Using waste glass to research foam glass

The use of waste glass to develop foam glass Li Yueming Li Hua Zou Zhuochen (Jingdezhen Ceramic Institute, 333001) foam glass formulation and foaming process system; trial production of foam glass with low bulk density, high compressive strength, firing cycle moment, easy to control Features. Using waste glass to develop foam glass, Li Yueming, Li Hua, Zou Zhuochen (Jingdezhen Ceramic Research Institute, 333001), foam glass formula and foaming process system; The trial produced foam glass has the characteristics of low bulk density, high compressive strength, short firing cycle and easy control.
1. Introduction foam glass is a kind of glass material, which is filled with countless open or closed cells in the glass body. The diameter of the glass hole is about 0.5 to 5 mm, which is characterized by good heat insulation, sound absorption and flame retardancy. This is an excellent low temperature. Ultra low temperature heat insulation, heat insulation and sound insulation materials.
As a new type of lightweight inorganic thermal insulation material, foam glass is widely used in thermal insulation pipelines, reaction tanks, oil storage tanks and underground refrigeration pipelines in refrigeration and refrigeration industries such as petroleum, chemical industry, electronics, metallurgy, etc. It can also be used as a thermal insulation wall material in cold regions. It is an energy-saving material with extensive application value. In recent years, due to the improvement of social consumption capacity, waste glass is inevitably produced. Such waste glass is difficult to decay naturally. Its accumulation not only pollutes the environment, but also consumes a lot of farmland, causing waste of resources. These glass wastes are used to make foam glass, which can reduce the production cost of foam glass, protect the environment, turn waste into treasure, and have extensive economic and social benefits.
With the increase of dosage, the performance of foam glass shows an upward trend. When the equivalent is less, the produced gaseous substance has less mass, and its role in reducing viscosity and surface tension is very significant, so it has foaming effect, but its performance is slightly poor. With the increase of the amount of added gas, the amount of generated gas increases. The continuous reduction of viscosity and surface tension is conducive to the polymerization and growth of gas, and the quality of foam glass rises rapidly; When the equivalent is large, the gas volume is large, the viscosity and surface tension are rapidly reduced, making the bubble diameter too large, the foam is uneven, and the quality is reduced.

2. The influence of various factors on the blister during the firing process This study was conducted from room temperature to 300°C and the temperature was raised at 5°C/min to preheat the batch materials. Because the raw materials used are powdery and naturally accumulate in the mold, their thermal conductivity is poor. If the temperature is increased rapidly, the surface carbon will oxidize and the surface glass powder melts prematurely, causing excessive temperature difference between the inner and outer layers of the batch material. Non-uniformity must be preheated below the ignition point of the blowing agent. 3.3 Influence of various factors on the blister during firing This study was conducted from room temperature to 300 ° C, and the temperature was raised to 5 ° C/min to preheat the batch. Because the raw materials used are powdery and naturally stacked in the mold, their thermal conductivity is very poor. If the temperature rises rapidly, the surface carbon will be oxidized and the surface glass powder will melt prematurely, resulting in excessive temperature difference between the inner and outer layers of the batch. The non-uniformity must be preheated to be lower than the ignition point of the foaming agent.
The heating rate is 680 ° C within the temperature range of 680 ° C. As the softening temperature of the glass is higher than 680 ° C, and the carbon within this temperature range is oxidized, NaN3 will decompose, and the gas generated by them can be easily discharged from the gap of powdered glass powder. Because the foaming gas is reduced and the foaming effect is poor, the temperature rise control at this stage is very important. From the results of orthogonal analysis (), it can be seen that when the heating rate Vi increases from 10C/min to 20C/min, the performance presents a downward trend. The reason is that the heating speed is too high. Due to the poor heat transfer capacity of the powder, the temperature difference between the internal and external surfaces is different. Larger, it may cause the surface inside has been vitrified but not sintered, or even surface blistering and intermediate sintering, so the performance will decline.
In this temperature range, the melting of the frit produces liquid phase and swells, which is an important stage to obtain the required properties. It can be seen that the higher the heating rate, the better. If the heating rate is low at this stage, the gas generated by decomposition or reaction may volatilize, and the rapid temperature rise may seal the gas inside the molten glass to produce foam.
Foaming temperature and time, as well as suitable foaming temperature and foam time, are the key to producing foam glass with excellent performance. It shows that the higher the temperature, the better the performance. This is because in the temperature range 770-810 ° C, the viscosity is reduced, but the surface tension is basically unchanged, so the performance will become better. However, as the temperature continues to rise, the viscosity will drop, the gas will not entangle, and the performance will decline. The foaming time refers to the holding time at the foaming temperature. A certain heat preservation time can ensure that the internal and external temperature of the product is uniform, foam is sufficient, and foam time is too short or too long, all of which will make the foam structure uneven. Therefore, 810C was used for 30 minutes in this experiment.
After the foaming is completed, after the foam temperature drops to 580C, cool it quickly to stabilize the foam temperature, enter the annealing state, keep it for 30 minutes, and then cool it slowly to eliminate the residual stress in the foam glass, so as to ensure that the product has a certain mechanical strength.
3. Conclusion The recycled waste glass and bottle glass can be used to produce foam glass with proper foaming agent and other additives.
The developed foam glass has low bulk density (0.3g/cm3), high compressive strength (1MPa), and low thermal conductivity (0). A reasonable foaming process system is the key to the production of foam glass. The following firing systems are used in this experiment: room temperature - 300 ℃, heating rate 5C/min; 300-680C heating rate 10C/min; 680-810C heating rate is 15C/min, holding at 810C for 30 minutes, then rapidly cooling to 560C, thermal annealing for 30 minutes, and slowly cooling to room temperature. This low-temperature foam ing process saves energy and reduces costs.