Study On One-dimensional Filler Reinforced And Toughened Ceramic Matrix Composite Resin Material

The application of computer-aided design/computer-aided manufacturing(CAD/CAM)in the field of dental prosthetics has brought great convenience to doctors and patients in reducing the operation steps of the prosthetic system,shortening the production time,minimizing the deviation of sample preparation and improving the accuracy of sample preparation.To the present,however,the performance of dental materials available for the CAD/CAM technology is still unsatisfactory.It is of great practical significance to develop dental restorative materials which can meet the demands of CAD/CAM technology,at the same time,have similar performance to natural teeth to extent their service life.To this end,a kind of dental restorative material is developed in this thesis based on the principle of multi-scale and multi-dimensional strengthening and toughening effect for composites,which can be used for the CAD/CAM purpose and achieve performances comparable with human natural teeth.The CAD/CAM machinable dental restorative materials are a kind of resin-ceramic interpenetrated networks that are prepared by using resin to infiltrate porous ceramic preforms under vacuum,followed by thermal curing.The novelty lies in the preparation of the porous ceramic preforms,which are prepared by mixing zero-dimensional ceramic powder with one-dimensional inorganic fibers/nano wires.The existence of one-dimensional inorganic fillers in composites can effectively reduce the wear loss of ceramic powders and improve the service life of materials.Briefly,the research is mainly carried out as follows:1.The optimized preparation of porous ceramic preforms was preliminarily explored.Firstly,porous ceramic preforms were prepared by compressing the same quality of barium glass powders,which were wetted by different liquids(3 wt.%PVA aqueous solution,anhydrous ethanol or deionized water)at different ratios under the same conditions(6 MPa,1 min).The minimum amounts required for efficient wetting were determined 1.00 g,0.50 g and 1.20 g,respectively,for 5.00 g of barium glass powder,which were determined by comparing the shaping and the liquid exudating of the preforms.Then,the preforms prepared as mentioned were infiltrated with a resin mixture(Bis-GMA:TEGDMA=6:4)under vacuum,which were thermally cured(110?,12 h)to obtain composites.The porosity of the porous ceramic preforms,as well as,the three-point flexural strengths and modulus,the contents of the infiltrated resin in the resulting composites and the micro-morphology of the fractured cross-section of the composites were systematically characterized.From the results,anhydrous ethanol was identified a better wetting liquid for preform preparation than water and PVA aqueous solution,leading to composites with fewer defects and better mechanical properties.2.Studies on the preparation and optimization of glass fiber(GF)reinforced and toughened ceramic matrix composite materials were systematically carried out.GF were prepared with different aspect ratios(33.4,22.0,8.0)by sieving.Firstly,the effects of compressing forces(1 MPa,2 MPa,3 MPa,6 MPa)on the performances of porous preforms and resulting composites were investigated by fixing the aspect ratio of the used GF being 22.0 and its content in preforms being 7.5 wt.%.The porosity of the obtained preforms was measured.After being infiltrated with resin mixture and thermally cured,the resulting GF/barium glass power co-reinforced composites were characterized as aforementioned.It turned out to be the composite prepared with 2 MPa pressure displaying the highest flexural strength(?132 MPa)and flexural modulus(?14.1 GPa).Then,the effects of the aspect ratios of GF on the performances of porous preforms and resulting composites were investigated.It was found that the aspect ratios of and the contents of the used GF would influence the final properties of the composites.When the aspect ratio of glass fiber was 22.0 and its content in the preforms was 7.5 wt.%,the composites would achieve flexural strength of?132.0 MPa,flexural modulus of?14.1 GPa,Vickers hardness of?121.7 and wear volume of-0.0465 cm3,which were the best among all the designs.By silanizing the GF,the interfacial bonding between the inorganic components and the resin matrix was increased.And thus,the flexural strength and flexural modulus of the resulting composites could be further increased to?137.5 MPa and?15.9 GPa,respectively.3.Studies on the preparation and optimization of hydroxyapatite(HA)nanowires reinforced and toughened ceramic matrix composite materials were systematically carried out.HA nanowires were silane treated by sol-gel process and used as a one-dimensional filler for HA nanowires/barium glass power co-reinforced composites.Firstly,the effects of the content(2 wt.%,4 wt.%,5 wt.%,6 wt.%,8 wt.%,10 wt.%)of HA nanowires on the performances of resulting co-reinforced composites were investigated.The results showed that the composites containing 5 wt.%HA nanowires would achieve flexural strength of?190.5 MPa,flexural modulus of?19.1 GPa,Vickers hardness of?137.5 and wear volume of-0.0342 cm3,which were the best among all the designs.Secondly,the effects of the sizes of barium glass powders(0.18,0.70 and 1.00 ?m)on the resulting co-reinforced composites were characterized.It was shown that the better dimension matching between the zero-dimensional and the one-dimensional fillers was,the better performance of the resulting composites was.Finally,the cytotoxicity test using extracts from the composites showed that HA nanowires/barium glass power co-reinforced composites were biocompatible and non-toxic,which could be used in oral environment.In summary,one-dimensional inorganic filler(particularly the HA nanowires)reinforced and toughened ceramic-based resin composites were prepared,which demonstrate good performances and are expected to be used as dental restorative materials.