Fireproof material develops the history:
Crockery appeared before 8000;
There was china before 2000;
There is natural raw material to begin to use before 1500.
1637, investment of crucible of black lead clay is used.
1951, domestic fireproof stuff throws production.
1966, gross of our country fireproof material is achieved produce per year 500 thousand tons.
1981, our country fireproof material begins mass production below governmental support.
1997, domestic fireproof stuff produces per year quantity gross to achieve 6.5 million tons.
2006, our country firebrick, pouring the fireproof product such as makings exports time each district.
The applied domain of fireproof material:
1, steely metallurgy, coloured metallurgy
2, building materials, be like cement, glass, pottery and porcelain
3, chemical industry, electric power
4, other industry, be like environmental protection respect, for instance the litter such as rubbish is handled.
The property of fireproof material:
The property of fireproof material basically includes heat property, mechanical property, reach high temperature to use property to wait.
Study the purpose of these property:
1, the use condition that can forecast fireproof material to fall in high temperature environment according to these property.
2, the fireproof material that can choose to heat up labor facilities place to need conversely.
The important thing reason of fireproof material is simple:
Air hole and porosity, air hole occupies the 0-90% of fireproof material total volume, of bulk of the stoma in fireproof material and total volume than calling porosity. The stoma in fireproof material can divide it is 3 kinds: Open pore (apparent pore) , stoma of be well versed in, close stomatic. If incorporate open pore and blowhole of be linked together,be a kind, the stoma of fireproof material can be divided mix for open pore close stomatic two kinds.
Stomatic formation:
1, the production such as extruding arises in the process
2, stomatic
3, interstitial
4, heat treatment arises
5, contractive
6, dry vapor eduction arises
7, stomatic and amalgamative
8, wool stoma
9, raw material itself is stomatic
Stomatic importance:
Air hole is fireproof material impartible cut one share, have beneficial effect already to fireproof material function, also have adverse effect.
1, porosity and stomatic dimension size and distributinging influence goods:
2, thermal shock stability;
3, fight aggressivity can;
4, air permeability;
5, intensity.
Bulk density is fireproof the quality of bulk of products unit apparent, express with G/cm 3 normally. (3) true density and true proportion are fireproof the quality of material is as true as its bulk (do not include stomatic volume namely) than, call true density, also express normally with G/cm 3. The concept of true proportion: Unit volume is fireproof the ratio of the weight of the weight of material and water of volume of unit of 4 ℃ . Come from numerical value say, true density and true proportion are equal. ＝ apparent pore leads true porosity ＋ closed pore rate
Air permeability:
Its physics meaning is mix inside proper time the quantity of the sample that presses the gas below difference to pass through certain section and ply certainly.
The technical index such as porosity and bulk density is token only the how many with goods compact degree of stomatic bulk in refractory products, the volume that can not reflect air hole, distributing and appearance. Refractory products is in use process, the size that erodes medium immerge, osmotic level and refractory products stoma, appearance closely related, generally speaking, the air permeability of refractory products is taller, its are counteractive and slaggy permeate, erodent ability is poorer.
The heat property of fireproof material and conductivity are qualitative:
1, heat expands
Definition: The bulk of fireproof material or length pledge as the content reason that lift and increases of temperature. It is OK that the heat of fireproof material expands with linear expansion coefficient or body coefficient of expansion expresses, also can expand with linear expansion percentage or bulk percentage expresses.
Coefficient of expansion: Fireproof material heats by room temperature inside the interval to experiment temperature, temperature every are elevatory 1 ℃ , the opposite change of sample bulk or length is led.
Meaning: The important parameter that kiln furnace designs, obligate expands seamed basis, can judge secondhand be able to bear or endure material thermal shock stabilizes function.
Influencing factor: Depend on its chemical and mineral composition, and the crystal structure with photograph of the crystallization in fireproof material and key are strong closely related.
2, thermal conductance
Definition: Below unit temperature gradient, the quantity of heat that unit vertical plane accumulates is passed inside unit time.
Influencing factor:
(1) porosity:
The air hole that contains in fireproof material is the largest to the influence of its thermal conductance. Say commonly, inside certain temperature limits, porosity is bigger, thermal conductance is lower. The chemical and mineral composition of fireproof material also has apparent effect to the heat conduction rate of material.
(2) other:
All sorts of blemish in crystal, impurity and grain interface can cause the scattering of case wave, equivalent also Yu Sheng child of average and free Cheng reduce, reduce thermal conductance thereby.
(3) thermal capacitance
In often press next heating the quantity of heat that 1kg material lifts place of 1 ℃ needs (with KJ plan) .
Thermal capacitance is the another main heat character of fireproof material, it is the temperature after token material be heated the parameter of elevatory circumstance. The temperature after any corporeal be heated wants to lift, but the quantity of heat that different corporeal temperature lifts place of 1 ℃ needs is different.
(4) conductivity
Fireproof material is undesirable conductor of report below room temperature normally, lift along with temperature, resistor is reduced, conductivity increases. If heat material to melt condition, can present stronger electric capability. Certain and fireproof material has conductivity, if contain carbon,refractory products has conductivity, and 2 zirconia goods also has better conductivity below high temperature, can regard high temperature as the calorific body below.
The mechanical nature of fireproof material:
Point to the physical index such as the intensity that products falls in different condition.
Token is fireproof the deformation that material resists the outside force below different temperature is caused with stress infrangible ability.
Include compression intensity, fight lose strength, reverse intensity, wearability, stretch pattern quantity and high temperature creep.
1, compression intensity
Include intensity of normal temperature compression and intensity of high temperature compression, it is to show normal temperature and high temperature condition fall respectively, on area of fireproof data unit can susceptive is the biggest pressure.
What index of intensity of normal temperature compression can reflect system of the craft in production normally is fluctuant. Tall compression intensity demonstrates goods shape preform treatment quality, shape the homogeneity of base substrate structure and case of bricky body agglomeration are good. Accordingly, intensity of normal temperature compression also is to examine the reliable index of active craft state and goods homogeneity.
Intensity of high temperature compression mirrorred fireproof material to combine the change of condition below high temperature. Join especially a certain quantity of of bond fireproof but plastic and pouring makings, because temperature is elevatory, when combining condition happening to change, of intensity of high temperature compression determine more useful.
2, fight lose strength
Include normal temperature to fight fold intensity and high temperature to fight lose strength, it is to show normal temperature and high temperature condition fall respectively, on area of cut of fireproof data unit can susceptive limit curves stress. Of its token is the capacity that material leaves resistance to bend quadrature in normal temperature or high temperature condition, use curved a law to measure at 3 o'clock.
The relation of intensity and structure
1.Normal temperature issues little grain and strength of persnickety aperture product to be more than the intensity of big grain products.
2.But the intensity below high temperature drops apparent also.
3.Close air hole is lesser to data strength effect.
4.The uniformity that air hole distributings also matters with intensity.
5.Of the photograph in goods distributing to also have very big concern with intensity.
6.If material stoma dimension is less than the granuality of grain, criterion the destruction of material is not begin from stomatic place.
7.First-rate grain is comprised and can not achieve lowermost porosity quite certainly.
3, function of high temperature creep
Definition: In some constant temperature and fixed load fall, the relation of the deformation of material and time. The basis brings to bear on of loading form different can divide compress creep of creep, high temperature drawing, high temperature to fight for high temperature fold creep to wait. Because high temperature is compressed,fight with high temperature fold creep to determine more easily, reason application is more. Our country is used normally compress creep.
The expression that high temperature compresses creep the method is common with some constant temperature (℃ ) with loading (MPa) below the condition, the deflection of goods (% ) with time (H) relation curve namely creep curve will express, inside period of time of usable also some (like 25-50 hour) the deflection of goods (% ) will express.
4, stretch model quantity
Material is inside its flexibility limits, in load (stress) below action, generation is out of shape (meet an emergency) , after load purify, material still restores original figure and measure, right now the ratio of stress and meet an emergency calls stretch model amount, also call Yang model the quantity. It shows ability of material resistance metabolic.
The high temperature of fireproof material uses property
When be being used in the kiln furnace that refractory products is in all sorts of differring, be in high temperature condition for a long time to fall, the property with fireproof high temperature resistant material whether the requirement of requirement of work of furnace of contented and of all kinds kiln, it is the main basis that material chooses, because this is fireproof,the high temperature property of goods also is the mainest main character.
(1) fireproof degree
Definition: Fireproof material is falling without loading condition, action of counteractive high temperature and infusible property.
Differ with the crystallization condition material that has fixed melting point, fireproof material is commonly by the polyphase solid mixture of a variety of mineral composition, without fixed melting point. Its melt undertakes inside constant temperature limits, should heat to its warm up to some occurrence fluid phase begins when temperature (the beginning that secures namely melt temperature) , continue to heat temperature still continues photograph of elevatory, fluid is measured also subsequently grow in quantity, till rise to turn into entirely to some temperature fluid photograph, inside this temperature limits, fluid get along with exists when firm is same.
(2) fireproof spending is index of a technology, become the product that be measured truncation triangle awl by certain square legal institutions. Try awl with warming up certainly speed heats, achieve some temperature to begin occurrence fluid phase, temperature continues to lift fluid photograph quantity increases gradually, viscosity is reduced, try awl to be below gravitational action gradually bate is bent, when its the turn falls to acme and the temperature that the bottom contacts, what be sample namely is fireproof degree.
Fireproof degree of distinction with melting point:
1, melting point shows the Hunan of fluid of crystallization get along with of simple matter is in the temperature when the balance;
2, melting point is constant of a physics;
3, fireproof material mixes style for heterogeneous, its melt undertakes inside certain temperature limits, it is index of a technology.
Fireproof material is achieved fireproof mechanical strength already was not had actually when spending, because this is fireproof those who spend is tall with low with material allow to use temperature and not be equal, that is to say fireproof degree of use temperature upper limit that is not material, consider the other function of material and use condition integratedly only, ability serves as reasonable the referenced basis that chooses fireproof material.
It is with magnesia brick exemple, its are fireproof degree be as high as above of 2000 ℃ , but allow to use temperature greatly under fireproof degree.
Fireproof spent meaning:
Evaluate raw material purity and difficult frit level.
Influencing factor
(1) the chemical and mineral composition of refractory products reachs his to distributing condition is an influence its are fireproof spent main factor. Foreign matter composition has the foreign matter of strong flux action especially, what will drop product badly is fireproof degree.
(2) determine condition
The pulverous granuality, installation that measures Wen Zhui, rate that warm up reachs the atmosphere inside furnace.
(3) loading bate temperature
Definition: Call high temperature loading to be out of shape again temperature, express material to use counteractive metabolic capacity in double re-act of temperature and loading. The loading softening point that says normally namely.
Meaning: The structural intensity below the condition that temperature of bate of high temperature loading can indicate to refractory products is using circumstance close with its on certain level and be out of shape circumstance, it is the main function index of refractory products consequently.
Influencing factor: The chemistry of goods - the scale of photograph of fluid of get along with of the mineral composition, property that organizes photograph of structure, microstructure, fluid, crystallization and interaction.
Determine method:
Fall in the fixed load of 0.2MPa commonly, with warming up certainly speed heats equably, determine sample compresses 0.6% , 4% , 40% The temperature when. Sample compresses the 0.6% is out of shape temperature is sample namely loading bate when to begin temperature.
Sample compresses 4 ％ (2mm) - be out of shape temperature;
Sample compresses 40 ％ (20mm) - debacle dot.
Affect the factor with soft carry on one's shoulder:
Chemical and mineral composition;
1 production technology; 2 bulk density is big, soft temperature of 3 carry on one's shoulder is higher.
4 determine condition; 5 rate-of-rise of air temperature are fast, soft temperature of 6 carry on one's shoulder is higher.
Determine the meaning with soft carry on one's shoulder:
1, can regard material as highest use temperature.
2, because this is fireproof,be being spent is the temperature of ideal upper limit that material uses only.
(4) stability of high temperature bulk
Definition: When stating fireproof material is used for a long time below high temperature, its appearance and bulk keep stable and do not produce metabolic property.
Meaning: Evaluate index of a of fireproof material quality important physics.
A: Firing goods is in process of high temperature to calcine, be in as a result of all sorts of reason goods firing when the end, physico-chemical reaction often did not achieve balance status;
B: Put in undersintering phenomenon, physico-chemical reaction is inadequate. Get in use process because of this goods high temperature is long-term when action, a few physico-chemical change are met proceed is accompanied not reversible bulk changes.
C: A few physico-chemical processes are accompanied when agglomeration, generation bulk changes.
These not reversible bulk change call remains to expand or remains contracts, also say to be burned again expand or contract.
Not big systole won't cause special complexity, not big expanding is beneficial even. Can make bricky substance thick.
The size token that burns bulk change again the stability of high temperature bulk of refractory products, the stability of the structure that waits for hot project facilities to furnace of high temperature kiln and operating mode has very important sense.
Determine meaning: Weigh the stand or fall of material agglomeration function.
(5) thermal shock stability
Definition: The function that fireproof material resists temperature changes quickly and is not destroyed, call heatproof concussion performance again.
The hot project facilities such as furnace of high temperature kiln is in moving process, its run temperature to often produce the wave motion with acuteness even change. The sharp change of this kind of temperature often can bring about fireproof material to produce crackle, flake, burst apart wait for structural sex destroy, and of the stability that affects operation of hot project facilities, security and production successional.
1, thermal shock basically is concerned with stress.
2, thermal stress has two kinds of kinds:
(1) the stress that temperature causes;
(2) chemical stress, because be not,be all pledge phenomenon, linear heat expands, chemical reaction, much brilliant is changed etc those who bring about, happen when constant temperature commonly.
Relatively sufficient to research of the first kind of thermal stress.
Produce the ingredient of thermal stress
The element of thermal stress of the coefficient of thermal conductivity of the hot coefficient of expansion of material, material, amortize (the volume that stretch model measures) .
The thermal shock stability of fireproof material, influencing factor and its heat expand rate (small) , heat conduction is led (big) and stretch model is measured (small) closely related, also the structure of macroscopical, microcosmic organization with goods, appearance structure and dimension are concerned. Refractory products can produce bulk to expand when temperature changes or contract, when be restrained, material interior can produce thermal stress. When thermal stress exceeds the intensity of goods, goods will produce craze, avalanche or rupture.
Another respect, expansile difference is heated up between different mine photograph, also can produce thermal stress.
Main influencing factor:
Stretch model quantity, hot coefficient of expansion, temperature is poor.
When the intensity limit that reachs material when thermal stress namely the intensity of material can't resist when thermal stress, goods is destroyed with respect to meeting generation.
Basic rule:
Heat conduction leads high products, the temperature in material distributings easily even, its surface layer and internal temperature are poor (temperature gradient) small, the thermal stress of generation is relatively lesser; Conversely, heat conduction leads low stuff, among them temperature distributings hard even, the temperature gradient in material is big, the thermal stress of generation is great also. Because this heat conduction leads expensive stuff, stability of its thermal shock is relative also taller.
In addition, of refractory products grand, microcosmic organization structure also has certain effect to the thermal shock stability of goods. Put in certain and subtle blemish when refractory products interior, wait like small air hole, micro-crack, what be helpful for deferring or stop crackle is patulous. The technology measure with be adopted certain makes goods in-house produce micro-crack and achieve the goal that prevents crackle to expand, it is current use generally increase stability of goods thermal shock one of significant step. What structure of refractory products appearance and dimension design is unreasonable, can bring about goods local stress is centered and generation is destroyed. Heatproof shake function is not physical function. Because it depends on not only the function of fireproof material, still concern with the element such as material appearance, dimension and coefficient of thermal conductivity.
The kind that thermal shock destroys has a variety of forms:
(1) one-time destroy, disastrous destroy (make crackle of the one or more type wearing brilliant in tasting in compact excel in for instance)
(2) level sex is destroyed (crackle of a lot of the type that wear brilliant are formed in the sample that reachs stomatic and many concentration in microcosmic crackle for instance)
(3) advance gradually type is destroyed, the sample with primitive for instance small porosity.
(5) contain carbon of fireproof material fight oxidisability
Contain carbon fireproof material is in oxidisability atmosphere, among them carbolic element material happens jointly with the oxygen in air hair should.
Methodological 1: Weightlessness law.
Below fixed temperature, continuous to air is connected inside furnace, at the same time perpetual notes weight changes, till weight changes no longer. Gain weight - time-speed-distance curve.
Methodological 2: Measure decarburized layer thickness (or area)
Sample: The cube of 50±2mm or diameter and the cylinder that are 50 ±2mm high;
Temperature: 1400 ℃ , heat preservation 3 hours, fixed discharge to air is connected inside furnace;
Evaluation: Incision sample, measure decarburized layer thickness.
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