The preheating of graphite crucible plays an important role in the process of crucible, and the service life of the crucible is greatly enhanced if the preheating method is right, conversely, the service life of crucible is over if the preheating method is incorrect. So what's the right way to warm it?

　　1).The graphite crucible is a ceramic product, it has a certain number of pores in the crucible wall , they are easy to absorb the moisture, so for the first time using crucible and under the conditions of having no any material in it ,the crucible must be preheated to ensure that no residual moisture in the crucible wall: it is best to put it nearby the stove which has the temperature and baked it more than 24 hours, in this period of time, the crucible need to be turned several times so that the heat evenly and removing the moisture inside of the crucible wall(or we can put some of wood inside the crucible and burn them about 3 hours to achieve the effect of preheating). We can avoid the crucible heating too fast and resulting in crucible thermal expansion,the bottom appeared off and delamination or cracking.

　　The humidity general is in the fastest evaporation in the 75-100 degrees temperature,so the heating must be slow in this temperature; after 2 hours ,the graphite crucible preheating to 150 to 200 degrees and holding this temperature an hour and then heating 150 degrees for an hour. The crucible don’t stay in this temperature range too long time because in the temperature range 315~650 degree ,the crucible wall will appear rapid oxidation, oxidation will not only shorten the life of the crucible , but also it will impact its use of performance because of its thermal conductivity be reduced.

　　2).The graphite crucible normally don’t need preheating again after the first time preheating if it is used continuously unless the crucible is exposed in the moist environment again.

　　3).The operators need make the graphite crucible fast warming up to 850 to 950 degrees in having no material and insulation for half an hour and then dropped to normal temperature and put the material in it after the the graphite crucible preheating. (the life of the preheating crucible will prolong when its temperature is higher than the normal working temperature.) Usually the graphite crucible is heated to a 815~930, it is useful to protect the glaze of the crucible, the high temperature heating can be each a week if it’s possible.

　　The graphite crucible has good thermal conductivity and high temperature resistance, high temperature in use process, small thermal expansion coefficient. It has a certain anti strain properties. The acid alkali solution, corrosion resistance strong, excellent chemical stability. The graphite crucible, because has more excellent performance, so in casting, metallurgy, machinery, chemical and other industrial sectors, is widely used for smelting alloy tool steel and non-ferrous metal and alloy smelting. And have a good technical and economic effect. The main raw material of graphite crucible is the crystallization of natural graphite, keep the physical and chemical properties of various original natural graphite. Graphite for acid and alkaline solution of stronger corrosion resistance, excellent chemical stability.

　　There are two kinds of domestic graphite crucible production process: plastic molding process and molding process. The clay as binder plastic molding production cycle length, high labor intensity, low efficiency, coal burning, pollution, but because of less investment, used in China the process; and equipment static pressure pressing forming process if sintering with the natural gas as a clean energy source, fundamentally solves the problem of pollution and reduce the production processes nearly 10, short period and high work efficiency.

　　The technical level of domestic graphite crucible production has reached or exceeded the quality of domestic imported crucible, crucible has the following characteristics:

　　1, the high density graphite crucible has the best thermal conductivity, the thermal conductivity is better than other imported crucible;

　　2, the appearance of a graphite crucible forming material special glaze layer and dense, greatly improving the product corrosion resistance, prolong the service life;

　　3 components of graphite and graphite crucible in all the use of natural graphite, the thermal conductivity is very good. Graphite crucible after heating cannot be immediately placed in cold metal on the desktop, in order to avoid it because of rapid cooling and rupture.

　　Beijing Great Wall Co., ltd is a leading company of graphite product. We always offer the best quality and the competitive price for our customer. We are looking forward to your enquiry and cooperation in the future.

　　Graphite crucible has a very wide range of application in the metallurgical industry. It is used for containing various liquid metal, as a manufacturer of metallurgy, we should know how to use graphite crucible, otherwise there will be some problems in the latter part of the production and application. Here we will introduce the matters which we should pay attention to:

　　1).Although the quality of graphite crucible is very good, not easy to damage, but we should handle it with care . The impact of falling from high altitude or bumps on the quality is not very big, but it will has crevice and even be broken for a long time so go on. We can’t give any remedy once the situation appear and can only change another one.

　　2).The graphite crucible is easier to damp, damp will make it become soft, it will be deformed when it is striked by some impprocedure items. And once the water goes into the inside of graphite crucible, it will influence the raw materials contained by it and dilute the raw material and maybe even some chemical reactions will happen and affect its quality, waterproof measures must be done well.

　　3).We can’t use the graphite crucible in the environment of sudden cold or sudden hot , it is easy to make its internal structure deformation, thus affecting its overall usage. Especially we should put it in the warm insulation to store it in the winter , do not put it in the cold outdoors, even we don't have a place to put it , we should use it ater its temperature become consistent with the ambient consistent.

　　4).We can’t heat in the the graphite crucible above the naked light. Because its thermal conductivity is not special enough, heating by the naked light has no meaning, and smoke and fire roasted will make it blackened, it isn’t beautiful.

　　5).We should pay attention to the distance between it wit the fire when we use the graphite crucible, this distance should be maintained at about 0.5 meters, there will be some problems if less than this distance.

　　6).The liquid inside graphite crucible should be poured out when it’s not in use , we wipe it up and then storage. It can cause corrosion phenomenon if there are other residual liquid in it, we can’t see much change in the short term , you will see the problem during the long-term observation .

　　Overall, the main component raw material of graphite crucible is graphite, it has all the properties of graphite, we hope we can use it with the correct , scientific and reasonable attitude.The use of graphite crucible is a very meticulous work, we need care and patience.

　　Many kinds of materials have been developed and used in graphite crucibles after many years of high speed development, and the graphite crucibles made of different materials has different characteristics in its application.

　　Graphite crucible materials can be roughly divided into artificial graphite, graphite - clay material and graphite - silicon carbide material.

　　Artificial graphite crucible is made from graphite electrode material.

　　The main component of graphite-clay crucible are natural flake graphite and clay. Now it’s only used in high temperature melting of iron casting and steel casting and the melting of precious metals.

　　Graphite - silicon carbide crucible is made from the natural flake graphite and silicon carbide .Most of the melting of non-ferrous metals such as copper alloy and aluminum alloy are using these crucibles.The Japanese crucible Co., Ltd. developed and producted the graphite - silicon carbide material crucible for the first time in Japan in 1955.The graphite-clay crucibles are replaced by it gradually because the graphite - silicon carbide material crucible has excellent durability compared with the graphite clay material. Now the demand for graphite silicon carbide crucible has accounted for about 97% of the total.

　　Graphite crucible is try its best to meet the use in harsh conditions in the raw materials,manufacturing and other aspects.

　　The main characteristics of graphite crucible are listed as follows:

　　1).High thermal conductivity: due to the use of graphite and other raw materials in high thermal conductivity, it ensures good thermal conductivity, shortens the time to dissolve and reduces energy consumption.

　　2).Heat shock resistance: the heat shock performance of graphite crucible is strong, it’s not easy to break for the urgent cold ,urgent heat and any process.

　　3).High heat resistance：graphite crucible has figures as high temperature, it can be in high temperature resistant 1200~1600.

　　4).Corrosion Resistance ：uniform and fine matrix design graphite of crucible make it strong to erosion against melt and delay the erosion degree of the product.

　　5).Anti mechanical shock: graphite crucible has a certain impact on the strength of the impact of mechanical properties (such as the input of the molten material, etc.).

　　6).Oxidation resistance: Graphite is easy to be oxidized in the high temperature oxidation aerial fog , it has less consumption of oxidation due to the prevention of oxidation treatment, .

　　7).Anti adhesion:the soakage and adhesion of melt soup to graphite crucible is less because of the characteristics of graphite which is not easy to adhere with the melt soup.

　　8).The metal pollution control: graphite crucible isn’t be mixed with impurity which can pollute melting soup the because of strict control of the material composition and the rare metal contamination.

　　9).Resistance to slag remover (in addition to slag agent) effect:graphite crucible has a good resistance to slag (slag remover) effect.

　　10).Acid resistance:in the addition of special materials ,we significantly improve the quality of the graphite crucible and make it has excellence performance in the acid resistance.

　　11).Quality stability: the production technology and quality assurance system of high pressure forming method of graphite crucible fully guarantee the stability of the quality.

　　Graphite crucible for everyone, perhaps not strange, many people may have heard of it, but they don’t understand the specific usage of the graphite crucible, today we , as the professional manufacturers will share with you and tell you what does the graphite crucible do.

　　Simply speaking ,graphite crucible is a heated container, in our daily lives, some of the objects will melt when we heat it and it take us have a lot of trouble, for example, we can not use aluminum vessel in the melting process of iron because the melting point of iron is high than aluminum, the things which we want to melt did not be melted, but the container melt . So at this time , the graphite crucible appeared, people can use this kind of graphite crucible for smelting some metals,it can ensures the smooth production of the accident and also can avoid the occurrence of burns,so it is very helpful for our life. Graphite crucible has been widely used because it has the characteristics of non-melt in high temperature and corrosion resistance, so it will be widely used in non-ferrous metal heating and molding.

　　Graphite crucible has good thermal conductivity and high temperature resistance, the thermal expansion coefficient of graphite crucible in the process of high temperature is small, graphite crucible has a certain anti strain properties to the heat and cold . For acid, alkaline solution , it has strong corrosion resistance and excellent chemical stability. In the metallurgy, casting, mechanical, chemical and other industrial sectors, graphite crucible is widely used in the smelting of alloy tool steel and non-ferrous metals and alloys. It has a good technical and economic results.

　　The production technology level of Chinese graphite crucible has reached or exceeded the imported crucible, the quality of Chinese crucible has the following characteristics:

　　1).The high density of graphite crucible makes the crucible has the best thermal conductivity, the heat conduction effect is better than other imported crucible;

　　2).The appearance of graphite crucible has a special glaze layer and dense molding material, it greatly improve the corrosion resistance of the product and prolong its service life;

　　3).The graphite components of graphite crucible are all natural graphite, its thermal conductivity is very good. it can not be placed on the cold metal table immediately after the graphite crucible is heated so as to avoid the cracking of the graphite crucible. Graphite crucible is suit for the melting of a variety of small number of alloy . you only need to exchange the graphite crucible If you want to change the type of alloy.Other fusion methods like melting used by reverberatory furnace and non-crucible induction furnace , they are suitable for the melting of a large number of single alloy , the metal will be polluted if the refractory lining don’t be replaced when we transform type of melting alloy.

　　Brief introduction:

　　Graphite gold crucible, specialized in the jewelry casting industry, mainly for the fusion of gold, silver casting.

　　Material description:

　　High pure graphite is widely used in casting, metallurgy, mold and other industries, high precision CNC machining equipment, the production of horizontal continuous casting with high purity, high strength, high density graphite crystallizer; electronic industry graphite mould; metallurgical industry with graphite mold and other various shapes, various uses of graphite processing finished parts can be realized, the needs of machining precision and roughness of graphite.

　　All materials using isostatic isotropic, high strength, high-density high pure graphite.

　　Products include high pure graphite crucible, graphite slide mold, graphite casting mold and all kinds of graphite special-shaped mold products manufactured by the high purity graphite, superior performance.

　　Characteristic

　　1 Thermal Stability: the use of the graphite crucible in the rapid cooling of the hot and cold conditions, specially designed to ensure the reliability of product quality.

　　2 corrosion resistance: matrix design fine uniform, delaying the crucible erosion degree.

　　3 impact resistance: graphite crucible can withstand the heat shock intensity is extremely high, so any process can be assured of.

　　4 acid resistance: the addition of special materials to improve the quality of the crucible, the resistance of the outstanding performance, and greatly extend the service life of the graphite crucible.

　　5 high thermal conductivity: high content of fixed carbon to ensure good thermal conductivity, shorten the time of dissolution, and significantly reduce the energy consumption.

　　6 metal pollution control: the strict control of the material composition, to ensure that the dissolution of graphite crucible on the metal without pollution.

　　7 the quality stability: the production technology and quality assurance system of high pressure forming process guarantee the stability of the quality.

　　Crucible characteristic

　　The following characteristics of the graphite crucible:

　　1 Thermal Stability: the use of the graphite crucible in the rapid cooling of the hot and cold conditions, specially designed to ensure the reliability of product quality.

　　2 corrosion resistance: matrix design fine uniform, delaying the crucible erosion degree.

　　3 impact resistance: graphite crucible can withstand the heat shock intensity is extremely high, so any process can be assured of.

　　4 acid resistance: the addition of special materials to improve the quality of the crucible, the resistance of the outstanding performance, and greatly extend the service life of the graphite crucible.

　　5 high thermal conductivity: high content of fixed carbon to ensure good thermal conductivity, shorten the melting time, and significantly reduce the energy consumption.

　　6 metal pollution control: the strict control of the material composition, to ensure that the dissolution of graphite crucible on the metal without pollution.

　　7 the quality stability: the production technology and quality assurance system of high pressure forming process guarantee the stability of the quality

       Graphite crucible which includes (1), and other static pressure molding silicon carbide - graphite crucible, (two) plastic forming, plastic forming, (three) the plastic forming of molten copper, (four) lead cast special clay graphite crucible.

　　(1) and other static pressure forming silicon carbide - graphite crucible series

　　It can also be divided into high temperature copper and copper alloy, special crucible for melting zinc and special crucible for melting. This series of crucible by isostatic pressure shaping, high density, high intensity. The material of the high purity natural flake graphite, high purity silicon carbide is used as main material and add advanced antioxidant and anti - corrosion agent, using resin as binder, the product has quick heat conduction, using ordered taller efficiency energy-saving features, has been widely used by many high-end melting, casting used by customers. Under the same condition, the average operating life is about four times of the ordinary clay crucible, and the same as the conventional crucible, which saves energy by 1/3. Energy saving crucible.

　　(2) plastic forming molten aluminium crucible

　　The series products are made of advanced formula, special equipment for forming equipment. The domestic leading level of melting aluminum crucible with plastic molding. Product thermal conductivity, corrosion resistance, oxidation resistance characteristics. For about three months to melt aluminum. And cost is high, the current has been used by the molten aluminum customers.

　　(3) a special crucible for plastic forming

　　This series of products is a common clay graphite crucible. Our company has accumulated decades of experience in the production, and after a series of transformation and upgrading, so that the series of products, stable performance, antioxidant, thermal shock resistance and corrosion resistance are better than similar products in the same industry. Simply referred to as the common crucible.

　　(4) lead cast special clay graphite crucible.

　　Lead cast products, is our company's patented product. This product is used for copper, copper processing, has one's own knack in. Life in the domestic lead, can be as long as three to five months. And the performance of the non domestic other manufacturers can be stable.

How to use the graphite crucible in a right is important.

　　The first time to use it,we should heat the crucible under a 1300~1500 centigrade,and after 2~3 times,the surface of the crucible could form a sinter layer,so the service life will be longer. If we use it without the sinter layer for the first time, and melting the fusible metal,such as tin,vanadium,aluminum etc,the crucible will be broken quickly,and the graphite will be fire when it reach 700 centigrade.

　　The crucible should be put onto the special base,and the Dia of the base should be the same as the crucible. And there should be some graphite powder and coal powder on the base. And the material of the base should also be graphite material,it doesn’t allow to put the crucible onto other material base.

　　It must be very careful to fill in the crucible,and it doesn’t allow to throw the metal into the crucible. And the crucible should not be very full of the metal, coz the metal will expand during the melting process,and the metal material should not be too close to each other.

　　During the melting process,it should not put the metal in times.

　　It doesn’t allow to put the crucible into the high-temperature furnace,coz the crucible will crack because of this,and before putting the metal into crucible,the metal must be baked to dry. The wet metal should not be put into the crucible. The temperature of the heating should be heating-up slowly,it’s better to make the same graphite cover on the crucible ,coz it can reduce the losing of the metal.

　　The crucible should not be put onto the furnace for a long time,coz it can reduce the service of the crucible.the pliers which used for the crucible should be the circle shape.

　　The service life of the graphite crucible is mainly affected by the way of using. Many customers say that their crucibles will be broken or crack after several times, and they think the problem is from the crucible quality, however,if we could use it in a better way or a right way,the service life will be longer.

　　1、the storage of the graphite crucible.

　　The graphite crucible is easy to be wet,because it’s easy to absorb the moisture of in the air,so it’s better to store the crucible in a dry place,it should not be in the wet place.

　　2、Drying of crucible

　　Before using each type of the crucible,it must be dry,and it should be put as bottom up display,the crucible should not be baked by flame. It should be in an indirect heating way to warm up or use the warm wind to bake.

　　The temperature must be rise up little by little,the start temperature should be 60~80 centigrade,and the final temperature should be 150~200 centigrade.and the time to bake it should be 5~7days.

　　3、the new crucible should not be used in the furnance under a very high temperature.it must be dried as the way above,then put it into the cold furnance,heating it slowly.keep it 1~2 hours(it depands on the size of the crucible),then heat the crucible to red colour,if no crack or broken under this situation,so there is no need to take it out,and we can put the metal inside under that situation,and the metal must be dry and pre-heated ones.(the coal used to heat the crucible is also dry).

　　When the temperature reach 1300~1500 centigrade,the crucible will melt,and it will form sinter layer on the surface of the crucible,so the crucible can be used for a long time even under the low temperature.

　　Making graphite,SiC,clay,silicon powder etc.as the raw material to process the graphite SiC crucible,the below are some results about the oxidation resistance from different factors such as:the raw material constitution,firing temperature,the method of forming and the different coating on the surface.

　　1) The firing temperature has a big influence on the density,and the density will lead to the service life of the crucible. When the temperature reach 1150 centigrade,the porosity of the graphite-SiC crucible is the lowest,and the density is the best.

　　2) The content of the SiC is also very important to the oxidation resistance of the graphite crucible,with the content of the SiC increasing,the porosity of the crucible is reducing,and the performance of the oxidation resistance will be better. The content between 35~50%,the porosity and weight loss rate are the best,when the content of SiC reach 50%,the density will be the highest,and the oxidation resistance is the best.

　　3) The silicon powder also has influence on the graphite-SiC crucible oxidation resistance,and with the different contents of the silicon powder changing,it can improve the the porosity,density and the oxidation resistance performance. When the silicon powder reach 15% content,the oxidation resistance performance is the best.

　　4) Different methods of forming also have different influence on the performance of the graphite-SiC crucibles. After the comparison between machine molding and isostatic molding,we could found that the way by isostatic molding is better than the machine molding ,because of the better density,lower weight loss rate,so it can tell that the oxidation resistance performance is better than the isostatic molding.

　　5) The coating on the surface of the crucible and the wall thickness also have influence on the oxidation resistance performance. When the thickness of the coating is the same,the crucible with B2O3 can reduce the weight loss rate of the crucible,and at the same time it can improve the oxidation resistance performance,and when the content of the coating is the same,the multi-storey coating is better than the single-storey on the density and the weight loss rate,and increase the oxidation resistance performance.