Temperature Effects on the Dimensions of CoCr Alloys: Dilatometric Study
Abstract
Cobalt-chromium (Co-Cr) alloys are widely employed in biomedical and dental applications due to their favourable mechanical properties, corrosion resistance, and thermal stability. This study investigates the effect of silicon (Si) addition on the chemical composition and dimensional behavior of Co-Cr alloys, with an emphasis on their suitability for removable partial denture frameworks. A series of Co-Cr alloys with variable Si content (0.5–7.05 wt.%) were analysed using optical emission spectrometry and dilatometry to establish correlations between composition and thermal expansion.
The experimental approach provides new insights into how silicon content modifies the thermal behavior and dimensional stability of Co-Cr alloys during heating up to 1200 °C. The novelty of this research lies in the systematic evaluation of Si addition as a compositional variable in Co-Cr dental alloys, which has not been extensively explored in relation to dilatometric behavior. The study demonstrates that controlled silicon enrichment not only reduces the linear thermal expansion coefficient but also enhances structural stability during thermal cycling, minimizing the risk of deformation or mismatch with low-fusing dental ceramics. These findings bridge the gap between alloy chemistry and thermal compatibility, offering a scientific basis for optimizing alloy formulations used in precision dental restorations.
The outcomes provide valuable guidelines for the development of advanced Co-Cr-Si alloys with improved dimensional accuracy and thermal performance, contributing to the reliability and longevity of metal-ceramic prosthetic components.
Downloads
References
[2]. Dăneț A., Spectroscopic Methods for Alloy Analysis, Bucharest: Editura Tehnică, 2010.
[3]. ***, ASTM E228-17 - Standard Test Method for Linear Thermal Expansion of Solid Materials with a Dilatometer. ASTM International, 2017.
[4]. ***, L75H/1400 Dilatometer Operation Manual, Linseis GmbH, Selb, Germany, 2018.
[5]. Davis J. R., Handbook of Thermal Expansion of Metals and Alloys, ASM International, 2002.
[6]. Ristic M. M., et al., Sintering and Related Phenomena, Pergamon Press, 2006.
[7]. German R. M., Sintering: From Empirical Observations to Scientific Principles, Elsevier, 2014.
[8]. Barbosa F. O., Araújo M. C., Fractographic analysis of K3 nickel-titanium rotary instruments submitted to different modes of mechanical loading, Journal of Endodontics, 34(8), p. 994-998, 2008.
[9]. Geis-Gerstorfer J., Dental alloys: Physical properties and clinical applications, Dental Materials Journal, 39(3), p. 345-356, 2020.
[10]. Anselme K., et al., Metal-ceramic compatibility in dental prosthetics, Journal of Biomedical Materials Research Part B, 106(5), p. 2027-2035, 2018.
[11]. Baba N., et al., Mechanical strength of laser-welded cobalt–chromium alloy, Journal of Biomedical Materials Research Part B, 69B, p. 121-124, 2004.
[12]. Baciu E. R., Forna N. C., Influenţa tehnicilor de finisare asupra rugozităţii suprafeţelor componentelor metalice ale restaurărilor protetice, Revista Medico-Chirurgicală a Societăţii de Medici şi Naturalişti din Iaşi, 114(4), p.1198-1203, 2010.
[13]. Behazin M., et al., Combined effects of pH and γ-irradiation on the corrosion of Co–Cr alloy Stellite-6, Electrochimica Acta, 134, p. 399-410, 2014.
[14]. Li W., Lee L. J., Low temperature cure of unsaturated polyester resins with thermoplastic additives: I. Dilatometry and morphology study, Polymer, 41(2), p. 685-696, 2000.
[15]. Callister W. D., Rethwisch D. G., Materials Science and Engineering: An Introduction, (10th ed.), Wiley, 2020.
[16]. Hans M., et al., Thermal and mechanical behavior of Co–Cr dental alloys, Journal of Prosthodontic Research, 63(2), p. 167-175, 2019.
[17]. Henriques B., et al., Mechanical behavior of Co–Cr dental alloys, Journal of the Mechanical Behavior of Biomedical Materials, 4(8), p. 1718-1726, 2011.
[18]. Nowacki J., Pieczonka T., Dilatometric analysis of sintering of iron–boron–cobalt P/M metal matrix composites, Journal of Materials Processing Technology, 157-158, p. 749-754, 2004.
[19]. Witek K., Polkowski W., Thermal expansion and microstructural stability of Al-Si alloys reinforced with ceramic particles, Materials Characterization, 145, p. 250-258, 2018.
[20]. Ceschini L., et al., Effect of thermal exposure on the wear and mechanical properties of aluminum matrix composites, Wear, 352-353, p. 144-152, 2016.
[21]. Kieback B., et al., Processing techniques for metal matrix composites, Materials Science and Engineering: A, 362(1-2), p. 81-106, 2003.
[22]. Liu C., et al., Thermo-mechanical fatigue behavior of Co–Cr–Mo alloys for biomedical applications, Materials Science and Engineering: C, 120, 111746, 2021.
[23]. Danninger H., Gierl C., Sintering of ferrous powder compacts: Mechanisms and practical aspects, Powder Metallurgy, 46(3), p. 213-221, 2003.
[24]. Xu X., et al., Effect of heat treatment on microstructure and wear resistance of Co–Cr dental alloys, Surface & Coatings Technology, 394, 125872, 2020.
[25]. Swaminathan V., Narayanasamy R., Tribological behavior of aluminum-based composites under dry sliding conditions, Journal of Materials Research and Technology, 4(2), p. 151-158, 2015.
[26]. Callister W. D., Rethwisch D. G., Materials Science and Engineering: An Introduction, (10th ed.), Wiley, 2020.
[27]. Hans M., et al., Thermal and mechanical behavior of Co–Cr dental alloys, Journal of Prosthodontic Research, 63(2), p. 167-175, 2019.
[28]. Henriques B., et al., Mechanical behavior of Co–Cr dental alloys, Journal of the Mechanical Behavior of Biomedical Materials, 4(8), p. 1718-1726, 2011.
[29]. Nowacki J., Pieczonka T., Dilatometric analysis of sintering of iron–boron–cobalt P/M metal matrix composites, Journal of Materials Processing Technology, 157-158, p. 749-754, 2004.
