The following are some methods to improve the stability of rubber magnets in high-temperature environments:
Material Improvement
Selecting High-Temperature-Resistant Rubber
The choice of the base rubber material is crucial for the high-temperature resistance of rubber magnets. High-temperature-resistant rubber materials such as silicone rubber can be selected to replace ordinary rubber. Silicone rubber has excellent thermal stability. Its molecular main chain consists of alternating silicon and oxygen atoms, and this structure enables it to maintain good flexibility and chemical stability at high temperatures. For example, methyl vinyl silicone rubber can still maintain a certain degree of elasticity within the temperature range of 200 - 300 °C, which provides better basic performance for rubber magnets in high-temperature environments.
Optimizing Magnetic Powder Materials
The high-temperature resistance of magnetic powder also needs to be considered. Ferrite magnetic powder itself has a certain degree of high-temperature resistance, but its performance can be further improved by surface treatment or adding high-temperature-resistant additives. For example, coating the surface of magnetic powder with high-temperature-resistant inorganic materials such as aluminum oxide and titanium dioxide can prevent the magnetic powder from being oxidized or undergoing adverse chemical reactions with the surrounding rubber materials at high temperatures. Meanwhile, adding some rare earth elements during the preparation of magnetic powder can also improve the high-temperature resistance of magnetic powder because rare earth elements can enhance the stability of the crystal structure of magnetic powder.
Process Optimization
Improving the Composite Process
During the process of compounding rubber and magnetic powder, adopting more advanced processes can improve the high-temperature stability of rubber magnets. For example, using a high-temperature mixing process, appropriately increasing the mixing temperature while precisely controlling the mixing time and rotational speed. This can make the rubber and magnetic powder blend better and reduce internal voids and stress concentration points. When rubber magnets are used in high-temperature environments, this good composite structure can reduce structural damage and the decline in magnetic performance caused by inconsistent thermal expansion.
Adding Curing Steps or Post-Treatment
Appropriate curing treatment or post-treatment of the molded rubber magnets can enhance their high-temperature resistance. For example, using a high-temperature curing process to cure them under conditions where the temperature is higher than the normal operating temperature of rubber magnets. This can make the rubber material further cross-link to form a more stable three-dimensional network structure, thereby improving the rubber's resistance to deformation at high temperatures and its binding ability to magnetic powder. In addition, post-treatment processes such as electron beam irradiation can also improve the performance of rubber. Electron beam irradiation can generate cross-linking between rubber molecular chains and improve the thermal stability and mechanical properties of rubber.
Adding Auxiliary Materials
Using Heat Stabilizers
Adding heat stabilizers to the formulation of rubber magnets is one of the effective methods to improve their high-temperature stability. Heat stabilizers can absorb heat and prevent the thermal decomposition reaction of rubber materials at high temperatures. For example, some metal soap heat stabilizers (such as calcium stearate and zinc stearate) can react with active groups in rubber to form stable compounds and inhibit the thermal aging process of rubber. Meanwhile, some organotin heat stabilizers also have a good improvement effect on the thermal stability of rubber. They can decompose hydroperoxides and prevent the auto-oxidation reaction of rubber.
Adding Antioxidants
Antioxidants can prevent the performance degradation of rubber magnets caused by oxidation in high-temperature environments. At high temperatures, both rubber materials and magnetic powder are vulnerable to the attack of oxygen. Hindered phenol antioxidants (such as antioxidant 1010) can capture free radicals and prevent the oxidation reaction of rubber molecular chains. Meanwhile, phosphite antioxidants (such as antioxidant 168) can decompose hydroperoxides. When used in combination with hindered phenol antioxidants, they can play a synergistic role to better protect rubber magnets from oxidation at high temperatures.
