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I. Influencing Factors

1. Chemical Reactions
   • Molybdenum rods undergo chemical reactions with oxygen in the air at low temperatures, resulting in the formation of oxide layers (primarily MoO3) on their surfaces. This oxide formation constitutes the primary cause of low-temperature oxidation in molybdenum rods.
   • Chemical Reaction Equation: 2Mo + 3O2 → 2MoO3
2. Temperature Factors
   • Molybdenum exhibits relatively poor oxidation resistance both at high and low temperatures. Notably, below 200°C, the oxidation rate of molybdenum significantly accelerates. Furthermore, studies have shown that molybdenum rods are prone to reactions with oxygen and water vapor in the temperature range of 400~700°C, leading to intensified oxidation or even melting.
3. Operating Environment
   • In addition to temperature, factors such as oxygen concentration and humidity in the operating environment also affect the low-temperature oxidation of molybdenum rods. Higher oxygen concentrations and humidity accelerate the oxidation process.
4. Material Properties
   • The chemical nature of molybdenum itself contributes to its susceptibility to oxidation under certain conditions. Moreover, factors like the manufacturing process and surface treatment of molybdenum rods can also influence their oxidation resistance.
     

II. Preventive Measures

1. Rational Material Selection
   • Given molybdenum rods’ vulnerability to low-temperature oxidation, consider substituting them with materials that exhibit better oxidation resistance or using them as protective layers. For instance, protective tubes made of beryllium oxide ceramics or high-temperature alloys with superior oxidation resistance can be employed.
2. Improving Operating Environment
   • Avoid prolonged use of molybdenum rods in low-temperature, high-humidity, or high-oxygen-concentration environments. Strategies like raising the operating temperature, reducing humidity, and minimizing oxygen exposure can slow down the oxidation rate.
3. Enhanced Maintenance
   • Regularly clean and polish molybdenum rods to remove oxide layers and impurities, restoring their surface smoothness. This reduces the occurrence of oxidation reactions and extends the rods’ service life.
4. Applying Antioxidant Coatings
   • Applying antioxidant coatings, such as alumina or silicon dioxide, on molybdenum rod surfaces can effectively isolate them from oxygen, thereby slowing down the oxidation process. The choice of coating should consider its compatibility with molybdenum and high-temperature resistance.
5. Reasonable Control of Usage Time and Temperature
   • Manage the usage time and temperature range of molybdenum rods to prevent prolonged exposure in temperature ranges prone to oxidation, thereby reducing oxidation reactions.
6. Monitoring and Detection
   • Regularly monitor and test the oxidation levels of molybdenum rods to promptly identify and address oxidation issues. This prevents oxidation from impacting equipment performance and service life.

By comprehensively applying these measures, the low-temperature oxidation rate of molybdenum rods can be effectively slowed down, extending their service life and enhancing the stability and reliability of equipment.