National University of Science and Technology MISIS, Moscow, Russia

V. E. Bazhenov, Associate Professor of the Department of Foundry Technologies and Art of Materials Processing, Candidate of Technical Sciences, e-mail: v.e.bagenov@gmail.com
E. P. Kovyshkina, Postgraduate Student of the Department of Foundry Technologies and Art of Materials Processing, e-mail: lena.kovyshkina@yandex.ru
A. A. Nikitina, Technician of the Department of Foundry Technologies and Art of Materials Processing, e-mail: nikitina.misis@gmail.com
A. V. Koltygin, Associate Professor of the Department of Foundry Technologies and Art of Materials Processing, Candidate of Technical Sciences, e-mail: misistlp@mail.ru

Water-soluble salt carbamide-based patterns are often used to manufacture large case castings by investment casting due to high strength and low linear shrinkage. However, now manufacturing plants gradually transfer to a technological process, when colloidal silica binders are used as a binder for manufacturing ceramic molds, instead of a hydrolysed solution of ethyl silicate, requiring additional studies on potential interactions between a mold and a binder. The paper describes influence of the components of pattern compounds (magnesium sulfate, potassium nitrate, polyvinyl alcohol and dimethylglyoxime) on the properties of salt pattern compositions. A rotational viscometer was used to study influence of the additives on nature of solidification and determine coherence temperature of pattern compounds, which turned out to be within a range of 112–126 ^oC. The lowest coherence temperature is found for pattern compounds with added potassium nitrate. Linear shrinkage measured with a manual 3D scanner has showed that depending on the composition of the pattern compound it may be low (0.3–0.55%), correlating well with coherence temperature. The higher coherence temperature of the pattern compound, the lower linear shrinkage, and vice versa. The interaction between the colloidal silica and pattern compounds was assessed by wetting angle and a spreading area. Two methods showed contradicting results, but in general it should be noted that added polyvinyl alcohol and dimethylglyo xime contributed to increasing wetting angle, and, consequently, to decreasing the interaction between the binder and the pattern compound. Roughness measured with a profile meter has showed that pattern compounds ensure low roughness within Rz 3.2–6.8 μm, when the pattern compound is solidified in a metal mold. Three-point bending tests showed that added potassium nitrate and polyvinyl alcohol ensured considerable strengthening of pattern compounds, and maximum bending strength was 15.9 MPa.
This research received financial support from the Ministry of Science and Higher Education in the Russian Federation (Agreement No. 075-11-2022-023 from 6 April 2022) under the program “Scientific and technological development of the Russian Federation” according to governmental decree N 218 dated 9 April 2010.

1. Kanyo J. E., Schaffoner S., Sharon Uwanyuze R., Leary K. S. An overview of ceramic molds for investment casting of nickel superalloys. Journal of the European Ceramic Society. 2020. Vol. 40. pp. 4955–4973.
2. Selvaraj S. K., Sundaramali G., Dev S. J., Swathish R. S. et al. Recent advancements in the field of Ni-based superalloys. Advances in Materials Science and Engineering. 2021. Vol. 2021. 9723450.
3. Kumar S., Karunakar D. B. Development of wax blend pattern and optimization of injection process parameters by grey-fuzzy logic in investment casting process. International Journal of Metalcasting. 2022. Vol. 16. pp. 962–972.
4. Pradyumna R., Sridhar S., Satyanarayana A., Chauhan A. S. et al. Wax patterns for integrally cast rotors/stators of aeroengine gas turbines. Materials Today: Proceedings. 2015. Vol. 2, No. 4-5. pp. 1714–1722.
5. Prokopchuk N. R., Gorshcharik N. D., Klyuev A. Yu., Kozlov N. G. et al. Pattern compositions for precision casting. Izvestiya natsionalnoy akademii nauk Belarusi. Seriya khimicheskikh nauk. 2015. No. 4. pp. 122–128.
6. Dubrovskiy V. A. Pattern composition for investment patterns. Patent RF, No. 2123902. Applied: 13.11.1997. Published: 27.12.1998.
7. Uskov D. I. Sand formulation for manufacturing precision castings. Youth and science : proceedings of the 10 th Anniversary All-Russian scientific and technical conference of students, postgraduate students and young scientists with international participation devoted to eighty years of establishing Krasnoyarsk Krai (15–25 April 2014). Krasnoyarsk : Siberian Federal University, 2014. pp. 1–4.
8. Gromakov A. I., Mikhnev M. M., Uskov D. I. Mixtures for manufacturing water-soluble cores. Proceedings of the International Scientific Conference “Reshetnev Readings” (9–12 November 2016). Vol. 2. Krasnoyarsk : Reshet nev Siberian State University of Science and Technology, 2016. pp. 332–333.
9. Fujita T. Pattern material for making foundry patterns for use in investment casting process. Patent US, No. 4939187. 1990.
10. Stadnichuk V. I. Method of making ceramic moulds by fusible patterns. Patent RF, No. 2499651. Applied: 20.07.2012. Published: 27.11.2013.
11. Lakeev A. S., Shcheglovitov L. A., Kuzmin Yu. D. Progressive methods of manufacturing precision castings. Kyiv : Tekhnika, 1984. 160 p.
12. Sumin E. I., Andrianov L. P. Composition for preparation of water-soluble models. Author’s certificate USSR, No. 602288. Applied: 17.02.1976. Published: 15.04.1978.
13. Marutani Y., Kamitani T. Manufacturing sacrificial patterns for casting by salt powder lamination. Rapid Prototyping Journal. 2004. Vol. 10, No. 5. pp. 281–287.
14. Seyedraoufi Z. S., Mirdamadi Sh. Synthesis, microstructure and mechanical properties of porous Mg – Zn scaffolds. Journal of the Mechanical Behavior of Biomedical Materials. 2013. Vol. 21. pp. 1–8.
15. Wen C. E., Yamada Y., Shimojima K., Chino Y. et al. Compressibility of porous magnesium foam: dependency on porosity and pore size. Materials Letters. 2004. Vol. 58, No. 3-4. pp. 357–360.
16. Hao G. L., Han F. S., Li W. D. Processing and mechanical properties of magnesium foams. Journal of Porous Materials. 2009. Vol. 16. pp. 251–256.
17. Rutto H. K. Urea-based moulding compounds for investment casting: Thesis for the degree Philosophiae Doctor in Chemical Engineering. Pretoria : University of Pretoria, 2006.
18. Shklennik Ya. I., Ozerov V. A. Investment casting. 2^nd ed., updated and revised. Moscow : Mashinostroenie, 1971. 436 p.
19. Bazhenov V. E., Kovyshkina E. P., Koltygin A. V., Belov V. D. et al. Developing a parting agent for soluble salt models during investment casting. Liteynoe proizvodstvo. 2023. No. 6. pp. 30–37.
20. Churkin B. S., Churkin A. B., Kategorenko Yu. I. Special methods of casting: study guide. Yekaterinburg : Russian State Vocational Pedagogical University, 2012. 189 p.
21. Rutto H., Focke W. Thermomechanical properties of urea-based pattern molding compounds for investment casting. International Polymer Processing. 2010. Vol. 25, No. 1. pp. 15–22.
22. Bazhenov V. E., Sannikov A. V., Kovyshkina E. P., Koltygin A. V. et al. The influence of injection temperature and pressure on pattern wax fluidity. Journal of Manufacturing and Materials Processing. 2023. Vol. 7. 141.
23. Dahle A. K., Tøndel P. A., Paradies C. J., Arnberg L. Effect of grain refinement on the fluidity of two commercial Al – Si foundry alloys. Metall. Mater. Trans. A. 1996. Vol. 27. pp. 2305–2313.
24. Dahle A. K., Arnberg L. Development of strength in solidifying aluminium alloys. Acta Mater. 1997. Vol. 45. pp. 547–559.