Corrosion and corrosion-fatigue behavior of cp-Ti and Ti–6Al–4V laser-marked biomaterials

Abstract

The aim of this work was to determine the influence of laser surface modification treatments on mechanical and electrochemical behavior in Ti and Ti-6Al-4V implants. For each metal, different samples were laser modified simulating the markings according to the international requirements. (It is necessary in each metallic biomaterial to mark the serial, batch and company numbers.) Microstructural changes produced by this treatment were observed: (a) the melting zone with small grain sizes and martensitic structures in above-mentioned metals and (b) the heat-affected zone (HAZ) with alpha phase in cp-Titanium with bigger grain sizes and Widmanstatten structure in Ti-6Al-4V. Positive tensile residual stress was determined by means X-ray analysis in the zones marked by laser. Furthermore, corrosion behavior was studied in a simulated body fluid at 37°C. Pitting was observed in different zones near the HAZ and the results showed a decrease of the corrosion resistance in the laser treated samples. Residual stresses and the martensitic microstructures favoured the decrease of the corrosion-fatigue life around 20% of both metals under physiological conditions.

Corrosion resistance and surface characterization of miniscrews removed from orthodontic patients

“…The open circuit potential (OCP) is defined as the potential of an electron conducting material immersed in an electrolytic ion-conducting medium; 25 and is obtained when the electrodes in open circuit achieve a relative electrolytic stabilisation with little variation of the potential with time; it depends on the environment of the test and the exposure time. 25 The potential stabilisation in the present study was seen within approximately 11 minutes in both groups, which is lower than in other studies that reported the potential stabilisation after 20 minutes, 5 60 minutes, 22,23,25,26 120 minutes 24 and 250 minutes 21 of keeping the electrodes in open circuit.…”

“…One of the parameters to determine the biocompatibility of a material is its corrosion resistance after insertion in the body, and the potentiodynamic polarisation test is one of the most widely used methods to test it. 21 Potentiodynamic polarisation can be performed with two 21,22 or three electrodes, 5,6,[23][24][25][26] as performed in the present research. In the system of three electrodes, the current is directed from the working electrode to the counter electrode while the potential is measured between the working and reference electrodes.…”

A review of the surface modifications of titanium alloys for biomedical applications

“…It is reported that the laser-treated surface has high purity and showed enough surface roughness for good osteointegration and had a regular pattern of micro pores with an interval of 10-12 μm, a diameter of 25 μm and a depth of 20 μm. Gill et al 51 studied the influence of laser surface modifications on the mechanical and electrochemical behaviour of Ti and Ti6Al4V implants. When laser modification was carried out for each metal, the microstructural changes were observed: a) melting zone with small grain size and martensitic structures in aforementioned metal and b) the heat-affected zone (HAZ) with a-phase in CP Ti with a higher grain size and Widmanstatten structure in Ti6Al4V.…”

Fracture and Fatigue of Titanium Narrow Dental Implants: New Trends in Order to Improve the Mechanical Response

“…On the other hand, the strain to fracture was lower for the Ti alloy and cold-worked Ti. Ti-15%Zr presented a significantly higher value of strain compared to the cold-worked Ti [13,14,15,16,17,18,19,20]. Consequently, the cold-worked Ti presented a lower value of toughness, without any effects on other properties such as the biocompatibility or corrosion resistance of cp-Ti.…”