Influence of in situ phase formation on properties of calcium zirconate refractories

Schafföner, Stefan; Fruhstorfer, Jens; Faßauer, Christina; Freitag, Lisa; Jahn, Constantin; Aneziris, Christos G.

doi:10.1016/j.jeurceramsoc.2016.08.017

Cited by 28 publications

(12 citation statements)

References 43 publications

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“…Since all three compounds have a very low Gibbs energy of formation, the homogeneity range in the respective (Ca,Sr,Ba)O-ZrO 2 phase diagrams is very narrow. During synthesis from (Ca,Sr,Ba)O hydroxides and carbonates it has to be ensured that the resulting raw materials are free of impurities such as ZrO 2 or (Ca,Sr,Ba)O [4,37]. Refractory raw materials based on alkaline earth zirconates can be generally produced by solidstate synthesis or electro fusion.…”

Section: Alkaline Earth Zirconatesmentioning

confidence: 99%

“…Refractory raw materials based on alkaline earth zirconates can be generally produced by solidstate synthesis or electro fusion. Electro fusion results in a higher density [38], which is often associated with a higher corrosion resistance, but the fusion process can also cause the evaporation of the alkaline earth component (CaO, BaO), causing free c-ZrO 2 [37,39,40]. Solid-state synthesis usually allows better control of the chemical composition.…”

Section: Alkaline Earth Zirconatesmentioning

confidence: 99%

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Reactions of alkaline earth zirconate refractories with titanium alloys

Schafföner¹

2020

MATEC Web Conf.

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The severe reactivity of titanium alloys with ceramics is a major challenge for their processing. Up to now refractories to melt and cast titanium alloys are selected on the basis of a low Gibbs energy of formation. This kind of selection assumes that an oxide should be stable if its Gibbs energy of formation is lower than the one of any titanium (sub)oxide. The present contribution reviews that these models trying to explain the stability of ceramic materials in contact with titanium alloys are often misleading. By contrast, a dissolution and evaporation based reaction model is more appropriate to describe the reaction of high temperature ceramics with titanium alloys. These explanations were exemplified by research findings of high temperature reactions of titanium alloys with calcium oxide and yttrium oxide. Based on the discussion on calcium and yttrium oxide, the reactions of alkaline earth zirconates such as calcium and barium zirconate with titanium alloys were discussed. The reaction of alkaline earth zirconates is also highly dependent on the titanium alloy composition. It was also demonstrated that not only thermodynamics but also kinetics should be considered to evaluate refractories for titanium processing.

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Section: Alkaline Earth Zirconatesmentioning

confidence: 99%

Section: Alkaline Earth Zirconatesmentioning

confidence: 99%

Reactions of alkaline earth zirconate refractories with titanium alloys

Schafföner¹

2020

MATEC Web Conf.

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“…However, residual ZrO 2 does not completely react with CaO and results in the formation of α‐case at the interface. When CaCO 3 was added instead of CaO into the ZrO 2 composites, the residual ZrO 2 reacted completely to form CaZrO 3 20 . Although α‐case decreased after Ti casting, several pores formed in the composites, which considerably reduced the thermal shock resistance and mechanical strength.…”

Section: Introductionmentioning

confidence: 99%

“…When CaCO 3 was added instead of CaO into the ZrO 2 composites, the residual ZrO 2 reacted completely to form CaZrO 3 . 20 Although α-case decreased after Ti casting, several pores formed in the composites, which considerably reduced the thermal shock resistance and mechanical strength. Lee In the current study, the ZrO 2 /CaTiO 3 composite was selected for Ti casting.…”

Section: Introductionmentioning

confidence: 99%

Microstructural evolution and interfacial reactions between Ti and ZrO₂/CaTiO₃ composites

Lin

2021

Int J Applied Ceramic Tech

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Various proportions of ZrO2/CaTiO3 powders were mixed and hot pressed at 1500°C/30 min for Ti casting. The hot‐pressed ZrO2/CaTiO3 composites were reacted with pure Ti at 1700°C/10 min in Ar. The interfacial reaction between Ti and ZrO2/CaTiO3 composites was investigated through X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy‐dispersive X‐ray spectroscopy. The ZrO2/CaTiO3 composites with less than 10 vol.%, CaTiO3, and a minor amount of residual TiO2 were found. When the content of ZrO2 was increased to larger than 10 vol.%, two Ca2Zr5Ti2O16 and CaZrTi2O7 phases appeared in the composites. The amount of CaTiO3 and CaZrTi2O7 in the composites gradually decreased as the amount of ZrO2 increased. When Ti came in contact with ZrO2/CaTiO3 composites with less than 10 vol.% ZrO2, the resulting eutectic reaction produced a liquid phase and induced melting. When ZrO2 was increased to more than 30 vol.% in the composites, Ca2Zr5Ti2O16 and CaZrTi2O7 changed completely to CaZrO3, Ti2O, CaO, and ZrO2. With more than 30 vol.% ZrO2, no other reaction phases occurred in the Ti side after contact with the ZrO2/CaTiO3 composites, which is conducive for producing ceramic composites for Ti casting applications.

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“…However, a hard and brittle α‐case is formed at the titanium surface because of the residual ZrO 2 reacting with titanium. To decrease α‐case formation, CaCO 3 is added to the composites to convert the residual ZrO 2 into CaZrO 3 . Although this addition decreases α‐case formation, the pore size of the CaZrO 3 composite increases, which reduces its thermal shock resistance and mechanical strength.…”

Section: Introductionmentioning

confidence: 99%

Interfacial reactions between Ti and Y₂O₃/Ca₄Ti₃O₁₀ composites

Lin

2019

Int J Applied Ceramic Tech

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In titanium casting, the interfacial reactions between selected Y 2 O 3 /Ca 4 Ti 3 O 10 composites in contact with titanium at 1600°C for 30 minutes in an argon environment were characterized using X-ray diffraction, scanning electron microscopy, and analytical transmission electron microscopy. Before contact with titanium, reaction phases of the Y 2 O 3 /Ca 4 Ti 3 O 10 composites formed through hot pressing at 1500°C or annealing at 1600°C. These phases were identified as Ca 4 Ti 3 O 10 , Y 2 O 3 , and minor amounts of CaO. The amount of Ca 4 Ti 3 O 10 in the composites gradually decreased as the amount of Y 2 O 3 increased. When the Y 2 O 3 /Ca 4 Ti 3 O 10 composites were in contact with titanium, a reaction layer of α-Ti and Y 2 O 3 was formed near the interface of the composite side. Large amounts of calcium and oxygen were expelled toward the composite side from Ca 4 Ti 3 O 10 near the interface to form CaO, which precipitated in the Ca 4 Ti 3 O 10 and Y 2 O 3 phases. Furthermore, no reaction phases were detected in titanium. Ca 4 Ti 3 O 10 and Y 2 O 3 can function as diffusion barrier layers to effectively suppress the diffusion of oxygen into titanium. K E Y W O R D S Ca 4 Ti 3 O 10 , ceramic composites, microstructures, TEM, titanium casting | 865 LU et aL.

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Influence of in situ phase formation on properties of calcium zirconate refractories

Cited by 28 publications

References 43 publications

Reactions of alkaline earth zirconate refractories with titanium alloys

Reactions of alkaline earth zirconate refractories with titanium alloys

Microstructural evolution and interfacial reactions between Ti and ZrO₂/CaTiO₃ composites

Interfacial reactions between Ti and Y₂O₃/Ca₄Ti₃O₁₀ composites

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Influence of in situ phase formation on properties of calcium zirconate refractories

Cited by 28 publications

References 43 publications

Reactions of alkaline earth zirconate refractories with titanium alloys

Reactions of alkaline earth zirconate refractories with titanium alloys

Microstructural evolution and interfacial reactions between Ti and ZrO2/CaTiO3 composites

Interfacial reactions between Ti and Y2O3/Ca4Ti3O10 composites

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Product

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Microstructural evolution and interfacial reactions between Ti and ZrO₂/CaTiO₃ composites

Interfacial reactions between Ti and Y₂O₃/Ca₄Ti₃O₁₀ composites