Study On The Properties Of Zirconia Ceramics Reinforced By Tourmaline Mineral Particles

Zirconia（ZrO₂）,which is attributable to its great properties of high strength,toughness,hardness as well as favorable biocompatibility,has been increasingly and widely applied to dental restoration.However,zirconia ceramic with the phase transformation toughness improves at the cost of shortening its service life.And ZrO₂ may suffer failure and fracture after long-term mastication in the oral surroundings due to the frequent changes in temperature and masticatory force,especially in the really complex biochemistry surroundings,such as extremely moist oral cavity and saliva.Thus,improving the mechanical properties and preventing toughening degradation of ZrO₂ has become a problem to solve and a hot topic to follow.Aiming at these crucial problems,3 mol%Y₂O₃stabilized tetragonal ZrO₂（3Y-TZP）by introduction of natural mineral tourmaline,which has great far-infrared emissivity was obtained in this work.The unique microstructure was systematically investigated through scanning electron microscopy（SEM）,X-ray diffraction（XRD）,and flourier transform-infrared spectrometer（FTIR）.The effect of tourmaline on improving the mechanical properties,functionalization and service aging of ZrO₂ were studied.And the strengthening and toughening mechanism of tourmaline in zirconia before and after aging were also discussed in this work.（1）The preparation of 3Y-TZP/tourmaline and the analysis of its structure.Zirconia ceramics added with different contents of tourmaline were sintered in air,the results showed that the composites mainly consisted of t-ZrO₂,mullite,silicon and alumina.Additionally,the addition of tourmaline could make the sintering more easier.（2）The mechanical properties of zirconia were increased by tourmaline mineral particles.And zirconia adding with 2 wt%tourmaline at 1300°C had the optimal mechanical properties obtaining with Vickers hardness（1.341 GPa）,flexural strength（826 MPa）and fracture toughness(10.53 MPa·m^1/2).This improvement was attributed to the generation of mullite and silicon,which were decomposed from tourmaline during heat treatment（3）The far-infrared emissivity and surface energy of zirconia were increased by tourmaline mineral particles.The results illustrated that the addition of tourmaline in3Y-TZP could increase its far-infrared emissivity and surface energy value to 6.44%and17.46%compared with 3Y-TZP,respectively,which was ascribed to Si-O,Al-O and B-O bonds generated from tourmaline after heat treatment.（4）3Y-TZP and 3Y-TZP added with 2 wt%tourmaline were experienced in the aging process.The result showed that tourmaline could improve the aging property of 3Y-TZP as a result of the formation of mullite,the product from tourmaline during sintering could decrease t→m transformation as well as grain precipitation on the composites′surface.Therefore,tourmaline in the zirconia ceramic composites played a role in suppressing toughness aging.