Abstract Hydroxyapatite (HA) coatings, reinforced with varied concentration (0–2 wt%) of Graphene nanoplatelets (GNPs) have been deposited on titanium alloys (Ti–6Al–4V) substrate using atmospheric plasma spraying. Present work studies the effect of GNP concentration on the electrochemical behaviour of the HA coatings in simulated body fluid (SBF). The HA coating exhibited 15% porosity, whereas reinforcement of 1 wt% GNPs in HA (HA-1G) shows 13% porosity, further addition of 2 wt% GNPs in HA reduced the porosity to 10%. Reduction in porosity was achieved as GNPs easily accessed the inter-lamellae to fill the gaps at inter splat region and minimized the occurrence of post-plasma spray defects such as porosity, voids, microcracks etc. These consequences nextward resulted in the significant enhancement in corrosion resistance of the matrix. HA-1G displayed a significant reduction by 67% in the corrosion rate in SBF solution, while this reduction came to 87% for HA-2G coatings. Randomly oriented wrinkles in the GNPs after corrosion process and their hydrophobic nature effectively hindered the SBF infiltration into the coating and resisted their movement towards the underlying substrate. This in turn improved the overall corrosion resistance of the system.

中文翻译：

---

等离子喷涂石墨烯纳米片增强羟基磷灰石复合涂层在模拟体液中的腐蚀行为

摘要 使用大气等离子喷涂在钛合金 (Ti-6Al-4V) 基材上沉积了用不同浓度 (0-2 wt%) 的石墨烯纳米片 (GNP) 增强的羟基磷灰石 (HA) 涂层。目前的工作研究了 GNP 浓度对模拟体液 (SBF) 中 HA 涂层电化学行为的影响。HA 涂层表现出 15% 的孔隙率，而 HA (HA-1G) 中 1 wt% GNP 的增强显示出 13% 的孔隙率，在 HA 中进一步添加 2 wt% GNP 将孔隙率降低到 10%。由于 GNP 很容易进入层间层以填充内部 splat 区域的间隙，并最大限度地减少了等离子喷涂后缺陷的发生，例如孔隙率、空隙、微裂纹等，从而减少了孔隙率。这些后果随后导致腐蚀的显着增强矩阵的电阻。HA-1G 在 SBF 溶液中的腐蚀速率显着降低了 67%，而 HA-2G 涂层的腐蚀速率降低了 87%。腐蚀过程后 GNP 中随机取向的皱纹及其疏水性有效地阻碍了 SBF 渗透到涂层中并阻止它们向下面的基材移动。这反过来又提高了系统的整体耐腐蚀性。