采用DSC-TG和XRD分析方法对铁矾渣热分解过程进行了研究。结果表明:铁矾渣的热分解包括脱水、脱氨、氧化和晶型转变等复杂步骤;经750℃焙烧,铁矾渣呈红棕色,最终产物主要为ZnFe_2O_4和Fe_2O_3;基于Kissinger法和Flynn-Wall-Ozawa法得到...采用DSC-TG和XRD分析方法对铁矾渣热分解过程进行了研究。结果表明:铁矾渣的热分解包括脱水、脱氨、氧化和晶型转变等复杂步骤;经750℃焙烧,铁矾渣呈红棕色,最终产物主要为ZnFe_2O_4和Fe_2O_3;基于Kissinger法和Flynn-Wall-Ozawa法得到铁矾渣在350~450℃和630~720℃温度区间热分解反应的活化能分别约为260和230 k J/mol,频率因子分别为3.07×10^(19)和1.29×10^(12)。展开更多
Pursuing significant thermal rectification effect with minimal temperature differences is critical for thermal rectifiers.While asymmetric structures enable spectral matching,they inherently limit thermal rectificatio...Pursuing significant thermal rectification effect with minimal temperature differences is critical for thermal rectifiers.While asymmetric structures enable spectral matching,they inherently limit thermal rectification performance.To address this issue,we developed a thermal rectification structure comprising a current-biased graphene-coated silicon carbide(SiC)substrate paired with another graphene-coated SiC substrate separated by a nanoscale vacuum gap.A current-biased graphene sheet generates nonreciprocal effect that actively modulates radiative energy transfer.Our theoretical framework demonstrates that the current-biased graphene achieves a high thermal diode efficiency even under a modest temperature difference.Remarkably,the thermal diode efficiency exceeds 0.8 at a temperature difference of just 100 K(between 300 K and 400 K).These findings highlight the synergistic enhancement from graphene coatings and current biasing,providing a viable strategy for nanoscale thermal management applications.展开更多
文摘采用DSC-TG和XRD分析方法对铁矾渣热分解过程进行了研究。结果表明:铁矾渣的热分解包括脱水、脱氨、氧化和晶型转变等复杂步骤;经750℃焙烧,铁矾渣呈红棕色,最终产物主要为ZnFe_2O_4和Fe_2O_3;基于Kissinger法和Flynn-Wall-Ozawa法得到铁矾渣在350~450℃和630~720℃温度区间热分解反应的活化能分别约为260和230 k J/mol,频率因子分别为3.07×10^(19)和1.29×10^(12)。
基金Project supported by the National Natural Science Foundation of China(Grant No.12364008)the Ph.D.Research Startup Foundation of Yan’an University(Grant No.YDBK2019-54)the Yan’an High-level Talent Special Project(Grant No.2019263166)。
文摘Pursuing significant thermal rectification effect with minimal temperature differences is critical for thermal rectifiers.While asymmetric structures enable spectral matching,they inherently limit thermal rectification performance.To address this issue,we developed a thermal rectification structure comprising a current-biased graphene-coated silicon carbide(SiC)substrate paired with another graphene-coated SiC substrate separated by a nanoscale vacuum gap.A current-biased graphene sheet generates nonreciprocal effect that actively modulates radiative energy transfer.Our theoretical framework demonstrates that the current-biased graphene achieves a high thermal diode efficiency even under a modest temperature difference.Remarkably,the thermal diode efficiency exceeds 0.8 at a temperature difference of just 100 K(between 300 K and 400 K).These findings highlight the synergistic enhancement from graphene coatings and current biasing,providing a viable strategy for nanoscale thermal management applications.
