The mechanism of penetration depth increased by activating flux in activating tungsten inert gas(A-TIG)weldingwas studied by measuring the distribution of trace element Bi in the weld and monitoring the change of arc ...The mechanism of penetration depth increased by activating flux in activating tungsten inert gas(A-TIG)weldingwas studied by measuring the distribution of trace element Bi in the weld and monitoring the change of arc voltageduring A-TIG welding of stainless steel 0Crl8Ni9 with fluxes SiO_(2)and TiO_(2).The results show that the mechanismof penetration depth in A-TIG welding depends on the sort of flux used.The weld pool convection after coating theflux SiO_(2)and flux TiO_(2)is changed inversely compared with convectional TIG welding without flux.The arc voltageis increased by flux SiO_(2)whilst flux TiO_(2)does not have effect on the arc voltage.The reason of penetration depthincrease for SiO_(2)is due to the constriction of arc plasma and the change of surface tension gradient.The increaseof weld penetration depth with TiO_(2)only ascribes to the change of surface tension gradient.展开更多
Sol-gel-derived nano-powders of lead magnesium niobate and lead titanate solid solutions （PMN-PT or PMNT） were prepared from lead acetate trihydrate （Pb（CH3COO）2·3H2O）, magnesium acetate trihydrate （Mg（CH...Sol-gel-derived nano-powders of lead magnesium niobate and lead titanate solid solutions （PMN-PT or PMNT） were prepared from lead acetate trihydrate （Pb（CH3COO）2·3H2O）, magnesium acetate trihydrate （Mg（CH3COO）2·3H2O）, niobium ethoxide （Nb（OC2H5）5） and titanium isopropoxide （Ti（OCH（CH3）2）4）. The key steps in the preparation process were discussed, The crystalline phases in the powders were investigated using X-ray diffraction （XRD） analysis and the size of grains was observed by field-emission scanning electron microscopy （SEM）. These powders, with good dispersion characteristics and narrow grain size distribution （ranging from 50 nm to 200 nm）, may be used to prepare PMNT thick films and ceramics.展开更多
基金This work was supported by the National High Technology Research and Developrment Program of China under grant Nc.200AA331160the Scientifc Research Foundation of Harbin Institute of Technology under grant No.H.IT.2001.20.
文摘The mechanism of penetration depth increased by activating flux in activating tungsten inert gas(A-TIG)weldingwas studied by measuring the distribution of trace element Bi in the weld and monitoring the change of arc voltageduring A-TIG welding of stainless steel 0Crl8Ni9 with fluxes SiO_(2)and TiO_(2).The results show that the mechanismof penetration depth in A-TIG welding depends on the sort of flux used.The weld pool convection after coating theflux SiO_(2)and flux TiO_(2)is changed inversely compared with convectional TIG welding without flux.The arc voltageis increased by flux SiO_(2)whilst flux TiO_(2)does not have effect on the arc voltage.The reason of penetration depthincrease for SiO_(2)is due to the constriction of arc plasma and the change of surface tension gradient.The increaseof weld penetration depth with TiO_(2)only ascribes to the change of surface tension gradient.
文摘Sol-gel-derived nano-powders of lead magnesium niobate and lead titanate solid solutions （PMN-PT or PMNT） were prepared from lead acetate trihydrate （Pb（CH3COO）2·3H2O）, magnesium acetate trihydrate （Mg（CH3COO）2·3H2O）, niobium ethoxide （Nb（OC2H5）5） and titanium isopropoxide （Ti（OCH（CH3）2）4）. The key steps in the preparation process were discussed, The crystalline phases in the powders were investigated using X-ray diffraction （XRD） analysis and the size of grains was observed by field-emission scanning electron microscopy （SEM）. These powders, with good dispersion characteristics and narrow grain size distribution （ranging from 50 nm to 200 nm）, may be used to prepare PMNT thick films and ceramics.
