Sulaiman, Wan Ruzaini Wan
(2014)
Effect Of Stand-Off Distance And Plasma Current On The
Properties Of Hydroxyapatite Coatings Produced By Plasma
Spray.
Masters thesis, Perpustakaan Hamzah Sendut.
Abstract
Plasma sprayed hydroxyapatite (HA) coatings on metallic implants for
biomedical applications are attracted significant researchers interest due to accelerated
rate of bone bonding that occurs following their implantation. This present work aims to
produce plasma sprayed HA coatings with varying spray parameters (i.e.; stand-off
distance, SOD and plasma current, PC) in order to control the coatings crystallinity. The
substrate used is 316L stainless steel. Five SODs were selected i.e. 80 mm, 100 mm, 120
mm, 140 mm and 160 mm combined with two different PCs (500 A and 600 A),
respectively. The coatings then divided into two groups (as sprayed and heat treated).
Both coating was subjected to in vitro test through immersion in SBF solution up to 28
days to determine their bioactivity. The coating properties before and after immersion in
SBF were analyzed using FESEM and XRD. The analysis showed coatings morphology
consists of type III, V and VIII splats with lamella and non-lamella structures. The
crystallinity of as-sprayed coatings is in vicinity of 50%. However, the crystallinity
increases more than 90% after heat treatment process. The in vitro analysis proved that
the highest apatite layer precipitations on surface with coatings surface was from the assprayed
coatings rather than the one being heat treated. Therefore, the quality of HA
coating via plasma spray coating technique can be modified through the suitable
combination is at SOD 120 mm and PC 600 A.
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