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        Ceramic shaft, ceramic piston, ceramic pump, ceramic seal through the use of alumina ceramic production process

        Writer:kSource:k Number of visits: Date:2012-05-13
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        Fabrication process of alumina ceramics

        Alumina ceramics are divided into two kinds of high purity and common type. High purity alumina ceramics Al2O3 content in more than 99.9% of the ceramic materials, due to its high sintering temperature of 1650-1990 DEG C, transmission wavelength is 1 ~ 6 m, usually made of molten glass to replace platinum crucible: using the transparence and alkali metal corrosion as sodium lamp; in the electronics industry can be used as integrated circuit substrates with high frequency insulating materials. Ordinary alumina ceramic system according to Al2O3 content of different into 99 porcelain, 95 porcelain, 90 porcelain, 85 porcelain and other varieties, sometimes Al2O3 content in 80% or 75% were also zoned for ordinary alumina ceramic series. Which 99% alumina ceramics material for making high temperature crucible, refractory furnace tube and special wear-resistant materials, such as ceramic bearings, ceramic sealing parts and valve piece and so on; 95 alumina ceramics is mainly used for the corrosion resistance, wear parts; 85 alumina ceramics since it is often mixed with some talcum and improve the electrical properties and mechanical strength, and molybdenum, niobium, tantalum metal sealing connection, and some used as electric vacuum device. The production process is as follows:

        Preparation of powder:

        The alumina powder of the factory will be prepared into powder material according to different requirements and different molding technology.. The particle size of the powder is 1 micron m micron, and the purity of alumina ceramic products is 99.99% apart from the pure alumina ceramic products, and the particle size distribution is uniform.. Using extrusion molding or injection molding, powder for the introduction of binder and plasticizer, the general is weight ratio in 10-30% of thermal plastic resin or plastic? The organic binder should be mixed with the alumina powder at the temperature of 150-200 for forming operation.. The powder material of hot pressing process is not required to add the binder.. If the semi or full automatic dry pressing, the powder has a special process requirements, need to adopt the spray granulation of powder processing, it presents a round ball, in order to improve the powder fluidity for molding automatic filling die wall. In addition, in order to reduce the friction between powder and mold wall, also need to add 1 ~ 2% lubricant? Such as stearic acid? And binder PVA.

        For dry pressing molding, the powder spray granulation is needed, and polyvinyl alcohol as the binder is introduced.. In recent years, a research institute in Shanghai has developed a water-soluble paraffin as binder for spray granulation of Al2O3, and has good fluidity in the heating case.. The powder of spray granulation must have good fluidity, loose density, and the friction temperature of flow angle is less than 30.. The condition of the particle size ratio is ideal, in order to obtain the large element density..

        Two, molding method:

        Alumina ceramic molding method with stem pressure, grouting, extrusion, cold and static pressure, casting, injection, hot pressing and heat pressing forming methods. In recent years at home and abroad and the development of pressure casting, direct coagulation casting, gel injection molding, centrifugal casting and solid free molding molding method. Different product shape, size, complex modeling and precision of the products need different molding methods. General introduction of its common forming:

        1 dry compression molding: alumina ceramic dry press molding technology is limited to the shape of pure and inner wall thickness of over 1mm, length and diameter of the ratio of 4: 1 of the object. The molding method has single axial or two-way. There are two kinds of hydraulic pressure type and mechanical type, which can be semi-automatic or automatic.. Press the maximum pressure of 200Mpa. output per minute of up to 50 ~ 15. Because the hydraulic pressure of the hydraulic press stroke is uniform, the height of the pressure parts is different when the powder filling is different.. And the mechanical type press is applied to the size of the powder filling, which can change the size of the powder, which can cause the shrinkage of the size after sintering.. So the distribution of powder particles in the dry pressing process is very important for the mold filling.. The accuracy of the filling volume is very great for the size accuracy control of the alumina ceramic parts.. Powder particles with more than 60 m, between 60 ~ 200 mesh can be the maximum free flow effect, and achieved the best pressure molding effect.

        2 injection molding method: the injection molding is the earliest forming method of alumina ceramics. Due to the use of plaster mold, low cost and easy to form large size, complex parts of the shape. The key of the injection molding is the preparation of alumina slurry. Usually in water flux as medium, adding solution of glue and adhesive, fully after grinding exhaust, then pour into the plaster mold. Because of the adsorption of water, the slurry was solidified in the mold.. Hollow grouting, the mold wall thickness requirements of slurry adsorption, it needs to be poured out excess slurry. In order to reduce the shrinkage of the body, the high concentration slurry should be used as far as possible..

        In order to make the slurry particles surface, the double layer of the slurry can be formed and the slurry is suspended without precipitation.. In addition to the need to join the vinyl alcohol, methyl cellulose, alginate amine binder and polypropylene amine, gum arabic divided powder, all aimed at the slurry suitable for injection molding operation.

        Three, burning technology:

        The technical method of compacting the granular ceramic body into densification and forming the solid material is called sintering.. The sintering of the particles in the body is eliminated, and the organic compounds of small amount of gas and impurities are eliminated, so that the mutual growth of the particles and the formation of new material are eliminated..

        Burn the most widely used electric furnace for heating devices. Except for atmospheric pressure sintering? There is no pressure sintering, there are hot pressing sintering and hot pressing, etc.. Continuous hot press sintering although the increase of output, but the cost of equipment and mold is too high, in addition due to the axial heating, the length of the product is limited. The hot, etc. static pressure burning with high

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        Keywords for the information:陶瓷轴、陶瓷柱塞、陶瓷泵、陶瓷密封,工艺 

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