Thermal Expansion Properties of Plasma-Sprayed Thick Coatings

1998 ◽  
Author(s):  
Y.-K. Lee ◽  
H.-J. Kim ◽  
R.-W. Chang
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Powder Size ◽  
Thermal Expansion Coefficients ◽  
Shock Resistance ◽  
Expansion Coefficients ◽  
Plasma Sprayed ◽  
Thick Coatings

Abstract The thermal expansion characteristics of plasmasprayed coatings were investigated. The thermal expansion measurements were carried out up to 1200°C on thick coatings that were substrate free. The effects on the thermal expansion coefficients were studied in terms of composition, powder size, porosity, and the phase transformation. The relationships between the thermal shock resistance and the thermal expansion properties of the coatings are also discussed.

Incorporation of Aluminium Residues in Dense Cordierite Formulations

2006 ◽  
Vol 514-516 ◽  
pp. 1722-1725 ◽  
Author(s):  
Fernando A. Costa Oliveira ◽  
Francisco Delmas ◽  
Ana Araújo ◽  
Jorge Cruz Fernandes ◽  
Diamantino Dias
Keyword(s):  
Thermal Expansion ◽  
Environmental Impact ◽  
Flexural Strength ◽  
Thermal Shock Resistance ◽  
Thermal Expansion Coefficients ◽  
Lower Thermal Expansion ◽  
Shock Resistance ◽  
Expansion Coefficients ◽  
Α Al2o3 ◽  
Batch Formulation

Additions of γ-Al2O3 and Al(OH)3 powders produced at INETI from spent baths resulting from the aluminium transformation industry were made to a commercial cordierite batch formulation (without Al2O3 addition), known as DC4, developed by Rauschert Portuguesa Lda., in order to evaluate the possibility of replacing with benefits the conventional α-Al2O3 source used. The resulting samples were found to be denser than the commercial ones. This is related to the higher reactivity of these particular sources of alumina as compared to that added to the commercial product. Consequently, higher Young’s modulus (100-114 GPa) and flexural strength (80-98 MPa) were achieved for the developed materials in comparison to those obtained for commercial cordierite (96±2 GPa and 67±5 MPa, respectively). In addition, slightly lower thermal expansion coefficients were observed (3.6x10-6 K-1) and the thermal shock resistance was found to increase from 325 K to 350 K. The developed technology can be regarded as suitable for reducing the environmental impact of deposition of wastes from the aluminium transformation industry.

scholarly journals Preparation of Al2TiO5 ceramic fibers and thermal expansion, insulation, and strength of ZrO2-Al2TiO5 fiberboards

2021 ◽  
Author(s):  
Wei Liu ◽  
Yongshuai Xie ◽  
Zhezhe Deng ◽  
Ying Peng ◽  
Jianhong Dong ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Thermal Shock ◽  
Thermal Insulation ◽  
Thermal Shock Resistance ◽  
Single Phase ◽  
Sol Gel ◽  
Ceramic Fibers ◽  
Thermal Expansion Coefficients ◽  
Shock Resistance

Abstract In the field of thermal insulation, Zirconia (ZrO2) fiber and its products have high thermal expansion coefficients and poor thermal shock resistance, which leads to great challenges in the industry. In this work, aluminum titanate (Al2TiO5) single-phase ceramic fibers were prepared by a sol-gel method, using polyacetylacetone titanium-aluminum (PAAT) as the precursors with electrospinning technology. The single-phase Al2TiO5 fibers exhibited excellent high-temperature resistance, and maintained fibers morphology at a high temperature of 1500 ºC. Next, ZrO2-Al2TiO5 (ZAT) fiberboards were prepared by mixing ZrO2 fibers and Al2TiO5 fibers. The mixture was heat-treated to 1500 ºC to prepare the ZAT fiberboards. Characterization results indicated that the contents of Al2TiO5 fibers have obvious effects on the performance of thermal insulation, strength, thermal expansion, and thermal shock resistance. Particularly, the thermal expansion coefficient of ZAT-8 fiberboards was about 20% lower than that of ZAT-0 fiberboards. These attractive characteristics might give ZAT fiberboards enormous potential in the field of high-temperature insulation.

Utilization of Fly Ash in the Synthesis of Refractory Forsterite-Spinel Ceramics

2021 ◽  
Vol 321 ◽  
pp. 131-140
Author(s):  
Martin Nguyen ◽  
Radomír Sokolař
Keyword(s):  
Thermal Expansion ◽  
Fly Ash ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Power Plants ◽  
Linear Thermal Expansion ◽  
Aluminium Oxide ◽  
Raw Material ◽  
Modulus Of Rupture ◽  
Shock Resistance

Forsterite refractory ceramics is utilized in the metallurgical and cement industries as a lining of metallurgical furnaces and rotary kilns for its high refractoriness up to 1850°C and refractoriness under load above 1600°C. Another significant property of forsterite is its coefficient of linear thermal expansion utilized in the electrotechnical industry for ceramic-metal joints. Addition of aluminium oxide into the raw material mixture results in creation of magnesium-alumina spinel (MgO·Al2O3) which improves sintering, thermal shock resistance and mechanical properties in comparison with pure forsterite ceramics. Inexpensive source of aluminium oxide is fly ash. Utilization of fly ash, secondary energetic product of coal-burning power plants, is important for the environment and sustainable development. This paper evaluated properties of fly ash-based forsterite-spinel ceramics in comparison with alumina-based forsterite-spinel ceramics. Forsterite-spinel ceramics was synthesized from olivine, calcined magnesite and fly ash/alumina powders. XRD analysis was used to determine mineralogical composition, thermal analyses were used to determine the behaviour during firing and scanning electron microscopy to determine the morphology of crystal phases. Refractoriness of pyrometric cones, refractoriness under load, thermal shock resistance, coefficient of linear thermal expansion, water absorption, porosity and modulus of rupture were also determined on fired test samples.

Influence of Zircon Addition on Thermal Shock Resistance of ZTA for Plasma Reactors

2007 ◽  
Vol 544-545 ◽  
pp. 379-382
Author(s):  
Kyung Hun Jang ◽  
Bum Rae Cho
Keyword(s):  
Thermal Expansion ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Sintering Temperature ◽  
Plasma Reactors ◽  
Alumina Ceramics ◽  
Low Thermal Expansion ◽  
Resultant Data ◽  
Shock Resistance ◽  
Zirconia Toughened Alumina

The effect of CaO, MgO and SiO2 as a flux on the sinterability of zirconia toughened alumina(ZTA) used for plasma reactors was investigated and the effect of zircon addition on thermal shock resistance of ZTA with 15wt.% of ZrO2 was also investigated. The resultant data revealed that ZTA shows the best sinterability at the composition of 2wt.% of CaO, 4wt.% of MgO and 2wt.% of SiO2 and at the sintering temperature of 1350°C. Thermal shock resistance of ZTA containing zircon was improved significantly. It is shown that ZTA containing 10wt.% of zircon shows better thermal shock resistance than others. This fact can be explained due to the low thermal expansion coefficient of zircon. It was concluded that zircon is an effective material to improve thermal shock resistance of alumina ceramics.

Thermal Shock Resistance of Plasma Sprayed Multi-Layered Functionally Graded Cr3C2-NiCr Coatings

2016 ◽  
Vol 852 ◽  
pp. 1000-1005 ◽  
Author(s):  
Dong Xing Fu ◽  
Jing Na Liu ◽  
Er Bao Liu ◽  
Zhao Bin Cai ◽  
Xiu Fang Cui ◽  
...  
Keyword(s):  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Functionally Graded ◽  
X Ray Diffraction ◽  
Coating Materials ◽  
Heating And Cooling ◽  
Structure Of Coatings ◽  
Functionally Graded Coatings ◽  
Shock Resistance ◽  
Plasma Sprayed

The interface properties of multi-layered functionally graded Cr3C2-NiCr coatings deposited by plasma spraying technique were experimentally studied in this paper. The microstructure and phase structure of coatings were studied with scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The thermal shock resistance was investigated by cyclic heating and cooling tests using an electro-calefaction furnace. The crack appearances of the coatings were observed carefully. Results show that the plasma sprayed multi-layered functionally graded coatings are compact and the adhesion between the layers and the substrate is good. The coatings have better macro-hardness than the substrate, and the 6-layers coating has the highest macro-hardness and the best wear resistance. Besides, the micro-hardness of coatings increases with increasing content of Cr2C3 in coating materials. Results of cyclic thermal shock show that the main failure styles of the coatings are crack and desquamation and the thermal shock resistance of the coatings is improved obviously by increasing the number of coating layers.

Improving Thermal Shock Resistance of Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings by Laser Remelting

2012 ◽  
Vol 472-475 ◽  
pp. 2502-2507
Author(s):  
Zong Yin Duan ◽  
Dong Sheng Wang
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coatings ◽  
Thermal Shock Resistance ◽  
Yttria Stabilized Zirconia ◽  
Thermal Barrier ◽  
Laser Remelting ◽  
Stabilized Zirconia ◽  
Barrier Coatings ◽  
Shock Resistance ◽  
Plasma Sprayed

This paper deals with the microstructure and thermal shock behavior of laser remelting of yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) deposited by plasma spraying. The microstructures of the coatings were analyzed by scanning electron microscopy (SEM). It was found that the as-sprayed ceramic coating had laminated structure with high porosity. However, the coating exhibited a dense lamellar-like layer with segment cracks on the remained plasma-sprayed porous layer. Thermal shock experiments for the two kinds of TBCs were performed by water quenching method. Testing result showed that the laser-remelted TBC had better thermal shock resistance than the as-sprayed one. The damage mode of the as-sprayed TBC was great-size whole spalling. In contract, the failure mechanism of the laser-remelted one was mainly local pelling. Segmented cracks of the top ceramic coatings caused by laser remelting improved the stress accommodation and were mainly attributed to the enhancement for thermal shock life of TBC.

Preparation and Performance of β-Sialon Bonded ZrO2 Composites

2011 ◽  
Vol 415-417 ◽  
pp. 138-141
Author(s):  
Rui Sheng Wang ◽  
Jun Hong Zhao ◽  
Ying Na Wei ◽  
Fu Hua Peng ◽  
Heng Yong Wei
Keyword(s):  
Thermal Expansion ◽  
Flexural Strength ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Reaction Sintering ◽  
Sintering Process ◽  
Carbon Addition ◽  
Shock Resistance ◽  
And Performance ◽  
Sialon Powder

β-Sialon bonded ZrO2 composites were prepared by reaction sintering process using β-Sialon and CaO stabilized ZrO2 powders as raw materials.The effect of β-Sialon powder additions on the properties of the composites was investigated. The results show that the samples with 10 wt% of β-Sialon addition had the lowest apparent porosity (29.80%) and the highest of flexural strength (68.70MPa). The thermal shock resistance in carbon addition of the composites could be improved by addtion of 5wt% β-Sialon. It may be relative with that the sample had the lowest thermal expansion coefficient in vacuum.

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