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Applications of Thin Films in Metallic Implants
Published in Sam Zhang, Materials for Devices, 2023
Katayoon Kalantari, Bahram Saleh, Thomas J. Webster
Among the different ceramic materials used for biomedical applications, zirconium dioxide (ZrO2) is considered a potential material for medical applications mostly focused on orthopedic implants and bone tissue engineering applications as well [107]. ZrO2 has been utilized extensively, because of its excellent properties including good fracture strength and compression resistance, good cell culture and proliferation, biocompatibility, and non-cytotoxicity [108, 109]. A study completed by Degidi et al. showed the effect of zirconium dioxide in biomedical implants leading to the creation of an inflammatory substrate in comparison with that of metal alloys demonstrating the formation of soft tissue on implant surfaces [110]. Zirconium dioxide has also been documented as a surface coating to improve cell adhesion, proliferation, and culturing properties on the surface of a metal alloy, as the material shows no cytotoxicity [107]. Compared to titanium implants, they showed enhanced mechanical strength and esthetic appearance as well as a lower accumulation of plaque [111].
Transport in porous solids: thermal conductivity of nanoporous solids and porous crystals
Published in J.-L. Auriault, C. Geindreau, P. Royer, J.-F. Bloch, C. Boutin, J. Lewandowska, Poromechanics II, 2020
The yttria content creates oxygen vacancies that allow ion transport (ionic conductivity), while scattering phonons and decreasing the thermal conductivity. A pure zirconium dioxide crystal has a monoclinic structure and impurities alter the structure to tetrahedral or cubic. The 1/T decay of thermal conductivity is an indication of phonon-phonon (Umk-lapp) scattering (Berman 1976). The phonon mean-free path λp for pure zirconium dioxide is smaller than the grain sizes in Figure 4. There is therefore no crystal size effect here. Introduction of impurities and phonon scattering at the pores decrease the conductivity and result in a temperature independence around and above room temperature (Schlichting et al. 2001). The high scattering, high temperature behavior is discussed next.
Ceramics
Published in William Bolton, R.A. Higgins, Materials for Engineers and Technicians, 2020
Zirconia (zirconium oxide, ZrO2) has been used for many years as a high-temperature crucible and furnace refractory where temperatures up to 2500°C must be sustained. Zirconia is a polymorphic substance (see Section 1.4.6) which at 1170°C undergoes a change in crystal structure similar to that in steel which leads to the formation of martensite. As with steel, a sudden volume increase is involved on cooling. Since zirconia, like martensite, is brittle then severe distortion and cracking are liable to occur, leading to spalling and disintegration. Fortunately, additions of yttria (yttrium oxide, Y2O3) suppress the martensite-type transformation to below ambient temperature – rather like the effect of nickel in 18/8 stainless steel. Lime and magnesia have a similar effect but the more expensive yttria is used because, unlike lime and magnesia, it does not lower the melting point of zirconia.
Advanced materials and technologies for oral diseases
Published in Science and Technology of Advanced Materials, 2023
Hao Cui, Yan You, Guo-Wang Cheng, Zhou Lan, Ke-Long Zou, Qiu-Ying Mai, Yan-Hua Han, Hao Chen, Yu-Yue Zhao, Guang-Tao Yu
It has been proven in numerous tests that the use of nanoparticles can effectively improve the mechanical strength of PMMA. The product type, particle size and concentration of fillers will have different effects on the mechanical properties of PMMA. Zirconium oxide (ZrO2) is a widely used metal oxide, one of the most commonly used materials for dental restorations due to its high mechanical strength, good surface properties, and good biocompatibility and biological properties. ZrO2 NPs can be used as a filler for PMMA among them and be effective in increasing the mechanical properties of PMMA [104,105]. Studies have shown that adding 2.5% ZrO2 NPs can be the best impact strength of PMMA [106]. 3.0% ZirO2 NPs can obtain the best bonding properties [107], and 5.0% ZrO2 NPs can improve the tensile strength of PMMA [108]. These experiments proved that the nanofiller has a specific concentration dependence. Also, silane-treated zirconia nanofillers can further improve the surface hardness and flexural strength of PMMA – zirconia nanocomposites [109]. Based on this, another study has been conducted to add alkylated ZnNPs as well as aluminum borate whiskers (ABWs) to PMMA at the same time, where the flexural strength of PMMA is significantly increased [204].
Fabrication and properties of a stable and porous YSZ/nano-HA structure by binder jetting processes
Published in Materials and Manufacturing Processes, 2023
Shuangjun Huang, Chunsheng Ye, Chengxing Wu
Zirconium oxide (ZrO2) has high mechanical properties and low toxicity. This compound is used as a biomaterial for hip joints, denture crowns and implants, and stand a chance to be a new bone repair material.[15–18] However, given the use of ZrO2 as a new bone repair material, the mechanical properties of ZrO2 after sintering are considerably greater than those of the cortical bone.[19,20] Therefore, when ZrO2 is combined with the host bone, with the differences in strength, the stress concentration is not uneven, and fractures are likely to occur. In addition, the poor affinity of ZrO2 for cells and tissues is also a key issue.[21–24] To solve these problems, numerous researchers prepared ZrO2/HA composite materials by different methods, and their mechanical properties were still notably higher compared with those of the cortical bone. The ZrO2/HA composite with a porous structure can improve its mechanical properties and biocompatibility. Matsumoto et al.[25] prepared porous ZrO2/HA composite with different particle size distributions by low-pressure compression, and studied the influence of the composition ratio of ZrO2 and HA on the strength and microstructure. Cao et al.[26] prepared a porous ZrO2/HA scaffold by photo-curing method and found that the biological scaffold containing 10 wt.% HA had better compressive strength.
Thermal efficiency enhancement using a ceramic coating on the cylinder liner and the piston head of the IC engine
Published in International Journal of Ambient Energy, 2021
P. Anand, D. Rajesh, M. Shunmugasundaram, I. Saranraj
Zirconium dioxide (ZrO2), sometimes known as zirconia (not to be confused with zircon), is a white crystalline oxide of zirconium. Its most naturally occurring form, with a monoclinic crystalline structure, is the mineral baddeleyite (Alkidas 1989). A dopant stabilised cubic structured zirconia, cubic zirconia, is synthesised in various colours for use as a gemstone and a diamond simulant. Zirconia can be found in three crystal structures and it can be seen in Figure 2. These are monolithic (m), tetragonal (t) and cubic (c) structures. The monolithic structure is stable between room temperature and 1170°C while it turns to a tetragonal structure above 1170°C. The tetragonal structure is stable up to 2379°C and above this temperature, the structure turns to cubic structure (Assanis et al. 1991).