Lutetium oxide is a promising refractory material due to its high temperature resistance, corrosion resistance, and low phonon energy. In addition, due to its homogeneous nature, no phase transition below the melting point, and high structural tolerance, it plays an important role in catalytic materials, magnetic materials, optical glass, laser, electronics, luminescence, superconductivity, and high-energy radiation detection. Compared with traditional material forms, lutetium oxide fiber materials exhibit advantages such as ultra-strong flexibility, higher laser damage threshold, and wider transmission bandwidth. They have broad application prospects in the fields of high-energy lasers and high-temperature structural materials. However, the diameter of long lutetium oxide fibers obtained by traditional methods is often larger (>75 μ m) The flexibility is relatively poor, and there have been no reports of high-performance lutetium oxide continuous fibers. For this reason, Professor Zhu Luyi and others from Shandong University used lutetium containing organic polymers (PALu) as precursors, combined with dry spinning and subsequent heat treatment processes, to break through the bottleneck of preparing high-strength and fine-diameter flexible lutetium oxide continuous fibers, and achieve controllable preparation of high-performance lutetium oxide continuous fibers.
Figure 1 Dry spinning process of continuous lutetium oxide fibers
This work focuses on the structural damage of precursor fibers during the ceramic process. Starting from the regulation of precursor decomposition form, an innovative method of pressure assisted water vapor pretreatment is proposed. By adjusting the pretreatment temperature to remove organic ligands in the form of molecules, the damage to the fiber structure during the ceramic process is greatly avoided, thereby ensuring the continuity of lutetium oxide fibers. Exhibiting excellent mechanical properties. Research has found that at lower pre-treatment temperatures, precursors are more likely to undergo hydrolysis reactions, causing surface wrinkles on the fibers, leading to more cracks on the surface of ceramic fibers and direct pulverization at the macro level; A higher pre-treatment temperature will cause the precursor to crystallize directly into lutetium oxide, causing uneven fiber structure, resulting in greater fiber brittleness and shorter length; After pre-treatment at 145 ℃, the fiber structure is dense and the surface is relatively smooth. After high-temperature heat treatment, a macroscopic almost transparent continuous lutetium oxide fiber with a diameter of about 40 was successfully obtained μ M.
Figure 2 Optical photos and SEM images of preprocessed precursor fibers. Pretreatment temperature: (a, d, g) 135 ℃, (b, e, h) 145 ℃, (c, f, i) 155 ℃
Figure 3 Optical photo of continuous lutetium oxide fibers after ceramic treatment. Pretreatment temperature: (a) 135 ℃, (b) 145 ℃
Figure 4: (a) XRD spectrum, (b) optical microscope photos, (c) thermal stability and microstructure of continuous lutetium oxide fibers after high-temperature treatment. Heat treatment temperature: (d, g) 1100 ℃, (e, h) 1200 ℃, (f, i) 1300 ℃
In addition, this work reports for the first time the tensile strength, elastic modulus, flexibility, and temperature resistance of continuous lutetium oxide fibers. The single filament tensile strength is 345.33-373.23 MPa, the elastic modulus is 27.71-31.55 GPa, and the ultimate curvature radius is 3.5-4.5 mm. Even after heat treatment at 1300 ℃, there was no significant decrease in the mechanical properties of the fibers, which fully proves that the temperature resistance of the continuous lutetium oxide fibers prepared in this work is not less than 1300 ℃.
Figure 5 Mechanical properties of continuous lutetium oxide fibers. (a) Stress-strain curve, (b) tensile strength, (c) elastic modulus, (d-f) ultimate curvature radius. Heat treatment temperature: (d) 1100 ℃, (e) 1200 ℃, (f) 1300 ℃
This work not only promotes the application and development of lutetium oxide in high-temperature structural materials, high-energy lasers, and other fields, but also provides new ideas for the preparation of high-performance oxide continuous fibers
Post time: Nov-09-2023