Perlite is a volcanic acidic vitreous rock, so named because of its pearl-fractured structure. Perlite is divided into expanded perlite and closed cell perlite. Foamed perlite is a kind of building material with thermal insulation, fire protection and environmental protection, but it has high water absorption rate, low particle strength, easy to break, large shrinkage rate, and it is difficult to maintain proper earthquake force. - Resistant and crack-resistant exterior walls, so can not be widely used.
Closed-pore perlite is heated in an electric furnace. Through the gradient heating of perlite ore and precise air time control, the surface of perlite ore is melted, the pores are closed, and the inside has a honeycomb structure. Closed cell perlite overcomes the shortcomings of traditional expanded perlite such as high water absorption, low strength, poor fluidity and high thermal conductivity, and expands the application area of expanded perlite.
The difference between glass beads and perlite:
Closed cell perlite is also called vitrified microgranules. Vitrified microbeads are a kind of surface vitrified zone obtained from low temperature to high temperature in a vitrification oven at a temperature of about 1100°. Hard shell, hollow spherical honeycomb-shaped particles. inside, very stable physical and chemical properties, strong aging and weather resistance, vitreous micro granules have excellent thermal insulation, fire protection and sound absorption performance, suitable for exterior wall insulation mortar, exterior wall insulation board, interior decoration. Lightweight filler in the board plays the role of thermal insulation, fire protection, sound absorption and heat preservation.
Because closed-cell perlite has a vitrified shell, it is referred to as vitrified microbeads. Vitreous balls are another name for closed cell perlite. Vitrified microbeads are divided into several grades: 30-50 mesh, 50-70 mesh and 90-120 mesh. Vitrified microspheres can replace floating fly ash pellets, glass microspheres, expanded perlite, polystyrene particles and many other traditional lightweight thermal insulation materials in various thermal insulation products. Vitrified microbeads are a new type of environmentally friendly high-performance inorganic lightweight heat-insulating, sound-absorbing and heat-preserving materials.
Vitrified microgranules are closed-cell perlite. The difference between closed cell perlite and expanded perlite is mainly the difference in calcination time and temperature. Perlite ore remains at a high temperature for a long time when heated in an electric furnace. Heating to a high temperature above 1200°C, the surface melts and glassy, forming a completely closed surface, with poor water absorption, high strength and large specific gravity. The bulk density is 100-150 kg/m3, and the water absorption rate is 35-50%. at high temperature short, the temperature is above 800℃, the specific gravity of expanded perlite is 80-110kg/m3, water absorption is 200-350%.
Tell us about the similarities and differences between two commonly used products: expanded perlite and glass microbeads.
Similar Points: 1. Firstly, both are preheated from perlite ore, and then flash fired and expanded at high temperature to produce white granular materials.
2. Second, both are products after high temperature expansion, so their chemical composition is the same, both are acid and alkali resistant, colorless, odorless and non-toxic, and both are A grade refractory materials promoted by the Ministry of Construction.
3. Both of the last two structures have certain micropores, so both of them have the characteristics of heat preservation, heat insulation and sound absorption, and are widely used in building heat preservation systems. Differences: 1. Different structure: foamed perlite is open-pore, and vitrified micro-granule is closed-pore, so vitrified micro-granule is also called closed-cell perlite.
2. Processing equipment is different: expanded perlite is heated and expanded using a gas generator, and vitreous microgranules are expanded using an electric furnace.
3. Different water absorption rate: Vitreous microgranules do not easily absorb water, and expanded perlite has a high water absorption rate. After water absorption, the thermal insulation effect of expanded perlite will be greatly reduced.
4. Bulk density is different: expanded perlite is usually 70-100 kg/m3, vitreous microgranules - 110-130 kg/m3.
5. The field of application is different: vitrified micro-granules are mainly used for external wall insulation and light gypsum. Expanded perlite is mainly used for roof and floor insulation.
Currently, there are many types of thermal insulation materials on the market. There are only three brothers in the category of inorganic lightweight aggregates: open cell expanded perlite, closed cell expanded perlite and Vitreous Microgranules. So what are they? What are the differences?
First: different scientific definitions. Theoretically, any perlite ore can be called sunpulverized perlite after high-temperature expansion. Among them, the closed surface, and the spherical shape with a hollow interior is called closed-cell perlite. This 30-50 mesh closed cell perlite contains vitrified microbeads.
2: Various processing methods When the buoyancy of expanded perlite products exceeds its own gravity, the expanded ore sand particles start to rise with the hot air flow, and then continue to heat up and expand. Vitrified microbeads and closed cell perlite are produced in electric furnaces, especially vitrified microbeads are heated in layers by sliding from top to bottom, and the temperature of each layer is precisely controlled, so that the vitrification of the surface can be better. guaranteed.
Third: Different applications of finished products Theoretically, the thermal conductivity of perlite is lower than that of closed-cell perlite, but the market price of perlite is not as good as the other two. The reason lies in its own water absorption! After absorbing water, the thermal conductivity of perlite will greatly increase, so it cannot be used directly. The method currently used in the market is to modify it with silicone, which solved the problem of water absorption.