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Manufacture of MoO3 Coating Layer Using Thermal Spray Process and Analysis of Microstructure and Properties

Hwang Yu-Jin, Kim Kyu-Sik, Park Jae-Sung, Lee Kee-Ahn

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 4

1535--1538

EN

MoO3 thick film was manufactured by using a thermal spray process (Atmospheric Plasma Spray, or APS) and its micro-structure, phase composition and properties of the coating layer were investigated. Initial powder feedstock was composed of an orthorhombic α-MoO3 phase, and the average powder particle size was 6.7 μm. As a result of the APS coating process, a MoO3 coating layer with a thickness of about 90 μm was obtained. Phase transformation occurred during the process, and the coating layer consisted of not only α-MoO3 but also β-MoO3, MoO2. Phase transformation could be due to the rapid cooling that occurred during the process. The properties of the coating layer were evaluated using a nano indentation test. Hardness and reduced modulus were obtained as 0.47 GPa and 1.4 GPa, respectively. Based on the above results, the possibility of manufacturing a MoO3 thick coating layer using thermal spray is presented.

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Influence of NaCl Additive on the Reduction Process of MoO3 to Mo2C by High-Purity CO Gas

Que Biao-Hua, Wang Lu, Wang Bao, Chen Yi, Xue Zheng-Liang

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 2

787--796

EN

In this work, influence of NaCl additive on the transformation process of MoO3 to Mo2C under pure CO atmosphere in the range of room temperature to 1170 K was investigated. The results showed that transformation of MoO3 to Mo2C can be roughly divided into two stages: the reduction of MoO3 to MoO2 (the first stage) and the carburization of MoO2 to Mo2C (the second stage). As to the first stage, it was found that increasing the content of NaCl (from 0 to 0.5 wt.%) was beneficial for the increase of reaction rate due to the nucleation effect; while when the content of NaCl increased to 2 wt.%, the reaction rate will be decreased in turn. As to the second stage, the results showed that reaction rate was decreased with the increase of NaCl, which may be due to the formation of low-melting point eutectic. The work also found that morphology of as-prepared Mo2C was irregular and particle size of it was gradually increased with increasing the NaCl content. According to the results, the possible reaction mechanism was proposed.

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Nanosized MoO3 as a reusable heterogeneous catalyst for the synthesis of 2,6-bis(benzylidene) cyclohexanones

Dighore N. R., Anandgaonker P. L., Gaikwad S. T., Rajbhoj A. S.

Materials Science Poland

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2015

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Vol. 33, No. 1

163--168

EN

Crystalline MoO3 nanoparticles were obtained by electrochemical synthesis process using tetrapropylammonium bromide as a stabilizer and structure-directing agent in ACN:THF(4:1) solvent. Formation of MoO3 nanoparticles took place at a constant supply current of 14 mA/cm2. These synthesized MoO3 nanoparticles were characterized by UV-Vis spectroscopy, FT-IR spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM). So prepared MoO3 nanoparticles were used as a heterogeneous catalyst for the synthesis of 2,6-bis(benzylidene)cyclohexanone derivatives. This protocol offers several advantages, such as simple work-up procedure, recyclability of the catalyst, excellent product yield in a short reaction time and purification of products with a non-chromatographic method.

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Osobliwości mechanochemicznej aktywacji MoO₃ w odniesieniu do katalitycznego procesu przetwarzania bioetanolu

Wieczorek-Ciurowa K., Litvin N., Zazhigalov V.

Przemysł Chemiczny

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2011

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T. 90, nr 7

1404-1411

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Matematyczna analiza metodą Numajiri-Furukawy procesu spalania kompozycji poliestrowych

Pofit-Szczepańska M., Półka M.

Polimery

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2003

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T. 48, nr 7-8

545-548

PL

Matematyczna analiza metodą numajiri-furukawy procesu spalania kompozycji poliestrowych Scharakteryzowano cechy pożarowe materiałów służące do oceny możliwości stosowania tych materiałów w różnych dziedzinach. Szczególną uwagę zwrócono na szybkość generacji ciepła (HRR) oraz związany z nią wskaźnik spalania (BT). Przedstawiono sposób opisu doświadczalnych krzywych HRR (HRRexp) na podstawie metody Numajiri-Furukawy. Wyznaczono krzywe HRRexp próbek żywicy poliestrowej (PES) nie-modyfikowanej oraz modyfikowanej dodatkami (7, 14 i 21% mas. MoO3) działającymi jako antypireny. Stosując metodę Numajiri-Furukawy, z krzywych HRRexp wyznaczono wartości BI. Dodatek MOO3 do PES powoduje, że BI modyfikowanych PES zmniejszają się w porównaniu z BI próbki niemody-fikowanej. Dodatek 21% mas. MoO3 powoduje zmniejszenie BI o 45%.

EN

Fire features of the materials, useful for an assessment of the possibility of these materials applications in various fields, were characterized. Special attention has been paid to heat release rate (HRR) and burning index (BI) related to HRR. The way of description of the experimental HRR curves (HRRexp) using Numajiri-Furukawa method [equations (1)-(5), Fig. 1] was presented. HRRexp curves of polyester resin (PES) samples, unmodified and modified with addition (7,14 and 21 wt. % Of MoO3) acting as fire retardant (Fig. 2a-d), were determined. Using Numajiri-Furukawa method, B1 values (Table 1 and 2) were determined from the HRRexp curves. MoO3 addition to PES causes that BI values of modified PES decrease in comparison with BI of unmodified sample. Addition Of MoO3 in the amount of 21 wt. %, causes 45% decrease in BI.