Application of Vertical Vacuum Furnace in Ceramic Industry

Vertical vacuum furnaces are widely and crucially used in the ceramic industry. Through vacuum environment control and precise heating technology, they significantly improve the sintering quality, production efficiency, and product performance of ceramic materials. Specific application scenarios and advantages are as follows:

1. Core application scenarios
High purity ceramic sintering
Application objects: high-performance ceramics such as alumina, silicon nitride, and silicon carbide.
Technological advantages:
The vacuum environment (with a basic pressure of 5 × 10 ⁻¹ Pa to 2 × 10 ⁻⁵ Pa) effectively eliminates oxygen, moisture, and impurities from the air, avoiding oxidation or the introduction of pores in ceramic materials at high temperatures, significantly improving product density (>99%) and purity (>99.5%).
Vertical structure: The vertical convection of hot air flow is combined with a forced circulation fan to eliminate temperature differences (≤± 5 ℃) inside the furnace, ensuring uniform sintering of large-sized ceramic parts (such as ceramic substrates with a diameter of ≥ 300mm) and reducing the risk of cracking.
ceramic to metal seal
Application object: Vacuum brazing of ceramics and metals (such as Kovar alloy, stainless steel).
Technological advantages:
Vacuum degassing: Under a vacuum degree of 10 ⁻ Pa, oxides and gases on the metal surface are completely removed, avoiding the formation of bubbles or cracks at the sealing interface, and increasing the sealing strength by more than 50%.
Accurate temperature control: The PID temperature control system (accuracy ± 1 ℃) achieves matching of thermal expansion coefficients between metal and ceramic, with a sealing layer thickness uniformity of ≤± 0.01mm, meeting the strict requirements for airtightness in aerospace, electronic packaging and other fields (leakage rate ≤ 1 × 10 ⁻¹¹ Pa · m ³/s).
Preparation of Transparent Ceramics
Application objects: YAG (yttrium aluminum garnet), MgAl ₂ O ₄ (spinel) and other transparent ceramics.
Technological advantages:
High vacuum+inert gas protection: high-purity argon gas (purity 99.999%) is introduced under a vacuum degree of 10 ⁻⁴ Pa to suppress abnormal grain growth and increase the transmittance to over 92% (wavelength 400-700nm).
Multi stage program heating: Accurately control the crystal phase transition through 30 heating curves (such as preheating section 500 ℃ → reaction section 1800 ℃ → cooling section 200 ℃) to avoid the formation of light scattering centers.

2. Analysis of Technical Advantages
Non oxidizing environment ensures material performance
Ceramic materials such as Si ∝ N ₄ and SiC are prone to react with oxygen at high temperatures to generate SiO ₂, leading to a decrease in strength. The vertical vacuum furnace maintains an ultra-high vacuum degree (≤ 10 ⁻⁴ Pa) to keep the oxygen partial pressure below 10 ⁻² ⁰ Pa, completely suppressing oxidation reactions and ensuring the mechanical properties and chemical stability of ceramic products.
Accurate temperature control improves product consistency
By using K-type thermocouples and PID temperature control systems, a temperature control accuracy of ± 1 ℃ can be achieved. Combined with 30 programmed heating curves, the sintering kinetics of ceramic materials (such as liquid-phase sintering and solid-phase diffusion) can be accurately simulated, resulting in product shrinkage fluctuations of less than 0.5% and performance differences between batches of less than 5%.
Vertical structure optimization production efficiency
Quick loading: Some models are equipped with underground quenching oil buffer tanks and scissor lifts, reducing the workpiece loading cycle time to 25 seconds and increasing efficiency by 40% compared to horizontal furnaces.
Modular design: supports multiple process switches such as vacuum sintering, air pressure sintering, and negative pressure debinding. One device can complete the entire process of ceramic debinding from raw materials to final sintering, reducing equipment investment and site occupation.

3. Industry application cases
In the field of electronic ceramics
MLCC (Multilayer Ceramic Capacitor) Sintering: A vertical vacuum furnace uses vacuum degassing (10 ⁻ ³ Pa) and rapid cooling (50 ℃/min) to eliminate internal stress in the ceramic film, resulting in a capacity deviation of<± 1% for MLCC and a 20% increase in withstand voltage strength, meeting the requirements of miniaturization and high reliability for 5G mobile phones. Structural ceramics field Ceramic cutting tool manufacturing: ZrO ₂ ceramic blades are sintered in a vertical vacuum furnace, with a hardness of HRA88 and a bending strength of>1200MPa. Compared with traditional hot pressing sintering processes, the efficiency is increased by 30% and the cost is reduced by 25%.
Bioceramic field
Hydroxyapatite (HA) artificial bone sintering: By low-temperature sintering at 1300 ℃ in a vacuum environment, the biological activity of HA is retained, and the porosity is controlled at 50-70% to meet the needs of bone tissue growth. The clinical application success rate is increased to over 95%.