Properties And Ultrasonic Grinding Experimental Study On The Nano Ceramics Toughened By Zro₂

This paper is mainly on the properties and ultrasonic vibration grinding of advanced engineering ceramics. Toughening and strengthening alumina with zirconia phase transition and microcrak toughening, submicron alumina-zirconia composites of different zirconia contents are prepared and the content is educed when it has the best properties and structure. Nano zirconia toughened alumina composites is prepared according to this content, and its physical and mechanical property, microstructure and toughening and strengthening mechanism are studied. The method of dry pressing and isostatic compaction are both used to prepare pure nano zirconia which is then tested with XRD, SEM and the physical and mechanical properties are also tested. The effect of different preparation technics on the properties of ceramics is researched. Finally the differential analysis of samples is proceeded to research the themal flux and weight variation and phase transition condition under the temperature between 20 and 1400 degree Centigrade. Traditional, one dimension and two dimension ultrasonic grinding experiments on samples are carried on the super precise plane grinder to research the effect of such factors as material itself, grinding depth ap, work speed Vw, wheel speed Vs, wheel granularity and ultrasonic vibration on the grinding force and grinding surface quality of composites. Material removal mechanism is researched and the grinding machining properties are valuated. The experimental result indicats that the content of zirconia and the extent of compaction are important factors that affect line shrinkage ratio. Material has the best physical and mechanical properties when the content of zirconia is 25 wt%. The porosity, water absorption and volume density of nano ZTA composites are all perfect. The mean flexural strength and fracture toughness reach 420.15±21.36 MPa and 5.22 MPa·m1/2 separately, each property of it is precede to that of submicron alumina-zirconia composites. The main crystal phase of zirconia-alumina isα-alumina and t-zirconia. The matrix has uniform and compact fracture surface, the ultrasonic grinding machining surface quality is very high and the grinding property is nice. The grinding mechanism generates in special grinding environment, and so it is affected by given factors such as grinding depth ap, work speed Vw, and wheel granularity. When the critical condition to generate brittle-ductile transition is satisfied, the grinding mode can realize the transition from brittle fracture to plastic flow. The grinding machining surface quality of nano ZTA composites outgoes submicron alumina-zirconia composites obviously. Under the condition that material composition and grinding state are both uniform, the ceramic prepared by isopressing gets better surface quality than that prepared by dry pressing, ultrasonic grinding gets better surface quality than traditional grinding, and two-dimensional ultrasonic grinding gets better surface quality than one-dimensional ultrasonic grinding.