Study On The Sintering Process Of Color Zirconia Ceramics

ZrO₂ is a new type of advanced ceramic material which has excellent electrical conductivity,high coefficient of thermal expansion,low coefficient of friction,high chemical stability and corrosion resistance and corrosion resistance.ZrO₂ is not widely applied in industry,but alsois the important material of the refractory materials and high temperature structural materials.Among all the ceramic materials,ZrO₂ has the best stability at high temperature,the best heat insulation,the lowest thermal conductivity and its thermal expansion coefficient is very close to the meta material.The specific martensitic transformation of ZrO₂ makes it a superior performance enhancer in composites.Except the excellent mechanical properties,ZrO₂ has a higher refractive index.With its preparation of color translucent polycrystalline materials,such as natural gemstones can be gorgeous colorful gemstones like colorful.Colorful Zr O₂ has the traits of vivid color,high metal color and unable to be allergic with people et al.So it dominates the market position which substitute with metal jewelry.Currently,colorful ZrO₂ is still simple and only has the color of black and white.And its research just focus on medical science.Also,the color of these ZrO₂ is not very brilliant.Most ceramic material colorants are always resolved in the high temperature and that bring the bad effects of color and low plumpness.Therefore,this work used Co2O3 and sodium metavanadate to be the colorants,using the high temperature to fabricate the golden and blue ZrO₂ ceramics.The results have been analyzed and best additional formulation of colorants and the best sintered technique have been found out.Firstly,the preparation process of colored zirconia was studied.The effects of different amount of coloring agent and different sintering temperature on the color of zirconia were discussed and the optimum formula and optimum sintering temperature were found out.The results show that:?1?the sintering temperature increases from 1450?to 1500?,the color of blue zirconia gradually deepened,and the surface smooth and uniform;improving the sintering temperature to 1550?,the blue zirconia color lighter;when the sintering temperature is 1500?and the addition of Co₂O₃ is 0.3wt.%,the color of blue zirconia did not change significantly.With the addition of Co₂O₃,its density,relative density and bending strength did not show a significant difference,but the maximum concentration of that is appeared at the Co₂O₃ addition of 0.9wt.%.Therefore,the best preparation process of blue zirconia is to add 0.9wt.%Co2O3 in the zirconia powder and green bodies after ball milling sinter at 1500?.?2?With the increase of the mass fraction of ammonium metavanadate,the color of gold zirconia was deepened and the color uniformity was enhanced.The increase in sintering temperature favors the golden zirconia fineness while enhancing its color.With the addition of ammonium metavanadate,the density and mechanical properties of gold zirconia were increased,and the increase of coloring agent not only made the color of gold zirconia more beautiful but also inhibit the crystal growth of zirconia and strengthen its mechanical properties.Therefore,the best preparation process of gold zirconia is:adding0.9wt.%of ammonium metavanadate in the zirconia powder,the green bodies after ball milling to sinter at 1550?.The effects of different addition amounts of alumina on the mechanical properties of colored zirconia were investigated.The effects of sintering temperature and the addition of alumina on the color of zirconia were studied.The results show that the bending strength and fracture toughness of blue zirconia increased firstly and then decreased with the increase of sintering temperature,and the bending strength increased from 626.78 MPa to758.12 MPa and then decreased to 720.37 MPa,and the fracture toughness increased from9.1 MPa?m^1/2 to 10.7 MPa?m^1/2 then decreased to 10.1 MPa?m^1/2.And the bending strength and fracture toughness of the gold zirconia increased with the increase of the sintering temperature,and the bending strength increased from 613.26 MPa to 876.07 MPa,and the toughness increased from 8.7 MPa?m^1/2 to 11.2 MPa?m^1/2.The mechanical properties of blue zirconia reached the highest value at 1500?,and the gold zirconia reached the highest value at 1550?.The bending strength and fracture toughness of gold zirconia and blue zirconia increased first and then decreased with the addition of alumina,and reached the highest value when adding 25wt.%of alumina.At this time,the bending strength of blue zirconia is 840.68 MPa,the fracture toughness is 12.6 MPa?m^1/2,the flexural strength of gold zirconia is 975.33 MPa,and the fracture toughness is 13.8 MPa?m^1/2.With the addition of alumina,the color of blue zirconia first increased and then weakened,and when the Al2O3 additional amount is 25wt.%,the blue zirconia color is better,the color is higher,the gloss is stronger,the color is uniform and it has a certain mirror effect.Also the best beautiful color and color uniform are in the same Al₂O₃additional amount of 25wt.%.