Improving bond strength and deposition efficiency of ceramic coatings via low pressure cold spraying: A study on hydroxyapatite coatings with Cu-Zn blends

• Published in: Surface & coatings technology Vol. 494; p. 131430
• Main Authors: Behera, Ajay Kumar, Mantry, Sisir, Roy, Sudesna, Pati, Soobhankar
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 30.10.2024
• Subjects: Bonding mechanism; Computational fluid dynamics; Coupled Eulerian Lagrangian; Hydroxyapatite-Cu-Zn composite coatings; Low pressure cold spray; Tamping; Coupled Eulerian Lagrangian; Computational fluid dynamics; Tamping; Hydroxyapatite-Cu-Zn composite coatings; Bonding mechanism; Low pressure cold spray
• ISSN: 0257-8972
• DOI: 10.1016/j.surfcoat.2024.131430

This study presents Low Pressure Cold Spraying (LPCS) method for ceramic coatings, aimed at enhancing efficiency and elucidating bonding mechanisms. It focuses on the deposition of ceramic coatings using LPCS, with hydroxyapatite (HA) on 316L stainless steel (SS) as an illustrative example. Despite the advantages of LPCS, retaining HA particles has proven challenging, resulting in thin coatings (11.09 ± 2.56 μm) with low bonding strength (1.80 ± 0.19 MPa). To address this issue, a composite coating strategy was developed by blending 20 wt% Cu and Zn powder with 80 wt% HA. This approach significantly improved coating properties, achieving enhanced bonding strength (33.70 ± 1.13 MPa), deposition efficiency (27 %), and hardness (136.30 ± 2.45 HV) compared to pure Cu-Zn coatings. Numerical simulations were conducted to interpret these experimental results, indicating that blending metal with HA improves deposition efficiency, bonding strength, and hardness. In HA coatings, particles fragment into submicron grains and embed into the substrate through mechanical interlocking (MI), with shockwave-induced bonding strengthening subsequent layers. For Cu-Zn coatings, bonding occurs through MI and adiabatic shear instability (ASI). In HA-Cu-Zn coatings, high-velocity HA particles and Zn particles enhance bonding further through in-situ tamping. An overview of hydroxyapatite (HA), Cu-Zn, and blended HA-Cu-Zn powders impacting a 316L stainless steel (SS) substrate at various impact velocities and temperatures, highlighting both the microstructure and the numerical simulation of the resulting coatings. [Display omitted] •Developed HA-Cu-Zn composite coating on 316L stainless steel substrate using low-pressure cold spray (LPCS) technique.•Achieved improved HA coating with Cu-Zn: 18x thickness, 16x bonding strength, 3x deposition efficiency, and 4x hardness.•Adiabatic shear instability, mechanical interlocking, and in-situ tamping effects enhanced hardness and bonding strength.