Yttria-stabilized zirconia–alumina composite sintering temperature effect on thermal diffusivity

Abstract

Yttria-stabilized zirconia (YSZ) is one of the most common materials used for a ceramic top coat in the thermal barrier coating (TBC). The high operating temperature used in the gas turbine engines causes the stress between the top coat and the bond coat. The stress relaxation can be assured by modifications of YSZ. Hence, studies on how to modify the chemical and phase composition of these coatings are still conducted. The laser flash analysis was used to determine the thermal diffusivity of composite mixture of 8 mol% yttria-stabilized zirconia with a-Al 2 O 3 in the range of temperatures between 20 and 1100°C. The powders were prepared with 5 and 25 mass% Al 2 O 3 addition to 8YSZ. The particle size distribution was done for each powder to analyse the grain size after milling of the a-Al 2 O 3 with 8YSZ in the ball mill. The density of each powder was measured in the helium pycnometer. The disc-shaped samples were produced by pressing using an isostatic press and then sintered at various temperatures: 1000, 1200, 1400 and 1600°C.

Flash sintering produces eutectic microstructures in Al2O3–LaPO4 versus conventional microstructures in 8YSZ–LaPO4

“…The prerequisite conditions and phenomena of flash sintering are material specific 1,9,10 . 8 mol% Y 2 O 3 ‐stabilized ZrO 2 (8YSZ) has been well established to flash sinter easily at low temperatures and low voltages 1,11 . The presence of 8YSZ can assist flash sintering for other materials in a composite 12‐15 .…”

“…1,9,10 8 mol% Y 2 O 3 -stabilized ZrO 2 (8YSZ) has been well established to flash sinter easily at low temperatures and low voltages. 1,11 The presence of 8YSZ can assist flash sintering for other materials in a…”

The new idea for modification of the surface area of silicate glass

“…It is also very developmental. At the same time, research results obtained in previous works indicate that formation of a new surface coating consisting of ZrO 2-Y 2 O 3 crystallites effectively modifies the properties of the glass by introducing favorable stresses on the surface and therefore increases its hardness and tensile strength [1,2,7,8].…”

“…Therefore, the assumption was adopted that application of stabilized ZrO 2 9 nY 2 O 3 oxide of micro-and nanometric particle size in the process of physical vapor deposition under reduced pressure and elevated temperature allows formation of stable and strengthened surface coating on the glass substrate. It was assumed that the produced coating will provide enhanced effect of strengthening of soda-calcium-silicate glass [7][8][9][10][11]. At the same time, an attempt was made to develop comprehensive selection criteria for both coating materials and process conditions for plasma spraying under reduced pressure to produce a strengthened and uniform coating that consisted of ZrO 2 9 nY 2 O 3 oxide in the industrial soda-calcium-silicate glass substrate.…”

Exploratory of novel thermal barrier coating on diesel engine performance

“…Compared to the baseline engine at full load, the smoke opacity levels in neat diesel, AMEB20, and 50 ppm cerium oxide mixed AMEB20 fuel in TBC condition decreased by 2.94%, 5.15%, and 12.2%, respectively. 27 Dychton et al revealed that manipulating the physical and chemical structure of 8YSZ and partly combining ZrO 2 with 8YSZ could endure coating materials that withstand beyond 1600 o C, and better stress relaxation of material was achieved. 28 Levent Urtekin et al investigated the thermal properties of ZrO 2 TBC with and without bond coating components and reported that ZrO 2 with Ni-Al bond coating provides good thermal performance.…”