Search

Aging, tooth trauma, and pathological infections cause partial or total tooth loss, leading to the usage of dental implants for restoration treatments. As such, mechanical and tribological properties play an important role in the osseointegration and durability of these implants. Metallic and ceramic implants are shown to have mechanical properties much higher than the natural teeth structure, leading to stress shielding-related failure of an implant. Stress shielding occurs due to the difference in the elastic modulus between the implant material and the surrounding teeth structure, leading to bone loss and implant failure. The implant's properties (i.e., mechanical) should be as close as human teeth components. To achieve this, various materials and coatings are being developed and investigated. This review is a comprehensive survey of materials, manufacturing, coating techniques, and mechanical and tribological characterizations of dental implants, with a particular focus on polyetheretherketone (PEEK) as a potential alternative dental implant material. PEEK has mechanical properties similar to natural teeth, which make it a promising material for dental implants. The findings of this review suggest that PEEK offers superior biocompatibility, osseointegration, and wear resistance for implant applications. With the help of bioactive coatings, bone growth on the implant surface can be promoted. In addition, PEEK dental implants made using three-dimensional (3D) printing technology can significantly reduce the cost of implants, making them more affordable and increasing access to dental care, which can improve oral health significantly. In summary, this review highlights the potential of PEEK as a promising alternative dental implant material, and provides an overview of various techniques, testing, and future directions for PEEK dental implants., (Copyright 2023, Mary Ann Liebert, Inc., publishers.)

The incorporation of rare earth oxides and nano-silica has been found to significantly enhance the mechanical and tribological characteristics of phenolic-based hybrid nanocomposites. In this work, the impact of these additives was investigated through single-factor experiments. The study revealed that cerium oxide and yttrium oxide were the primary factors influencing changes in the impact strength, shear strength, coefficient of friction, and wear rate. Additionally, the content of nano-silica exerted the most substantial influence on the hardness and compressive strength of the specimens. Furthermore, the material ratios of the phenolic-based hybrid nanocomposites were optimized using an orthogonal experimental design and a fuzzy comprehensive evaluation method. The optimal material ratio for these nanocomposites was determined to be 2% cerium oxide, 2.5% yttrium oxide, and 3% nano-silica, based on their mechanical, frictional, and wear properties. This research provides valuable insights for the development of new brake friction materials with low friction and high wear resistance and contributes to meeting the demand for polymer composites with superior mechanical performance in diverse applications.

Coatings in a Zr-Mo-Si-B-N system were deposited by the magnetron sputtering of ZrB 2 -MoSi 2 targets in argon and nitrogen. The structure of the coatings was investigated using scanning electron microscopy, X-ray diffraction, energy-dispersive spectroscopy, and glow-discharge optical emission spectroscopy. Mechanical and tribological properties were measured using nanoindentation and pin-on-disc testing. Oxidation resistance and oxidation kinetics were estimated via annealing in air at 1000-1500 °C and precision weight measurements. We found that the coatings deposited in Ar demonstrate a superior combination of properties, including hardness of 36 GPa, elastic recovery of 84%, a friction coefficient of 0.6, and oxidation resistance at temperatures up to 1200 °C. High oxidation resistance is realized due to the formation of the protective (SiO 2 + ZrO 2 )/SiO 2 oxide layer, which inhibits the diffusion of oxygen into the coating.

As part of the tests, a two-phase NiAl/Ni 3 Al alloy and a composite based on this alloy with 4 vol% addition of TiB 2 were produced by the reactive FAST/SPS (Field Assisted Sintering Technology/Spark Plasma Sintering) sintering method. The sintering process was carried out at 1273 K for 30 s under an argon atmosphere. The effect of reactive SPS on the density, microstructure, and mechanical and tribological properties of a dual-phase Ni-Al intermetallic compound and Ni-Al-TiB 2 composite was investigated. Products obtained were characterized by a high degree of sintering (over 99% of the theoretical density). The microstructure of sinters was characterized by a large diversity, mainly in regard to the structure of the dual-phase alloy (matrix). Compression tests showed satisfactory plastic properties of the manufactured materials, especially at high temperature (1073 K). For both materials at room temperature, the compressive strength was over 3 GPa. The stress-strain curves were observed to assume a different course for the matrix material and composite material, including differences in the maximum plastic flow stress depending on the test temperature. The brittle-to-ductile transition temperature was determined to be above 873 K. The research has revealed differences in the physical, mechanical and tribological properties of the produced sinters. However, the differences favourable for the composite were mostly the result of the addition of TiB 2 ceramic particles uniformly distributed on grain boundaries.

Since obtaining a highly oriented structure based on a large-scale commercial ultra-high molecular weight polyethylene (UHMWPE) is considered very difficult due to its high molecular weight and melting index, modifying the structure of these cheap commercial UHMWPE brands into a supra-molecular structure with fiber-forming properties by adding a small amount of polyethylene wax (PE-wax) will provide the possibility to obtain highly oriented UHMWPE products with enhanced mechanical and tribological properties. In this work, highly oriented UHMWPE/PE-wax films were prepared. The PE-wax affected the UHMWPE as an intermolecular lubricant. The obtained lamellar structure of the UHMWPE/PE-wax composites had a better processability. The UHMWPE and UHMWPE/PE-wax structures for the xerogels and the films were studied by using differential scanning calorimetry and scanning electron microscopy. The PE-wax presence enhanced the mechanical properties of the UHMWPE/PE-wax films to a high degree. The highest average value of the tensile strength was 1320 MPa (an increase of 78%) obtained by adding a PE-wax content of 1.0 wt.%, and the highest average value of the Young's modulus was 56.8 GPa (an increase of 71%) obtained by adding a PE-wax content of 2.0 wt.%. The addition of the PE-wax increased the work of fracture values of the UHMWPE/PE-wax films up to 233%. The formation of the cavities was observed in the virgin UHMWPE films more than in the UHMWPE/PE-wax films, and the whitening of the oriented films was related to the crystallization process more than to the cavitation phenomenon. The coefficient of friction of the oriented UHMWPE/PE-wax films improved by 33% in comparison with the isotropic UHMWPE, and by 7% in comparison with the oriented virgin UHMWPE films.