Selective laser melting (SLM) is a potential additive manufacturing (AM) technology. However, the application of SLM was confined due to low efficiency. To improve efficiency, SLM fabrication with a high layer thickness and fine powder was systematically researched, and the void areas and hollow powders can be reduced by using fine powder. Single-track experiments were used to narrow down process parameter windows. Multi-layer fabrication relative density can be reached 99.99% at the exposure time-point distance-hatch space of 120 µs-40 µm-240 µm. Also, the building rate can be up to 12 mm 3 /s, which is about 3-10 times higher than the previous studies. Three typical defects were found by studying deeply, including the un-melted defect between the molten pools, the micro-pore defect within the molten pool, and the irregular distribution of the splashing phenomenon. Moreover, the microstructure is mostly equiaxed crystals and a small amount of columnar crystals. The averages of ultimate tensile strength, yield strength, and elongation are 625 MPa, 525 MPa, and 39.9%, respectively. As exposure time increased from 80 µs to 200 µs, the grain size is gradually grown up from 0.98 µm to 2.23 µm, the grain aspect ratio is close to 1, and the tensile properties are shown as a downward trend. The tensile properties of high layer thickness fabricated are not significantly different than those with a coarse-powder layer thickness of low in previous research.
ZrO2 ceramic exhibits the characteristics of high hardness, good thermochemical stability, desirable biocompatibility, and unique stress‐activated tetragonal to monoclinic transformation toughening, thus having broad development prospects. However, as a typical ceramic material, it has the common shortcoming of brittleness and seriously limits the possible applications. In recent years, worldwide efforts have been made to improve the toughness of ZrO2 ceramic materials, which has great significance in promoting its industrial application. Herein, the influences of phase composition, stabilizer, grain size, and sintering method on fracture toughness of ZrO2 ceramic are introduced. The mechanism of phase transformation toughening, single‐phase and multiphase material dopant toughening, and lamellar ceramic toughening are also summarized. Moreover, the prevailing applications of toughened ZrO2‐based materials in structural ceramics, coatings, and biomaterials are discussed. The present review may offer insights in designing and fabricating ZrO2 materials with high strength and toughness to provide better performances in diverse applications fields.
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