Elsevier

Surfaces and Interfaces

Volume 7, June 2017, Pages 125-133
Surfaces and Interfaces

Aqueous electrophoretic deposition and corrosion protection of borate glass coatings on 316 L stainless steel for hard tissue fixation

https://doi.org/10.1016/j.surfin.2017.03.010Get rights and content

Highlights

Abstract

The present work was essentially concerned with an improvement of the biocompatibility of 316 L stainless steel (316 L SS) by coating its surface by bioactive borate glass layer using electrophoretic deposition (EPD) technique. Suspension of glass particles in double distilled water was used in this study as a coating suspension. The EPD parameters pH, applied voltage, glass concentration and time were optimized. The obtained coated substrates were investigated using FT-IR, X-ray diffraction, SEM/EDX analyses. The optimum conditions applied to obtain smooth, uniform, cracked-free, dense and adhesive layers with even glass particles distribution were achieved at voltage 35 V, pH 7 and 15 min deposition time. Additionally, the in vitro biodegradation was compared applying biochemical and electrochemical corrosion assessment of the developed glass coatings in two biological fluids, SBF (ISO 23,317) and DMEM (ISO 13,485) at body temperature (37 °C). The resulted coated 316 L SS specimens showed good corrosion resistance in both SBF and DMEM solutions at 37 °C using potentiodynamic polarization (PDP) techniques.

Graphical abstract

Schematic illustration of borate glass preparation and its coating on SS steps by EPD process.

Image, graphical abstract
  1. Download : Download high-res image (169KB)
  2. Download : Download full-size image

Introduction

Metallic alloys of titanium, cobalt, magnesium and 316 L stainless steel were used as orthopedic implants due to their high tensile strength, fatigue strength, and fracture toughness. Metallic biomaterials have likely been applied as supporting artificial joints, bone plates, screws and intramedullary nails. Additionally, they have been used for spinal fixations and spacers, external fixtures, pacemaker cases, as well as, they have been employed in artificial heart valves, wires, stents and dental implants [1].

Importantly, 316 L stainless steel alloys were used vastly for human body implants. Although such metal implants are impressively corrosion resistant in many environments, localized corrosion could be faced when subjected to human body fluids. Reducing metallic ions and electrons transport could lead to passive oxide films that hinder corrosion rate. Moreover, some corrosive attacks on stainless steel may occur when subjected to body fluid, whereas, it contains various kinds of corrosive constituents, such as water, dissolved oxygen and large amounts of chloride ions (Cl) beside other electrolytes like bicarbonate and small amounts of potassium, calcium, magnesium, phosphate, sulphate and amino acids, proteins, and plasma. Expectedly, the combined presence of these components results in initiation of some degree of corrosion of metal implants throughout the long period of implantation. As a result, the corrosion products can be very harmful to the human body [2], [3], [4]. The stainless steel common corrosion products, such as nickel, cobalt, chrome and their compounds are known as an allergens [5]. Beyond individual concentrations, a disturbance of the proper behavior of the osteoblast-like bone marrow cells could be expected [5]. Consequently, it is essential to develop techniques to minimize the corrosion products of such implants within the aggressive body environment. Coating metallic implants with bioactive layer has been proposed as a promising approach to overcome such problem. In this context, bioactive glass [6], [7], [8], glass-ceramics [9], [10], [11] free of cracks and phosphate ceramic family as hydroxyapatite have been widely developed as bioactive coatings for metal implants [12], [13], [14] due to their controlled surface reactivity beside bone bonding ability.

Recently, borate glasses have attracted biomedical scientists attention due to their low chemical durability as fast conversion to HA compared to the widely applied silicate 45S5 bioactive glass [15], [16], [17]. Boron among other elements such as nickel, cobalt, chrome and their compounds play the essential roles in many life processes including embryogenesis. The active anti-inflammatory influence of boron containing compounds with little side effects was evidenced by several researchers [18], [19]. Positive effects in bone, brain, inflammation, and hormone function were demonstrated in a previous study [20]. The anti-inflammatory functions of boron with minimum side effects were attributed to the suppression of serine proteases that are released by inflammation-activated white blood cells. Reduced reactive oxygen species, generated during neutrophil's respiratory burst along with T-cell activity suppression and antibody concentrations are additionally effective [15], [21]. Consequently, the boron delivery upon biodegradation of borate glass is of particular interest for biomedical applications [22], [23], [24], [25], [26], [27].

However, research on borate bioactive glass is rather limited [8] while borosilicate glass was reported as coating materials [11]. Reports concerned with the surface of the borate-based glass coatings on load bearing metallic implants are seldom found despite its promising bioactivity.

Various coatings techniques including plasma spraying [10], [28], [29], sol–gel [30], [31], [32], [33], electrophoretic deposition [34], [35], [36], [37], electrochemical deposition, biomimetic process [38], [39], [40], [41], [42] and sputter coating [43], were reported. The bioactive material coatings are considered potential methods for improving the orthopedic devices performance to reduce corrosion and achieve better biocompatibility [4]. Mostly implantable devices are required to exhibit stable long-term performance at the host interface with minimum foreign body reaction [44].

Electrophoretic deposition (EPD) gained considerable attention among biomaterials coating techniques specifically bioactive ones and biomedical nanostructures. Its advantages include short processing time, simple apparatus setup, and few restrictions on substrate shape, requiring no binder burnout as the green surfaces contain negligible organics. It is usually carried out in the two-electrode cell. The mechanism involves two steps of electrophoresis and deposition. Initially, an electric field is applied between two electrodes. The charged particles being suspended in a suitable liquid move towards the oppositely charged electrode constituting the electrophoresis step. The particles accumulation at the deposition electrode creates a relatively compact and homogeneous film and is referred to as the deposition step. Essentially, a stable suspension containing the charged particles is free to move when an electric field is applied in a suitable electrolyte. Dispersion media of organic solvents are preferably used more than water in EPD to avoid the problems of electrolysis and gas evolution. Solutions of high oxidation–reduction potentials like benzene or ketenes could also be used [45]. However, water is preferable avoiding organic media being costly and for environmental impact [45]. Further, a heat-treatment step is essential to eliminate porosity and enhance the deposits density.

The present work aimed to improve the biocompatibility and in turn functionality of 316 L SS alloy through coating its surface with bioactive borate glass layer using EPD technique. Furthermore, the study mainly aimed to perform coating process in the cost-effective and environmental impact aqueous solution, rather than organic solvents. For these purposes, different coating conditions were studied to determine the optimum coating conditions.

Section snippets

Materials

The bioactive borate glass powder in B2O3single bondCaOsingle bondNa2O-MgO system, with the composition shown in Table 1, was prepared by melting process. Reagents grade of H3BO3, CaCO3, and Na2CO3 and MgO were mixed thoroughly and further melted in a platinum crucible at 1050 °C for two h using the electrical furnace. The melted glass was quenched in water to prevent crystallization and achieve the glass frit. Further, it was dried at room temperature and ground using an electrical porcelain ball mill for 2.5 h

Characterization

The particle size of the glass powder was measured by particle size analyzer and SEM image. On the other hand, the density of bulk glass with irregular shape was measured by the Archimedes method, using distilled water as a liquid. The density (D) was calculated by the equation:D=WairL/(WairWliquid)g/cm3.

Where Wair is the weight of the sample in the air, W liquid is the weight of the sample in the liquid and L is the density of the immersion liquid (equal 1 for water).

Fourier transform

Conclusions

The developed borate bioactive glass was successfully prepared and coated onto 316 L SS substrates by the electrophoretic deposition technique in aqueous solution, (green electrolyte), which is a cheap and environmentally desirable solution. The EPD parameters, namely, suspension particle concentrations, applied voltage, pH, and deposition time which control the deposition yield were thoroughly investigated. The optimum parameters were attained at 4 wt% glass level and a potential of 35 V at pH 7

Acknowledgements

The financial support of the present work within National Research Centre, Biomaterials group, Cairo, Egypt is appreciated. The authors acknowledge and thank National Research Centre, Central Labs, Cairo, Egypt for providing measurement facilities applied in this research.

References (54)

  • W.-T. Jia

    Elution characteristics of teicoplanin-loaded biodegradable borate glass/chitosan composite

    Int. J. Pharm.

    (2010)
  • J. Ning

    Synthesis and in vitro bioactivity of a borate-based bioglass

    Mater. Lett.

    (2007)
  • M. Erol

    Copper-releasing, boron-containing bioactive glass-based scaffolds coated with alginate for bone tissue engineering

    Acta Biomater.

    (2012)
  • M. Monsalve

    Bioactivity and mechanical properties of plasma-sprayed coatings of bioglass powders

    Surf. Coat. Technol.

    (2013)
  • R.A. Surmenev

    A review of plasma-assisted methods for calcium phosphate-based coatings fabrication

    Surf. Coat. Technol.

    (2012)
  • S. Pourhashem et al.

    Double layer bioglass-silica coatings on 316 L stainless steel by sol–gel method

    Ceram. Int.

    (2014)
  • K. Cheng

    The interfacial study of sol–gel-derived fluoridated hydroxyapatite coatings

    Surf. Coat. Technol.

    (2005)
  • C. Garcia et al.

    Bioactive coatings prepared by sol–gel on stainless steel 316 L

    J. Non-Cryst. Solids

    (2004)
  • R. Rojaee

    Electrophoretic deposition of bioactive glass nanopowders on magnesium based alloy for biomedical applications

    Ceram. Int.

    (2014)
  • A. Boccaccini

    Electrophoretic deposition of carbon nanotube–ceramic nanocomposites

    J. Eur. Ceram. Soc.

    (2010)
  • I. Corni et al.

    Electrophoretic deposition: from traditional ceramics to nanotechnology

    J. Eur. Ceram. Soc.

    (2008)
  • F.-H. Lin

    The growth of hydroxyapatite on alkaline treated Ti–6Al–4 V soaking in higher temperature with concentrated Ca 2+/HPO 4 2− simulated body fluid

    Mater. Chem. Phys.

    (2004)
  • H.I. Mohammed et al.

    Noble metals role in autocatalytic phosphate coatings on TAV alloys. I. Ag functionalization of autocatalytic phosphate deposition on TAV alloys

    . Surf. Coat. Technol.

    (2015)
  • L.-l Tan

    Preparation and characterization of Ca-P coating on AZ31 magnesium alloy

    Trans. Nonferrous Metals Soc. Chin.

    (2010)
  • C.-Y. Zhang

    Preparation of calcium phosphate coatings on Mg-1.0 Ca alloy

    Trans. Nonferrous Metals Soc. Chin.

    (2010)
  • D.R. Merrill

    Materials considerations of implantable neuroengineering devices for clinical use

    Curr. Opin. Solid State Mater. Sci.

    (2014)
  • L. Besra et al.

    A review on fundamentals and applications of electrophoretic deposition (EPD)

    Prog. Mater Sci.

    (2007)
  • Cited by (27)

    • Enhanced antibacterial and corrosion resistance properties of Ag substituted hydroxyapatite/functionalized multiwall carbon nanotube nanocomposite coating on 316L stainless steel for biomedical application

      2019, Ultrasonics Sonochemistry
      Citation Excerpt :

      Metallic bioimplant materials are mainly used in artificial bone plates, intramedullary nails, joints and screws due to their fracture toughness, high tensile and fatigue strength. Moreover, they are employed for external fixtures, spinal fixations, spacers, pacemaker cases, artificial heart valves, stents, wires and dental implants due to their excellent hemodynamics, durability, strength and low thrombogenicity [1,2]. Also, artificial metallic implant has increasing demand due to frequently occurring fracture, age-related bone defects and bone degradation.

    • Comparative study of tribological properties of carbon fibers and aramid particles reinforced polyimide composites under dry and sea water lubricated conditions

      2019, Wear
      Citation Excerpt :

      Hence, the tribological performance of PI composites under lubricated conditions was better than that under dry conditions. However, corrosion of Cu indicated by arrows occurred in the region where tribofilm was absent (Fig. 5d) [30,32,33]. The corrosion of Cu seemed serious when sliding against PI/AP/PTFE, it was believed that sea water could remove the wear debris and inhibit tribofilm formation due to the weak stress between aramid particles and Cu.

    • Tuning the tribofilm nanostructures of polymer-on-metal joint replacements for simultaneously enhancing anti-wear performance and corrosion resistance

      2019, Acta Biomaterialia
      Citation Excerpt :

      In comparison to the data obtained from the corrosion-only condition, the zero-current potential under the sliding condition shifts towards the cathodic direction and the current is higher due to the superimposed effect of wear and corrosion. This phenomenon has been identified in the works of Soltis et al. [52] and Rashidy et al. [53] and was attributed to mechanical destruction of the passive layer. In comparison to the sliding against neat PEEK, the zero-current potential of the steel when rubbed with CF/PEEK shifts towards the anodic direction indicating mitigated corrosion.

    • Significance of an in-situ generated boundary film on tribocorrosion behavior of polymer-metal sliding pair

      2018, Journal of Colloid and Interface Science
      Citation Excerpt :

      However, a significant cathodic shift of the corrosion potential and an increase in the currents were observed when sliding took place with PEEK/SCF or PEEK/SCF/h-BN. This is an indication of the destruction of the passive state and activation of the steel surface in the wear scar due to sliding [50,51]. Nevertheless, in comparison to the sliding with PEEK/SCF/h-BN, the zero-current potential shifted cathodically by about 70 mV/SCE when sliding took place with PEEK/SCF.

    View all citing articles on Scopus
    View full text