Data from: Chromium oxide coatings with the potential for eliminating the risk of chromium ion release in orthopaedic implants

Chromium oxide coatings prepared by radiofrequency reactive magnetron sputtering on stainless steel substrates were exposed to Ringer's physiological solution and tested for their electrochemical corrosion stability using an open circuit potential measurement, potentiodynamic polarization, electrochemical impedance spectroscopy and Mott–Schottky analysis. The coatings were found to be predominantly Cr2O3, based on the observation of the dominance of A1gA1g and Eg symmetric modes in our Raman spectroscopic investigation and the Eu vibrational modes in our Fourier transform infrared spectroscopic measurements on the coatings. We investigated for the presence of chromium ions in Ringer's solution after all of the above electrochemical tests using atomic absorption spectroscopy, without finding a trace of chromium ions at the ppm level for coatings tested under open circuit and at the lower potentials implants are likely to experience in the human body. The coatings were further exposed to Ringer's solution for one month and tested for adhesion strength changes, and we found that they retained substantial adhesion to the substrates. We expect this finding to be significant for future orthopaedic implants where chromium ion release is still a major challenge.Raman spectroscopy investigation of chromium oxide coatingThe raw data was generated with a thermo-scientific DXR Raman microscope using the Omnic software that was supplied with equipment.Electronic file for figure 1 Raman Spectra of chromium oxide coatings prepared at various deposition powers and constant oxygen flow rate of 10sccm.pdfFTIR investigation of chromium oxide coatingThe raw data were generated with Nicolet is50 FTIR equipment using the omnic software that was supplied with the machine.Electronic file for figure 2 The FTIR spectrum of chromium oxide coatings deposited on silicon wafer at various deposition powers and constant oxygen flow rate of 10sccm.pdfXPS Survey scan of chromium oxide coatingScienta ESCA 300 spectrophotometer equipped with a monochromatic Al Kα (1486.6 ev) x-ray source were utilised for the measurements.Electronic file for Figure 3 (a) Survey scan.pdfXPS Cr2P doublet for chromium oxide coatingScienta ESCA 300 spectrophotometer equipped with a monochromatic Al Kα (1486.6 ev) x-ray source were utilised for the measurements. The obtained XPS data was analysed with CasaXPS software, Shirkley method was used for the background subtraction and the binding energy calibration was implemented by using the C1s peak taking it as 285eV. A mixture of Gaussian and Lorentzian model was used in the fitting of the spectrumElectronic file for Figure 3 (b) Cr2P doublet.pdfXPS O1S peak for chromium oxide coatingScienta ESCA 300 spectrophotometer equipped with a monochromatic Al Kα (1486.6 ev) x-ray source were utilised for the measurements. The obtained XPS data was analysed with CasaXPS software, Shirkley method was used for the background subtraction and the binding energy calibration was implemented by using the C1s peak taking it as 285eV.Electronic file for Figure 3 (c) O1S peak.pdfStructural characterization of chromium oxide coating using XRDThe raw data were generated with Siemens D5000 X-ray Diffractometer using Diffrac plus XRD commander software supplied with the machineElectronic file for Figure 5 The XRD data for chromium oxide coatings prepared on glass slides at various oxygen flow rates and constant deposition power of 500W.pdfPotentiodynamic polarisation curves of chromium oxide coated and uncoated stainless steel substrates in Ringers solution at 37The experiment was performed with VoltaLab 40 PGZ301 manufactured by Radiometer analytical, France. VoltaMaster 4 software supplied with the equipment was used for data acquisition and analysisElectronic file for Figure 6 Potentiodynamic polarisation curves of chromium oxide coated and uncoated stainless steel substrates in Ringers solution at 37.pdfEIS plots for chromium oxide coated and uncoated stainless steel in Ringers solution at 37 (a) Nyquist plotsThe experiment was performed with VoltaLab 40 PGZ301 manufactured by Radiometer analytical, France. VoltaMaster 4 software supplied with the equipment was used for data acquisition and analysis.Electronic file for Figure 8 EIS plots for chromium oxide coated and uncoated stainless steel in Ringers solution at 37 (a) Nyquist plots.pdfEIS plots for chromium oxide coated and uncoated stainless steel in Ringers solution at 37 (b) Bode plots (Magnitude versus frequency)The experiment was performed with VoltaLab 40 PGZ301 manufactured by Radiometer analytical, France. VoltaMaster 4 software supplied with the equipment was used for data acquisition and analysis.Electronic file for Figure 8 EIS plots for chromium oxide coated and uncoated stainless steel in Ringers solution at 37 (b) Bode plots (Magnitude versus frequency) .pdfEIS plots for chromium oxide coated and uncoated stainless steel in Ringers solution at 37 (c) Bode plots (phase angle versus frequency)The experiment was performed with VoltaLab 40 PGZ301 manufactured by Radiometer analytical, France. VoltaMaster 4 software supplied with the equipment was used for data acquisition and analysis.Electronic file for Figure 8 EIS plots for chromium oxide coated and uncoated stainless steel in Ringers solution at 37 (c) Bode plots (phase angle versus frequency).pdfMott Schottky plots of chromium oxide coatings prepared at different oxygen flow rates in Ringers solution at 37The experiment was performed with VoltaLab 40 PGZ301 manufactured by Radiometer analytical, France. VoltaMaster 4 software supplied with the equipment was used for data acquisition and analysis.Electronic file for Figure 10.Mott Schottky plots of chromium oxide coatings prepared at different oxygen flow rates in Ringers solution at 37.pdfMott Schottky plot of uncoated stainless steel in Ringers solution at 37The experiment was performed with VoltaLab 40 PGZ301 manufactured by Radiometer analytical, France. VoltaMaster 4 software supplied with the equipment was used for data acquisition and analysis.Electronic file for Figure 11. Mott Schottky plot of uncoated stainless steel in Ringers solution at 37 .pdfchromium ion release in Ringers solutionA Perkin Elmer Analyst 300 Atomic absorption spectroscopy facility was used to probe the Ringer's solution from the corrosion test for a determination of chromium ion concentrations released into the solution.Electronic file for Figure 12 chromium ion release in Ringers solution.pdfMeasured crack spacing for coating strained to 20 and 25 percentThe measured crack spacing obtained from substrate straining was analysed statistically using SPSS software to obtained the frequency distribution of the crack spacing. The observed crack distribution was fitted to the normal, lognormal and weibull probability distribution function. The function that gave the best fit was used to calculate the mean crack spacing of the coatings.Electronic file for figure 14 Measured crack spacing for film strained to 20 and 25 percent.pdfFitting of the observed spacing distribution to various distribution functionsThe measured crack spacing obtained from substrate straining was analysed statistically using SPSS software to obtained the frequency distribution of the crack spacing. The observed crack distribution was fitted to the normal, lognormal and weibull probability distribution function. The function that gave the best fit was used to calculate the mean crack spacing of the coatings.Electronic file for figure 15 Fitting of the observed spacing distribution to various distribution functions.pdfcrack spacing frequency of chromium oxide in Ringers solution for 1 monthThe measured crack spacing obtained from substrate straining was analysed statistically using SPSS software to obtained the frequency distribution of the crack spacing for the films exposed to Ringers solution for 1 month. The observed crack distribution was fitted to the normal, lognormal and weibull probability distribution function. The function that gave the best fit was used to calculate the mean crack spacing of the coatings exposed to Ringers solution.Electronic data for figure 16 crack spacing frequency of chromium oxide in Ringers solution for 1 month.pdfObserved spacing distribution at saturation in the chromium oxide films soaked in Ringers solution for 1 monthThe measured crack spacing obtained from substrate straining was analysed statistically using SPSS software to obtained the frequency distribution of the crack spacing for the films exposed to Ringers solution for 1 month. The observed crack distribution was fitted to the normal, lognormal and weibull probability distribution function. The function that gave the best fit was used to calculate the mean crack spacing of the coatings exposed to Ringers solution.Electronic data for figure 17 Observed spacing distribution at saturation in the chromium oxide films soaked in Ringers solution for 1 month.pdfthe change in interfacial shear strength for chromium oxide coatings exposed to Ringers solution for period of one month.Adhesion strength was calculated using the relation adopted from shear-lag model which relate the mean crack spacing, fracture strength and thickness of the coatingElectronic file for Figure 19 showing the change in interfacial shear strength for chromium oxide coatings exposed to Ringers solution for period of one month..pd