Study On The Preparation And The Modification Of Silicate Inorganic Foaming Thermal Insulation Materials

In recent years, the burning of the organic foam materials which used forexterior insulation of the building caused serious casualties and propertylosses in the fire accident. It makes people pay more attention to the inorganicfoam insulation materials. But now the inorganic foam insulation materialswhich used for the insulation of the external wall, such as the foam cement,aerated concrete, have the problems of high density, easy to crack and highthermal conductivity. The cycle of the preparation and the technology of thepreparation are long and complex. And the condition of preparing thesematerials need to autoclaved maintenance. The others inorganic foammaterials, such as foam glass, have low strengh, easily broken, high foamingtempreture and other problems. At present, there is no inorganic foam thermalinsulation materials with excellent performance, simple preparationtechnology and widely used. This paper is to the foam slurry with sodiumsilicate and azodicarbonamide reaction as the main research object, analysis ofthe bubble nucleation mechanism and the effect of the different temperature,time, viscosity and surface tension on the bubble pore strcture. This paper discuss on foam temperature, heating rate, holding time processing technologyand all kinds of different kinds of modified agents on the influence of thestructure and the properties of the material, and screened the proper processingcondition and modifier. This study prepared an inorganic foam insulationmaterial with light weight, high strengh, low thermal conductivity, fireprevention, no pollution, low cost, simple process and used convenience.1. The synthesis of foaming material was optimized by consideringtemperature, heating rate, holding time to analyze the foam structure andproperties of foaming material, with5°C/min of heating rate, stage type ofwarming way to500°C temperature foa calcining, foaming, cooling, parting,can be prepared a kind of density for275kg/m3, compressive strength is2.03MPa, the coefficient of thermal conductivity of0.081W/(m·K), thevolume is bibulous rate is26.37%silicate inorganic foam insulation materials.2. The foaming mechanism and curing progress were investigated and theresults showed that under the foaming temperature of100-350°C, the foamingprocess was composed by pHysical foaming of steam and chemical foamingof foaming agent pyrolysis. The curing progress of the wall material wasunder350-500°C, and the chain-typed of silicon-oxygen tetrahedral formedthree dimensional network structure by polycondensation.3. The effect of water-soluble polymer, mineral powder, boracic acid wasstudied on mechanical properties and insulation performance. The resultsshowed that water-soluble played an important role in the stable bubble process by increasing the viscosity of slurry and restraining the excessiveexpansion of gases.The mineral can change the uniformity of bubble andimprove the strength of material by reducing interfacial tension of gas-liquidand imporving the strength of bubble film.Boracic acid can adjust pH andimprove the strength of slurry,which could restrain the connection of bubbleand reduce the coefficient of thermal conductivity of material.