<p>Thermophysical properties of niobium were measured from 1000&#xa0;K to 2700&#xa0;K using a multi-stepwise pulse-heating technique that enables quasi-static and dynamic evaluations within a single heating sequence. Electrical resistivity, hemispherical total emissivity, specific enthalpy, and isobaric heat capacity were obtained, and the difference between enthalpy values obtained from quasi-static and transient analyses served as an internal indicator of time-scale-dependent effects, especially near <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\({T}_{\text{m}}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>T</mi> <mtext>m</mtext> </msub> </math></EquationSource> </InlineEquation>. To assess cross-property consistency, we re-derived a Schmidt–Eckert relation using Fresnel-based optical modeling with Planck-weighted hemispherical integration, providing a resistivity-derived emissivity reference over the present <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\rho T\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>ρ</mi> <mi>T</mi> </mrow> </math></EquationSource> </InlineEquation> range. The calorimetrically measured emissivity agrees with the Drude/Hagen–Rubens-based reference over 1400–2300&#xa0;K, defining an intrinsically reliable window for emissivity-corrected heat capacity evaluation, while data up to 2700&#xa0;K remain practically usable for engineering applications when their expanded combined uncertainties are considered. Within these validated limits, working enthalpy and heat capacity were obtained with expanded combined uncertainties (<i>k</i> = 2) of ~ 2.9&#xa0;% and ~ 2.0&#xa0;%, respectively. This combined strategy—time-scale analysis plus resistivity-based validation—strengthens confidence in pulse-heating thermophysical data and provides insight into near-<InlineEquation ID="IEq3"> <EquationSource Format="TEX">\({T}_{\text{m}}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>T</mi> <mtext>m</mtext> </msub> </math></EquationSource> </InlineEquation> behavior of refractory metals.</p>

错误:搜索内容不能为空,请输入英文关键词
错误:关键词超出字数限制,请精简
高级检索

Thermophysical Properties of Niobium (1000–2700 K): Multi-stepwise Pulse-Heating Measurements with Consistency Validation via a Revised Emissivity–Resistivity Relation

  • Hiromichi Watanabe

摘要

Thermophysical properties of niobium were measured from 1000 K to 2700 K using a multi-stepwise pulse-heating technique that enables quasi-static and dynamic evaluations within a single heating sequence. Electrical resistivity, hemispherical total emissivity, specific enthalpy, and isobaric heat capacity were obtained, and the difference between enthalpy values obtained from quasi-static and transient analyses served as an internal indicator of time-scale-dependent effects, especially near \({T}_{\text{m}}\) T m . To assess cross-property consistency, we re-derived a Schmidt–Eckert relation using Fresnel-based optical modeling with Planck-weighted hemispherical integration, providing a resistivity-derived emissivity reference over the present \(\rho T\) ρ T range. The calorimetrically measured emissivity agrees with the Drude/Hagen–Rubens-based reference over 1400–2300 K, defining an intrinsically reliable window for emissivity-corrected heat capacity evaluation, while data up to 2700 K remain practically usable for engineering applications when their expanded combined uncertainties are considered. Within these validated limits, working enthalpy and heat capacity were obtained with expanded combined uncertainties (k = 2) of ~ 2.9 % and ~ 2.0 %, respectively. This combined strategy—time-scale analysis plus resistivity-based validation—strengthens confidence in pulse-heating thermophysical data and provides insight into near- \({T}_{\text{m}}\) T m behavior of refractory metals.