Magnesium and its alloys are interesting materials for biodegradable implant applications. Magnesium alloys have very good strength properties, they are lightweight, but their main disadvantage is a low corrosion resistance in the physiological environment. Various modifications of a Mg alloys surface by deposition of different coatings are used to prevent untimely dissolution. The article presents the investigation results of a thin ZnO coating deposited on a MgCa2Zn1Gd3 alloy by means of the magnetron sputtering method. The studies include: scanning electron microscope observation of the ZnO surface, X-ray phase analysis, surface roughness measurement in atomic force microscopy, the microhardness test and potentiodynamic corrosion resistance test in the Ringer solution at 37°C. It was found that the ZnO coating is compact and continuous. It increases the hardness of the MgCa2Zn1Gd3 alloy and also improves its corrosion resistance. The corrosion potential is shifted slightly towards the positive values from -1.52 V to -1.50 V for the alloy with the ZnO coating.
Zr-based bulk metallic glasses attract the attention because of their good mechanical properties and glass-forming ability. A laser welding process has been applied to increase the capability of using amorphous materials in the industry. The plates of Zr₅₅Al₁₀Ni₅Cu₃₀ alloy were produced by die pressure casting method and welded by the TruLaser Station 5004. X-ray analysis and microscopic observation provided information about the structure and morphology of the cross-section of weld on the boundary of the heat affected zone and the fusion zone. Nanohardness and reduced Young modulus of the particular heat affected zone, fusion zone, and parent material were examined with Hysitron TI950 Triboindenter and with the Berkovich indenter. The presence of the amorphous and amorphous-crystalline phases was confirmed by related tests. The detailed topographic analysis revealed that the heat affected zone demonstrated a slight roughness characteristic of the crystalline phase and a smooth surface in the fusion zone. The main value of the nanohardness of particular weld zones has the similar order of magnitude. In turn, Er value is restricted in the range of 105.76-108.80 GPa. The main goal of this work is to present the structure and chosen nanomechanical properties of the Zr₅₅Cu₃₀Ni₅Al₁₀ laser weld.
The corrosion behavior of the bulk glassy samples of Ca₆₅Mg₁₅Zn₂₀ alloy was studied by electrochemical measurements and immersion tests in a simulated body fluid, physiological fluid, and the Ringer solution. The results of immersion show that the volume of H₂ evolved after 2 h in simulated body fluid (29.8 ml/cm²) is the highest in comparison with the results of measurements conducted in physiological fluid (11.3 ml/cm²) and the Ringer solution (7.4 ml/cm²). The electrochemical measurements indicated a shift of the corrosion potential (E_{corr}) from -1.58 V for plate tested in a physiological fluid to -1.56 V and -1.54 V for samples immersed in the Ringer solution and simulated body fluid, adequately. The X-ray diffraction measurements were used to determine composition of corrosion products. The corrosion products were mainly identified to be calcium carbonates and calcium/magnesium hydroxides.
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.