Abstract
Air plasma spray technique (APS) is widely used in the biomedical industry for the development of HA-based biocoatings. The present study focuses on the influence of powder homogenization treatment by high-energy ball milling (HEBM) in developing a novel hydroxyapatite-barium titanate (HA/BT) composite coating deposited by APS; in order to compare the impact of the milling process, powders were homogenized by mechanical stirring homogenization (MSH) too. For the two-homogenization process, three weight percent ratios were studied; 10%, 30%, and 50% w/w of BT in the HA matrix. The phase and crystallite size were analyzed by X-ray diffraction patterns (XRD); the BT-phase distribution in the coating was analyzed by backscattered electron image (BSE) with a scanning electron microscope (SEM); the energy-dispersive X-ray spectroscopy (EDS) analysis was used to determinate the Ca/P molar ratio of the coatings, the degree of adhesion (bonding strength) of coatings was determinate by pull-out test according to ASTM C633, and finally the nanomechanical properties was determinate by nanoindentation. In the results, the HEBM powder processing shows better efficiency in phase distribution, being the 30% (w/w) of BT in HA matrix that promotes the best bonding strength performance and failure type conduct (cohesive-type), on the other hand HEBM powder treatment promotes a slightly greater crystal phase stability and crystal shrank conduct against MSH; the HEBM promotes a better behavior in the nanomechanical properties of (i) adhesive strength, (ii) cohesive/adhesive failure-type, (iii) stiffness, (iv) elastic modulus, and (v) hardness properties.
Highlights
In recent decades, biomaterials research has focused on the improvement of implant design features to accelerate bone healing as well as to provide support to the affected part of the human body
The histograms obtained confirm that the average particles sizes of the commercial powders are around 47 ± 7 μm for HA and 201 ± 6 nm for barium titanate (BT)
Discussion oped by high-energy ball milling (HEBM) powder processing showed the highest values in this behavior, which is According to the standards the mechanical strength behavior, phase degradation and mainly due to a greater effect of BT distribution in the HA matrix and the greater mechancrystallinity of coatings is some of the main properties required for the development of ical interlocking by that powder processing, the identified maximum
Summary
Biomaterials research has focused on the improvement of implant design features to accelerate bone healing as well as to provide support to the affected part of the human body. Surface modification in biomaterials has been more common in commercialized processes because the implant is the first part that interacts with the host tissue. Unlike the other calcium phosphates, the HA is a natural bioceramic, it is the major component of bone tissue and had a low solubility in contact with body fluids. In this manner, HA has gradually become an indispensably bioceramic used as a coating to promote a good biological response and a corrosion barrier for metallic substrates [11,12,13,14,15,16]
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