The materials of laboratory ball mill jars are mainly categorized into three types: metal, non-metal, and composite. Different materials correspond to different grinding requirements, with core differences in hardness, wear resistance, and whether they introduce impurities. The selection should be based on the characteristics of the samples.
1. Metal Materials: High Hardness, Suitable for Coarse Grinding or Hard Samples
Metal jars have high hardness and strong impact resistance, making them suitable for grinding hard samples such as ores and metal powders. However, they may introduce metal impurities due to wear, so subsequent purification should be noted.
Stainless Steel Jars (304/316L)
Features: Low cost, durable, and capable of withstanding relatively high rotation speeds (≤600r/min). 316L has better corrosion resistance than 304, making it suitable for samples containing a small amount of moisture.
Disadvantages: Prone to generating metal impurities such as Fe and Cr during grinding, not suitable for samples with high purity requirements (e.g., food, pharmaceutical fibers).
Application Scenarios: Coarse grinding of wood fibers and mineral fibers, or as grinding jars for the pretreatment stage.
Tungsten Carbide Jars (WC)
Features: Extremely high hardness (HV1500-1800), strong wear resistance, almost no impurity shedding, and suitable for fine grinding (particle size ≤1μm).
Disadvantages: Expensive, heavy, easy to crack under impact, and cannot grind acidic samples (as they will corrode tungsten).
Application Scenarios: Grinding of high-purity hard fibers (e.g., carbon fibers, glass fibers) or experiments requiring ultra-fine processing.
2. Non-Metal Materials: Low Contamination, Suitable for High-Purity or Soft Samples
Non-metal jars have good chemical stability and hardly introduce impurities, making them suitable for food, medicine, biological fibers, or experiments with high purity requirements.
Agate Jars (SiO₂)
Features: Natural material with high hardness (Mohs hardness 7), strong chemical inertness, no reaction with acids and alkalis, no impurity contamination, good light transmittance, and allows observation of the grinding state.
Disadvantages: High brittleness, easy to break under impact, higher price than stainless steel jars, and not suitable for grinding samples harder than itself (e.g., corundum).
Application Scenarios: Grinding of high-purity fibers (e.g., plant fibers, cellulose), pharmaceutical-grade sample processing, or experiments requiring avoidance of metal contamination.
Alumina Ceramic Jars (Al₂O₃)
Features: Artificial ceramics with high hardness (Mohs hardness 9), better wear resistance than agate, high temperature resistance (≤1200℃), and suitable for high-temperature assisted grinding.
Disadvantages: May introduce trace Al₂O₃ impurities due to wear, with a price between stainless steel and agate.
Application Scenarios: Grinding of medium-to-high hardness fibers (e.g., ceramic fibers, basalt fibers) or experiments requiring a high-temperature environment.
Polytetrafluoroethylene (PTFE) Jars
Features: Extremely strong chemical stability (resistant to strong acids and alkalis), low density, light weight, and no impurity shedding, making them suitable for soft or heat-sensitive samples.
Disadvantages: Low hardness (Mohs hardness 2), poor wear resistance, only suitable for low-speed grinding (≤300r/min), and easy to be scratched by sharp samples.
Application Scenarios: Grinding of soft fibers (e.g., cotton fibers, wool fibers) and samples containing strongly corrosive solvents (e.g., acidic fiber suspensions).
3. Composite Materials: Balancing Hardness and Low Contamination
Composite materials are made by combining two materials to balance wear resistance and low impurity levels, suitable for experiments with complex requirements.
Lined Composite Jars (e.g., Stainless Steel Jar + Agate Liner)
Structure: The outer layer is stainless steel (to ensure strength), and the inner layer is agate/ceramic (to avoid contamination).
Features: Both impact-resistant and able to avoid metal impurities, solving the problems of pure agate jars being fragile and pure stainless steel jars causing contamination.
Disadvantages: High price, and the liner needs to be replaced as a whole if damaged, resulting in high maintenance costs.
Application Scenarios: Experiments requiring both purity and equipment strength (e.g., grinding of special fibers for aerospace).