In this study the densification behavior of bimodal YTZP powder compacts consisting of nano/submicronsized particles was studied and an explanation for their improved flexural strength while biscuitsintered is provided. An in situheating TEM analysis revealed that up to 800 degrees C only the nanoparticles sinter in a bimodal mixture without any densification. By increasing the temperature to 900 degrees C the densification of the nanoparticles begins and partially densified nanoparticle clusters migrate into the contact area between the core particles. Consequently, the driving force for the sintering of the powderblend compacts is reduced and this is reflected in a slower densification compared to that of the core material. At 1000 degrees C the sintered nanoparticle clusters begin to incorporate into the core material, resulting in a sharp increase in the strength due to the increased neck area. Biscuit-sintered powderblend compacts reached a plateau of strength at 670 MPa, which was reached at a relative density of 70%.
COBISS.SI-ID: 26453031
The purpose of this study was to evaluate the effect of Y-TZP ceramic surface functionalization with a nano-structured alumina coating on bond strength of the resin modified glass ionomer dental cement. A total of 160 disc-shaped specimens were produced and randomly divided into two groups of 80. Half of the discs in each group received an alumina coating which was fabricated by exploiting the hydrolysis of aluminum nitride (AlN) powder. The shear bond strengths of the resin-modified glass ionomer cement FUJI+ (GC Japan) and the composite resin luting agent RelyX Unicem (3M ESPE, USA) were then studied forthe coated and uncoated surfaces The SEM analyses revealed that the application of an alumina coating to the Y-TZP ceramics created a highly retentive surface for bonding. The bond strengths for the coated groups in both cements were significantly higher than the uncoated groups.
COBISS.SI-ID: 29929945
An in vitro study was designed to monitor the t–m transformation of biomedical grade 3YTZP ceramics produced from two readytopress granulated powders of the same nominal chemical composition, but differing in their specific surface area. The sinteringtemperaturedependent transformability during ageing was confirmed, whereby therole of the starting powder characteristics was more pronounced at lower sintering temperatures and was almost negligible at higher sintering temperatures.
COBISS.SI-ID: 25760807
In this article, a new rapid biomimetic method for the deposition of octacalcium phosphate coatings on zirconia ceramics (YTZP) is described. Such coatings are bioactive and enable the growth of bone tissue on the sruface of bone implants. The method described is fast, simple and very reproducible. After the thermal treatment the coatings exhibit good mechanical properties and excellent adhesion to the substrate.
COBISS.SI-ID: 26983975
The role of surface preparation, hydrothermal ageing exposure and subsequent cyclic fatigue testing on the biaxial strength of a dental Y-TZP material are investigated. The initial strength and survival rate of a dental Y-TZP ceramic material to fatigue testing was found to be highly dependent upon surface preparation more so than exposure to various hydrothermal exposure conditions. The results suggest that the monoclinic phase generated by either surface damage (especially sandblasting) and to a lesser extent hydrothermal exposure does appear to mitigate strength and fatigue degradation. The results are discussed in terms of the size of defects generated following various surface treatments and the role of cyclic fatigue induced crack growth. A critical ratio is established between the monotonic strength and fatigue stress survival. From the specimens that failed and exhibited reduced strength after cycling a plot of averaged crack growth rate versus max cyclic stress intensity factor was established which closely matched existing results for Y-TZP ceramics.
COBISS.SI-ID: 31554521