水-表面活性剂比对微乳液法制备磁性Ni-Fe复合纳米微粒的影响

用XRD和TEM等技术研究了水 (W )与表面活性剂 (S)比R(n(W ) /n(S) )对微乳液制备Ni Fe纳米复合物微粒的影响。结果表明 ,R值不同 ,得到的Ni Fe复合物微粒不但粒径不同 ,产物的组成也有差异。当R <18时 ,可得到Ni Fe合金相。所得复合物微粒的比饱和磁化强度为 5 0 0 2× 10 - 3～ 2 17 68× 10 - 3A/(m·g) ,而矫顽力可达 2 3 88～ 10 0 3 0kA/m ,剩余磁感应强度 2 8 2 8× 10 - 3～ 3 7 7× 10 - 3A/(m·g)。矫顽力随Ni

Effect of CaO doping on mechanical properties and thermal shock resistance of 10NiO-NiFe_2O_4 composite ceramics

The CaO doped 10NiO-NiFe2O4 composite ceramics were prepared by the cold isostatic pressing-sintering process, and the effects of CaO content on the phase composition, mechanical property and thermal shock resistance of 10NiO-NiFe2O4 composite ceramics were studied. The results show that the samples mainly consist of NiO and NiFe2O4 when content of CaO is less than 4%(mass fraction), bending strength increases obviously by CaO doping. Bending strength of the samples doped with 2% CaO is above 185 MPa, but that of the samples without CaO is only 60 MPa. Fracture toughness is improved obviously by CaO doping, the samples doped with 2% CaO have the maximum fracture toughness of 2.12 MPa ·m1/2 , which is about two times of that of the undoped ceramics. CaO doping is bad to thermal shock resistance of 10NiO-NiFe2O4 composite ceramics.