How much is the coefficient of thermal conductivity of firebrick?

Qualitative, porosity concerns the coefficient of thermal conductivity of firebrick and material, namely bulk density, the material qualitative sort of firebrick is more, the coefficient of thermal conductivity of carborundum is bigger, the coefficient of thermal conductivity of brick of light qualitative fireproof heat preservation is smaller.

The stoma in 　 　 firebrick is opposite firebrick of light qualitative heat preservation the influence that heat conducts, the light transmittance that depends on degree of stomatic amount, size, UniCom and tall aluminium brick and different. Below microtherm, stoma of grow in quantity reduced the average and free Cheng of phonon, reduce the thermal conductance of material, but as temperature heighten, radiation and convection are more and more important. To photon heat conduction, stomatic size is smaller, hole wall block breaks radiant probability taller; To aeriform heat conduction, stomatic size is smaller, the probability that block breaks convection to conduct heat is higher also. The density of common firebrick: 1, argillaceous firebrick 　 of 1.8 ～ 2.0g/cm3 　 2, compact clay firebrick is 　 of 　 of 2.05 ～ 2.20g/cm3 commonly 3, firebrick of tall compact clay is 　 of 　 of 2.25 ～ 2.30g/cm3 commonly 4, silica brick is 　 of 　 of 1.8 ～ 1.95g/cm3 commonly 5, magnesia brick is 2.6 ～ 2.70g/cm3 commonly 　 , fireproof degree for: 1690-1790, loading bate spends for: 1570-1700 is spent, compression intensity is: 32-88/mpa 　 　 7, magnesian carbon brick, for 2.95-3.34g/cm3, compression intensity is the thermal conductivity coefficient of firebrick of 　 of 35-50/mpa 　 　 , it is to point to the coefficient of hot velocity of flow that passes bricky unit area below condition of unit temperature gradient namely, stomatic coefficient heals big, criterion thermal conductivity coefficient is smaller.    Producing actual in, common hot project device needs to consider the loss amount after quantity of heat passes firebrick, need the heat preservation effect of firebrick of computational heat insolation, in some the heating furnace that lie between blaze is like Jiao Lu to wait, the partition that still needs firebrick has taller thermal conductivity coefficient, because this is in hot project design,the thermal conductivity coefficient of firebrick is one of target that consider mainly. Following plan institute show the thermal conductance of all sorts of firebrick. The thermal conductance with different qualitative capable person often the difference is very big. Below normal temperature, the thermal conductance of all sorts of firebrick is OK from hundred arrive tens of (W/(m · ℃ ) ) , highest value and lowermost value differ close thousandfold. Lift as temperature, although the thermal conductance poor value of all sorts of firebrick tends reduce, but the difference is very big still. When be like 1000 ℃ , the thermal conductance of light qualitative silica is 0.35W/(m · ℃ only) the left and right sides; Recrystallization carborundum goods is 17.5W/(m · ℃ ) the left and right sides; Black lead can be as high as) of 35W/(m · ℃ . The thermal conductance of firebrick is divided outside sufferring temperature to affect (for example tall aluminous brick, magnesia brick) , closely related as chemical as its still mineral composition and constituent structure. When firebrick is formed by crystal, the property of crystal has apparent effect to thermal conductance. Well-known, the thermal conductance of inorganic metalloid material compares a metal commonly a lot of lower. Because inorganic metalloid material and the metal that have metallic key are different,this is, have few free electron only.    The heat conduction that causes by free electron in this kind of material is very finite, basically is degree of resonance of deviate of vibration of You Jing case and calm. Deviate resonance degree heals big, thermal conductance heals small. And degree of deviate of crystal lattice vibration is followed again make each constituent material rub the difference of Er quality increases and increase, the thermal conductance of simple substance is the so biggest (the thermal conductance of black lead is bigger depend on this) namely. Have the crystal of complex structure, bigger to the heat radiation action of crystal lattice, thermal conductance becomes smaller. Be like MgO, a12O3 and MgAl2O4 are brilliant waiting for an axis together, but because MgAl2O4 structure is complex, thermal conductance is inferior. Be different from tropism crystal, in the direction with the concentrated particle in edge crystal, thermal conductance is bigger. Like quartz particle of direction of edge C axis piles up more concentrated, its thermal conductance (13.6W/(m · ℃ ) ) it is about perpendicular at C axis direction person (7.2W/(m · ℃ ) ) 2 times.    Be like the black lead of layer shape structure again, parallel is about at the thermal conductance of level direction 4 times at level direction more perpendicular. Brick of argillaceous heat preservation coefficient of thermal conductivity: Model BrandNG-0.5NG-0. 6NG-0. 8NG-1.0NG-1.3NG-1.5 　 coefficient of thermal conductivity Thermal Conductivity of 　 of 　 of 400 ℃ 0.14-0.25-0.35-0.41-0.51-0.6 (W/m.k) , 600 ℃ , 0.16-0.29-0.45-0.43-0.61-0.71
Brick of tall aluminous heat preservation coefficient of thermal conductivity: 25 ℃ of ± of W/m.k(350 of coefficient of thermal conductivity) 0.25-0.29-0.35-0.45
How much is the coefficient of thermal conductivity of firebrick? The ＞ of coefficient of thermal conductivity of heavy qualitative firebrick is much at 1 o'clock, brick of light qualitative heat preservation differs according to bulk density, coefficient of thermal conductivity is in 0. A few.