Stress influence on interface in plasma-sprayed hydroxyapatite coatings on titanium alloy

Area of Science:

• Biomaterials science
• Materials engineering
• Surface science

Background:

• Hydroxyapatite (HA) coatings are crucial for implant biocompatibility.
• Residual and mechanical stresses significantly impact HA-coated implant performance.
• Understanding stress distribution is vital for improving implant longevity.

Purpose of the Study:

• To investigate macrostresses induced by plasma-spraying in HA coatings and at the implant interface.
• To compare the effectiveness of neutron diffraction and X-ray diffraction for stress analysis.
• To evaluate the impact of plasma-spraying on the stress state of HA coatings.

Main Methods:

• Neutron diffraction for bulk strain distribution analysis.
• Conventional X-ray diffraction for residual stress determination in the HA coating.
• Non-destructive and destructive stress measurement techniques were employed.

Main Results:

• Neutron diffraction showed no significant stress difference between coated and non-coated samples near the interface.
• X-ray diffraction revealed compressive stress within the hydroxyapatite coating.
• Neutron diffraction offers non-destructive analysis of thick coatings, but with a large-gauge volume.

Conclusions:

• Plasma-spraying induces compressive residual stresses in hydroxyapatite coatings.
• Neutron diffraction is suitable for non-destructive bulk stress analysis, while X-ray diffraction is effective for surface/near-surface stress measurements.
• Destructive methods like polishing for X-ray diffraction can potentially alter the measured stress field.