Multilayer PPy/HAp coatings on functionally graded 316L lattices for additively manufactured knee implants
Ceramics International, cilt.52, sa.21, ss.37358-37372, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 52 Sayı: 21
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.ceramint.2026.06.222
- Dergi Adı: Ceramics International
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Compendex, INSPEC, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO)
- Sayfa Sayıları: ss.37358-37372
- Anahtar Kelimeler: Additive manufacturing, Coating adhesion, Electrochemical corrosion behavior, Multilayer PPy/HAp coating, Porous 316L stainless steel, Surface engineering
- Süleyman Demirel Üniversitesi Adresli: Evet
Özet
Additive manufacturing (AM) enables porous 316L stainless-steel structures with bone-matching compliance; however, maintaining coating–substrate integrity and stable electrochemical behavior on highly porous load-bearing surfaces remains a critical materials challenge. In particular, establishing a clear relationship between the porosity-controlled microstructure and mechanical strength, while preserving interfacial stability after surface modification, is essential for reliable load-bearing performance. In this study, selectively laser-melted 316L lattices integrating trabecular-like (275-1) and cortical-like (475-2) unit-cell configurations were combined with multilayer polypyrrole/hydroxyapatite (PPy/HAp) coatings to link geometry-driven stiffness control with surface functionalization. Representative geometries were selected via numerical compression analyses and experimentally validated through compression, shear, torsion, adhesion, wettability, fatigue, and immersion-dependent corrosion testing. Reducing porosity from 89% to 67% increased elastic modulus from 340.7 MPa to 17,472 MPa and yield strength from 5.0 MPa to 61.6 MPa, while shear modulus rose from 9.67 to 1740 MPa and torsional rigidity from 336.7 to 1295.3 N m/rad, demonstrating a strong porosity-dependent enhancement in load-bearing capacity and structure–strength scaling behavior. Fatigue evaluation further confirmed that the porous architectures retained their mechanical stability under repeated loading, supporting their suitability for load-bearing implant conditions. The multilayer PPy/HAp coating exhibited strong adhesion up to 2.158 MPa and complete wetting, while 28-day immersion-dependent electrochemical evaluation showed a decrease in Icorr from 245.1 to 46.6 μA/cm2 and an increase in Rp' from 0.065 to 0.385 kΩ cm2, indicating improved interfacial corrosion stability over time. Under a 710 N biomechanical load, the coated porous design increased contact area from 1149 to 2198 mm2 and reduced mean contact pressure from 0.618 to 0.323 MPa, confirming improved load transfer without altering the base alloy.