Effect of Ga on the Oxide Film Structure and Oxidation Resistance of Sn-Bi-Zn Alloys as Heat Transfer Fluids.

Qingmeng Wang,Xiaomin Cheng,Qianju Cheng,Zhi Liu,Zean Lv

doi:10.3390/ma13235461

Qingmeng Wang, Xiaomin Cheng + Show 3 more

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https://doi.org/10.3390/ma13235461

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Abstract

The effect of gallium on the oxide film structure and overall oxidation resistance of low melting point Sn–Bi–Zn alloys was investigated under air atmosphere using thermogravimetric analyses. The liquid alloys studied had a Ga content of 1–7 wt.%. The results showed that the growth rates of the surface scale formed on the Sn–Bi–Zn–Ga alloys conformed to the parabolic law. The oxidation resistance of Sn–Bi–Zn alloys was improved by Ga addition and the activation energies increased from 12.05 kJ∙mol−1 to 22.20 kJ∙mol−1. The structure and elemental distribution of the oxide film surface and cross-section were found to become more complicated and denser with Ga addition. Further, the results of X-ray photoelectron spectroscopy and X-ray diffraction show that Ga elements accumulate on the surface of the liquid metal to form oxides, which significantly slowed the oxidation of the surface of the liquid alloy.

Highlights

Fusible alloys are widely used in solar power generation, chip-heat dissipation, and nuclear power systems due to their excellent thermal properties and high-temperature stability [1,2,3]
The thermal stability of alloys and their encapsulating materials is the key factor of heat transfer systems in the long-term service process at high temperature
The weight increase of Sn–Bi–Zn alloy without the addition of Ga was large, and the oxidation weight gain when heating to 700 ◦ C was 0.45 mg

Summary

Introduction

Fusible alloys are widely used in solar power generation, chip-heat dissipation, and nuclear power systems due to their excellent thermal properties and high-temperature stability [1,2,3]. Fusible metals can be used as heat transfer medium in solar energy fields [6,7]. The thermal stability of alloys and their encapsulating materials is the key factor of heat transfer systems in the long-term service process at high temperature. There are still serious oxidation phenomena during the preparation process and high-temperature use, which greatly affects the service life of the heat transfer fluid. Oxidation resistance is the key to high-temperature performance of alloy, especially in an air environment [8,9,10]

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