The work efficiency that improves kiln furnace and dropping hear rate and one of important step that reduce oneself weight is to use light simple fireproof stuff to replace heavy simple fireproof stuff to build kiln lining, ask the use temperature of adiabatic and fireproof material is higher and higher. And tall, stomatic big, adiabatic effect owes impurity of traditional existence of makings of light qualitative synthesis beautiful, use temperature is low (<1200 ℃ ) insufficient, artificial synthesis raw material is like alumina fiber, alumina is hollow the ball its use temperature normally prep above 1500 ℃ , be like,basically use alumina, zirconia this kind high pure the electric frit gush of oxide blows hollow ball to serve as aggregate. This kind of material has use temperature tall, adiabatic sex is good wait for an advantage, but the price is high, intensity is low, use extensively very hard. Be necessary to develop use temperature to be in consequently 1200-1500 ℃ , intensity tall, coefficient of thermal conductivity as far as possible low, porosity is tall and air hole is more close globose, purity is tall, the systole below high temperature is small, the high-powered light qualitative aggregate with high intensity. The article uses the combustible that burn ashes Fabingtong is adopted too wet craft, control combustible pink body to reach micron level, discuss different to calcine system to compound the effect that expects Molaishi changes rate and partial property to small Kongmolaishi.
Experiment
1. raw material
The experiment is main raw material with pink of industrial alumina, silica, adscititious anthracitic, it is bond with yellow dextrin, add a few dispersive agents additionally. The test is basic the recipe is shown 1 times like the watch. Among them the photograph group of industrial alumina is become: 70-80% is γ - Al2O3, 5-10% is α - Al2O3, 5-10% is 3 water aluminous stone.
2. experiment process
Put raw material in grind in all in machine in order to expect: Ball: Water weight compares 1:1: 1Wet grind in all, rotate speed is 300rpm. Abrade time is 24 hours, 30mm is the stock after be being ground in all in the diameter, what be 50mm high is cylindrical shape in the mould. Shape sample is in 110 ℃ sweatbox stoving 24 hours, have heat treatment next. Sample is natural in air dry the drawing of patterns after 48 hours. The compound that has mixed industrial alumina undertook DSC-TG and large sample heat weigh an analysis, decide with this burn those who break temperature and Molaishi to change anthraciticly to begin temperature. Provide a basis to make sound heat treatment system then. Compared system of two kinds of to calcine to change the effect of rate to Molaishi: The one attune that it is sheet warms up, next heat preservation; another for in on any account heat preservation of two temperature section. If express 2, express 3. Detected by relative standard the bulk density of the sample after burning, apparent pore rate.
3. test result and discuss
3.1 warm up means is decided really
This job uses the kind that adds combustible to form small hole. Uses initiative stock can happen to change to answer instead with solid in be heated process. Burn the temperature limits that break and reaction to make temperature range of Molaishi for ascertain combustible, provide a basis to make proper calcination temperature and heat preservation time, be necessary the hot behavior after ascertain preform be heated, use DSC-TG method to undertake detecting to the hot behavior of preform for this. Graph 1 to determine result.
By the graph 1 visible, there is grain of one absorption of heat on line of DSC of 250 ℃ left and right sides, the department decomposes be caused by by the hydroted alumina that contains in industrial alumina, the quality on corresponding TG curve also is somewhat reductive. In 600 ℃ the left and right sides appears big radiative peak, the combustible that the department joins is acuteness combustion be caused by, the quality on corresponding TG curve decreases quickly. 1200 ℃ have radiative peak to appear later, as a result of detected temperature finite, right half fail to be shown. This is to not come petrochemical begins, through X diffraction at the same time the analysis confirmed this concludes, see a table 4. However, corresponding TG has weightening finish on the curve, its reason is unidentified, the be caused by of weightening finish of mechanical iron oxidation of the interfuse in be preform probably.
The measurement that analyses as a result of DSC-TG uses makings amount mostly ≤ 100mg, and want wear fine white. Method of this kind of experiment represents the case with real compound very hard, and devoid uniformity and representative, driven is mechanical go up to also cannot be mirrorred pouring makings heat the circumstance of solid Ruan change of the process. Mix to dimension at present qualitative generous sample, can heat through sample only the change of around quality comes token total reaction situation. The model that uses whole piece large sample heats more adjacent and true. Large sample heats up heavy appearance to undertake heating up weighing an analysis to the sample after stoving, determine the room temperature change to the weight in 1400 ℃ process, if pursue,as a result 2(a) place is shown. By the graph knowable, heating continuously not below the circumstance of heat preservation, quality just keeps stable to 1100 ℃ all the time. Analyse a result again according to DSC-TG and large sample heat, compound all can generate Molaishi in 1200 ℃ above, be Molaishi only generate speed and change rate differ along with temperature and meet somewhat difference. The main purpose of this job is the Mo Laishi aggregate that synthesis has small hole structure, ask synthetic makings has certain porosity already, bore diameter small, system is secret light, ask its intensity is high again, the Molaishi that should have ideal namely is changed rate, at the same time even cost of installation cost of to calcine of give attention to two or morethings, production, because this fumbles,heat treatment system is opposite ideal to work originally and character is crucial.
Integrated above each respect element, this job had specific aim ground to contrast the influence of system of two kinds of heat treatment. A kind of mode that it is sheet warms up law, warm up with the tradition the method is same, specific warm up means is shown 5 times like the watch, in 100min of 600 ℃ heat preservation, light adequately burn lost property. Upper limit temperature is 1350 ℃ , part heat preservation 3h, 6h and 12h, label respectively with D1, D2, D3. The 2nd kind warms up to be not drab type law, warm up with the tradition the method is different, those who use is after rising first, fall again the process of heat preservation. This kind of attune that be not sheet warms up the law depends on temperature in theoretic consideration is the main impetus that Molaishi changes, through raising upper limit firing temperature makes Molaishi is changed rate rise somewhat. And at the same time need is helpful for development of Mo Laishi crystal be brought up considering high temperature, because crystal is long,mean structure of partial small hole greatly lose and material brittleness increases. Reason is in the upper limit temperature that reachs set and heat preservation is little paragraph of time hind, come down thermal drop again, time of main heat preservation spends next undertaking that finish in second low temperature. The attune is not sheet of this working set warms up if means expresses 6 to show. In 100min of 600 ℃ heat preservation, light adequately burn lost property. Raise the high temperature to 1400 ℃ , 1450 ℃ respectively next, heat preservation 10min or 60min, back-to-back move comes thermal drop 1300 ℃ , continue respectively heat preservation is different time, ordinal mark is F1~F5.
Among them D1 and F1, d3 and F3, d2 and F2, F4, F5 has equal heat treatment total time respectively. The key contrasted above synthesizes Molaishi to pledge the Molaishi of aggregate is changed gently below all sorts of heat treatment systems rate.
System of 3.2 heat treatment expects to synthesis the influence of physical function
If the bulk density that system of different heat treatment issues two series to pledge Mo Laishi synthesis expects gently and apparent pore rate express 6 to show.
From the watch 5 can see, in a kind drab type warms up below means, as the extension of heat preservation time, synthesize the trend that after the density of body trifoliate orange of aggregate of light qualitative Mo Laishi appears to rise first, falls, apparent pore leads the tide that after appearing to fall first, rises, the Molaishi in this and heat preservation process changes rate relevant.
Below 1350 ℃ , happen to not come petrifaction, as the elapse of time, mo Laishi changes degree to will achieve an upper limit to be worth, before this, because Molaishi changes accompanied bulk to expand,effect makes the bulk density that synthesis expects drops, apparent pore leads ascendant; to be in after achieving upper limit Mo Laishi to change rate, the contractive process that agglomeration creates holds dominant, the bulk density that synthesis expects begins to rise again. Apparent pore rate falls somewhat.
And move litre of lukewarm law to differ with sheet, the synthesis after using the attune that be not sheet to rise lukewarm means to handle pledges the bulk density of Mo Laishi aggregate and apparent pore rate let time of the heat preservation below second high temperature gently lengthen and change is not apparent. The main impetus; that this result proved to temperature is Molaishi is changed on one hand from certain level returns specification and photograph of aggregate of compact Mo Laishi to compare on the other hand, the Molaishi of aggregate of small qualitative small hole is changed degree and compact the sensitivity that changes pair of temperature all inferior, originally to answer instead at this point and character, as a result of the existence of a large number of small hole, make the solid according to legend of small hole material qualitative mechanism suffocate suffocate.
System of 3.3 heat treatment expects to synthesis Molaishi changes the effect of rate
If the substance appearance composition that synthesis of each light qualitative Mo Laishi expects below system of different heat treatment expresses 6 to show. Substance appearance uses the method of X ray diffraction to undertake an analysis, the face can undertake at XRD half ration determines only, because this key pays close attention to,not come among them the metabolic trend of stone photograph.
The odd mode that comparative tradition uses warms up means D1, D2 and the substance appearance after D3 is handled are comprised, knowable the extension as heat preservation time, not come petrifaction rate rises gradually. Among them the Molaishi below D2 and D3 system is changed rate comparative roughly, the specification times when temperature, the Molaishi that synthesis expects spends frank meeting as heat preservation time lengthen and gradually hasten is stable at a certain limits. This phenomenon and blame sheet are increased the comparative result photograph of the F1 below lukewarm means, F2 and F3 is consistent, namely below F1 change rate is minor, and below F2, F3 change rate rise somewhat, but both comparatives.
Below time of fixed total heat treatment, comparative and drab type warms up law and blame odd mode warm up the law expects to synthesis Molaishi changes the effect of rate. The time of total heat treatment of D1 and F1 all is 610min, the time of total heat treatment that the Molaishi below D1 changes those who lead F1 of apparent prep above to fall to change rate;D2 and F2, D3 and F3 is 790min and 1150min respectively, traditions of two comparative Yiwei are drab the Molaishi after rising lukewarm law heat treatment is changed rate is higher.
Considering F1, F2, F3 the heat preservation time below high temperature has 10min only, be not to strengthen this to plant further drab heat the influence of the system, below the 1400 ℃ in F4 system heat preservation time is lengthened to 60min, the fast temperature rise of F5 comes 1450 ℃ , heat preservation time also is 60min. Assure of photograph of time of total heat treatment and F2, D2 at the same time. Pass contrast knowable, the Molaishi that the heat preservation time below the high temperature when extending length can raise synthesis effectively to expect is changed rate (if F4); rises short when value of upper limit temperature is right Molaishi is changed of rate improve the result more remarkable, the Molaishi of F5 changes rate and traditional high temperature + the heat preservation when growing (below D2) system change rate quite. Can push accordingly know, if continue to rise short when value of upper limit temperature, mo Laishi is changed rate may continue to rise, and the time of microtherm heat preservation also can shorten.
By above the analysis can be seen, the mode that be not sheet warms up the method is in likely cost the circumstance make known to lower levels with shorter, can less waste time to be changed to taller Molaishi rate. And the synthesis after using the attune that be not sheet to rise lukewarm means to handle expects the place that there is He Du spy on characteristic of function of the etc on microstructure is worth succeeding activity to have thorough research.
Be worth what carry is, what list in the watch without the Bo glass photograph that is not common sense to go up, however Al2O3, SiO2 has reacted but have not the imperceptible Molaishi of apparent crystallization.
The aperture that 3.4 Mo Laishi synthesis expect distributings
Light to Mo Laishi of the complex below 1350 ℃ qualitative aggregate determines with the appearance that press mercury bore diameter distributinging state, if pursue,as a result 3 are shown.
Synthetic makings is after heat treatment of 6h of 1350 ℃ × , in bore diameter is 5.1 μ M about. The light qualitative Molaishi of this working place preparation has friend small hole structure.
3.5 show differential analyse
Graph the 4 synthesis after be being burned for 6h of 1350 ℃ × Molaishi pledges gently the fracture surface of aggregate and mating plate, in microscopical of the constituent structure that observes synthesis expects below electric lens and Molaishi generate with crystallization state. After base substrate expects classics is firing, the Al2O3 in the system, SiO2 does not have complete reaction. The α of photograph of high temperature of industrial alumina translate into that did not react - Al2O3, and the silica that did not react can be in drop in temperature happen to change in the process, make the appearance that silica grain presents cauliflower shape craze, the place that be in is put in vitreous photograph, the Molaishi with columnar needle is generated, if pursue,4(a) place is shown. Because the solid according to legend of porous material suffers character,be restricted, the solid photograph reaction of place happening is more " former " model reaction, the place that contacts in Al2O3 and SiO2 namely former make Mo Laishi new appearance, and be in both the grain interior area that does not contact, carry internal state severally, if pursue,4(b) place is shown. OK and suppositional, the Molaishi that synthesizes aggregate of light qualitative poriferous Mo Laishi with this experimental craft is changed rate one upper limit is worth, this upper limit changes the character of the size of the quantity and reactant and be closely bound up of dispersive and even degree. Of source of the Al2O3 in this job and SiO2 source fineness it is 10-20 μ M about, microscopical and even degree still is paid no attention to want, restricted Molaishi to change of rate rise. In working next, the dispersive and even rate between the Al2O3 in how raising preform and SiO2 composition also deserves thorough research.
4. conclusion
(Makings of 1) base substrate burns lost property mediumly to be controlled in 580 ℃ acuteness burn break, base substrate makings begins to produce Molaishi to convert reaction from 1200 ℃ . Below system of heat treatment of 6h of 1350 ℃ × , in air hole bore diameter is 5.1 μ M about, concentration distributings in limits of 3-7 μ M, mo Laishi is changed rate 60% the left and right sides.
(2) temperature and time are to affect synthesis to pledge small Kong Mo comes gently the main external cause of stone aggregate, carry appropriately high temperature is spent and lengthen heat preservation time to be able to obtain taller Molaishi to change rate, bulk density and apparent pore rate are in of an experiment each are firing the difference below the system is not big. With general synthetic agglomeration Molaishi differs, light qualitative aggregate pledges as a result of solid according to legend finite bring about its to originally to should reach agglomeration instead not sensitive to temperature and time.
(3) temperature is the main impetus that Molaishi changes, use short when high temperature + the mode is not sheet of inferior lukewarm heat preservation warms up the method is in likely cost the circumstance make known to lower levels with shorter, can fewer bad news to be changed to taller Molaishi rate, and have distinct effect possibly also to synthesizing the microstructure of makings and other property.
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