technology information

Physical Properties ( Silicon-carbide (SIC) heating elements ) ITEM UNIT FIGURE DENSITY g/cm3 ≥2.6 POROSITY RATE% 18~20 ANTI-FOLD STRENGTH kg/cm2 ≥500 HARDNESSMohs'scale 9.8 THERMAL EXPANSION EFFICIENT ×10-6K-1 4.８ SPECIFIC HEAT Kcal/kg℃ 0.183 THERMAL CONDUCTIVITY Kcal/Mh℃ 0.0365 HOT ZONE ELECTRIC SISTANCE Ω·mm2/m ７５０～１５００ COLD END ELECTRIC SISTANCE (200C) Ω·mm2/m 18-24 RADIATION 0.87

Physical Properties (Molybdenum disilicide (MoSi2) heating elements) MOSI2 heating elements is brittleness and hardness under high temperature meanwhile Bend strength is lower than usual . Because the plasticity of elements will become soft above 13500C . elements can be curved and form wished shape under high temperature. ITEM UNIT FIGURE Density g/cm3 5.6 Bend strength kg/cm2 ≥15 Vickers hardness kg/cm2 1200 POROSITY RATE % 7.4 Absorbent rate % 1.2 Hot strength length % 4-5

Chemical properties 1,silicon carbide heating element is type of non-metal high temperature heating device Silicon carbide heating element is first made into a blank followed by high temperature silication and recrystallization and becomes high quality stick shaped SIC electric heating devices 2, aging characteristic:Along with the horary increment in usage, the electric resistance value of the carbon stick increases gradually, this kind of phenomenon calls the " aging" of the carbon stick. 3, atmosphere inside the to the influence of the carbon stick: 4, SIC and hydrochloric acid( HCl), sulfuric acid( H2SO4) at heat hour do not take place the chemical reaction. 5, The carbon stick can rise with alkaline oxide, alkali and such soil metalses chemical reaction, So using temperature should control 1000 ℃ .

Chemical properties Elements is used in high temperature under the oxidizing atmosphere, its surface form a light SIO2 glass film which can protect the element not to be oxidized. The MOSI2 heating elements must not be used in the temperature between 4000C and 2000C for a long time . Other wise the element will be cremated under the strong oxidizing function in the low temperature . Max using temperature under different atmosphere: Atmosphere in furnace chamber Max using temperature of element NO2, CO2, O2, AIR 1800C He , Ar , Ne 17500C SO2 1700C CO , N2 1600C WET H2 1500C DRY H2 14500C

Electric properties 1, the electric resistance value of the carbon stick suffers the temperature influence very big, at 0 ～ 600 ℃ hour the electric resistance temperature coefficient of the carbon stick presents the negative value, at 600 ℃ above, the electric resistance temperature coefficient of the carbon stick presents the just happen.Electric resistance that carbon stick mark settle is its at 1050 ℃ ± 50 ℃ hour measurese of hot electric resistance value. 2, the electric resistance temperature characteristic curve of the carbon stick.The electric resistance of the carbon stick goes up along with the stick surface temperature but present not line variety regulation. 3, the carbon stick connects the line method : Triangle( Δ ) conjunction;Star polygon( Y) conjunction;Establish;Merge;Combine to establish;The string merges. 4, carbon stick surface temperature and the relation that electric resistance gather speed: 5, the carbon stick surface temperature, surface carries density three it relation 6　Electricity hot a relation for having fever first set the biggest surface carries density and.

Electric properties The resistance of MOSI2 heating elements increases fast along with the temperature going up. When the temperature don’t change , resistance is constant . Under the normal condition, the elements resistance does not change along with used time generally . So the old and the new element can be used together Surface load According to the furnace structure , furnace atmosphere, furnace temperature , correct choosing the elements surface load can make the elements use for a long time . The following picture shows the relations among furnace temperature , element temperature , and surface load. When the heating elements are radiating without hindering condition. The shadow part is the surface load used usual temperature limits.

Attention Silicon carbide heating elements are easily broken Hot zone length should equal to the with of furnace span If hot zone reach out furnace wall it will burn down furnace wall. Cold end length should equal to the thickness of furnace wall plus ext length our of furnace wall Generally ext length at cold end is 50-150mm so that cooling end and Connecting clamp and jumper strap. Inside diameter of element passing furnace hole should 1.4-1.6 times as large as outside diameter at cold end If furnace hole is smaller or be filled tightly It will block SIC element break when the temperature is high SIC heating element should move freely while installing. The distance among SIC heating element heated goods and furnace wall should be larger or 3 time as long as hot zone diameter Central distance between rod and rod should not less 4 times than hot zone diameter. Cold end connect main circuit with aluminum braids or aluminum leaf The clamp at cold end should be fixed tightly. Before the new furnace or the furnace has not been used for a long time is used they must be dried when drying then it is better to use old elements or other heat source. SIC heating element should prevent damp white depositing After be damper aluminum layer at cold end will easily resole shed off which cause electric resistance value enlarging between cold end and clamps So elements cracks easily after switching on power source. Before installation resistance distribution must be carried We should connect same or equal resistance value together. You should prepare the adjustable voltage equipment lnitial voltage sent should be half of its normal working voltage stabilize a period of time then raise voltage slowly and gradually if you can not like this silicon carbide heating elements will be damaged by over current impulse. Service life of elements is longer if using it continually Service life of elements is shorter if using it interrupted . You should choose reasonable surface load density and using temperature white applying Using temperature should not more than 1650℃ In harmful air environment prevent evenly to take chemical reaction with harmful air.

1. Elements’ erection The brittleness of MOSI2 heating elements is relative more under the usual temperature, it also has plasticity under the high temperature. So you had better hang and erect vertically the “U”- shape element. You can erect it by the other way at the request of combining completely with heat model . The cone-part of the element must extend inside the furnace . At first the fixture of MOSI2 connector can’t be screwed too tightly . When temperature of the element is going up . Please twist it tightly again . So the element is not easily broken at this time because of plasticity. In order to prevent erecting vertically and touch with the end of boiler , the distance is not less than 25mm between element and the end of boiler. The furnace top must be a good function of heat-preservation. In general , the temperature of furnace top can’t be over 3000C . In order to avoid connector over-hot , the voltage should be low 0.1V between the power connector and the element . The distance is not less than 50mm between the low end of connector . Generallyφ6/12 element can not be used of 170A for a long time . φ9/18mm element can not be used of 300A for a long time 。 2. Usage of the elements The large furnace is dried over a long period of time . you had better use other heating elements to dry the furnace so that the elements is oxidized in low temperature .Using MOSI2 heating elements can avoid current impulsive and make electric equipment over weight (load) . Power is supplied in the follow methods。 When shifting gears , the time can not be too long . The element’s temperature can not drop down 300-4000C usually. Otherwise , it easily lead to current impulsive and damage the electrical equipment。