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Emre TOY, MSc. Student

Metallurgical and Materials Engineering

Yıldız Technical University

 

emretoy98@gmail.com

https://www.linkedin.com/in/toyemre/

 

 

Boron Carbide (B4C) Synthesis via Aluminothermic Reaction
Advisor:
Oğuz KARAAHMET 

 

Boron carbide (B4C), crystalline compounds that various combinations of boron and carbon, is widely preferred in engineering applications thanks to its unique combination of properties which are extremely high hardness (31.5GPa Vickers Hardness)[1][2], high elastic modulus (462GPa)[3][4][5], high wear resistance, high melting point (2,427 °C)[6], and low density (2.52 g/cm3)[5][6]. It has good shielding properties against neutrons and stability to most chemical and ionizing radiation.[1][2] Thanks to its properties, B4C can be used in tank armors, bulletproof applications, abrasive powders, wear resistance products, lightweight composites, and nuclear applications like control rods.[1] The methods used in B4C synthesis are carbothermic reduction, metallothermic reduction, synthesis from elements, vapor phase reactions, synthesis from polymer precursors, liquid-phase reactions, ion beam synthesis, and VLS growth.[2] However, the synthesis of this material has several disadvantages such as the using of expensive raw materials, not being suitable for the mass production, long processing time, high energy consumption and processing temperature (>2000°C).[2] In our study, we are investigating to synthesize B4C at lower temperatures (1400-1600°C) via aluminothermic reduction, which is one of the metallothermic reduction reactions, in order to reduce the high energy, temperature, and cost requirement by using heat that is generated as a result of the exothermic reaction between the boron oxide (B2O3)  and metallic aluminum powder. The starting materials are B2O3 as boron source, carbon black and activated carbon as carbon source, and metallic aluminum powder as reducing agent which are assumed as pure. All mixtures are homogenized in a planetary ball mill machine and B4C synthesis is aimed at 1400-1600 °C for 1-3h under argon gas atmosphere.

 

References

 

[1] A.W. Weimer, Ed., Carbide, Nitride and Boride Materials Synthesis and Processing. Springer Netherlands, 1997.

[2] A. K. Suri, C. Subramanian, J. K. Sonber, and T. S. R. Ch Murthy, Synthesis and consolidation of boron carbide: A review, vol. 55, no. 1. 2010.

[3] M. H. Manghnani, Y. Wang, F. Li, P. Zinin, and W. Rafaniello, “Elastic and Vibrational Properties of B4C to 21 GPa”; pp. 945–8 in Science and Technology of High Pressure, Edited by M. H. Manghnani, W. J. Nellis, and M. F. Nicol. Universities Press, Hyderabad, India, 2000.

[4]  J. H. Gieske, T. L. Aselage and D. Emin, “Elastic Properties of Boron Carbides”; pp. 376–9 in Boron-Rich Solids. AIP Conf. Proc., Vol. 231, Edited by D. Emin, T. Aselage, C. L. Beckel, A. C. Switendick, and B. Morosin. American Institute of Physics, New York, 1991.

[5]   Domnich, V., Reynaud, S., Haber, R. A., & Chhowalla, M. (2011). Boron Carbide: Structure, Properties, and Stability under Stress. Journal of the American Ceramic Society, 94(11), 3605–3628. doi:10.1111/j.1551-2916.2011.04865.x

[6]    I.G. Crouch, G.V. Franks, C. Tallon, S. Thomas, M. Naebe,7 - Glasses and ceramics, In Woodhead Publishing in Materials, The Science of Armour Materials, Woodhead Publishing, 2017, Pages 331 393, ISBN 9780081010020,

 

Development of High Near-Infrared Reflectance (NIR) Black Pigments

Advisor: Assoc Prof. Dr. Buğra Çiçek

 

Pigments are organic or inorganic substances that are used to color, protect and give different properties to materials, which are slightly or completely insoluble in the area of ​​application. [1] While organic pigments consist of carbon chains, inorganic pigments are generally formed by metal oxides and the combination of these oxides. Inorganic pigments can be preferred over organic pigments due to their high heat and weather fastness, high opacity and low cost. [2,3]   It is highly preferred in applications requiring high temperatures such as ceramics and glass, and in the polymer industry due to its relatively high heat resistance.[1]  In addition to the aforementioned properties, inorganic pigments are preferred in the classification of polymers, air conditioning and military applications, thanks to their ability to reflect electromagnetic waves in the near infrared region. [4-7] Carbon black, which is used as a black colorant in the polymer industry, absorbs electromagnetic waves in the Near Infrared (NIR) region. As a result of this property of carbon black, it prevents the determination of the characteristic spectrum of the polymers in the NIR region. As a result, black polymeric products cannot be classified according to their chemistry and cannot be recycled. As an alternative to carbon black, complex inorganic coloured pigments (CICPs) that can reflect in the NIR region are used. In contrast to carbon black, the pigments used can reflect at high rates and thus do not prevent with the determination of the characteristic spectrum of the polymer. In the studies carried out, pigments that can give black color and reflect in the NIR region have been developed by using combinations of elements such as Fe, Zn, Cr. [8,9]  In future studies, parameters that may affect color and reflectance such as composition,dopants, particle size, synthesis temperature and time in the NIR region will be examined and alternative pigments will be produced to the carbon black pigments currently used.

 

References

 

[1] Gerhard Pfaff, Inorganic Pigments. In Angewandte Chemie International Edition, 6(11), 951–952. ISBN: 9783110484519

[2] Jesionowski T., Ciesielczyk F. (2021) Inorganic, Hybrid and Functional Pigments. In: Shamey R. (eds) Encyclopedia of Color Science and Technology. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-27851-8_180-2

[3] Jiri George Drobny,3 - Additives,Handbook of Thermoplastic Elastomers (Second Edition),2014,ISBN 9780323221368,https://doi.org/10.1016/B978-0-323-22136-8.00003-X.

[4] Suwan, M, Sangwong, N ,Supothina, S, EFFECT OF Ni DOPING AND SYNTHESIS TEMPERATURE ON THE PROPERTIES OF NIR-REFLECTIVE ZnFe2O4 BLACK PIGMENTS, CERAMICS-SILIKATY, DOI 10.13168/cs.2020.0006

[5] Sangwong, N, Suwan, M, Supothina, S, Synthesis and Optical Band Gap Study of NIR-Reflective CoFe2O4 Black Pigments Doped with MgO, CaO and Al2O3, CHIANG MAI JOURNAL OF SCIENCE

[6] Baneshi, M, Maruyama, S, Komiya, A, AESTHETIC AND THERMAL PERFORMANCES OF BLACK CUPRIC OXIDE AND TITANIUM DIOXIDE NANO-PARTICULATE COATINGS, VI. PROCEEDINGS OF THE 6TH INTERNATIONAL SYMPOSIUM ON RADIATIVE TRANSFER

[7] Qin, J, Song, JR, Qu, J, The methods for creating building energy efficient cool black coatings, ENERGY AND BUILDINGS, DOI 10.1016/j.enbuild.2014.08.022

[8] Hwang, JS, Jung, KY, Effect of calcination temperature and Ti substitution on optical properties of (Fe,Cr)(2)O-3 cool black pigment prepared by spray pyrolysis, RSC ADVANCES, DOI 10.1039/d1ra08300g

[9] Suwan, M, Sangwong, N, Supothina, S, Effect of Co and Pr doping on the properties of solar-reflective ZnFe2O4 dark pigment, 17TH IUMRS INTERNATIONAL CONFERENCE IN ASIA (IUMRS-ICA 2016), DOI 10.1088/1757-899X/182/1/012003