Preparation And Properties Of Zirconia Inks Used For Ink-jet Printing

Zirconia ceramic,as a new biological ceramic material,is applied to restorative dentistry.But it is difficult to process it in precision because of its hardness and brittleness,the requirements of the manufacturability of 3Y-TZP dental restorations were successfully fulfilled after the introduction of computer-aided design and computer-aided manufacturing?CAD/CAM?technology to the field of restorative dentistry.This is a complex process,which is not very suitable to produce dental restorations,and this can result in a considerable amount of wasted valuable raw material.If the three dimensional printing?3DP?technology is introduced into the production of 3Y-TZP dental restorations,it has better economic and social benefits.The inkjet printing technology is the key of the preparation of ceramic ink,owing to its particularity.In this paper,we have obtained a better ceramic ink by using different dispersants and different additives,and by using a planetary ball mill.?1?The experimental results of this study show that: in six different dispersing agents,ammonium polyacrylate?PAA-NH₄?has the best dispersing effect,and the zeta potential of inks at pH=10.5 increases with increasing the content of PAA-NH₄ to0.2wt%,and then the zeta potential maintain the same level with increasing the amount of dispersant.?2?The viscosity of the ink decreases as the shear rate rises,and when the shear rate is higher than ?0,the viscosity turns to increases with the increase of shear rate.?3?The ink of 0.2wt% dispersant has the lowest viscosity,and the viscosity increases as increasing or lowering the content of dispersant.And the increase of solid content and the addition of additives could also make the critical value of shear rate ?0rise,which makes the viscosity of the ink lower than the one of original ink at relatively high shear rate.?4?As temperature increases,the viscosity of the ink without any additives decreases,so do the inks with diethylene glycol?DEG?and 10wt% 1,1,1-Tris?hydroxymethyl?propane?TMP?.Notably,ethylene glycol?EG?and 5wt% TMP could change the relationship of the viscosity and temperature,when the temperature reaches about 50 degrees Celsius,the viscosity of the ink increases with temperaturerise.And in theory,this characteristic of the ink with EG could be used to weaken the Coffee Ring Effect by heating the substrate to higher than 50?,which could weaken the particle flow.?5?Inks with low solid content can be printed,but the random arrangement of the droplets on substrate could be observed,and the print qualities of multi-printing of the ink were better.The zirconia ceramic prepared by plaster mould show not only compact structure,but also relatively high bending strength,which decreases with the increase of solid content.