In order to save chromium resources, technology of flux-cored wire surfacing is of great practical interest. In this case, Cr2O3 chromium oxide and carbon as a reducing agent are used as fillers. The thermodynamic probability assessment of 16 reactions between them under standard conditions, as well as for certain reactions under different standard conditions, was carried out using tabulated thermodynamic data of reactants in the temperature range of 1500–3500 K. The following were considered as standard states for reactants: Cr(ref) (reference state, melting point 2130 K, boiling point 2952 K), Cr(liq), Cr(gas), Cr2O3(cr, liq), Cr2O3(gas), C(ref), and as possible reaction products and standard states for them CO(gas), CO2(gas), Cr23C6(сr), Cr7C3(cr), Cr3C2(cr). The reaction probability was estimated using standard Gibbs energy and was calculated using the Van Goff isotherm equation. The chromium dissolution in metal of surfacing bath or probable partial pressures of CO and CO2 in gas phase was considered and then calculated from the equilibrium of carbon gasification reaction. The carbon presence in flux-cored wire with chromium oxide Cr2O3 as a reducing agent will necessarily lead to the occurrence of reduction reactions with chromium carbide generation, and possibly chromium itself. The generation of Cr7C3(сr) carbide is likely. With a longer life span of chromium oxide and carbon at a temperature above 2500 K, chromium generation as a component of the surfacing bath is more thermodynamically probable than carbide generation. Chromium oxide has the highest reactivity in Cr2O3(liq) state. Direct reduction is preferential. The generation of CO(gas) as a carbon oxidation product is more probable. The chromium dissolution in metal increases the thermodynamic reaction probability with its generation, as well as further reduces the reaction probability in which chromium is the starting material.

中文翻译：

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碳还原 Cr2O3 的热力学方面

为了节约铬资源，药芯焊丝堆焊技术具有重要的现实意义。在这种情况下，使用Cr2O3氧化铬和作为还原剂的碳作为填料。使用在 1500-3500 K 温度范围内的反应物热力学数据表，对标准条件下它们之间的 16 个反应以及不同标准条件下的某些反应进行热力学概率评估。以下被认为是标准状态对于反应物：Cr(ref)（参考状态，熔点 2130 K，沸点 2952 K）、Cr(liq)、Cr(gas)、Cr2O3(cr, liq)、Cr2O3(gas)、C(ref)和作为可能的反应产物和它们的标准状态 CO(gas), CO2(gas), Cr23C6(сr), Cr7C3(cr), Cr3C2(cr)。使用标准吉布斯能量估计反应概率并使用范戈夫等温方程计算。考虑铬在堆焊金属中的溶解或气相中CO和CO2的可能分压，然后由碳气化反应的平衡计算。以氧化铬 Cr2O3 作为还原剂的药芯焊丝中存在的碳必然会导致发生还原反应，生成碳化铬，也可能是铬本身。Cr7C3(сr)碳化物的生成是可能的。由于氧化铬和碳在高于 2500 K 的温度下具有更长的寿命，因此作为堆焊浴的组分生成铬比生成碳化物在热力学上更有可能。氧化铬在 Cr2O3(liq) 状态下具有最高的反应性。直接减免优先。更有可能产生 CO（气体）作为碳氧化产物。铬在金属中的溶解增加了其产生的热力学反应概率，并进一步降低了以铬为起始材料的反应概率。