Yttria-stabilized zirconia (YSZ), as a high-performance structural ceramic material, has demonstrated irreplaceable application value in fields such as aerospace, energy and environmental protection, and biomedicine due to its excellent mechanical properties, chemical stability, and thermophysical characteristics. Its core advantage lies in the addition of yttrium during the zirconia crystal form stabilization process, which enables the material to maintain a stable tetragonal or cubic phase structure from room temperature to high-temperature environments, thereby avoiding the volume expansion issue of pure zirconia caused by phase transformation. This property makes it a key material in the field of structural ceramics. In recent years, with breakthroughs in nanotechnology and preparation processes, its application boundaries have been continuously expanded.

Phase Transformation Toughening Mechanism and Breakthroughs in Mechanical Properties

The most prominent technical feature of YSZ lies in its unique phase transformation toughening mechanism. When the material is subjected to external forces, the metastable tetragonal zirconia undergoes a transformation to the monoclinic phase. This process is accompanied by a 3%-5% volume expansion, which can effectively inhibit crack propagation. Studies have shown that the fracture toughness of 3 mol% yttria-stabilized zirconia (3Y-TZP) can reach 10-15 MPa·m¹/², significantly higher than that of traditional alumina ceramics (3-5 MPa·m¹/²). According to a case of aerospace components reported by Sohu Technology Channel, turbine blades fabricated with nano-scale YSZ have seen a 300% increase in the number of thermal shock resistance cycles under a working environment of 1400℃. This benefit stems from the size effect of nano-grains, which reduces the critical stress for phase transformation and enables the material to achieve self-healing functionality at the microscale.

Structural Stability in High-Temperature Environments

In the field of high-temperature structural components, 8 mol% yttria-stabilized zirconia (8YSZ) has become the preferred choice due to its fully stabilized cubic phase structure. According to Baidu Encyclopedia, this material can still maintain a flexural strength of over 200 MPa at 1000℃, with a thermal conductivity as low as 2.3 W/(m·K), making it an ideal substrate for thermal barrier coatings (TBCs) in aero-engines. An 8YSZ coating prepared by a research institute via plasma spraying technology can reduce the surface temperature of the nickel-based superalloy substrate by 100-150℃, significantly extending the service life of the components. Notably, the newly developed gradient composite structures (such as YSZ/Al₂O₃ layered materials) have further addressed the issue of interface spallation caused by thermal expansion coefficient mismatch through stress gradient design.

Precision Applications in the Biomedical Field

Medical implants have extremely high requirements for the biocompatibility and wear resistance of materials. 3Y-TZP has become the mainstream choice for dental restorations due to its metal-like elastic modulus (210 GPa) and natural ivory color. Data disclosed by Sohu Health Channel shows that the occlusal surface flexural strength of nano-YSZ all-ceramic crowns exceeds 1200 MPa, and their X-ray transmission performance is superior to traditional metal-ceramic teeth. In the field of orthopedic joints, the YSZ-titanium alloy composite hip joint prosthesis treated with surface activation has a wear rate only 1/20 that of cobalt-chromium alloy and can effectively inhibit the release of metal ions. However, recent studies have also found that low-temperature degradation (LTD) should be concerned in long-term body fluid environments, and the hydrothermal stability of the material can be significantly improved by incorporating 0.3 wt% alumina.

Despite the significant application achievements of yttria-stabilized zirconia (YSZ), it still faces three major challenges: cost control in the large-scale production of nano-powders, near-net shaping technology for complex-shaped components, and the establishment of long-term reliability databases under extreme environments. Industry experts predict that with the maturity of artificial intelligence-aided material design technology and atomic layer deposition processes, the next-generation intelligent YSZ materials are expected to achieve the synergistic function of crack self-diagnosis and phase transformation self-healing, which will drive structural ceramics into a new stage of development. Against the backdrop of carbon neutrality, the exploration of applications of YSZ-based composites in emerging fields such as hydrogen energy storage and transportation, and nuclear waste encapsulation may redefine the technical boundaries of high-performance structural ceramics.