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Material Science and Technology of Japan, 57（2020）228〜234

Dec. 2020

Regular PaperCorrosion Behavior of Sintered YSZ with Volcanic Ash for Thermal
Barrier CoatingsSeung-Hyeon KIM1, Yoshitaka MATSUSHITA2 and Byung-Koog JANG1,*
1Interdisciplinary Graduate School of Engineering Science, Kyushu University, 6-1 Kasuga-koen, Kasuga-shi, Fukuoka 816-8580, Japan
2Research Network and Facility Services Division, National Institute for Materials Science, 1-2-1 Sengen,Tsukuba, Ibaraki 305-0047, Japan
Received Sep. 30, 2020; Accepted Oct. 21, 2020
Abstract
In this study, the high-temperature corrosion behavior by volcanic ash was evaluated for sintered yttria-stabilized
zirconia (YSZ) used as a thermal barrier coatings (TBCs). To evaluate high-temperature corrosion resistance, real
volcanic ash was stacked on the surface of the sintered body at 40 mg/cm2 and exposed to 1300°C heat for 2, 12, and48 h. The phase change due to the reaction of YSZ and volcanic ash was characterized using high temperature X-ray
diffraction (HT-XRD) at 25°C, 1100°C, 1200°C, 1300°C. As a result of HT-XRD, the t-ZrO2 phase and NaAlSi3O8(Albite) phase were observed at 25°C. However, the NaAlSi3O8 (Albite) phase disappeared and the m-ZrO2 and ZrSiO4
phases were analyzed at 1300°C. The results indicated that the chemically reacted with the ZrO2 and the SiO2 frommolten volcanic ash to form ZrSiO4 connected in a spherical morphology. The thickness of the spherical ZrSiO4
increased with increasing heat-treatment time.
Keywords: YSZ, Thermal barrier coatings, Volcanic ash, Corrosion behavior, Spark plasma sintering

1.

Introduction

and millions of passengers, resulting in billions of dollars in

Thermal barrier coatings (TBCs) are used to protect gas

economic losses [9]. Over the past 20 years, more than 100turbine engine hot-section components to meet future high fuelcommercial aircraft have encountered volcanic ash, and someefficiency and low engine emissions targets. The rise inhave been severely damaged. Recently, volcanoes have erupted

temperature in gas turbine engines creates problems. TBCs arearound the world, including Japan, Australia, and the Philippines.

applied to the hot parts of the engine to overcome this demand

Volcanic eruptions blow ash into the sky. The volcanic ash led

because their melting temperature is higher than that of the metalauthorities to halt all flights to and from airports, causingparts. The outside of the hot metal parts in gas turbine engines isenormous economic damage. Minimizing TBCs reactivity tocoated with TBCs, which reduce the base metal temperatures by

volcanic ash can reduce economic stagnation and damage.

up to 300°C. These new gas turbine designs are gradually

For TBCs applications [10–11], 7–8 wt.% yttria-stabilized

approaching the goal of higher gas-inlet temperatures, improving

zirconia (YSZ) is widely used as a coatings material. Generally,

thermodynamic efficiency to reduce fuel consumption and7–8 wt.% YSZ is used as a coatings material for turbine blades due

environmental impact [1–2].

to its excellent thermal properties. However, volcanic ash deposits

Silicate particles can be produced by various substances, suchproceed along the boundary of the YSZ particles, and t-ZrO2 canas volcanic ash [3–6], desert sand, and dust, and can be sucked

crack due to significant volume changes (4–5 V.%) when cooled

together into the air [7–8]. In 2010, the eruption of the[12–13]. When the volcanic ash attack becomes severe, ZrO2 isEyjafjallajökull volcano in Iceland affected thousands of flights

converted only into spherical particles, which are produced in theprocess of melting and re-deposition into typical micros spherical*Corresponding author: jang.byungkoog@kyudai.jp(228)