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Yixing Jingke Optical Instrument Co., Ltd
Mastering the standardized operating methods of quartz crucibles is the core of ensuring process purity and experimental safety
Date: 2025-12-23Read: 0
Quartz crucible is made of high-purity fused silica, which has excellent high temperature resistance (softening point is about 1650 ℃), low thermal expansion coefficient and extremely low impurity precipitation rate. It is widely used in the fields of monocrystalline silicon growth, semiconductor purification, high-temperature material sintering and precious metal smelting. However, it is brittle, sensitive to thermal shock, and susceptible to alkali metal corrosion. Improper use can lead to cracking, contamination, and even bursting. Mastering the scientific and standardized operation methods of quartz crucibles is the core of ensuring process purity and experimental safety.
1、 Preparation before use
Check appearance: Confirm that there are no cracks, bubbles, scratches, or white spots (possibly due to Na2 or K2 contamination);
Cleanliness check: The new crucible needs to be soaked in high-purity HF acid (5-10%) or specialized cleaning agent, and then rinsed multiple times with ultrapure water to achieve a water resistance rate of 18M Ω· cm that meets the standard;
Match checking: Ensure that the size and shape of the crucible are compatible with the heating furnace, induction coil, or support frame to avoid uneven stress.
2、 Heating and cooling
Strictly prohibit rapid cooling and heating: the heating rate should be controlled at ≤ 5 ℃/min (especially below 300 ℃) to prevent the volume change caused by the α - β quartz phase transition (573 ℃) from leading to rupture;
Recommended step heating: such as room temperature → 300 ℃ (insulation for 30 minutes) → 800 ℃ → target temperature, to fully release stress;
Cooling must be carried out along with the furnace: Do not directly expose the high-temperature crucible to air or come into contact with cold metals. It is recommended to cool down at a rate of ≤ 3 ℃/min.
3、 Loading and operation specifications
Dry and anhydrous materials: Water containing or volatile substances (such as nitrates and carbonates) decompose upon heating to produce gases, which can easily cause splashing or internal pressure rupture;
Avoid contact with alkaline substances: NaOH, K2CO2, etc. can severely corrode quartz, generate low melting point silicates, and cause crucible softening and perforation;
Handle with care: Use quartz pliers or ceramic fixtures, and prohibit metal tools from directly touching the inner wall.
4、 Special process precautions
Monocrystalline silicon growth: It needs to be used in an inert atmosphere (Ar) to prevent oxygen diffusion from affecting crystal quality;
Metal melting: limited to metals such as Pt, Au, Ag that do not react with SiO2, and active metals such as Al, Fe, Ca are strictly prohibited;
Reuse: After each use, remove the residue and check if the inner wall turns white or opaque. If it does, it should be scrapped.