Oxidation Protective Hybrid Coating for Thermoelectric Materials

Area of Science:

• Materials Science
• Thermoelectric Materials Science

Background:

• Magnesium silicide stannide and zinc-doped tetrahedrite are key thermoelectric materials.
• High-temperature oxidation and electrical resistivity increase limit thermoelectric device performance and lifespan.
• Protective coatings are crucial for enhancing the stability and efficiency of thermoelectric devices.

Purpose of the Study:

• To evaluate the effectiveness of two commercial hybrid coatings in protecting thermoelectric materials.
• To assess the impact of these coatings on the oxidation resistance and electrical properties of magnesium silicide stannide and zinc-doped tetrahedrite.
• To determine the suitability of low-temperature cured coatings for thermoelectric applications.

Main Methods:

• Application of solvent-based and water-based hybrid coatings to thermoelectric samples.
• Exposure of coated samples to high-temperature air environments (500 °C for magnesium silicide stannide, 350 °C for zinc-doped tetrahedrite).
• Analysis of oxidation rates and electrical resistivity changes over time.

Main Results:

• The solvent-based coating significantly reduced the oxidation rate of magnesium silicide stannide by 120 hours at 500 °C, with a slight power factor increase.
• The water-based coating prevented electrical resistivity increase in zinc-doped tetrahedrite for 48 hours at 350 °C, preserving its power factor.
• Both coatings were cured at temperatures below 300 °C, indicating low-temperature processing feasibility.

Conclusions:

• Commercial hybrid coatings offer effective protection for thermoelectric materials against high-temperature degradation.
• Solvent-based coatings enhance oxidation resistance and power factor of magnesium silicide stannide.
• Water-based coatings maintain the electrical stability and power factor of zinc-doped tetrahedrite.