The adhesion strength and residual stress of colloidal-sol gel derived β-Tricalcium-Phosphate/Fluoridated-Hydroxyapatite biphasic coatings

Adhesion of sol–gel derived hydroxyapatite nanocoatings on anodised pure titanium and titanium (Ti6Al4V) alloy substrates

“…The residual thermal stress in the anodised layer and HA coating were estimated from: where E f is the Young's modulus and ν f is Poisson's ratio of HA (using ν f =0. 22), ΔT is the difference between the treatment temperature and ambient and α is the thermal expansion coefficient of the coating (α f =9.4×10 −6°C−1 for TiO 2 [14] and α f =10×10 −6°C−1 for HA [26]) and substrate (α s = 9.9× 10 −6°C−1 for cp Ti and α s =9.5×10 −6°C−1 for Ti6Al4V [27]). As a first-order approximation, the thermal stress of the HA coatings on anodised substrates was taken as the superposition of the calculated stress components for each individual layer.…”

Calcium orthophosphate deposits: Preparation, properties and biomedical applications

“…With further drying and heat treatment, the gel is then converted into dense ceramic or glass materials [411]. The deposited gels create coatings, films and layers, which commonly are put down using dip coating [412][413][414][415][416][417][418][419][420][421][422][423][424][425][426][427]; however, other deposition techniques such as spraying or spin coating [415,[427][428][429] are used as well (the details of these techniques are given below).…”

“…To improve their properties, the coated substrates are annealed at temperatures of 400 -1000 °C[380,[412][413][414][415][416][417][418][419][420][421][422][423][424][425][426][427][428][429]. Depending upon both the Ca/P ratio and the calcining temperature, different CaPO 4 compounds are obtained.…”

“…Biphasic deposits, in which particles of one type of CaPO 4 were embedded into a continuous coating of another type of CaPO 4 , could be prepared as well(Fig. 17)[420]. In order to improve the bond strength between the deposits and substrates, an intervening layer of another compound might be applied prior the sol-gel Since biomimetics (synonyms: bionics, biomimicry) seeks to apply biological methods and systems found in nature, biomimetic deposition appears to be a method whereby a biologically active bone-like apatite deposits are formed on substrates by immersion in various simulating solutions, such as Hank's balanced salt solution (HBSS), PBS or SBF[37, 39, 51, 56, 68-71, 324, 327, 431-443].…”

In Vitro Dissolution, Microstructural and Mechanical Characterizations of Microplasma‐Sprayed Hydroxyapatite Coating

“…There are many methods reported for preparation of HAp and/or HAp composite coatings including their in vitro and in vivo testing . These include the conventional macroplasma spraying (MAPS), microplasma spraying (MIPS), laser‐assisted processes, other thermal spraying techniques, sputtering, electrophoretic deposition (EPD) techniques, sol–gel (SG)‐derived techniques, biomimetics, electrohydrodynamic atomization (EHDA) spraying, and dip/slurry coatings …”