Different Morphology of Hydroxyapatite Coatings on Titanium by Electrophoretic Deposition

Abstract

The objective of the present study was to define the optimal conditions and characterizations of hydroxyapatite (HA) coatings on titanium by electrophoretic deposition (EPD). The EPD processing parameters, such as deposition time, HA concentration level in the suspension, and applied voltage are experimentally determined. A good packing, crack-free and uniform HA coating on titanium was prepared. Then the coatings were sintered at 800 °C for 2 h. The sintered coatings presented a very homogeneous polycrystalline structure free of cracks. The results show that the application of EPD is an effective method in obtaining HA coatings with good properties.

Calcium orthophosphate coatings, films and layers

“…Since electrophoretic deposition is designed to apply materials to any electrically conductive surface, it is used to achieve calcium orthophosphate coatings, layers or films on various metallic substrates only (Ducheyne et al 1986, 1990; Zhitomirsky and Gal-Or 1997; Han et al 1999a; Zhitomirsky 2000; Wei et al 2001; Stoch et al 2001; Wang et al 2002; de Sena et al 2002; Ma et al 2003a; Mondragón-Cortez and Vargas-Gutiérrez 2004; Meng et al 2006, 2008). This approach is especially useful for porous metallic structures.…”

“…An applied electric field is the driving force of the deposition (Besra and Liu 2007). Depending on the mode and sequence of voltage applied, electrophoretic deposition of calcium orthophosphates can be carried out at either constant (Meng et al 2006) or dynamic (Meng et al 2008) voltage.…”

“…The surface morphology of the electrophoretically deposited calcium orthophosphate coatings was found to depend on applied voltage (Mondragón-Cortez and Vargas-Gutiérrez 2004), deposition time (Mondragón-Cortez and Vargas-Gutiérrez 2004) and powder concentration (Meng et al 2006), namely, at 200 V, the deposited particles had dimensions within 0.20 to 0.35 μm; at 400 V, the particle size range increased up to 0.35 to 0.80 μm and at 800 V, the particle size range increased up to 0.80 to 1.20 μm. Furthermore, increasing voltages resulted in increasing of the amount of deposited calcium orthophosphates.…”

“…At higher HA concentrations, the coatings became uniform and crack free, and there was less agglomeration. At very high concentrations of HA, many cracks were found (Meng et al 2006). These results indicate that powder concentration, deposition time and applied potential have a significant effect on the coating morphology.…”

Calcium phosphate‐based coatings on titanium and its alloys

“…Using dynamically applied voltage, an electrophoretic method was developed to produce a gradient structure in which the part of the layer attached to the substrate is dense, while the outer layer is porous 130. Electrophoretic deposition of HA powders on titanium was carried out in the range of 0–200 V with three increments: 0–10 V at a rate of 0.0333 V/s followed by a voltage of 10–50 V at a rate of 0.1 V/s and final voltage of 50–200 V at a rate of 1 V/s.…”