Microwave Absorbency Change of Zirconia Powder and Fiber during Vacuum Heating

2010 ◽  
Vol 63 ◽  
pp. 85-90 ◽  
Author(s):  
Saburo Sano ◽  
Shoji Kawakami ◽  
Yasumasa Takao ◽  
Sadatsugu Takayama ◽  
Motoyasu Sato
Keyword(s):  
Microwave Absorption ◽  
Stoichiometric Composition ◽  
Wave Guide ◽  
Stabilized Zirconia ◽  
Zirconia Powder ◽  
Partially Stabilized Zirconia ◽  
Zro2 Powder ◽  
Zirconia Fiber ◽  
Vacuum Heating ◽  
Absorption Measurements

Stabilized zirconia shows rather high microwave absorbency at room temperature, and the absorbency become higher with increasing temperature. In this study, stabilized zirconia powder, partially stabilized zirconia powder and zirconia fiber were subjected for microwave absorption measurements at elevated temperature. Microwave absorption measurements were done by using a system consists of a microwave vector network analyzer, a circular wave-guide fixture and a vacuum furnace. Microwave absorbency was evaluated by the reflection power change from the sample in the circular wave-guide fixture under vacuum heating. Microwave absorbency of stabilized zirconia powder, partially stabilized zirconia powder and zirconia fiber gradually increased with the increase of temperature. We supposed that the increase of microwave absorbency is related to the ionic (oxygen) conduction behavior of stabilized zirconia. Stoichiometric composition ZrO2 powder was also subjected for a measurement to consider the relation between microwave absorbency and ion conduction of zirconia. As the result, stoichiometric composition ZrO2 powder was not absorbed microwave power even when the powder was heated up to 900oC because it isn’t an oxygen ion conductor.

Corrosion Resistance of Partially Stabilized Zirconia Materials to Alkaline Steel Slag

2020 ◽  
Vol 852 ◽  
pp. 119-128
Author(s):  
Liang Zhao ◽  
Qian Huang ◽  
Hua Yin Sun ◽  
Xiang Li
Keyword(s):  
Corrosion Resistance ◽  
Steel Slag ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Zirconia Powder ◽  
Slag Film ◽  
Partially Stabilized Zirconia ◽  
Stabilizing Agents ◽  
The Relationship

Partially stabilized zirconia (PSZ) materials were fabricated using 4 wt% CaO, 3 wt% MgO, and 5.4 wt% Y2O3 as stabilizing agents together with monoclinic zirconia powder. The physical properties, phase compositions, and microstructures of the Ca-PSZ, Mg-PSZ, and Y-PSZ samples were investigated by X-ray diffraction, scanning electron microscopy, and energy spectrum analysis. A crucible method was used to explore the relationship between the stabilizing agent and erosion resistance to alkaline steel slag. The results revealed that the zirconia materials stabilized by different stabilizing agents showed obvious differences in their bulk densities, apparent porosities, microstructures, and erosion resistances to alkaline steel slag. The structure of Y-PSZ showed highest density, containing a small number of uniformly distributed pores. In terms of Mg-PSZ, the intergranular bonding in its structure was observed to not be close, and the sample contained some cracks, but no pores. A large number of intragranular pores and a small number of overall pores was observed in Ca-PSZ, resulting in this material having the lowest bulk density. The pores and cracks provide the path to penetrate and diffuse for alkaline steel slag, which weakens the corrosion resistance of PSZ materials. The phase composition of the affected layers in all of the samples after corrosion was almost completely transformed from monoclinic phase to cubic phase, and the phase transition of both the original and transition layers was not obvious due to the formation of a slag film. Y-PSZ did not react with components of the steel slag such as SiO2 and Al2O3, showing the best corrosion resistance to alkaline steel slag.

Microwave Absorbency Change of Nitride Powders under Vacuum Heating

2014 ◽  
Vol 88 ◽  
pp. 31-36
Author(s):  
Saburo Sano ◽  
Sadatsugu Takayama ◽  
Akira Kishimoto
Keyword(s):  
Microwave Absorption ◽  
Millimeter Wave ◽  
Wave Guide ◽  
Heating Process ◽  
Vacuum Furnace ◽  
Metal Powders ◽  
Mixed Powder ◽  
Compact Sample ◽  
Vacuum Heating ◽  
Increasing Temperature

We measured the microwave and millimeter-wave behaviors of ceramics and metal powders as a basis for developing microwave and millimeter-wave heating technology. In this study, nitride powders were subjected to microwave absorption measurements at elevated temperature. These measurements were performed using a system comprising a vector network analyzer, a circular wave-guide fixture, and a vacuum furnace. The sample’s microwave absorbency was evaluated by the change in reflection power from the sample in the circular wave-guide fixture under vacuum heating. Measurements were performed at approximately 24 GHz and at temperature up to approximately 1100°C. Boron nitride (BN) exhibited almost no absorption of microwaves up to 1100°C, similar to the results of a low-loss oxide powder such as alumina. Dichromium mononitride (Cr2N) powder exhibited a rather high absorption of microwaves at room temperature. During vacuum heating, absorbency of Cr2N started to decrease at 300°C, and became almost zero at temperature greater than 600°C, similar to the behavior of iron powder. This result indicated that roughly packed Cr2N powder absorbs microwave radiation; however, during vacuum heating, the compact body was sintered and the whole sample body became a reflector of microwaves. This change was irreversible, and the sample maintained its reflection behavior upon the cooling. When a mixed powder of Cr2N (20 mass%) and Al2O3 was heated under vacuum, the compact sample exhibited microwave absorption that increased with increasing temperature. This change was reversible upon cooling. These results indicated that the mixed powder did not become reflector of microwaves; Cr2N particles were not electrically connected each other because the Al2O3 particles kept the Cr2N particles separate during the vacuum heating process.

Effects of Monoclinic ZrO2 with Different Particle Size on Properties of Zirconia Refractories

2011 ◽  
Vol 335-336 ◽  
pp. 721-727
Author(s):  
Hong Gang Sun ◽  
Shuang Zhi Yan ◽  
Peng Tao Li ◽  
Qing Hua Tan ◽  
Ai Jun Wu
Keyword(s):  
Particle Size ◽  
Phase Composition ◽  
Grain Boundaries ◽  
Bulk Density ◽  
Modulus Of Rupture ◽  
Monoclinic Zirconia ◽  
Stabilized Zirconia ◽  
Zirconia Powder ◽  
Partially Stabilized Zirconia ◽  
The Matrix

The zirconia refractories were prepared using partially stabilized zirconia grain and monoclinic zirconia powder as the matrix, partially stabilized zirconia particles as the aggregate, and phenolic resin as the binder, and four sizes of monoclinic zirconia powder (D50=1 μm, 3 μm, 6 μm, 10 μm) were used as additives. Besides, an improved specimen was prepared using a specific monoclinic zirconia powder as additive. Properties of specimens with different sizes of m-ZrO2powders were researched, including apparent porosity, bulk density, cold modulus of rupture, pore size distribution. Moreover, phase composition and microstructure were analyzed. The results show that, particle size of monoclinic zirconia powders greatly affect the sintering of materials. The specimens with finer m-ZrO2powder have lower porosity, higher bulk density and cold modulus of rupture, and the grain boundaries of zirconia particles were fuzzy, showing that the matrix of the specimens were almost sintered completely. While in specimens using coarser m-ZrO2powder, the grain boundaries of zirconia particles were clear, showing that the matrix of the specimens were not sintered completely.. Though finer monoclinic zirconia powder promoted the sintering of materials in the test, it had negative impact on the microporus structure, for large pores were observed in the specimen with fine m-ZrO2powder. Finally, the improved specimen with promoted sintering and optimized microstructure as well as phase composition was obtained by using specific monoclinic zirconia powder as additive.

A mode of deformation in partially stabilized zirconia

1981 ◽  
Vol 16 (5) ◽  
pp. 1428-1431 ◽  
Author(s):  
R. H. J. Hannink ◽  
M. V. Swain
Keyword(s):  
Stabilized Zirconia ◽  
Partially Stabilized Zirconia

A ceramic based on partially stabilized zirconia: Synthesis, structure, and properties under dynamic load

2011 ◽  
Vol 49 (5) ◽  
pp. 685-689 ◽  
Author(s):  
V. V. Milyavskii ◽  
A. S. Savinykh ◽  
F. A. Akopov ◽  
L. B. Borovkova ◽  
T. I. Borodina ◽  
...  
Keyword(s):  
Dynamic Load ◽  
Structure And Properties ◽  
Stabilized Zirconia ◽  
Partially Stabilized Zirconia

Nitriding of yttria-stabilized zirconia in atmospheric pressure microwave plasma

2009 ◽  
Vol 24 (6) ◽  
pp. 2021-2028 ◽  
Author(s):  
R. Milani ◽  
R.P. Cardoso ◽  
T. Belmonte ◽  
C.A. Figueroa ◽  
C.A. Perottoni ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Atmospheric Pressure ◽  
Microwave Plasma ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Zirconium Nitride ◽  
Stabilized Zirconia ◽  
Partially Stabilized Zirconia ◽  
X Ray ◽  
Yttria Partially Stabilized Zirconia

High temperature plasma nitriding of yttria-partially-stabilized zirconia in atmospheric pressure microwave plasma was investigated. The morphological, mechanical, and physicochemical characteristics of the resulting nitrided layer were characterized by different methods, such as optical and scanning electron microscopy, microindentation, x-ray diffraction, narrow resonant nuclear reaction profiling, secondary neutral mass spectrometry, and x-ray photoelectron spectroscopy, aiming at investigating the applicability of this highly efficient process for nitriding of ceramics. The structure of the plasma nitrided layer was found to be complex, composed of tetragonal and cubic zirconia, as well as zirconium nitride and oxynitride. The growth rate of the nitrided layer, 4 µm/min, is much higher than that obtained by any other previous nitriding process, whereas a typical 50% increase in Vickers hardness over that of yttria-partially-stabilized zirconia was observed.

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