Can the vacuum heat treatment electric furnace used in the experiment be used for impurity removal experiments?

The vacuum heat treatment electric furnace used in experiments can be fully utilized for impurity removal experiments, especially in scenarios where oxidation avoidance, precise atmosphere control, or processing of high-purity materials are required. Its vacuum environment and high temperature control capabilities can significantly improve impurity removal efficiency. The following is a specific analysis:

1. The unique advantage of vacuum environment in impurity removal
Inhibit oxidation and impurity introduction
Traditional impurity removal problem: When removing impurities in air or ordinary protective atmosphere, materials are prone to react with oxygen and water vapor, generating oxides or introducing new impurities (such as carbon and nitrogen).
Vacuum environment effect: By vacuuming to 10 ⁻³~10 ⁻⁵ Pa, oxygen and other active gases are completely isolated to avoid surface oxidation or impurity doping of materials, especially suitable for materials with extremely high purity requirements (such as semiconductor silicon and high-purity metals).
Typical case:
High purity aluminum (99.999%) is melted under vacuum to remove impurities, which can prevent aluminum from reacting with oxygen to form aluminum oxide inclusions, significantly improving conductivity and corrosion resistance.
Before the growth of semiconductor single crystal silicon, the surface oxide layer and adsorbed impurity gases (such as H ₂, O ₂) are removed by vacuum annealing to improve the crystal quality.
Promote impurity volatilization and removal
Low vapor pressure impurity removal: Vacuum environment can reduce the partial pressure of impurity elements and promote their volatilization. For example:
Metal purification: Low melting point impurities such as lead (Pb) and bismuth (Bi) remaining in copper can evaporate under vacuum at 1000-1200 ℃, with a purity of over 99.99%.
Ceramic purification: Residual chlorides (such as NaCl) in alumina (Al ₂ O ∝) ceramics decompose and evaporate under vacuum at 1600 ℃, reducing the loss of electrical insulation performance.
High vapor pressure impurity control: By adjusting the vacuum degree, specific impurities can be selectively removed. For example:
The residual iron (Fe) impurities in magnesium alloys preferentially evaporate under vacuum at 700-800 ℃ (the vapor pressure of iron is higher than that of magnesium), reducing the iron content to below 0.01%.
Degassing and purification effect
Gas escape inside the material: Vacuum environment can accelerate the diffusion and escape of adsorbed gases (such as H ₂, N ₂, CO) inside the material, reduce pores and microcracks, and indirectly improve the density and performance of the material.
Application scenarios:
Powder metallurgy products (such as neodymium iron boron permanent magnets) are vacuum treated to remove impurities, eliminate residual pores and gases during the pressing process, and improve magnetic properties and mechanical strength.
Vacuum impurity removal of welded parts, removal of hydrogen gas in the weld seam, and prevention of cold cracking.

2. Support multiple types of impurity removal processes
The experimental vacuum heat treatment electric furnace can achieve the following impurity removal methods:
Vacuum melting for impurity removal
Principle: Melting materials under vacuum, utilizing the difference in vapor pressure between impurities and the main material, and achieving purification through volatilization or solidification separation.
Applicable materials: high-purity metals (such as aluminum, copper, titanium), alloys (such as nickel based high-temperature alloys), semiconductor materials (such as silicon, germanium).
Process parameters:
Melting temperature: higher than the melting point of the material but lower than the impurity volatilization temperature (such as copper melting temperature of 1083 ℃, lead volatilization temperature of 1740 ℃, and partial volatilization of lead at 1200 ℃ under vacuum).
Vacuum degree: 10 ⁻³~10 ⁻⁵ Pa, ensuring sufficient evaporation of impurities.
Insulation time: determined based on impurity content and volatilization rate (usually 1-5 hours).
case
Vacuum consumable arc melting of titanium alloy (Ti-6Al-4V) removes interstitial impurities such as oxygen, nitrogen, and hydrogen, improving fatigue performance.
High purity germanium (99.9999%) is melted in the region, and impurities are concentrated at the end of the melting zone and removed through directional solidification and impurity segregation effects, increasing the purity to semiconductor level.
Vacuum annealing for impurity removal
Principle: By heating to a specific temperature and keeping it warm, impurities are promoted to diffuse to the material surface or evaporate, while eliminating internal stress.
Applicable materials: metals, ceramics, composite materials.
Process parameters:
Annealing temperature: determined based on the material phase transition point and impurity diffusion coefficient (such as aluminum alloy annealing temperature of 300-500 ℃, promoting hydrogen diffusion and escape).
Vacuum degree: 10 ⁻³~10 ⁻⁴ Pa, to prevent oxidation.
Cooling method: slow cooling (furnace cooling) or rapid cooling (air cooling), depending on material requirements.
case
Vacuum annealing of high-speed steel cutting tools to remove residual hydrogen gas after quenching and prevent cracking during use.
Vacuum annealing of zirconia ceramics eliminates residual carbide impurities during sintering and improves transparency.
Vacuum hot pressing for impurity removal
Principle: Apply unidirectional pressure to the material under vacuum to promote densification and eliminate impurity gases in the pores.
Applicable materials: high hardness, high melting point materials (such as Si ∝ N ₄ SiC）、 Metal based composite materials.
Process parameters:
Hot pressing temperature: 1500~2000 ℃, higher than the sintering temperature of the material.
Pressure: 10-50 MPa, promoting densification.
Vacuum degree: 10 ⁻³~10 ⁻⁴ Pa, to prevent oxidation and gas addition.
case
Silicon nitride ceramic bearing balls are vacuum hot pressed to remove oxygen and water vapor from the pores, improving wear resistance and reliability.
Carbon fiber reinforced aluminum based composite materials are vacuum hot pressed to eliminate impurity phases generated by interface reactions and improve mechanical properties.

3. The flexibility advantage of experimental equipment
Small batch testing capability
The experimental furnace has a small volume (several to tens of liters), suitable for small-scale trial production in the research and development stage, reducing material costs and process validation cycles.
Case: Comparing the effects of different vacuum degrees on copper purification efficiency, only a few tens of grams of sample are needed to complete the experiment.
Rapid process iteration
By adjusting parameters such as temperature, pressure, and vacuum degree, the impurity removal process can be quickly optimized.
Case: Study the effect of insulation time on the rate of hydrogen content reduction in aluminum alloys, and determine the optimal process window through multiple experiments.
Multi functional scalability
Some experimental furnaces can expand their atmosphere control functions (such as filling with protective gases such as Ar and N ₂), or integrate pressure loading systems to achieve composite processes (such as vacuum+hydrogen annealing).
case
Vacuum+hydrogen annealing is performed on high-strength steel to accelerate the removal of decarburization layer by utilizing the diffusion effect of hydrogen.
Vacuum+argon hot pressing is applied to titanium alloys to prevent the formation of brittle phases due to the reaction between titanium and nitrogen at high temperatures.

4. Typical application scenarios
Semiconductor industry
Vacuum annealing before single crystal silicon growth: removes surface oxide layer and adsorbed impurity gases (such as H ₂, O ₂) to improve crystal quality.
High purity metal sputtering target material vacuum melting: removes impurities such as oxygen and carbon, improves film uniformity and adhesion.
aerospace field
Vacuum impurity removal of titanium alloy parts: eliminates residual stress and surface oxide layer generated by forging or machining, and prevents cracking during subsequent use.
Nickel based high-temperature alloy vacuum melting: removes low melting point impurities such as sulfur and phosphorus, and improves high-temperature creep performance.
In the field of new energy
Vacuum annealing of lithium-ion battery cathode materials (such as LiCoO ₂): removes residual moisture and organic matter, and enhances electrochemical performance.
Vacuum heat treatment of bipolar plates in hydrogen fuel cells: removing surface oxide layer and reducing contact resistance.