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Thermal barrier ZrO2 - Y2O3 obtained by plasma spraying method and laser melting

100%

Kobylańska-Szkaradek K.

2009

tom Vol. 36, nr 1

12-19

Purpose: The aim of the paper is to determine the influence of laser melting upon the selected physical properties of ZrO2 - Y2O3 ceramic coatings deposited by APS (Air Plasma Spraying) method on super-alloys which function as TBC (Thermal Barriers Coatings). Design/methodology/approach: Laser melting which helps eliminate pores and other structural defects of coatings deposited by plasma spraying method should contribute to the improvement of their density and durability as thermal barriers. In order to prove the assumptions made in the paper, coatings featuring varied porosity and deposited upon the nickel base super-alloys surface with the initially sprayed NiCrAlY bond coat have been subjected to laser melting and then their structure, thermal conductivity and thermal life prediction in the conditions of cyclic temperature changes from 20 to 1200°C have been examined. Findings: It has been revealed that the coatings featuring low porosity laser melted on part of their thickness and heated up to about 700°C demonstrate the highest thermal life prediction under the conditions mentioned and at slightly lower thermal conductivity. Heating is intended to lower the structural stresses which are connected with the change of ceramic volume at crystallization as well as thermal stresses resulting from varied expansion of coating and metal substrate. Research limitations/implications: Low wettability of metal by ceramic which results from various surface tensions of these materials is the cause of their lower adhesion to the substrate during laser melting all through their thickness. It is so because delaminations occur between phases the boundary and cracks. Practical implications: The worked out conditions of laser melting might be used in the process of creation of ZrO2 - Y2O3 coats which feature high working durability upon super-alloy elements. Originality/value: It has been found that homogenization of chemical composition of coatings occurs during laser melting leading to the reduction of ZrO2 - Y2O3 phase with monoclinic lattice participation as well as to the reduction of structural stresses which accompany this phase transformation during heating and cooling process.

Structure and thermo-physical properties of selected ceramic coatings deposited on the heat resistant nickel alloy.

51%

Kobylańska-Szkaradek K. , Kusiński J. , Swadźba L.

1998

tom R. XIX, nr 4

1073-1076

The results of an investigation of the structure, phase composition, physical and thermo-physical properties of mono- and double-layerd ZrO2-Y2O3 and ZrO2-Y2O3/NiCrAlY plasma sprayed coatings have been presented. In addition applicable properties of coatings have been determined. Presented results are the part of the large research project.