Preparation of adherent HA coating on sodium silicate treated carbon/carbon composite by induction heating deposition and hydrothermal treatment techniques

Abstract

An adherent hydroxyapatite (HA) coating was deposited on sodium silicate treated carbon/carbon composites (ST-C/C) through the induction heating deposition technique and the hydrothermal process. The sodium silicate modified C/C surfaces have been characterised by X-ray photoelectron spectroscopy. It demonstrates that the C/C surfaces can be bonded to the sodium silicate. Besides, the phase compositions and morphology of the coatings on ST-C/C were identified by X-ray diffraction, scanning electron microscopy (SEM) and energy dispersive spectroscopy. The final coating consists of dense rectangular HA crystals, which agglomerate and follow the outline of the monetite crystals. Scratch tests show that HA coating on ST-C/C is not scraped off until a shear stress of 43·2 MPa. Cross-sectional observation by SEM shows a strong adhesive interface formed between the HA coating and the ST-C/C substrate. Images from the scratch tracks display that the coating materials are squashed without fracturing inside or at the border of the tracks until the failure point of the coating.

Keywords:

• CARBON/CARBON COMPOSITE
• BIOACTIVE
• HYDROXYAPATITE
• COATING
• INDUCTION HEATING
• HYDROTHERMAL TREATMENT