Electric frit not comes stone brick

Electric frit not comes stone brick is main have burden by tall aluminous alumina or industrial alumina, clay or silica, in the melt inside electric arc furnace, again mould shapes the firebrick that reachs anneal to be made, its are main and mineral composition is Molaishi.
1, composition
Mo Laishi group becomes 3AI2O3 2SiO2-2A12O3·SiO2, melt temperature is 1827-1890 ℃ about, hardness is big. When crystallization of refrigeration of fluid of frit of its high temperature, meeting generation is bulky inhomogenous crystallization tendency, make electric frit not comes easily stone brick generation is interstitial. Should be in low in all when frit mixture is comprised, the frit fluid after melt has good liquidity, even and petty crystallization can be generated when Mo Laishi crystallization, make cast produces interstitial possibility to decrease. Accordingly, the composition of Mo Laishi brick should be in electric frit Al2O3/SiO2 quality is compared when be 79/21 advisable. But aborning still considers to there is a certain quantity of foreign matter composition in raw material, they produce reaction with AI2O3, SiO2 below high temperature, . Corresponding ground changed the specific value of A12O3 and SiO2. Consequently, the AI2O3/SiO2 specific value that takes actually wants a bit some lower.
The effect that to electric frit Mo Laishi brick produces basically has foreign matter:
(1) the oxide of iron and TiO2 are same, in can entering Mo Laishi solid solution partly, not big to melting point influence of Molaishi, but add vitreous content, make the vitreous photograph part of cast is caught brunet, reduce the firebrick performance of goods.
(2) alkali metal oxide is crystal to Molaishi effect of the fluid that reach frit is serious, can reduce Mo Laishi content, produce more vitreous look.
(3) although oxidation calcium affects bore with a reamer, but the effect that also has crystallization of block up Mo Laishi.
(4) magnesian to Molaishi crystallization is affected, second at oxidation calcium, when a few existence, make appear to wait with aluminous pointed spar, cordierite and corundum in crystallization mixture, corresponding ground reduces Mo Laishi amount.
Join charcoal or coke reducer to be in melt is reductive in the process but Fe2O3 eliminate, the others impurity cannot by reductive eliminate, basically be enter fuse-element and put 9 in vitreous photograph.
2, raw material
Choose alumina of tall aluminous alumina, bauxite, industry and clay to be raw material normally. When using tall aluminous alumina and bauxite, AI2O3/SiO2 is compared should ＞ 3.2, fe2O3 ＜ 1.5% , tiO2 ＜ 3.0% , 1 ％ of CaO ＜ . Aluminous raw material cries undertake pre-burning, remove structural water, when with avoiding to be in water vapour of internal cause of electric arc furnace decomposes eduction centrally, produce fulmination and cause splash.
3, burden
Composition of right choice burden is to make take Molaishi content is high, the electric frit with corundum and vitreous photograph little quantity the vital technology condition of Mo Laishi brick. The aluminous silicon coefficient of burden (AI2O3/SiO2 quality is compared) the opposite content of the AI2O3 in token burden and SiO2. From theoretic analysis, should employ Mo Laishi solid solution the silicon aluminous coefficient when critical composition (2.8-2.9) . But when high temperature melt, the volatilization of SiO2 and reductive reaction should use up one part SiO2, make the content of the Al2O3 in burden rises relatively. Accordingly, in actual burden, the control cost of aluminous silicon coefficient is lower than theoretical value, general and desirable 2.5 the left and right sides.
Reducer joins a quantity to inspect content of the Fe2O3 in raw material and calm, unfavorable and overmuch, normally the iron of reductive Lkg needs the activated carbon of 0.225kg about. If add a capacity overmuch, want to be able to make SiO2 is crossed by reductive amount like that much, affect Mo Laishi amount. The gas that produces to make melt process medium easily transgression, still should join right amount wood chip in burden.
4, melt
The main facility of melt is electric arc furnace, stationary and bend use formula two kinds. In industrial production, commonly used is bend uses formula single-phase or furnace of three-phase electric arc. Use system of power of low voltage, tall electricity, general voltage is 150-190V, voltaic intensity amounts to 1600-2000A. Melt temperature is between 1900-2200 ℃ . Electric energy is used up it is 2500-3000kWh/t goods about.
5, pouring
frit fluid infuse proper form is mixed in the model of dimension, make the structure that has proper form and measure via refrigeration the goods with compact, even organization. Cast should be had as far as possible the size with exact essence, so that make treatment amount small. Pouring using a model is with purity taller quartz is arenaceous (96 ％ of ＞ of content of molding sand SiO2) , join comfortable member (5 one 7 ％ ) bond (waste liquid of water glass, pulp, linseed oil and cottonseed oil) , mix synthesis classics dry and into.
6, heat treatment
It is to be made so that contain a large number of given crystallization photograph and the ingot of a few glass. The ingot after classics heat treatment should have enough strength and had not had great internal stress. General component is heat treatment crystallization and anneal two phase.
(1) crystallization. Not come to electric frit stone brick, the Mo Laishi crystallization of hope goods interior shows fiber shape or petty grain, distributing equably. The main factor that decides grain size is cooling rate. The research that from Al2O3 one SiO2 department pursues evenly is knowable, mo Laishi is consistent melt compound, from inside frit fluid direct and caky crystallization, not beforehand separate out corundum. But when a certain quantity of flux should be being contained in frit fluid, melt content is when refrigeration first separate out corundum, and Mo Laishi crystal should be under 1750-1800 ℃ just begin steadily separate out. Should maintain so crystallization begins to come in melt content inside the temperature limits between 1800 ℃ rapid refrigeration, and the goody that beginning crystallization under Mo Songshi is spent, give proper heat preservation time, or sufficient slow refrigeration, form Molaishi in order to make the corundum grain of inchoate separate out has enough time and frit fluid effect, make the Molaishi in goods has big content thereby.

(2) anneal (the refrigeration of cast) . The cast after crystallization is in cooling process, because departmental and dispersive heat is inhomogenous, make cast interior is put in temperature gradient, produce very great stress, can create the waste product of edge damage of craze give up, vertex damage. Cooling rate is older, the liability that reject produces is bigger also. Accordingly, cast peacefuls slow refrigeration.
The method of anneal has two kinds, from anneal and anneal of exterior heat addition. From anneal it is support mould is external good thermal insulation, commonly used vermiculite makes layer of adiabatic insulation material. Cooling rate can come by the ply of thermal insulation square. Delay Leng Wen spends limits, basically be in 1800-1100 ℃ , ordinary control is in 60 one 70 ℃ / H. Anneal of exterior heat addition often uses channel type annealing furnace, cooling rate is controallable in ＜ 100-150 ℃ / H.
7, machining
Because model appearance is insufficient correct, pouring when fluctuation systole is abhorrent, generation shrinkage cavity, and casting mouth and exterior fold, all need to undertake cut is machined, ability is used. But cast hardness is very big, treatment is very difficult. The cut of emery wheel of thick bead diamond that adopts couple of phenolic aldehyde colophony normally.
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