Electro-Discharge Machining of Zr67Cu11Ni10Ti9Be3: An Investigation on Hydroxyapatite Deposition and Surface Roughness

Abstract

This study attempts to simultaneously machine and synthesize a biomimetic nanoporous hydroxyapatite coating on the Zr67Cu11Ni10Ti9Be3 bulk metallic glass (BMG) surface. The aim is to investigate and optimize the hydroxyapatite deposition rate and the surface roughness during the electro-discharge coating of Zr67Cu11Ni10Ti9Be3 BMG. Scanning Electron Microscopy (SEM), X-ray powder Diffraction (XRD) and Energy-dispersive X-ray Spectroscopy (EDS) were employed to characterize and analyze the results. Response Surface Methodology using D-optimum custom design approach was utilized to generate the models and optimize the input parameters. A globule nanostructured and nanoporous coating of about 25.2 µm thick, containing mainly Ca, O, and K were ascertained. Further XRD analysis confirmed the deposition of biocompatible oxides (HA, CaZrO3, and ZrO2) and hard ZrC coating on the Zr67Cu11Ni10Ti9Be3 BMG surface. A significant improvement in cell viability was observed in the HA electro-discharge coated BMG specimens. The numerical models for the Hydroxyapatite Deposition Rate (HDR) and Surface Roughness (SR) were developed and experimentally validated using the optimized parameters setting suggested by the software. The achieved average predicted error of 4.94 and 5.09% for the HDR and SR respectively confirmed the excellent reproducibility of the developed models.

Surface modification during hydroxyapatite powder mixed electric discharge machining of metallic biomaterials: a review

“…During EDM process the various intermetallic alloys, biocompatible oxides, and carbides are formed on the coating surface of metallic biomaterial, which [202] Pure graphite/hydrocarbon oil [203] Pure Ti/deionized water [204] Pure Ti/hydrocarbon oil [205] Pure Ti/deionized water [206] Pure Ti/deionized water [210] Pure Ti/deionized water × × √ √ √ × √ × × × Zr-based bulk metallic glass/HAp [212] Pure Ti/hydrocarbon fluid [213] Copper/EDM oil [220] Pure Ti (Grade 2)/deionized water [223] Pure titanium/mineral oil Cu 11 Ni 10 Ti 9 Be 3 /HAp [224] T i [226] Graphite, tungsten, tungsten + copper/deionized water…”

“…When 20 g L −1 of HA powder is employed, the surface becomes a dendritic nanostructured and nanoporous covering (Figure 6(d)). HAp lowers surface roughness by increasing flushing capacity and stabilizing the HAp-EDM process by expanding the machining gap [224]. Micro-HAP (MHAP) and nano-HAP (NHAp) applied to deionized water (DW) in EDM were explained by Yaşar and Ekmekci [220].…”

“…Yaşar et al [220] examined the effect of mixing of micro and nano-HAp powder in dielectric during HAp-EDM of Ti alloy and observed the presence of oxides and carbide of Ti on the coated surface. Al-Amin et al [224] revealed the effect of mixing carbon nanotube (CNT) in dielectric during HAp-EDM of 316L SS and noticed the formation of Cr 2 C, Fe 14 Cr 2 C, Cr 7 C 3 , Fe 5 C 2 , and Fe 7 C 3 compounds due to decomposition of mixed CNT and mineral oil. These compounds improve corrosion resistance, micro-hardness, and wear resistance.…”

“…Surfaces with comparable surface roughness levels may have different topographies.

Figure 6 SEM results of Zr-based BMG processed by changing the HAp amount: (a) no HAp, (b) 5 g L −1 , (c) 15 g L −1 , and (d) 20 g L −1 at constant peak current-8 A and pulse duration-8 μs [224] (reprinted with permission).

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Laser-based additive manufacturing of bulk metallic glasses: recent advances and future perspectives for biomedical applications

“…The strain rate and stresses of the bulk Cu-Zr MGs is indicated by the yellow solid ellipse while the yield strain and strength are of the small MGs is donated by the green square solid. The measured fracture strength and the fracture strain are presented by the blue open diamond [22,39] J o u r n a l P r e -p r o o f yield strength [40] Currently, BMGs are conventionally processed through various metallurgical processing routes like powder metallurgy [41][42][43][44][45][46], rapid cooling of liquid melts [40,[47][48][49], melt spinning [50,51], magnetron sputtering [52][53][54], pulsed laser quenching [55,56], liquid splat quenching [57], electro-discharge machining/coating [58][59][60][61][62][63][64], and thermoplastic forming [65,66]. It has to be noted that, melt spinning and thermoplastic forming are currently well-established BMG processing techniques.…”