Mechanical and corrosion properties of Mg68-xZn28+xCa4 (x=0,2,4) metallic glasses
Institute of Engineering Materials and Biomaterials, Silesian University of Technology, Konarskiego 18a St., 44-100 Gliwice, Poland
Metallic amorphous alloys, which consisted of the biocompatible elements such as Ca, Mg and Zn, can be used as potential resorbable materials for short term orthopedic implants [1,2]. The concept of resorbable metallic implants is based on combination of two factors: good bearing capacity, sufficiently high mechanical strength and stable implants geometry, invariable during concrescence of bone, and controllable corrosion rate (dissolution rate). Therefore, the following criteria on Mg-based metallic glass for resorbable implant were chosen: Rc > 160 MPa , H2 ≤ 1ml/h  and Vcorr ≈ 0.01 - 0.1 mm/year . The glass-forming ability (GFA), volume of evolved hydrogen, corrosion rate, compression strength and hardness of Mg68-xZn28+xCa4 (x=0,2,4) metallic glasses were examined. Results of corrosion studies and mechanical properties tests were compared with assumed criteria. Results of corrosion tests showed that the corrosion rate (Vcorr) and the volume of released hydrogen decreased with the increase zinc concentration in the tested alloys. For the Mg66Zn30Ca4 amorphous alloy with a diameter of 2 mm, the highest hardness about 300 HV and the compressive strength about 400 MPa were determined.
Keywords: amorphous magnesium alloys; resorbable metallic glasses, corrosion rate, compressive strength
2019, Vol. 62, nr 6, pp.192-196
Influence of higher and high temperature on anti-corrosive properties of diamond-like carbon coating on S355 steel
Instytut Chemii, Uniwersytet Jana Kochanowskiego w Kielcach, ul. Świętokrzyska 15G, 25-406 Kielce
Influence of higher and high temperature on anti-corrosive properties of a diamond-like carbon coating (DLC), produced by plasma enhanced chemical vapor deposition (PECVD) on S355 steel substrate (S355/DLC), was investigated. Corrosion test of materials was carried out by electrochemical method. Corrosive environment was an acidified sodium chloride solution. It has been demonstrated that the DLC coating effectively protects the S355 steel surface from contact with an aggressive corrosive environment. The thermal treatment was carried out in an atmosphere of hot air at temperatures of 400 or 800 °C. It was found that after thermal treatment at 400 °C the DLC coating partially loses its anti-corrosive properties. Due to changes in the surface structure of the S355/DLC layer its microhardness (HV) increases. However, after heat treatment at 800 °C the carbon coating is destroyed and thus loses its protective effect.
Keywords: S355 steel, diamond-like carbon (DLC) coating, corrosion, microhardness
2019, Vol. 62, nr 6, pp. 197-202