| The development of modern time's new techology not only has provided requestment to the chemical composition of materials, but also has strict standard to the formation and pattern of them.Research , production and applied development of the high quality altrafine nanometer powder is an important part in the area of modern high technology. With the development of modern technology, performance demand of silica ultrafine powder materials becomes more and more important in electronic industry , aeronautical and space technology and new type of catalytic ahent, the powder is also more and more frequently used in toothpaste, plastics and rabber, which entitles silica research and development to receive increasing attention.At present, among the frequent methods in silica ultrafine powder research and development, the major ones are chemical vapor deposition, coprecipition, the sol-gel process and microemalsion , there methods all have cortain defects. Athongh silica made by chemical vapor deposition is of good quality, it is demanding in reactor design technology hence high production costProduct size is hard to control, poor in evenness and purity, and has special demand in product making and subsequent treatment process , limiting its application and production.As for nanosilica powder, its spreading is the crux of the matter, in either its preparation on its applying, due to the fact that nanosilica powder is generally collected from among the dissolvent by physical or chemical methods.Furthermore, nano powder is easy to become united for the Fan.D.F, so its valuable for the nano material research to find a way to prevent the nano powder from the union in its preparation, drying, transport and applying.lt is against this background in research that this paper emphasize the following:1. In the process of the colloidal bundle method for preparation of the nanosilica, in the liquid reacted system, colloidal bundle is obtained by addingdifferent types of surface activity agent to itf which assist to control the minienvironment of the reaction of coprecipitation in the liquid reacted system. Based on the conditions under which analysis of the silica ultrafine powders fenerated is conducted.A set of effective measures have been taken to maintain a considerably higher dispersiveness and to make the powders smaller in order to dimit its distribution range.The added surface activity agent can also cause the deposition powders is prevented and deposition powders generated can be treated by the method of normal filtration. As a result, the most serious defect in making silica ultrafine powders by the method of coprecipitation , i.e. conglomeration, has been avoided.2. The highly pure silica ultrafine powders require high content inpurity ions.Some materials which can get rid of impurity , are added to low the content of impurity ions.Test of the material chosen dimonstrates that it can get rid of the impurity ions within silica ultrafine powders more thoroughly which guarantee the high purity of silica ultrafine powders.3. In the process of the sol-gel method for the preparation of the nanosilica, here there is a new method of catalysis and a new kind of catalyst.On the basis of the reasonable elect of the dessolvent and its amount, the selected subject shows a wonderful experiment performance its gelation time greatly shortened, its tempreture greatly reduced, its density dropped, its structure dispersed.The prepared nanopowder is well-distributed and well-disperseded.4. Through a series of condition test, a set of factors have been reached including PH of the solution, temperature, reaction duration, surface activity agent and its dosages, washing mode and storage mode, which have a considerable influence on reaction during production.Physical and chemical analysis of the product reveal that synthetic silica ultrafine powder is above 99.9% in purity, ball-shaped with small and even diameter (20-40nm) .5. When the nanopowder surface covered and then applied, its DBF and surface area is compa...
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