A Novel Bioactive Ceramic Coating for Improved Fixation of Orthopedic Implant
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1236-SS08-17
A Novel Bioactive Ceramic Coating for Improved Fixation of Orthopedic Implant Ahmed El-Ghannam and Aniket Department of Mechanical Engineering and Engineering Science, The University of North Carolina at Charlotte, Charlotte, NC 28223 ABSTRACT
Electrophoretic deposition (EPD) coating of medical grade Ti-6Al-4V substrate with a novel silica-calcium phosphate nano-composite (SCPC) in the particle size range 50 nm-5 ȝP has been described. The influence of EPD parameters and thermal treatment on the coating homogeneity, thickness and adhesion strength has been studied. SEM analyses showed that EPD carried out in 5% (w/v) SCPC/ethanol suspension at 50 V produced a homogeneous coating on passivated Ti alloy discs. Tensile tests carried out to evaluate the adhesion strength at the ceramic/metal interface showed that the SCPC coating layer developed adhesion strength of 47 ± 4 MPa with Ti alloy after thermal treatment at 800 ºC for 1 hr. SEM – EDX analyses of the fracture surface revealed that the presence of SCPC layer on the surface of the Ti alloy indicating high interfacial stability. Upon immersion of the SCPC-coated Ti alloy substrate in PBS, a surface biological hydroxyapatite layer was deposited suggesting bone bonding ability. The successful coating of SCPC on the Ti-6Al-4V has the potential to stimulate rapid fixation and lower stress shielding by enhancing the bone bonding ability of the implant. INTRODUCTION
Tissue integration between bone and orthopedic implant is essential for implant fixation and longevity. Bioactive ceramic coating has been applied as a mean of improving the in vivo performance of orthopedic and dental load-bearing implants. Traditionally, coatings for Ti alloys have been mainly produced from hydroxyapatite (HA) employing plasma spraying [1, 2]. The limitations in the use of HA apatite coating arises either due to the instability at the ceramic/metal interface or reduced bioactivity because of high processing temperatures [3, 4]. Silica-calcium phosphate nanocomposite (SCPC) is a novel bioactive resorbable ceramic that has the ability to bond to bone and expedite bone formation [5-7]. Moreover, SCPC has demonstrated superior mechanical properties and resorbability than hydroxyapatite or bioactive glass [5, 8, 9]. The objective of the present research is to coat the surface of medical grade Ti6Al-4V implants with SCPC particles using electrophoretic deposition (EPD). The adhesion strength between the ceramic and metal is optimized by thermal treatment. Moreover, the interaction of SCPC coated Ti implants with physiological solution has been studied.
EXPERIMENT Zeta potential and SCPC coating SCPC50 containing 50/50 weight ratio of calcium hydrogen phosphate/silica components was prepared following the method reported in the literature [5]. The zeta potential of SCPC50 was determined by measuring the electrophoretic mobility of the bioactive ceramic particles in pure ethanol following the same procedures reported earlier [10]. Prior to EPD coating, the surface of Ti alloy dis
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