Search

The FeCoCrAlNiTi high-entropy alloy (HEA) coatings modified by CeO2 were synthesized on 304 stainless steel substrate with Co-Cr-Al-Ni-Ti-xCeO2 powders by laser high-entropy alloying. The phase composition, microstructure and nano-mechanical and wear properties of FeCoCrAlNiTi-based HEAs were investigated by performing XRD, SEM, EBSD, nanoindentation testing and wear resistance tests. The results displayed that the FeCoCrAlNiTi-xCeO2 HEA coating only had simple FCC and BCC solid solution phases. The microstructure of the FeCoCrAlNiTi-xCeO2 exhibited typical dendrite and interdendritic structures, and the addition of CeO2 resulted in the refined microstructure of the alloyed coating. It was found that BCC phase structure predominantly distributed at the grain boundaries in the HEAs. For the 1 wt.% CeO2 adding HEA, the ratios of the hardness (H) and elastic modulus (E) were much higher than that of FeCoCrAlNiTi HEA coating, indicating that it had the satisfactory property for resistance to scoring and plastic deformation. The wear mechanisms were abrasive, oxidation and adhesive. Among of the three samples, FeCoCrAlNiTi-1 wt.% CeO2 HEA coating displayed the best wear resistance, and the specific wear rate and wear volume loss were 2.748 × 10–5 mm3/N m and 3.71 × 106 μm3, respectively. [ABSTRACT FROM AUTHOR]

Zirconia surface treatment using different techniques could be employed to overcome the delamination issue reported between veneering ceramic materials and the corresponding zirconia core. The study subjected yttria partially stabilized zirconia core material to grinding and sandblasting as a first surface treatment. An airbrush gun spraying technique was used to coat a uniform thin layer of veneering ceramic (IPS e.max Ceram and Noritake Cerabien ZR) on the core materials followed by performing laser scanning as a second surface treatment. The specimens were investigated for surface topography, interface analysis, elemental compositions, phase transformation, and fracture mode patterns using profilometer, SEM, EDS, XRD, and stereomicroscope. The impact of laser scanning on the shear bond strength before and after storage of specimens in artificial saliva was also studied. Transformable tetragonal phase to monoclinic was predominant in sandblasted specimens followed by laser scanning with observation of micro-cracks at interface. The grinding followed by laser scanning yielded satisfactory outcomes in terms of the presence of coating property. The phase transformation was not detected through the latter technique. The technique greatly enhanced the roughness property and bond strength values which might be considered as a reliable application to improve the longevity of fixed dental crowns in load bearing areas. [ABSTRACT FROM AUTHOR]

Objectives: This study was performed to assess the morphological appearance, incidence of bridging, and linear dimensions of the sella turcica (ST) in Bosnian and Iraqi subjects, and to identify associations of sex, age, and racial group with the size of the ST. Methods: The digital standardised lateral cephalograms of 360 Bosnian and Iraqi patients (116 female, 64 male; age range 8–28 years) were retrospectively analysed. The following ST-related parameters were analysed on the lateral cephalograms: sella morphology, sella bridging, and sella size. The data were correlated with sex, age, and race. Results: The ST exhibited a normal morphology in most subjects of both races (86.7%). The frequency of partial bridging was found in 38.9 and 37.2% of Bosnian and Iraqi subjects, respectively. A significant correlation was detected between the length of the ST and sex in both the Bosnian and Iraqi subjects (p < 0.05). A direct correlation was present between patient age and the size of the ST in both races at the 0.01 and 0.001 levels for depth, length, and diameter. When race was compared with sella size, a significant difference was found in the length and depth of the ST (p < 0.001). Conclusions: Similarities were found between Bosnian and Iraqi subjects in the morphology, incidence of bridging, and linear dimensions of the ST. Length was the only parameter significantly associated with sex, age, and racial group. These findings could be used as reference standards for studying the ST in both races. [ABSTRACT FROM AUTHOR]