The production process of ferrochromium nitride mainly includes raw material preparation, reaction equipment preparation, reaction process and post-processing steps. The following is a detailed process introduction:
1. Raw material preparation
Ferrochromium raw material: Select high-quality ferrochromium as the raw material, usually micro-carbon ferrochromium or low-carbon ferrochromium. These raw materials need to be broken into small particles for subsequent processing.
Nitrogen: Prepare high-purity nitrogen as the nitriding raw material. The purity and supply of nitrogen must be sufficient to ensure the smooth progress of the nitriding reaction.
2.Reaction equipment preparation
Reactor: Select a reactor that can withstand high temperature and high pressure, such as a vacuum induction furnace or a resistance furnace. The internal structure of the reactor must ensure that the ferrochromium raw material and nitrogen can be fully contacted.
Temperature and pressure control system: Ensure that the reactor has an accurate temperature and pressure control system so that it can be adjusted as needed during the reaction process.
3.Reaction process
There are many methods for producing ferrochromium nitride, mainly including liquid nitriding and solid nitriding. The following are the detailed steps of the two methods:
Liquid nitriding:
It is carried out in an induction furnace. First, the liquid low-carbon ferrochrome is heated to 1650~1700℃.
Nitrogen with a pressure of 0.10.5 MPa is introduced into the ferrochrome melt. The nitriding process lasts for 2060 minutes before casting.
The nitrided ferrochrome prepared by liquid nitriding is more dense, but the nitrogen content is relatively low, generally 2%~3%.
Solid nitriding:
It is carried out in a vacuum induction furnace or a resistance furnace. First, the ferrochrome raw material is heated to an appropriate temperature (such as 1100℃).
After the decarburization reaction is completed, the vacuum is stopped and nitrogen is filled into the furnace for nitriding.
The nitriding process is the diffusion process of nitrogen atoms from the surface to the inside of the alloy under positive pressure conditions. The diffusion rate of nitrogen needs to be controlled to avoid premature sintering of the charge.
The nitrided ferrochrome alloy produced by solid nitriding has a high porosity, but it can be densified by processes such as remelting. However, the nitrogen content will decrease during the remelting stage.
4.Post-processing
Purification: The produced ferrochrome nitride may contain some unreacted raw materials or other impurities. It can be purified by physical or chemical methods, such as filtering to remove solid impurities or converting residual substances by chemical reaction.
Testing and analysis: The purified ferrochrome nitride is tested and analyzed to ensure that it meets the predetermined quality standards and performance requirements.