Quartz crucibles are extensively utilized in diverse fields, including photovoltaic crystal pulling, semiconductor manufacturing, and laboratory analyses, owing to their high purity, high-temperature resistance, and excellent chemical stability. The potential for reuse and the decision regarding scrapping are intrinsically linked to production costs, product quality, and production safety, necessitating a comprehensive evaluation in conjunction with application scenarios and usage conditions.

1. Can quartz crucibles be reused?

The reusability of quartz crucibles varies by scenario, mainly depending on the degree of damage and contamination after use.

(1) Laboratory scene

Small-capacity quartz crucibles for laboratory use can be reused after cleaning (such as soaking in dilute hydrochloric acid to remove residues or high-temperature incineration to remove organic matter) if they are used for heating non-strongly corrosive substances and show no obvious cracks, deformations or severe contamination after use. However, it should be noted that if the crucible comes into contact with strong alkali, hydrofluoric acid (HF) or molten metals (such as aluminum, sodium), the inner wall will be corroded, resulting in a decrease in purity or structural damage. In such cases, it is not advisable to reuse it.

(2) Industrial scenarios (photovoltaic/semiconductor)

Quartz crucibles used in the process of photovoltaic crystal pulling or semiconductor epitaxy, due to the harsh operating environments they are subjected to and their reaction with silicon materials at high temperatures, are usually used only once. During the crystal pulling process, the silicon melt reacts with the inner wall of the crucible to form a SiO₂-Si solid solution, creating an erosion layer of approximately 0.5 to 2mm thickness, and microcracks may occur simultaneously. If reused, the eroded layer is prone to peel off and enter the silicon single crystal, leading to excessive oxygen content or an increase in crystal defects, which affects the efficiency of photovoltaic cells or the quality of semiconductor chips.

However, some used industrial crucibles can be recycled through regeneration processes. These include crushing, acid washing to purify and remove metal impurities, and high-temperature remelting. The crucibles are then made into low-grade quartz products, such as laboratory crucibles. It should be noted that they are not directly reused in the original high-purity scenarios.

2. Criteria for scrapping quartz crucibles

(1) Apparent defects

Cracks: Cracks visible to the naked eye or micro-cracks detected by ultrasonic testing all need to be scrapped. Cracks can cause stress concentration during the heating process, which may result in the crucible breaking and consequent melt leakage.

Deformation: Abnormal shapes such as an unrounded mouth, bulging bottom, and concave side walls can affect installation or uniformity of heating, leading to poor crystal growth.

Surface damage: Severe scratches, pits or the adhesion of impurities that are difficult to remove (such as silicon slag, metal particles) will increase the risk of melt contamination.

(2) Decline in physical properties

Failure of thermal shock stability: Following the heating and cooling cycle, if the crucible exhibits a tendency to crack or break, this signifies a decline in its thermal shock performance and indicates that it is no longer able to withstand sudden temperature changes.

Reduced mechanical strength: The crucible wall becomes thinner and more fragile, unable to bear the weight of the melt or operational stress.

(3) Excessive chemical pollution

When used in semiconductor or high-purity experiments, if the impurity content on the surface of the crucible exceeds the specified standard, the crucible must be scrapped, even if its appearance is intact. Pollution sources include raw material residues and cross-contamination during the usage process, etc.

(4) Service life has exceeded the limit

Industrial crucibles are rated for either the number of uses they can withstand (for example, photovoltaic crystal pulling crucibles are usually used once) or the cumulative heating time. Once exceeded, even in the absence of any obvious defects, they will be scrapped due to performance degradation.

3. Conclusion

The reuse of quartz crucibles should be determined based on the scenario and damage conditions: in non-corrosive laboratory scenarios, they can be cleaned and reused, while in high-purity industrial scenarios, they are mostly used only once. The process of scrapping must adhere strictly to the established standards regarding appearance, physical properties, chemical pollution and service life. This ensures production safety and product quality. Appropriate judgment on the subjects of scrapping and recycling can reduce costs and minimize resource waste, which is in line with the concept of green production.