Research On The Preparation Of Lightweight Ceramic Pellets And Foamed Ceramics Using Silicon Carbide Foaming

With the promotion and implementation of energy saving and green building in China,many research experts have devoted great attention to the development of high performance thermal insulation materials.Lightweight ceramic pellets and foamed ceramics are favored by the industry for their light weight and high strength,good mechanical strength,low thermal conductivity,good thermal insulation and thermal structure,safety,and environmental protection,a wide range of raw material sources,and low prices.At present,traditional aggregates with non-renewable resources such as clay shale as the principal raw material are required to withdraw from the market because they do not meet the concept of green and sustainable development;Pulverised coal pellets are declining in production year on year due to their performance defects;In recent years,there have been more and more studies and reports on the preparation of lightweight ceramic granules and foamed ceramic lightweight wall materials with solid waste as the principal raw material,promoting the comprehensive utilization of solid waste.However,for the use of solid waste preparation of lightweight ceramic pellets and foamed ceramics of the mechanism of research is not deep enough,to a certain extent,affect the regulation of product performance,to carry out the preparation of lightweight ceramic pellets mechanism and process conditions for lightweight ceramic pellets and foamed ceramics of the impact of the law of performance research is particularly urgent.This thesis uses potassium feldspar from the Luonan region as the principal raw material,introduces an appropriate amount of white gangue as a binding agent,and uses silicon carbide as a foaming agent to prepare lightweight ceramic pellets and foamed ceramics.The influence of firing temperature,particle size,and silicon carbide content on the properties and microstructure of lightweight ceramic pellets and the foaming mechanism were first investigated using X-ray fluorescence spectrometry,X-ray diffractometry,scanning electron microscopy,micro X-ray 3D imaging system analysis（CT）,Factsage 7.0 software viscosity simulation calculations and integrated thermal analysis-infrared spectroscopy coupling.The influence of the process conditions on the microstructure and properties of the foamed ceramics prepared using the same material system was investigated.（1）Potassium feldspar as the principal raw material,the appropriate amount of white gangue as a binding agent,the use of silicon carbide as a foaming agent,lightweight ceramic pellets can be prepared for the stacking density of 0.3 g/cm³-0.5 g/cm³,including when the firing temperature of 1220℃,silicon carbide addition at 3.0 wt%,the lowest lightweight ceramic pellets stacking density of 0.3 g/cm³.（2）Under the condition of fixed potassium feldspar and white gangue addition,with the change of firing temperature and silicon carbide addition,the amount of high temperature liquid phase and viscosity changes,two types of structure of lightweight ceramic pellets can be obtained,respectively honeycomb structure and single pore structure,and the thickness of the pore wall also changes,which makes the lightweight ceramic pellets load-bearing capacity changes.（3）silicon carbide is an excellent performance of high temperature foaming agent,its foaming mechanism is:with the firing temperature increases,ceramic particles in high temperature melt to form silicate glass phase with a suitable viscosity to wrap CO₂released due to the oxidation of Si C to form a large number of closed pore structure and achieve foaming effect.（4）The ratio of potassium feldspar to white gangue in the ingredients,the firing temperature,and the content of silicon carbide all affect the properties of the foamed ceramics;At a potassium feldspar content of 77 wt%,a firing temperature of 1240°C and a silicon carbide addition at 3.0 wt%,a foamed ceramic material with an apparent density of 0.28 g/cm³,a compressive strength of 1.09 MPa and thermal conductivity of 0.065W/m K can be produced.