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Impact of Zn and Ca on dissolution rate, mechanical properties and GFA of resorbable Mg–Zn–Ca metallic glasses

Nowosielski R., Cesarz-Andraczke K.

Archives of Civil and Mechanical Engineering

2018

Vol. 18, no. 1

1--11

This article presents investigations utility of Mg-based metallic glasses for resorbable orthopedic implants. Exploration of biocompatible Mg–Zn–Ca alloys in order to determine Zn and Ca optimum concentration were conducted, based on three criteria: sufficiently high GFA (glass forming ability), sufficiently high tensile strength, microhardness and the suitable dissolution rate (corrosion rate) in Ringer's solution. Fulfillment of these criteria should ensure bone union before implant dissolution. The optimatization of Ca and Zn concentration in the range of 4–6 at.% Ca and 28–32 at.% Zn was executed. The samples in form of ribbons (0.02–0.05 mm thickness) and rods (about diameter up to 4 mm) with amorphous structure were produced. These investigations allowed to determine the GFA. The optimal results for Mg66Zn30Ca4 and Mg64Zn32Ca4 alloys: tensile strength: 191–166 MPa, microhardness: 291–263 HV and volume of released hydrogen 0.04–0.12 ml/cm2/h. The corrosion studies - immersion and potentiodynamic methods were conducted (including measurement specific corrosion current density for Mg alloys). Finally, a comparative analysis was performed, which indicated the impact of Ca and Zn concentration on: GFA, mechanical properties and dissolution rate of studied metallic glasses.

Szybkość rozpuszczania źródeł zanieczyszczeń w złożach ziarnistych

Adach A., Wroński S., Łukaszewska J., Krokwa J.

Inżynieria i Aparatura Chemiczna

2010

Nr 2

17-18

Badano szybkość rozpuszczania źródeł masy (tabletek) dla różnych geometrii ich rozkładu w złożu ziarnistym. Wykazano wzrost szybkości rozpuszczania ze wzrostem natężenia przepływu cieczy. Zaobserwowano niewielkie zmniejszenie szybkości rozpuszczania substancji wraz ze wzrostem skupienia tabletek. Badano zmianę powierzchni tabletek w czasie: początkowo jedynie zmniejszają one swoje rozmiary, po pewnym czasie stają się porowate, pokruszone, co powoduje chwilowy wzrost powierzchni wymiany masy.

Substance migration from a mass sources (tablets) placed in different geometrical configurations was investigated. An increase of fluid flow rate caused quicker tablets dissolution. A little lower dissolution rate was observed for a more then symmetrical clustered placement. The estimation of tablets' surface change in time was examined. Tablets' size decreased only in the beginning. Later the tablets become porous and crushed which caused the bigger interface surface.