Defect and Prevention of Phosphide Treatment
Defect and Prevention of Phosphide Treatment
Phosphide treatment is a widely-used method for treating metal materials, which is widely used in a variety of fields including metallurgy, petroleum and water conservancy engineering. This treatment requires careful control of parameters such as temperature and concentration, and any defects caused by improper control of the process parameters may affect the properties of the treated surface. The common defects and preventive measures of phosphide treatment are discussed in this paper.
The main defects of phosphide treatment are segregation and cracks. When the temperature is too high, the phosphorus atoms will continue to react and dissolve in the molten phosphide, resulting in segregation of phosphorus-rich and phosphorus-poor areas on the surface of the workpiece. This kind of segregation of the ordinary is irregular, and can cause a decrease in the mechanical properties of the parts and serious corrosion pitting of the surface. Besides, too high temperature can cause thermal fatigue cracking along the normal direction of the grain boundaries in the workpiece surface, thereby greatly reducing the fatigue strength and service life of the treated part.
In order to prevent the above-mentioned defects, it is important to control the relevant parameters in the phosphide treatment. In general, the phosphide treatment temperature should be kept below a certain temperature (generally within 450℃), and its concentration should be within a certain range (generally 0.5-2% w (mass fraction) phosphorus). If the temperature is too high and the concentration is low, it is recommended to adjust the cooling rate. A properly restrained cooling rate can avoid the undesirable effects of segregation and cracking caused by long cold work. In addition, it is also necessary to strictly control the impurities carried in the phosphide working solution during the phosphide treatment, and it is recommended that the content of floating impurities should be ≤50mg/L.
The phosphide treatment process is relatively complicated and requires considerable attention. If the relevant parameters are not properly controlled during the process, it will often cause undesirable defects such as segregation and cracking, which will significantly reduce the mechanical properties and service life of treated parts. By controlling the temperature, concentration and cooling rate of the phosphide treatment, as well as other factors such as impurity content, it is possible to avoid the generation of undesirable defects and thus ensure the quality of the workpiece treatment.
