Preparation of CaO-MgO-ZrO 2 refractory and its desulfurization effect on Ni-based alloy in vacuum induction melting (VI
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RESEARCH
Preparation of CaO-MgO-ZrO2 refractory and its desulfurization effect on Ni-based alloy in vacuum induction melting (VIM) Tao Zhang 1 & Yaowu Wei 1 & Junfeng Chen 1 & Nan Li 1 & Bingqiang Han 1 Received: 10 June 2019 / Revised: 24 September 2019 / Accepted: 23 October 2019 # Australian Ceramic Society 2019
Abstract The effect of micromonoclinic ZrO2 addition on properties of CaO-based refractories was investigated in our work. Zero, 5 wt%, 10 wt%, and 15 wt% micromonoclinic ZrO2 powders were added into CaO-MgO (CaO-based) refractories. The obtained results indicated that with the introduction of micromonoclinic ZrO2, the density increased slightly after heated at 1600 °C for 3 h. The results indicated that the density and mechanical properties of the samples were improved after introducing micromonoclinic ZrO2. The hydration resistance of the samples was improved with appropriate proportion of ZrO2. However, excessive ZrO2 damaged the hydration resistance of the samples. The influence of monoclinic ZrO2 on the samples was mainly caused by CaZrO3, the reaction product of CaO and ZrO2. The details of the CaZrO3 effects on the samples were discussed in this paper. Besides, based on the experiment results, CaO-based crucible was prepared and used in desulfurization. The desulfurization effects were compared with desulfurizer: Al. Desulfurizer reduced the content of [O] and [S] in the alloy obviously. Keywords CaO granules . Monoclinic ZrO2 . Hydration resistance . Thermal shock resistance . Desulfurization
Introduction Ni-based alloys are widely used in the aircraft, power, petroleum, and chemical industry due to the high-temperature oxidation resistance, strength, ductility, and workability, as well as welding performance [1–4]. The presence of impurities in the alloys influences the quality of the final product directly [5–7]. Vacuum induction melting (VIM) technology is an important process in melting and casting of superalloys. It is necessary to use VIM for melting Ni- and Ni-Fe-based superalloys as well as other advanced alloys due to their high reactivity in oxygen- and nitrogen-containing atmospheres. The refining conditions of VIM, high refining temperature and high vacuum degree, are critical for refractories. Chen et al. [8] studied the effects on oxygen contents during the VIM process using calcia crucibles. Scholars also studied the
* Yaowu Wei [email protected] 1
The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Mail Box 181, No.947, Heping Avenue, Qingshan District, Wuhan 430081, Hubei Province, China
influence of refractories on the liquid steel [9]. Choosing appropriate refractories for VIM process is very important. Lime, which is basic in character, possesses certain excellent properties such as high-temperature melting, low vapor pressure, and thermodynamic stability [7, 8]. Besides, free CaO in the refractories could remove sulfur, phosphorus, and oxide impurities in molten steel [10, 11]. Thus, it is considered to be potential re
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