Study On Technology Of Silicate Thermal Insulation Coating

The utilization of thermal insulation coatings can alleviate the serious problem of energy waste in the industry and the building consumption,improve energy efficiency and result in considerable economic benefits.However,with the development of thermal insulation technology and higher practical application requirements,their thermal insulation performance needs to be further improved.In addition,the service temperature range of most thermal insulation coatings is not high enough,which greatly restricts their development in high temperature energy saving areas.In this paper,a new type of silacate thermal insulation coating with wider application scope,better heat insulation performance and good comprehensive properties was studied in the light of several heat insulation mechanisms,the choosing of appropriate components and the design of suitable preparation process,in order to improve thermal insulation performance and increase service temperature range.The silicate thermal insulating coating was prepared by means of high speed mechanical agitation when the sodium silicate was used as the binder and,hollow ceramic microspheres,aluminosilicate fibers and silica aerogel were added as thermal insulating aggregetes,in the respective presence of K₂Ti₆O₁₃ whisker（PTW）,rutile titanium dioxide（TiO₂）and TiO₂ sol as infrared opacifiers.The curing process of the coating was studied and the preparation process of the coating was determined.The effects of the types and the contents of thermal insulation fillers on the thermal conductivity of the coating were studied.The influence of the types and the contents of the infrared opacifiers on the thermal conductivity,infrared transmittance and extinction coefficient of the coating was studied.The microstructures were also observed.The general properties of the coating were tested and the high temperature stability of the coating was studied.The results show that the thermal conductivity of the coating can be reduced in the respective addition of 300,600,1250,2000 and 2500 mesh hollow ceramic microspheres,while the thermal conductivity of the coating added with 600 mesh hollow ceramic microspheres is the lowest.The thermal conductivity of the coating decreases with the increase of the content of hollow ceramic microspheres,aluminum silicate fibers and SiO₂ aerogels,but after a certain amount of addition,the decreasing trend begins to be gentle.Compared with hollow ceramic microspheres and aluminosilicate fibers,the influence of SiO₂ aerogels on the thermal conductivity of the coating is larger.The respective addition of PTW,TiO₂ and titanium sol can all reduce the thermal conductivity of the coating,decrease the infrared transmittance of the coating and improve the extinction coefficient of the coating.The more the amount of PTW,TiO₂ and titanium sol is,the more obvious the effect is.However,after a certain amount of addition,the thermal conductivity of the coating added with PTW or TiO₂ increases instead.Among these three infrared opacifers,titanium sol has the best dispersion in the coating,which results in the best light-shielding performance and the lowest thermal conductivity to 0.032 W·m^-1·K^-1.The micromorphology of the coating heated at 1000℃ is found to be well bonded compared with that of the coating curing at 30℃.The whole system forms a three-dimensional network structure full of micropores inside and a smooth surface with no cracks on it outside.The respective addition of PTW,TiO₂ and titanium sol all increases the upper service temperature of the coating,while the coating added with titanium sol has the highest service temperature up to 1078℃.The appearance of the coating is good.The viscosity of the coating can meet the requirments for utilization.The slurry pH is 11.The pulp density is 965kg/m³ and the dry density is 210kg/m³.The volume shrinkage is 16%.The coating cured completely has good hardness,adhesion,layer water resistance,acid resistance,alkali resistance,salt resistance and weather resistance.