- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Synthesis and characterization of a series of new green solar heat-reflective pigments: Cr-doped BiPO4 and its effect on the aging resistance of PMMA (Poly(methyl methacrylate))
摘要： A series of new green Cr-doped BiPO4 materials were synthesized by hydrothermal method and first used as solar heat-reflective pigments. XRD, FTIR, FE-SEM and HR-TEM analyses confirm that the phase structure was transformed from low-temperature monoclinic phase (LTMP) to hydrated hexagonal phase (HP), the particle size decreased and the morphology changed from irregular prism-shaped to rod-shaped, which all attributed to the incorporation of Cr3+ ions. Moreover, the valance of chromium ions was also confirmed by XPS. Color and ultraviolet-visible-near-infrared (UV–Vis–NIR) analysis indicate that different hues of green were obtained in these solid solutions and they possessed high NIR reflectance (> 83%) and solar reflectance (> 86%) in total NIR region. Meanwhile, the reason of decrease in NIR reflectance of doped samples was also analyzed, which mainly due to the decrease of free carrier concentration. TG-DTA and corrosion resistance tests prove that these pigments have excellent thermal and chemical stability. Compared with pure PMMA and the existing reports on pigmented PMMA, the NIR reflectance of PMMA pigmented with Cr-doped BiPO4 pigments have been greatly improved and have good coloring performance. The NIR solar reflectance of PMMA colored with Bi0.85Cr0.15PO4 in shortwave NIR region reaches up to 77.83%, an increase of nearly 52%. Heat aging test shows that Cr-doped BiPO4 pigments significantly improve the aging resistance of PMMA. In conclusion, these pigments have potential to become plastic colorants to increase the NIR reflectance and aging resistance of plastics.
关键词： Green pigments,Cr-doped BiPO4,Aging resistance,NIR reflectance,PMMA
更新于2025-09-23 15:23:52
-
Novel laser textured surface designs for improved zirconia implants performance
摘要： The development of new surface designs to enhance the integration process between surgically placed implants and biological tissues remains a challenge for the scientific community. In this way and trying to overcome this issue, in this work, laser technology was explored to produce novel textures on the surface of green zirconia compacts produced by cold pressing technique. Two strategies regarding line design (8 and 16 lines design) and different laser parameters (laser power and number of laser passages) were explored to assess their influence on geometry and depth of created textures. The produced textures were evaluated with Scanning Electron Microscopy (SEM) and it was observed that well-defined textured surfaces with regular geometric features (cavities or pillars) were obtained by laser combining different strategies lines design and parameters. The potential of proposed textures was also evaluated regarding surface wettability, friction performance (static and dynamic coefficient of friction evolution) against bone, aging resistance and flexural strength. Results demonstrated that all the produced textures display a super hydrophilic or hydrophilic behavior. Regarding the friction behavior, it was experimentally observed a high initial static coefficient of friction (COF) for all produced textures. Concerning the aging resistance, all the textured surfaces revealed a low monoclinic content, less than 25% after 5?h of hydrothermal aging. The flexural strength results showed that the mechanical resistance of zirconia was not significantly compromised with the laser action. Based on the obtained results, it is possible to prove that the processing route used for manufacturing the new and different surface designs (cold pressing technique followed by laser texturing) showed to be particularly effective for the production of zirconia implants with customized surface designs according to the properties required in a specific application. These new surface designs besides to enhance the surface wettability and also to improve the fixation at the initial moment of the implantation, do not significantly compromise the resistance to aging and the mechanical performance of zirconia. Hence, a positive impact on the long-term performance of the zirconia implants may be expected with the proposed novel laser textured surface designs.
关键词： Flexural strength,Aging resistance,Zirconia,Surface wettability,Coefficient of friction,Laser surface texturing
更新于2025-09-12 10:27:22