Table 5.
Summary of bioactive oxide coatings.
| Coating | Coating method | Ref. | Post-treatments | Phase | Influencing factors in bioactivity |
|---|---|---|---|---|---|
| TiO2 | Solution precursor plasma spray process | [234] | Chemically treated in 5M NaOH solution at 80 °C | Rutile | Formation of Ti-OH groups |
| Sol-gel | [235] | none | Anatase | Surface topography; charge; charge density | |
| [222] | 450 °C, 2 h | Anatase | Abundant Ti-OH groups and negatively charged surfaces | ||
| [223] | Heat-treatment | Anatase | Crystal structure: anatase show more ability to induce apatite formation in SBF than rutile | ||
| Plasma spraying & plasma immersion ion implantation (PIII) | [236] | Hydrogen incorporation by PIII | Rutile (bulk) & anatase (surface) | Combination of nanostructure and hydrogen incorporation can endow the coating with bioactivity | |
| Cathodic electrolytic deposition | [237] | None | Anatase (subcrystalline) | Crystal structure | |
| Below 300 °C | Anatase | ||||
| Above 500 °C | Rutile | ||||
| Anodic oxidation | [238] | H2SO4 and Na2SO4 solutions | rutile or rutile/anatase | Crystal structure: amorphous titania cannot induce apatite formation in SBF solution | |
| CH3COOH and H3PO4 solutions | amorphous titania | ||||
| ZrO2 | Plasma spraying | [219,224] | None | Tetragonal (CaO-ZrO2) | Nanostructured surface; crystal structure |
| None | Monoclinic (undoped ZrO2) | ||||
| Cathodic arc deposition | [239] | None | Tetragonal (undoped ZrO2) | Nanostructured surface | |
| Micro-arc oxidation | [225,227] | None | Monoclinic and small amount of tetragonal ZrO2 | Basic Zr-OH group | |
| NaOH treatment | |||||
| [226] | Ultraviolet (UV) irradiation | Monoclinic and small amount of tetragonal ZrO2 | |||
| SiO2 | Sol-gel | [222] | Heat-treatment at 400 °C for 2 h | amorphous silica | Silanol group (Si-OH) |