Preparation of NiCr/YSZ two-layered burn-resistant coating on γ-TiAl alloys based on plasma surface metallurgy and ion plating methods

Abstract

The NiCr/YSZ coating was fabricated on ?-TiAl alloy by double glow plasma surface metallurgy technology and multi-arc ion plating technology. The microstructure, microhardness, bonding strength and burn resistance of NiCr/YSZ coating were studied in detail. The results showed that the NiCr/YSZ coating was dense and homogeneous, including a duplex structure of top YSZ ceramic coating and underlying Ni-Cr bond coating. The average microhardness of NiCr/YSZ coating was raised by a factor of about 2 compared to the ?-TiAl substrate. The thermal shock test indicated that the composite structure had superior bonding strength and the defects such as metal droplets on the ceramic coating were the source of cracks. The high-energy laser beam destroyed the surface of ?-TiAl alloy, forming protruding combustion products in ablation zone and splashing residues around ablation zone. When coated by NiCr/YSZ coating, the combustion process was delayed through isolating and dissipating heat. The ablation range was controlled and the ablation damage was reduced at the same irradiation power. The NiCr/YSZ coating preliminarily realized to improve the burn resistance of ?-TiAl alloy.

Perspectives on Developing Burn Resistant Titanium Based Coatings—An Opportunity for Cold Spraying

“…Further, the YSZ ceramic layer that was prepared using multi-arc ion plating technology acts as the blocking layer. The double-layer coating hardness and the burn-resistant performance were found to be superior to Ti-based materials [27]. The Double-glow plasma surface alloying technology, which is also known as the Xu-Tec process, is a surface alloying technology based on ion nitriding technology that can realize metal elements on the surface of the metal materials [28].…”

“…Laser Cladded(LC) Ti-25V-15Cr-0.2Si High residual stress [13] Laser Solid Forming(LSF) Ti-35V-15Cr High thermal stress [14] Ti-25V-15Cr Dendrites, Voids, Thermal stress [15] Direct Laser Fabrication (DLF) Ti-25V-15Cr Dendrites, Voids, Thermal stress [16] Ti-25V-15Cr-2Al-0.2C Dendrites, Voids, cracks, High oxygen content, and Significant thermal impact [17][18][19][20][21] Double glow plasma surface metallurgy (DG) Ti-Cu, Ti-Cr, Ti-Mo Small coating thickness [27][28][29][30][31][32][33][34][35][36] Plasma spraying Ti, TiZr-YSZ High thermal impact, high porosity, cracks [37][38][39] Electron beam cladding Ti-25V-15Cr-0.2Si Coarse grains, high residual stress, cracks [40,41] High-energy mechanical alloying Ti-Cr, Ti-Cu Small scope of application [42,43] Plating Ti-Cr, Ti-Ni Low bonding strength [44,45] In conclusion, to address the challenge of spontaneous combustion in Ti alloy components, the development of new methods for constructing highly efficient and reliable burn-resistant coatings is imperative. A comprehensive analysis should consider factors such as material selection, deposition techniques, coating parameters, characterization methods, and innovative coating architectures.…”