Research On The Half-hard Plastic Extrusion Preparation And Mechanical Performance Of High Voltage Electric Porcelain

High voltage electric porcelain was prepared by the half-hard plastic extrusion usingbauxite, feldspar, clay (Chapter village soil, floated Qing Cao Ling soil, kibushi clay),talcum and barium carbonate, and then sintered. The effect of sintering temperature,holding time and firing atmosphere on the properties of high voltage electric porcelainwere researched in this paper. The sintering temperature range was determined byvitrification and porosity test; flexural strength was measured by SGW-engineeringmaterial strength tester; bulk density was calculated by the Archimedes law;thermostability was measured through thermal stability tests; the phase composition wasanalyzed by XRD; microstructure and the elements in microarea was analyzed by SEMand EDS; and a series of physical and chemical changes in the process of sintering of thesamples were represented by sintering temperature range of the measurement test. Theresults show that:1) The best formula of high voltage electric porcelain prepared by the half-hardplastic extrusion was: bauxite37%, feldspar9%, Chapter village soil18%, floated QingCao Ling soil29%, kibushi clay5%, talcum2%, barium carbonate2%. The lowest firingtemperature was1240℃, the sintering temperature range from1240℃to1270℃, and thebest sintering system was: in oxidic atmosphere, the holding time was25h in980℃and inreducing atmosphere, the temperature rising time was20h when temperature was risingfrom980℃to1240℃, and in the neutral atmosphere, the holding time was2.5h in1240℃. The bulk density of sample was2.806g/cm3, the apparent porosity was0.026%,the flexural strength was180.64MPa, the dielectric strength was28kV/mm and thethermostability was300K.2) With temperature increasing, Al2O3reacted with SiO2to form mullite, and mullitecontent was increasing, corundum content was reducing.3) Under the same firing atmosphere, density of sample increased with increase ofthe holding time at350℃,980℃,1050℃and1240℃, respectively.4) Under the same sintering temperature and holding time, density of samplespreparaed in oxidic atmosphere was higher than that preparaed in reducing atmosphere.Density of samples had largely improved, which were made at pre-sintering temperature1050℃in oxidic atmosphere，and then in reducing atmosphere.