Journal of Thermal Spray Technology

, Volume 27, Issue 8, pp 1302–1321 | Cite as

HVOF Hydroxyapatite/Titania-Graded Coatings: Microstructural, Mechanical, and In Vitro Characterization

  • J. HenaoEmail author
  • M. Cruz-bautista
  • J. Hincapie-Bedoya
  • B. Ortega-Bautista
  • J. Corona-Castuera
  • A. L. Giraldo-Betancur
  • D. G. Espinosa-Arbelaez
  • J. M. Alvarado-Orozco
  • G. A. Clavijo-Mejía
  • L. G. Trapaga-Martínez
  • C. A. Poblano-Salas
Peer Reviewed


The present contribution aimed at exploring the HVOF deposition process of bioactive multilayered HAp/titania composite coatings on Ti-6Al-4V substrates. These coatings can be regarded as functionally graded as the weight fraction of the constituent phases gradually changes layer by layer, from pure titania at the substrate–coating interface to pure HAp at the outer surface of the coating. Microstructural investigations were carried out on the graded coatings using scanning electron microscopy coupled with EDS microanalysis to confirm that the compositional gradient met the initial specifications. On the other hand, the in vitro properties of the coatings were studied in simulated body fluid (SBF) for periods ranging from 1 to 14 days. Moreover, mechanical characterization of both as-sprayed and soaked coatings in SBF was carried out by performing Vickers microhardness measurements through their cross section. The apparent interfacial toughness (KCa) of HAp/titania coatings, which is representative of their interfacial crack initiation resistance, was determined by performing indentation tests at the coating–substrate interface. Fracture toughness of both pure hydroxyapatite and functionally graded coatings was also calculated. The results revealed that the graded coatings produced in this work exhibited good reactivity and mechanical stability after being immersed in SBF indicating their potential for biomedical applications.


bioactivity graded coatings hydroxyapatite thermal spray titania 



The authors gratefully acknowledge the support to the National Science and Technology Council of Mexico “CONACYT” and to its program of “Cátedras” CONACYT (Project Number 848). The authors thank Christian Felix from CIDESI-CONMAD for hardness and fracture toughness measurements, Dr. M. Gutierrez, Eng. René Diaz, and Dr. M. Dehonor for SEM analyses; and Dr. J. Coronel-Hernandez from Universidad Autónoma del Estado de Querétaro for his support on preparing the feedstock powder. The authors gratefully acknowledge to the Mexican laboratory of thermal spray (CENAPROT) for allowing the development of the in vitro tests in their facilities.


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Copyright information

© ASM International 2018

Authors and Affiliations

  • J. Henao
    • 1
    Email author
  • M. Cruz-bautista
    • 1
  • J. Hincapie-Bedoya
    • 1
    • 2
  • B. Ortega-Bautista
    • 1
  • J. Corona-Castuera
    • 1
  • A. L. Giraldo-Betancur
    • 2
  • D. G. Espinosa-Arbelaez
    • 3
  • J. M. Alvarado-Orozco
    • 3
    • 4
  • G. A. Clavijo-Mejía
    • 2
    • 5
  • L. G. Trapaga-Martínez
    • 1
  • C. A. Poblano-Salas
    • 1
  1. 1.CONACyT-CIATEQ A.C.El MarquésMexico
  2. 2.CINVESTAV-Unidad QuerétaroCONACyT-Centro de Investigación y de Estudios Avanzados del IPNQuerétaroMexico
  3. 3.Centro de Ingeniería y Desarrollo Indutrial (CIDESI)QuerétaroMexico
  4. 4.Consorcio de Manufactura AditivaCONMADQuerétaroMexico
  5. 5.Institute of Research for Ceramics–IRCER, UMR 7315 CNRS, Centre Européen de la Céramique (CEC)Université de LimogesLimogesFrance

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