Natural tourmaline as an efficient alternative to ceramic-type material for plasma spraying

0490095 - ÚFP 2019 RIV ZA eng J - Journal Article
Ctibor, Pavel - Nevrlá, Barbara - Pala, Zdeněk - Vrtiška, L.
Natural tourmaline as an efficient alternative to ceramic-type material for plasma spraying.
Journal of the Southern African Institute of Mining and Metallurgy. Roč. 118, č. 4 (2018), s. 387-393. ISSN 2225-6253. E-ISSN 2411-9717
Institutional support: RVO:61389021
Keywords : Plasma spraying * Tourmaline * Crystallinity * Annealing
OECD category: Environmental and geological engineering, geotechnics
Impact factor: 0.467, year: 2018
www.saimm.co.za/Journal/v118n04p387.pdf

Expensive synthetic materials are often used to prepare coatings deposited by plasma spraying. We selected natural mineral tourmaline as an inexpensive alternative material and sprayed it successfully, forming a ceramic-like coating. The experimental powder for spraying was as-mined tourmaline schorl, and was crushed and sieved to the proper size for plasma spraying with a hybrid water-argon stabilized plasma torch (WSP-H). Deposits on metallic and ceramic substrates, as well as self-supporting plates and samples annealed in air at 1 000 °C, were further studied by optical microscopy, X-ray diffraction, thermal and mechanical analysis, and optical reflectance tests. The results showed that the coatings are highly porous (44 ± 8 % in the most extreme case) and partly amorphous. The crystallinity depended on the process parameters. During subsequent annealing tourmaline decomposed to a mullite-like phase and hematite whereas this process was accompanied by a microhardness increase. Plasma spraying of a material with structurally bonded water and with incongruent melting, where both factors are being considered as large disadvantages, was demonstrated
Permanent Link: http://hdl.handle.net/11104/0284389