steam oxidation resistance of plasma sprayed chromium‐containing coatings at 1200 °C

Abstract

In order to improve the high‐temperature steam oxidation resistance of Zircaloy fuel claddings, chromium‐containing coatings (Cr3C2‐NiCr and NiCr) were deposited on a Zr‐4 substrate by air plasma spray. The steam oxidation resistance of the two coatings was evaluated at 1200 °C under atmospheric pressure. The weight changes, phase compositions, and microstructures of the coatings before and after the oxidation test of 1 h were characterized. Results revealed that the Cr3C2‐NiCr coating effectively protected Zr‐4 from oxidation. A protective Cr2O3 scale with a thickness of about 7 µm was formed on the surface of the Cr3C2‐NiCr coating after 1 h duration and the formed oxide layer was about 100 times thinner than that formed on the uncoated sample. A none protective oxide scale was formed on the surface of the NiCr coated Zr‐4 samples. Severe inter‐diffusion between the NiCr coating and the Zr‐4 substrate was observed. The oxidation mechanisms of the two types of chromium‐containing coatings were analyzed and compared in detail.

Recent Advances in Protective Coatings for Accident Tolerant Zr-Based Fuel Claddings

“…However, the coated samples showed poor corrosion resistance in supercritical water at 400 • C and 10.3 MPa, caused by a bimetallic effect (this coating can build up bimetallic couple with the Zr-2.5Nb alloy, resulting in the acceleration of the corrosion rate). Yang et al demonstrated high oxidation resistance of 120 µm-thick HVOF Cr 3 C 2 -NiCr coating at 1200 • C in steam for 1 h due to the formation of a dense chromia scale [149]. However, the high coating thickness and heterogeneous/porous microstructure formed by the HVOF method may limit the usefulness of such coatings for ATF Zr claddings.…”

Review on chromium coated zirconium alloy accident tolerant fuel cladding

“…Up to now, many types of coating materials have been developed, including MAX phase coatings [10][11][12][13][14], carbide coatings [15,16], nitride coatings [17][18][19][20], pure metal coatings [21][22][23][24][25][26] and alloy coatings [27][28][29][30][31][32]. Previous studies show that MAX phase coatings such as Ti-Al-C and Cr-Al-C are susceptible to cracking through the coating during heat treatment, water corrosion, and high temperature steam oxidation [33,34].…”

Degradation of Cr-coated cladding under the simulated Loss-of-Coolant Accident phenomena

“…However, the HT oxidation experiments performed so far have focused mainly on the performance of the ideal coating without defects [11][12][13][14]. According to existing studies, the HT steam oxidation process of Cr-coated Zr-based alloys can be divided into three groups.…”