Mechanical Properties and Corrosion Resistance of Hot-Pressed Dysprosium Molybdate Samples

The purpose of this work was to study the consolidation features using hot pressing method of dysprosium molybdate billets and to study their mechanical properties and corrosion resistance.

Methods. The technological and physical properties of the mechanosynthesised dysprosium molybdate powder were investigated. Properties and structure of the obtained dysprosium molybdate powder were studied by methods of chemical and X-ray phase analyses and scanning electron microscopy. Bulk density of dysprosium molybdate powder was studied according to GOST 19440-94. Flowability of dysprosium molybdate powder was determined according to GOST 20899-75. The specific surface of dysprosium molybdate was determined using a specific surface analyser NOVA 1200e (USA) by the method of low-temperature nitrogen adsorption (BET). X-ray phase analysis of mechanosynthesised dysprosium molybdate powder was carried out on a diffractometer

Results. The bending strength of hot-pressed dysprosium molybdate specimens was determined, it was found that the highest value of the bending strength was recorded for these specimens at a pressing pressure of 35 MPa and is 314 MPa. The corrosion resistance of hot-pressed dysprosium molybdate samples in aqueous coolant at a temperature of 100 °C was studied. It was recorded that the mass of the mechanosynthesised dysprosium molybdate specimens remained practically unchanged throughout the corrosion resistance test in aqueous coolant.

Conclusion. Tests on corrosion resistance have shown absence of change of mass of samples from dysprosium molybdate during 60 hours. The bending strength of samples from dysprosium molybdate obtained by hot pressing at pressure 35 Pa, temperature 1400 oÑ and time of holding under pressure 5 min is 314 MPa.

1. Evdokimov A. A., Efremov V. A., Trunov V. K., eds. Khimiya redkikh elementov. Soedineniya redkozemel'nykh elementov. Molibdaty. Vol'framaty [Chemistry of rare elements. Compounds of rare earth elements. The molybdates. Tungstates]; ed. I. V. Tananaev, B. K. Trunov. Moscow, Nauka Publ., 1991. 266 p.

2. Batyreva V. A., German A. I., Serebryannikov V. V., Yakunina G. M. Sintezy soedinenii redkozemel'nykh elementov [Syntheses of REE compounds]. Tomsk, Tomsk Univ. Publ., 1986, pt. 2, pp. 35–40.

3. Shmytko I. M., Kudrenko E. A., Sinitsyn V. V., Redkin B. S., Ponyatovsky E. G. Features of phase transitions in single crystals Eu2(MoO4)3 under thermobaric influences. JETF Letters, 2005, vol. 82, no. 7, pp. 409–412.

4. Trunov V. K., Efremov V. A., Velikodny Yu. A. Kristallokhimiya i svoistva dvoinykh molibdatov i vol'framatov [Crystal chemistry and properties of double molybdates and tungstates]. Leningrad, Nauka Publ., Leningrad. otd-nie, 1986, pp. 133–135.

5. Kozhevnikova N. M., Mokhosoev M. V. Troinye molibdaty [Triple molybdates]. Zhurnal neorganicheskoi khimii = Journal of Non-organic Chemistry, 1992, vol. 37, no. 11, pp. 2395–3401.

6. Zvezdina I. M., Balkina T. I., Komissarova J. H., Pushkina G. Ya., Spiridonov F. M., Shatsky V. M. Ftorid-molibdaty nekotorykh lantanoidov tipa LnMoO4F [Ftoride - molybdates of some lanthanides of the LnMoO4F type]. Koordinatsionnaya khimiya = Coordination Chemistry, 1985, vol. 11, no. 8, pp. 1074– 1076.

7. Dmitriev V., Sinisyn V., Dilanyan R., Machon D., Kuznetsov A., Ponyatovsky E., Lucazeau G., Weber H. H. P. In situ pressure-induced solid-state amorphization in Sm2(MoO4)3, Eu2(MoO4)3 and Gd2(MoO4)3 crystals: chemical decomposition scenario. J. of Phys. And Chem. Solids, 2003, vol. 64, рр. 307–312.

8. Szafraniak-Wiza I., Hilczer B., Talik E., Pietraszko A., Malic B. Ferroelectric perovskite nanopowders obtained by mechanochemical synthesis. Processing and Application of Ceramics, 2010, no. 4, pp. 99–106.

9. Shi F., Meng J., Ren Y. Semiconductor to metal transition in Ln2MoО9 compounds. Mat. Res. Bull., 1995, vol. 30, no. 10, pp. 1285–1291.

10. Shmytko I. M., Kudrenko E. A., Sinitsyn V. V., Redkin B. S., Ponyatovsky E. G. Structural aspects of solid-phase amorphization in Eu2(MoO4)3 single crystals. Physics of the Solid State, 2007, vol. 49, no. 5, pp. 941–948.

11. Antipin A. M., Sorokina N. I., Alekseeva O. A., Dudka A. P., Chernyshov D. Y., Voronkova V. I. Polimorfizm i struktura monokristallov Nd2MoO6 [Polymorphism and structure of Nd2MoO6 single crystals]. Kristallografiya = Crystallography, 2017, vol. 62, no. 4, pp. 551–558.

12. Badmaeva E. Yu., Tushinova Yu. L., Bazarov B. G., Solodovnikov S. F., Bazarova Zh. G. Fazovye ravnovesiya i kristallicheskaya struktura faz v sistemakh Ln2(MoO4)3-Hf(MoO4)2 (Ln=La-Lu, Y, Sc) [Process and crystal structure phase in the system Ln2(MoO4)3-Hf(MoO4)2]. Vestnik Buryatskogo gosudarstvennogo universiteta. Seriya 1: Khimiya = Bulletin of the BSU. Series 1: Chemistry, 2004, no. 1, pp. 21– 27.

13. Hadasheva Z. S., Venskovsky N. U., Safronenko M. G., Golubko N. V., Politova E. D., Stefanovich S. Yu., Mashkovtseva A. A. Fazovyi perekhod v novykh kislorod-ionnykh provodnikakh na osnove molibdata lantata La2Mo2O9 [Phase transition in new oxygen-ion conductors based on lanthanum molybdate La2Mo2)9]. Izvestiya Rossiiskoi akademii nauk. Seriya fizicheskaya = Proceedings of the Russian Academy of Sciences. Physics Series, 2003, vol. 67, no. 7, pp. 972–974.

14. Voronkova V. I., Kharitonova E. P., Leonidov I. A., Patrakeev M. V., Leonidova O. N., Belov D. A. Novye flyuoritopodobnye redkozemel'nye molibdaty so smeshannoi elektronno-kislorodnoi provodimost'yu [New fluorite-like rare earth molybdates with mixed electron-oxygen conductivity]. Fundamental'nye problemy ioniki tverdogo tela. 11 Mezhdunarodnoe soveshchanie [Fundamental problems of solid state ionics. 11 International meeting]. Moscow, Graniza Publ., 2012. 132 p.

15. Alekseeva O. A., Gagor A. B., Pietraszko A. P., Sorokina N. I., Bolotina N. B., Artemov V. V., Kharitonova E. P., Voronkova V. I. Crystal structure of the oxygen conducting compound Nd5Mo3O16. Zlitschrift Kristallographie, 2012, vol. 227, no. 12, pp. 869–875.

16. Evans I. R., Howard J. A. K., Evans J. S. O. The crystal structure of a-La2Mo2O9 and the structural origin of the oxide ion migration pathway. Chemistry Materials, 2005, vol. 17, pp. 4074–4077.

17. Egerton R. F. Fizicheskie printsipy elektronnoi mikroskopii. Vvedenie v prosvechivayushchuyu, rastrovuyu i analiticheskuyu elektronnuyu mikroskopiyu [Physical principles of electron microscopy. Introduction to transmission, scanning and analytical electron microscopy]. Moscow, Technosphera Publ., 2010. 304 p.

18. Kurtz R., Paulmann C., Bismayer U. Real structure investigations at PbNd4Mo3O16. HASYLAB Ann. Rep., 2004, pt. 1. P. 12812.

19. Ravel B., M. Newville. Data analysis for X-ray absorption spectroscopy using IFEFFIT. J. Synchrotron Rad., 2005, vol. 12, pp. 537–541.

20. Gusev A. I. Nanomaterialy, nanostruktury, nanotekhnologii [Nanomaterials, nanostructures, nanotechnology]. Moscow, Fizmatlit Publ., 2005. 416 p.