Search

Advanced high-entropy (Hf-Ta-Zr-Nb-Ti)C ceramics were successfully fabricated by the combination of ball milling and a two-step sintering process at 2100 °C for 5, 10, and 20 minutes from commercially available powders. The microstructure characteristics and mechanical properties of the developed systems were investigated. The high-entropy ceramics exhibit: medium grain size from 8 μm to 11 μm, high compositional uniformity, and high relative density above 99.5 %. Vickers hardness for all systems decreased with increasing applied load, with the highest value HV1 = 22.0 GPa for the system sintered for 5 minutes, while the fracture toughness changed from 2.70 MPa.m1/2 to 3.50 MPa.m1/2. The highest four-point flexural strength of 284 MPa was measured for the system with the smallest grain size.

Tetracalcium phosphate/monetite biocement was modified with 10 and 30 wt. % addition of highly porous silicon nitride/α-tricalcium phosphate (αTCP) microgranules with various content of αTCP. A composite cement powder mixture was prepared using mechanical homogenization of basic components. The accelerated release of dexamethasone from composite cement was revealed, which indicates their possible utilization for controlled drug release. The wet compressive strength of cements (

The aim was to investigate the enamel health benefits of a novel toothpaste with active tetracalcium phosphate/monetite mixtures under de/remineralization cycling. The enamel de/remineralization cycling protocol was consisted of demineralization in 1% aqueous solution of citric acid at pH 3.6 with following treatment with toothpastes and soaking in remineralization storage solution. Effectiveness of toothpastes to promote remineralization was evaluated by surface microhardness measurements, enamel erosion depth, analysis of surface roughness and fluorescent optical method. The novel tetracalcium phosphate/monetite toothpaste had the same remineralization potential as commercial calcium silicate/phosphate toothpaste and significantly higher than control storage solution group (p0.66). The results showed that dentifrice formulations containing active tetracalcium phosphate/monetite mixture with or without fluoride addition had excellent enamel remineralization potential under de/remineralization cycling and successfully promote remineralization of enamel with daily using in the form of toothpaste.

Prepared powder polyhydroxybutyrate – chitosan - calcium phosphate composite system with 10 wt % of biopolymer component can be utilized as biocement which is characterized by the prolonged setting time and achieves wash out resistance after 5 minutes of setting. The origin powder tetracalcium phosphate/nanomonetite agglomerates were coated with the thin layer of biopolymer which decelerates both the transformation rate of calcium phosphates and hardening process of composites. The porosity of hardened composite was around 62% and the compressive strength (8 MPa) was close to trabecular bone. No cytotoxicity of composite resulted from live/dead staining of osteoblasts cultured on substrates.