Experimental design of plasma spraying and laser treatment of hydroxyapatite coatings

Production and characterization of plasma-sprayed TiO2–hydroxyapatite functionally graded coatings

“…In fact, it is known from the literature that plasma spraying usually induces a thermal decomposition of HAp, decreasing its crystallinity and giving place to various decomposition products. 4,20,26 As regards the HAp crystallinity, though it is usually acknowledged that a small amount of amorphous HAp may be advantageous at the coating surface, because it may promote profitable physiological activities, a high degree of crystallinity is generally preferable, 27,28 because highly crystalline HAp may create a direct bond with bone in vivo and show low dissolution rates. On the other hand, as regards the CaO, since its content in the feedstock HAp powder was negligible, its presence in the sprayed coatings could be considered as representative of the development of byproducts.…”

“…3 However, atmospheric plasma spraying is nowadays the most commonly used method in the industrial practice. 4 Plasma spraying is widely adopted to obtain HAp coatings onto titanium/titanium alloy implants since it is a well established and cost-effective surface treatment process, 2 nevertheless it has been asserted that the adhesiveness of HAp coatings is relatively weak and decreases in the case of thick coatings, 5 probably due to the mismatch in the coefficients of thermal expansion of HAp and titanium (11.5 × 10 −6 K −1 and 8.9 × 10 −6 K −1 , respectively). 6 In order to solve this problem, Khor et al proposed to create a promising HAp/titanium alloy graded coating.…”

Post-deposition laser treatment of plasma sprayed titania-hydroxyapatite functionally graded coatings

“…7 Recently, laser treatments have been increasingly investigated as an alternative solution, since they are extremely quick and highly localized. [8][9][10][11][12] Their main advantage with respect to traditional thermal treatments is their effectiveness on a limited portion of the substrate-coating system, which makes it possible to treat just the coating or a selected zone of it, without involving (and altering) the substrate. 13 Practical advantages of the laser treatments include generally small treating system, limited manipulations and transportations of the components to be treated, environmental and operative safety, low running cost and energy consumption.…”

Finite Element Methods to Optimize by Factorial Design the Solidification of Cu-5wt%Zn Alloy in a Sand Mold

“…Representing the direct and interactive effects of process parameters through two and three-dimensional plots. If all variables are assumed to be measurable, the response surface can be expressed as follows (Aslan, 2007;Yetilmezsoy et al, 2009;Pierlot et al, 2008;Dyshlovenko et al 2006): y= f x , x , x , …xk…”