Parts, tools and die in the use of the process except a few due to brittle damage, mostly due to fatigue and wear failure, some due to high temperature oxidation and medium corrosion failure. These damages often originate on or near the surface of the component. Therefore, to improve the service life of machine parts, it is necessary to strengthen the surface of the workpiece.
Compared with other chemical heat treatment methods such as carburizing, nitriding has higher surface hardness, wear resistance, better residual compressive stress, low temperature required by the process, small deformation, strong corrosion resistance. These advantages make nitriding technology widely used in aerospace, shipping and machining fields.
Since Bell et al published the work of controlled nitriding based on the concepts of "nitrogen potential" and "threshold value of nitrogen potential" in 1973, it has aroused extensive interest in Chinese academia and had a research upsurge. In recent years, with the development of production and technological progress, the process of nitriding precision has become the inevitable trend of nitriding technology development.
In the process of gas nitriding, there are many process factors to be controlled, and the "nitrogen potential" is generally replaced by ammonia decomposition rate as the process control factor. The ammonia decomposition rate has significant influence on the nitriding quality and the nitriding speed.
Therefore, it is necessary to test frequently in order to adjust ammonia flow in time and ensure that ammonia decomposition rate is within the range specified in the process. How to accurately measure and control the size of ammonia decomposition is the key to the whole nitriding process.
There are many ways in which ammonia decomposition rates can be controlled, and recent research has found that they can be measured using laser technology. Adopt Wu Hanhua sensitive nitriding atmosphere monitoring system, all factors will be laser nitrogen potential analysis sensor installed on the nitriding furnace, sensor consists of a set of more to laser, each pair of transmitter sent a bunch of specific wavelength and intensity of laser beam, laser beam through the cavity into the sensor of gas nitriding, by the receiver to receive and measure to the different light intensity change, application of lambert beer's law, the atmosphere of the sensor can be calculated directly to the corresponding channel content (CO, CO2, NH3, CH4, etc.) to obtain a complete nitriding atmosphere.
On 2018-08-08 11:45:46
