English
The material of Laboratory Calibration Weights is critical to their stability under different environmental conditions, especially under the influence of factors such as temperature, humidity and oxidation. The material of the weight must have good stability and durability to ensure that the accuracy is not affected by external environmental changes. Here are the performances of common materials under these environmental factors:
Stainless Steel
Stainless steel is the most common material used in laboratory calibration weights because of its excellent corrosion resistance, strength and stability.
Temperature Effects
High Temperature Resistance: Stainless steel exhibits good heat resistance in high temperature environments. Its low coefficient of thermal expansion means that the volume of stainless steel weights changes less when the temperature changes, which helps to maintain the stability of its weight.
Stability under temperature changes: The density and hardness of stainless steel do not change much in the normal to moderate temperature range, but the performance of stainless steel may decrease in extreme high temperatures (over 1000℃). Extreme temperature changes are usually avoided in laboratories to reduce this effect.
Humidity Effects
Moisture Resistance: Stainless steel has a strong resistance to moisture, so it can remain stable in high humidity environments without rusting or corroding. Stainless steel weights are less affected by humidity changes, so they can maintain their accuracy when used in humid environments.
Oxidation and rust: Although stainless steel has strong oxidation resistance, it may still show slight surface oxidation if exposed to extremely high humidity or salt spray for a long time. Therefore, when used in humid environments, it is necessary to clean it regularly and prevent moisture from contacting the surface for a long time.
Cast Iron
Cast iron is a weight material commonly used for industrial weighing. It is relatively cheap, but it is still used in some laboratory environments.
Temperature Effect
Thermal Expansion: Cast iron has a high thermal expansion coefficient, so the volume and mass of cast iron weights may change significantly in environments with large temperature changes. Cast iron weights at high temperatures may cause measurement accuracy to decrease.
Poor high temperature resistance: Cast iron is not suitable for use in extremely high temperature environments. When the temperature is too high, it may cause deformation or strength loss.
Humidity Effect
Rust: Cast iron is easily affected by humid environments. It is prone to oxidation and rust when exposed to high humidity for a long time, affecting its accuracy and appearance. Therefore, in environments with high humidity, the use of cast iron weights requires special attention to moisture and rust prevention.
Surface protection: Cast iron weights are often coated or plated to prevent rust, but these coatings may age or deteriorate over time, causing the weight to degrade.
Copper alloys (Bronze or Brass)
Copper alloys are corrosion-resistant and highly stable materials and are often used in some high-precision calibration weights.
Temperature effects
Good thermal conductivity: Copper alloys have good thermal conductivity and can quickly adapt to temperature changes, but their thermal expansion coefficient is large, so the quality of the weight may change under large temperature fluctuations.
High temperature resistance: Although copper alloys can withstand medium and high temperatures, they may still deform or other physical property changes at extremely high temperatures. Therefore, they are not suitable for use at extremely high temperatures.
Humidity effects
Oxidation resistance: Copper alloys have good oxidation resistance, but over time, especially in humid environments, the surface may develop a patina (patina), affecting its appearance and accuracy. Therefore, copper alloy weights in humid environments need to be cleaned and maintained regularly.
Corrosion: If it is in a high humidity or acidic environment for a long time, the copper alloy may corrode and cause surface damage, so it is necessary to avoid contact with corrosive substances when using it.
Aluminum Alloy
Aluminum alloy is gradually used for some low-precision or medium-precision weights due to its light weight, corrosion resistance and high mechanical properties.
Temperature influence
Thermal expansion: The thermal expansion coefficient of aluminum alloy is large, so in an environment with large temperature fluctuations, aluminum alloy weights may undergo significant volume changes, affecting the calibration accuracy. Especially under high temperature conditions, its expansion may cause measurement errors.
Poor high temperature tolerance: Aluminum alloy has poor high temperature resistance and may soften or deform in a high temperature environment, limiting its use in high temperature environments.
Humidity influence
Moisture resistance: Aluminum alloy has strong oxidation resistance, so it shows good corrosion resistance when used in a high humidity environment. The oxide film formed on the surface of aluminum alloy can effectively prevent further oxidation.
Corrosion resistance: Although aluminum alloy has good oxidation resistance, it may also corrode under certain extreme conditions (such as strong acid or salt spray environment), affecting the accuracy of the weight.
Laboratory calibration weights made of different materials have different stability under environmental factors such as temperature, humidity and oxidation. Stainless steel performs best, has strong moisture and temperature resistance, and is suitable for a variety of environments; although cast iron is cheap, it is easy to rust and be affected by temperature changes; copper alloys and aluminum alloys also have certain corrosion resistance in high humidity environments, but still need to pay attention to environmental conditions and maintenance measures. Correctly selecting the right weight material and taking appropriate protective measures will help improve calibration accuracy and extend the life of the weight.
