The Influence Of A1 On The Structure And Properties Of ZTA Ceramics

ZrO₂ was main toughening agent of ZTA ceramics.Agglomerate was general problem with nano-ZrO₂/micron-Al₂O₃ powder,lead to ZTA ceramics slower properties.It was important to improve powder dispersion.To decrease Agglomerate size,nano-ZrO₂-micron Al₂O₃ powder modified with adding Al by ball milling in this paper.Microstructure and properties of modified powder and ceramics was studied.The main research results were as follows:1.Dispersion of milled ZTA powder were improved by adding Al.ZrO₂ agglomerated and distributed between Al₂O₃ spherical particles before Al adding.The milled grinding force was enhanced by added Al,which cracking Al particles into smaller block.Nano ZrO₂ powder was embed into smaller block with particle size of 0.10 to 0.17 ?m.Part smaller block adhered to the surface of Al₂O₃ spherical particles.Some part smaller block agglomerated again with particle size of 0.50 ?m to 0.90 ?m.Uniformity of ZrO₂ particle in milled powder was best with adding 1wt.% Al.The phase compositions of milled powder was investigated by X-ray diffractometer.Content of m-ZrO₂ improved with Al adding increasing.2.Sintering modified ZTA powder,Al powder turned to liquid at 660°C.ZrO₂ powder was coated by Al liquid with capillary force.Increase sintered temperature to 1200°C,Al liquid was oxidized.Al coating of ZrO₂ powder turn to Al₂O₃.Smaller block turn into half spherical raised which bridging Al₂O₃.3.Al Addition and Sintering Temperature had effect on microstructure and properties of pressing modified ZTA powder.1).Flexural strength and hardness of ZTA ceramics were improved by adding Al.The more m-ZrO₂ of ZTA ceramics had,The higher toughening of microcracks.XRD results shown: Adding powder could increase transformation of t-ZrO₂.The amount of transformation was parabolic with the percentage of Al powder added.Content of m-ZrO₂ was highest at ZTA ceramics when the addition of Al was 1wt.%.2).The lower sintering temperature was used in sintering modified ZTA ceramics.Sintering temperature 1650°C turn to 1550°C.Pores volume and grain size of Adding Al ZTA ceramics decreased.That leaded to bending strength 604.84 MPa and vickers hardness 1645.88 HV1.3.Feed of adding 1wt.% Al ZTA powder shaped by powder injection molding.The parameters of powder injection molding were injection temperature 140°C,injection pressure 25 MPa,injection rate 10 mm/s,mold temperature 50°C.Solvent debinding of feed acted at 40⁵0°C.The best temperature was 50°C.Debinding rate of solvent debinding was parabolic with debinding time.Debinding time less than 300 min,the longer debinding time was,the higher debinding rate.And then debinding rate kept.4.Comparing with pressing,ZTA ceramics shaped by powder injection molding had higher bending strength and vickers hardness.The properties of ZTA ceramic powder injection molding increased to 697.65 MPa and 1762.45 HV1,respectively increased 15.34% and 4.80%.The main reasons added mixing process which increased uniformity of ZTA powder.ZrO₂ agglomerates and grain size decreased.The uniformity of inter-granular ZrO₂ and content of intra-granular ZrO₂ increased.The mechanical properties of ZTA ceramic powder injection molding improved with the dispersion toughening.