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Preparation And Application Of Sub-micron Alumina Of Narrow Particle Distribution

Posted on:2019-01-25Degree:MasterType:Thesis
Country:ChinaCandidate:L MeiFull Text:PDF
GTID:2321330548462956Subject:Material Chemical Engineering
Abstract/Summary:PDF Full Text Request
In this paper,submicron ?-alumina of narrow particle distribution was prepared by dispersion stability of Mechanical-chemical method and applied in sintering alumina ceramic and modidying the coating diaphragm of lithium ion battery.Firstly,received ?-alumina powder,whose mean diameter is 2.7 ?m and particle size distribution is 6,was studied in sand-milling experiments.In view of grinding efficiency and energy of the sand mill,the best operating parameters were obtained by comparing the effect of milling time,grinding speed and grinding media on powder grain size,crystal phase and slurry rheological property.Secondly,the dispersion stability of milled ?-alumina powder in water suspension was studied.According to the dispersion principle,the optimized dispersing condition was obtained by studying the effect of the process,like dispersion mode,etc.Settling classification was conducted under this optimum condition.Submicron ?-alumina of narrow particle distribution can be received by vacuum freeze.At last,the obtained sample powders were applied to the alumina ceramic and lithium ion battery diaphragm coated modification.The effect of submicron ?-alumina of narrow particle distribution on the compactness of sintered ceramics and the improvement on the physical properties of the diaphragm respectively.The main results were as follows:(1)Sub-micron ?-alumina powder was prepared by Mechanical-chemical method.The processing parameters,like slurry concentration of solid phase,rheological property,ball mill speed,medium and so on,was studied to determine the sand milling condition,under which the powder of ideal size can be obtained in 7h successfully.The condition consisted of solid content=50%,slurry pH =2,and choosing 0.6 mm yttrium stabilized zirconia grinding beads,rated speed 2200 RPM.Specific surface area of the sub-micron alumina powder was changed from 5.24 m2/g to 8.27 m2/g;after grinding.Crystalline phases had no change,but the crystal face had been damaged of different degrees and crystallinity was lowered.(2)The suspension stability of ballmilling pulp was study to conclude the optimum dispersing condition,which is solid mass fraction= 1%,pH = 2,temperature =50 ? and static-ballmilling dispersion mode.And by the time-sharing equinoctial sampling way.0.4 to 0.6?m?-alumina powder was successfully prepared by-37 ? freeze-drying.(3)The applications of submicron ?-alumina of narrow particle distribution in ceramic and lithium ion diaphragm coated modification were studied.Under the condition where there were no sintering aids,will the density of sintering ceramic was increased from 3.7 g/cm3 to 3.8 g/cm3,the relative density was up to 95%or more.The a-alumina coating of the PE diaphragm helped to improve the physical properties and enhance the safety of diaphragm.
Keywords/Search Tags:Mechanical-chemical method, Suspension stability, Narrow particle distribution, Sub-micron ?-alumina, Coating modified PE diaphragm
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