Tech Team · Kintek Solution

To make a KBr (potassium bromide) disc, the process involves preparing a finely ground mixture of KBr and the sample, transferring it into a die, and then using a hydraulic press to compress the mixture into a solid, transparent pellet. This pellet is then used for spectroscopic analysis, such as FTIR (Fourier-transform infrared spectroscopy). The key steps include ensuring the mixture is homogeneous, applying consistent pressure, and carefully handling the die and press to avoid contamination or damage to the pellet.

Key Points Explained:

1. Preparation of the KBr and Sample Mixture:

   • The first step is to grind the KBr and sample into a fine powder. This ensures that the mixture is homogeneous and free of large particles that could interfere with the transparency of the final pellet.
   • The sample should be mixed with KBr in the correct ratio, typically around 1% sample to 99% KBr, to ensure the pellet is suitable for spectroscopic analysis.

2. Loading the Die:

   • The die, which is a cylindrical mold, is inserted into the cavity of the pellet press. The ground mixture is then transferred into the die cavity.
   • A bolt press is inserted into the die, and it is rotated to evenly distribute the particles within the cavity. This step is crucial to ensure that the pellet has a uniform thickness and density.

3. Transferring to the Hydraulic Press:

   • The die set, now containing the mixture, is transferred to a hydraulic pellet press. The die is secured tightly in the press to prevent any movement during the pressing process.
   • Hydraulic pressure is applied to compress the mixture. The pressure applied should be consistent and sufficient to form a solid, transparent pellet. Typically, pressures of around 8-10 tons are used, but this can vary depending on the specific equipment and sample.

4. Releasing the Pellet:

   • After applying the necessary pressure, the die is carefully released from the press. The pellet should now be a solid, transparent disc.
   • The pellet is then removed from the die and inspected for clarity and uniformity. Any cracks, cloudiness, or unevenness may indicate issues with the preparation process, such as insufficient grinding or improper pressure application.

5. Handling and Storage:

   • Once the pellet is formed, it should be handled with care to avoid contamination or damage. It is typically stored in a dry environment to prevent absorption of moisture, which can affect the spectroscopic analysis.
   • The pellet is now ready for use in FTIR or other spectroscopic techniques, where it will be analyzed to provide information about the sample's molecular structure.

6. Troubleshooting Common Issues:

   • If the pellet is not transparent, it may indicate that the mixture was not ground finely enough or that the pressure applied was insufficient.
   • Cracks in the pellet can result from uneven distribution of the mixture or from releasing the pressure too quickly.
   • Contamination can occur if the die or press is not cleaned properly between uses, leading to inaccurate spectroscopic results.

By following these steps carefully, you can create a high-quality KBr disc suitable for accurate spectroscopic analysis.

Summary Table:

Step	Key Actions	Tips
1. Preparation	Grind KBr and sample into a fine powder (1% sample, 99% KBr).	Ensure homogeneity for a transparent pellet.
2. Loading the Die	Transfer mixture into the die and rotate bolt press for even distribution.	Avoid air gaps to ensure uniform thickness.
3. Hydraulic Pressing	Apply consistent pressure (8-10 tons) to form a solid, transparent pellet.	Secure the die tightly to prevent movement during pressing.
4. Releasing the Pellet	Carefully remove the pellet and inspect for clarity and uniformity.	Check for cracks or cloudiness, which indicate preparation issues.
5. Handling and Storage	Store in a dry environment to prevent moisture absorption.	Handle with care to avoid contamination or damage.
6. Troubleshooting	Address issues like non-transparency, cracks, or contamination.	Ensure proper grinding, pressure, and cleaning of equipment.

Need help creating KBr discs for your spectroscopic analysis? Contact our experts today for guidance and support!