June 19, 2024

Corrosion of Ceramic Crucible in High-Temperature Alloy Smelting and Casting Processes

Corrosion of ceramic crucibles is an important consideration in the smelting of high-temperature alloys.
A high-temperature environment is a prerequisite for corrosion to occur. At high temperatures, the contact interface between the ceramic crucible and the high-temperature alloy melt becomes active, providing the necessary energy for chemical reactions. Certain elements in the high-temperature alloy, especially those with high reactivity, react chemically with the material of the ceramic crucible. These reactions may be of the type of oxidation, reduction, vulcanization, etc., depending on the specific chemical composition of the alloy and the crucible material. These reactions result in the gradual dissolution of the crucible material or the formation of new compounds that change the chemical composition of the alloy. Impurities and oxides in the high-temperature alloy melt may also react with the ceramic crucible. These impurities and oxides may originate from the alloy itself, the atmosphere during the melting process, or other factors. Their reaction with the crucible material may exacerbate the corrosion process and further change the composition and properties of the alloy. Melt flow and agitation also play an important role in this process. They increase the contact area and contact time between the alloy melt and the crucible surface, making the corrosion reaction more likely to occur and accelerate. The surface condition and structure of the ceramic crucible also influence the corrosion process. Crucibles with uneven, cracked, or defective surfaces are more susceptible to corrosion because these areas provide more active sites for chemical reactions. Corrosion of ceramic crucibles during the smelting and casting of high-temperature alloys can have a range of effects on high-temperature alloys.
Al2O3 Crucibles 202404
Al2O3 Crucibles 202404

1. Corrosion of ceramic crucible introduces impurities into the high-temperature alloy. During the corrosion process, the material of the crucible may react chemically with the alloying elements, leading to the dissolution of some of the crucible’s components into the alloy melt. These impurity elements will change the chemical composition of the alloy, and then affect its physical and mechanical properties.

2. Corrosion will lead to unevenness and defects on the surface of the crucible. Corrosion will destroy the original smooth surface of the crucible and form pits, cracks, or other irregularities. This kind of surface unevenness and defects will directly affect the flow state of alloy and heat destabilization during the smelting and casting process, which leads to quality degradation and even affects the performance of final products.

3. corrosion also affects the stability and controllability of the smelting and casting process. Corrosion caused by the crucible deformation, cracking or perforation, and other problems may cause alloy melt leakage, overflow, and other conditions in the smelting and casting process, which affects the continuity and uniformity of the smelting and casting. This not only increases the operating difficulty but also may reduce production efficiency and safety. To ensure the quality and stable performance of high-temperature alloy, effective measures must be taken to reduce the corrosion of ceramic crucibles. This includes the selection of crucible materials with good corrosion resistance, optimization of smelting and casting process parameters, and so on.

BN Crucibles 2403
BN Crucibles 2403
In order to reduce the corrosion rate of ceramic crucibles in smelting and casting process, the following measures can be taken:
1. Optimize the melt composition: Reduce the possibility of chemical reaction with the crucible material by adjusting the composition of the melt. This may require the introduction of specific dopants, such as indium, gallium, thallium, arsenic, antimony, etc., to change the oxygen evaporation condition of the melt so as to reduce the corrosion of the crucible.
2、 Optimize the smelting and casting process and control the temperature and atmosphere: Reduce the contact time and reaction chance between metal and ceramic crucible by controlling the process parameters such as smelting temperature, melt flow, and stirring speed. Appropriately reducing the temperature of the smelting and casting process or adjusting the atmosphere pressure can reduce the corrosive effect of high temperature on the crucible.
3、Select suitable crucible material: choosing ceramic material with higher corrosion resistance as a crucible can fundamentally improve the corrosion resistance of the crucible. This requires in-depth research on the corrosion resistance of different ceramic materials in order to find the most suitable crucible material for specific smelting and casting processes. Depending on the chemical composition of the alloy being smelted and the smelting temperature, ceramic materials with higher corrosion resistance are selected. For example, alumina, silicon nitride, and other ceramic materials have high corrosion resistance and high-temperature resistance, suitable for high-temperature alloy smelting.
4、Increase corrosion resistance design: surface treatment of ceramic crucible can further improve its corrosion resistance. For example, a layer of corrosion-resistant coating on the crucible surface can form a protective layer to prevent high-temperature alloy from direct chemical reaction with the crucible material.
Specific corrosion causes and solutions may vary depending on the specific smelting and casting process, equipment, and materials. Therefore, in practice, it is necessary to consider various factors and develop suitable anti-corrosion measures. At the same time, crucibles are regularly inspected and replaced to ensure smooth smelting and casting processes and stable product quality.

The corrosion resistance of ceramic crucibles can be further improved by researching and developing new ceramic crucible materials and technologies. For example, advanced material preparation technology can be used to prepare ceramic crucibles with higher chemical stability and thermal shock resistance; or new coating technology can be developed to improve the adhesion and corrosion resistance of the coating.

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