As the key refractory material of the glass furnace, the quality stability and reliability of the fused cast AZS sidewall blocks are particularly important. However, in the actual production process, fused cast AZS sidewall blocks often have various intrinsic quality defects, such as glass phase seepage, loose structure, uneven composition, bubbles and cracks, etc. These problems seriously affect their performance and life, and then have an adverse effect on the overall performance of the glass furnace and the quality of glass products. Therefore, in-depth analysis of the causes of intrinsic quality defects of fused cast AZS sidewall blocks and the proposal of effective control measures are of great significance for improving the operating efficiency and service life of glass furnaces and improving the quality stability of glass products.
Ⅰ. Analysis of intrinsic quality defects of fused cast AZS sidewall blocks
Ⅱ. Control measures for the intrinsic quality defects of fused cast AZS sidewall block
Ⅲ. Conclusion
Ⅰ. Analysis of intrinsic quality defects of fused cast AZS sidewall blocks
1.1 Glass phase seepage
Glass phase seepage is one of the common intrinsic quality defects of fused cast AZS sidewall block. Under long-term high-temperature operation, the glass phase inside the fused cast AZS sidewall block will gradually seep out to the surface, forming a glassy film. This film not only reduces the erosion resistance of the block body, but may also cause safety hazards in the operation of the glass furnace, such as adhesion of the inner wall of the furnace, thermal stress concentration, etc.
The main reasons for the seepage of the glass phase are as follows:
· Improper control of the degree of oxidation during the melting and casting process:
During the melting and casting process, if the degree of oxidation is too high, the oxide content in the glass phase will increase, making the glass phase easier to precipitate. In addition, the uneven degree of oxidation will also lead to uneven distribution of the glass phase inside the block body, aggravating the seepage phenomenon.
· Unreasonable pore structure inside the block body:
The pore structure inside the fused cast AZS sidewall block has an important influence on its performance. If the porosity is too high or the pore distribution is uneven, it will make it easier for the glass phase to seep out to the surface through the pores. In addition, the unreasonable pore structure will also affect the overall strength and erosion resistance of the block body.
1.2 Loose structure
Loose structure is another common inherent quality defect of fused cast AZS sidewall blocks. Blocks with loose structure are prone to cracking and peeling under physical and chemical effects, thus affecting their service life. Loose structure not only reduces the mechanical properties of blocks, but also greatly reduces their anti-corrosion performance.
The main reasons for loose structure include:
· Improper raw material ratio:
During the melting and casting process, the ratio of raw materials directly affects the composition distribution and crystal structure inside the block. If the raw material ratio is improper, it will lead to uneven distribution of components inside the block, which will affect the perfection of its crystal structure.
This uneven distribution of components will make the block more prone to cracking and peeling under physical and chemical effects.
· Unreasonable control of melting and casting temperature and cooling rate:
Melting and cooling rate are key factors affecting the crystal structure of blocks. If the melting and casting temperature is too high or the holding time is too long, the grains inside the block will be too large and the structure will be loose. If the cooling rate is too fast, it will cause excessive thermal stress inside the block, which will cause cracking and peeling.
· Too high porosity:
Similar to glass phase seepage, too high porosity is also one of the important reasons for loose structure. High porosity will reduce the overall strength and corrosion resistance of the block, making it more prone to cracking and peeling under long-term high-temperature operation.
1.3 Uneven composition
Uneven composition is one of the inherent quality defects of fused cast AZS sidewall blocks, which is mainly manifested in the large difference in chemical composition of different parts inside the block. This uneven composition will lead to a decrease in the corrosion resistance and thermal shock stability of the block, thereby affecting its service life.
The main reasons for uneven composition include:
· Uneven mixing of raw materials:
Before melting and casting, the mixing uniformity of raw materials has an important influence on the composition uniformity of the block. If the raw materials are not mixed evenly, the chemical composition of different parts in the melting and casting process will be greatly different, which will affect the overall performance of the block.
· Insufficient stirring during melting and casting:
During the melting and casting process, the sufficiency of stirring directly affects the composition distribution inside the melt. If the stirring is insufficient, the composition distribution inside the melt will be uneven, which will affect the composition uniformity of the block.
· Unreasonable control of melting and casting temperature and holding time:
The melting and casting temperature and holding time have an important influence on the uniformity of the melt and the diffusion of the composition. If the melting and casting temperature is too high or the holding time is too long, it will cause uneven diffusion of the components inside the melt, which will in turn affect the uniformity of the composition of the block.
1.4 Bubbles and cracks
Bubbles and cracks are common appearance defects of fused cast AZS sidewall blocks, but they will also affect their internal quality. The presence of bubbles and cracks will reduce the strength and corrosion resistance of the block, thereby shortening its service life.
The main causes of bubbles and cracks include:
· Incomplete gas discharge during melting and casting:
During the melting and casting process, if the gas is not completely discharged, bubbles will form inside the block. These bubbles will not only reduce the mechanical properties of the block, but also become areas of thermal stress concentration, increasing the risk of cracking.
· Unreasonable control of melting and casting temperature and cooling rate:
Similar to loose structure, unreasonable control of melting and casting temperature and cooling rate will also cause excessive thermal stress inside the block, thereby forming cracks. In addition, uneven cooling rate will also cause residual stress inside the block, further aggravating the formation of cracks.
· Impurities or bubbles in the raw materials:
If the raw materials contain impurities or bubbles, they will be brought into the block during the melting and casting process, forming defects.
Ⅱ. Control measures for the intrinsic quality defects of fused cast AZS sidewall block
For the intrinsic quality defects of fused cast AZS sidewall block, the following control measures can be taken to improve their quality stability and reliability:
2.1 Optimizing the raw material ratio and mixing process
Optimizing the raw material ratio and mixing process is one of the important measures to control the intrinsic quality defects of fused cast AZS sidewall block. By reasonably proportioning the raw materials, the uniformity and stability of the internal components of the block body can be ensured. At the same time, the use of advanced mixing processes can improve the mixing uniformity of the raw materials and avoid the problem of uneven composition.
► In terms of raw material ratio, the appropriate raw material types and ratios should be selected according to the operating conditions and requirements of the glass melting furnace. At the same time, factors such as the particle grading and shape of the raw materials should also be considered to ensure the fluidity and uniformity of the melt during the casting process.
► In terms of mixing technology, efficient mixing equipment and technology should be used to ensure the full mixing and uniform distribution of the raw materials. At the same time, the mixing uniformity of the raw materials can also be ensured by optimizing parameters such as mixing time and mixing intensity. In addition, the mixing equipment should be inspected and maintained regularly to ensure its normal operation and mixing effect.
2.2 Controlling the melting and casting temperature and cooling rate
Controlling the melting and casting temperature and cooling rate is one of the key measures to control the intrinsic quality defects of the fused cast AZS sidewall blocks. The melting and casting temperature and cooling rate directly affect the crystal structure and performance of the block body.
► During the melting and casting process, the melting and casting temperature and holding time should be reasonably controlled according to the characteristics of the raw materials and the capacity of the melting and casting equipment. During the cooling process, a reasonable cooling method and speed should be adopted to avoid excessive thermal stress and cracks inside the block body. For example, a segmented cooling method can be adopted, first cooling to a certain temperature range at a faster speed, and then continuing to cool to room temperature at a slower speed; at the same time, forced convection or natural convection can also be used to improve cooling efficiency and reduce thermal stress.
► In addition, the melting and casting equipment should be inspected and maintained regularly to ensure its normal operation and melting and casting effect. For example, the slag and impurities in the melting furnace should be cleaned regularly to avoid contamination and influence on the melt; at the same time, the melting temperature controller and cooling system should be checked and calibrated regularly to ensure their accuracy and stability.