| La2O3-MgO-Al2O3-SiO2 glass ceramic/BMT ( Ba(Mg1/3Ta2/3)O3 ) ceramic composite were compounded and sintered. The composite was achieved. There become many different crystals after different heat-treatment systems on the composite. The crystals were analyzed by DTA, XRD and SEM. We create a new reaction condition different from old conditions for solid reaction.After the high-temperature sintering and different heat-treatment, the main phase is Ba5.5 Ta21.8O60(tetragonal) , and others are La2MgTiO6(cubic), BaO(face-centered cubic), BaAl2Si2O8, MgB4O7 (orthorhombic), La2TiO5(orthorhombic) and Ba3La2(BO3)4 (orthorhombic). Under some other conditions, a little of crystals would appear.Under the condition of solid reaction, there are hollow tubular crystals with unknown component and structure in the sample which was prepared by heat treatment at 400°C for 4hrs. The diameter of the hollow tube is about 200nm500nm, and its length is 2μm3μm. The ratio of length to diameter is about 10. And the thickness of tubular wall is about 50 nm. The length of the tubular crystals has saturation. They grow lengthways to a saturation state, and then grow radically.In the sample (800°C/1hr, 400°C /30hrs, 600°C/2hrs), there are a little of white nana sheet crystals. Such crystals grow from glass ceramics. In the cutting experiment, we find the sample have high rigidity, like diamond. There is no corresponding JCPDS card with this kind of white crystals.The sample has the tougher wearable intensity, because there are hard nano sheet crystals. The quantity of these crystals is little, and they distribute at some area of the sample. So they have no direct effect on the hardness of the composite.
|
PDF Full Text Request