Magnesium Alloys Forging Chemical Oxidation Solution Formula and Process Conditions
Magnesium alloys are one of the most widely used materials in industrialized manufacturing. As the demand for lighter and more durable parts and components continues to increase, magnesium alloys are becoming increasingly important in the automotive, aerospace, medical and electronics industries. The chemical oxidation process is a common process used to improve the surface characteristics and corrosion resistance of magnesium alloy forgings, and the following formula and process conditions summarise the recommended standards for this process.
Solution Preparation
The chemical oxidation of magnesium alloy forgings requires a saturated solution of sodium nitrite, NaNO2, and sodium hydroxide, NaOH, in water. The concentrations of each of these chemicals can vary considerably depending on the desired process result, however the recommended standards are to dissolve 20g/L NaNO2 and 10g/L NaOH into a solution of deionized water.
The solution can be pre-heated between 500-1000C to achieve faster dissolution and process results, however it is important to ensure that the solution is fully cooled before application. Additionally, it is important to note that the pH of the solution should be between 10 and 12 for optimal results, and can be adjusted with the addition of other caustic chemicals if required.
Application
The chemical oxidation solution can be applied to the magnesium alloy forging in any of several different ways, including immersing the part in the solution, spraying it on with a fountain, or dipping the part into the solution. In all cases, the part should be completely submerged in the solution, and a protective coating should be applied to ensure that the oxidation reaction is uniform across the entire surface. Additionally, vigorous shaking can be used to increase the efficacy of the oxidation process.
Process Conditions
Once the solution has been applied to the part, the oxidation process can begin. The part should remain submerged in the solution for no less than one minute, and can be left in the solution for up to three minutes depending on the desired oxidation result. After the part has been exposed to the solution for the recommended time, it can be removed and allowed to dry naturally.
When using the chemical oxidation process, it is important to note the temperature of the solution. For optimal process results, the operating temperature should remain between 80 and 100°C, though higher temperatures can be used for softer metals such as magnesium alloys. It is also important to note that some magnesium alloys may react poorly at higher temperatures, and precautions should be taken to dissipate excess heat quickly.
Conclusion
In conclusion, the chemical oxidation process can be used to improve the surface characteristics and corrosion resistance of magnesium alloy forgings. The recommended solution formula for chemical oxidation for these forgings is to dissolve 20g/L NaNO2 and 10g/L NaOH into a solution of deionized water. The solution can be applied to the part using several different methods, and should remain in the solution for no less than one minute and no more than three minutes. Finally, it is important to maintain the operating temperature between 80 and 100°C for optimal results.
