原位氧化FeNiMnAlCrC高熵合金的光热转换性能

Photothermal conversion performance of in situ oxidizing FeNiMnAlCrC high entropy alloy

本文采用经济的原位氧化和选择性刻蚀工艺,通过调控氧化温度和表面粗糙度,研究了Fe_(40)Ni_(11)Mn_(35)Al_(7)Cr_(6)C_(1)(摩尔分数,%)高熵合金表面的氧化产物变化及其对太阳能光热转换性能的影响。结果表明:在500~700℃范围内,随着温度升高和刻蚀引起的初始表面粗糙度的增大,氧化后高熵合金表面的氧化物尺寸、氧化层厚度、粗糙度和氧化物种类均呈上升趋势,使得光热转换性能逐渐提升。预先刻蚀并经700℃氧化2 h后,合金的太阳能吸收率和光热转换效率分别达到峰值90.4%和87.9%。当氧化温度继续升高至800℃后,由于热膨胀系数不匹配导致热应力增大,合金表面生成的氧化层均开始大面积脱落,进而导致材料的光热性能开始下降。本研究为金属氧化层的有效设计提供了理论支持,有助于实现高熵合金光热性能的优化与提升。

In this paper,the variations in the oxidation products on the surface of a Fe_(40)Ni_(11)Mn_(35)Al_(7)Cr_(6)C_(1)(mole fraction,%)high entropy alloy and its effects on photothermal conversion performance were studied by adjusting oxidation temperature and surface roughness using economical in situ oxidation and selective etching techniques.The results show that,in the range of 500-700℃,as temperature and initial surface roughness increase,the oxide size,oxide thickness,roughness and oxide species on the alloy surface after oxidation exhibit an increasing trend,and the photothermal conversion performance gradually improves.After pre-etching and oxidation at 700℃for 2 h,the solar energy absorptance and photothermal conversion efficiency of the alloy reach the peak values of 90.4%and 87.9%,respectively.When the oxidation temperature continues to rise to 800℃,thermal stress that is increased due to the mismatch of thermal expansion coefficients,causes the oxide layer generated on the alloy’s surface before and after etching to begin flaking off extensively,leading to a decline in the photothermal conversion performance of materials.This study provides theoretical support for the effective design of metal oxide layers,and helps to optimize and improve the photothermal performance of high entropy alloys.