Fabrication and characterization of spray dried Al2O3–ZrO2–Y2O3 powders treated by calcining and plasma

In this paper, the Al2O3-20 wt.%ZrO2 (8 wt.%Y2O3) feedstocks were fabricated and treated by spray drying, calcination, and plasma treatment technology. The morphology of feedstocks was characterized by scanning electron microscope (SEM). The phase structure and grain size were analyzed by X-Ray diffraction (XRD). The flowability and density were measured by Hall Flowmeter and density instrument, respectively. The sphericity and flowability of feedstocks treated by plasma flame increased greatly compared with that of the feedstocks without plasma treatment, and the particle surfaces were very smooth. The optimum flowability was obtained when the critical plasma spray parameter (CPSP) was 363. The compactness also increased greatly with the increment of CPSP, and the maximum value of compactness was got with CPSP of 325. Calcination can make the grain grow and plasma treatment can lead to the decrement of grain size. The phase structure of Al2O3 did not change, which was α-Al2O3 in the composites. The phase structure of ZrO2 (8 wt.%Y2O3) changed from t-phase to c-phase which was affected greatly by plasma treatment.

In this paper, the flowability and density of the Al2O3–ZrO2 feedstock are the important properties for the plasma spraying process, which can be affect the mechanical performance of the coatings. The densified coatings can be obtained with high flowability and density. The plasma treatment is used to increase flowability and density with different plasma spraying parameters, showing in following Fig.Figure optionsDownload as PowerPoint slideResearch highlights
► The nano materials were granulated into micron particles.
► The micron particles keep their nano structures.
► The process of granulation was studied for nano Al2O3 and ZrO2 (8 wt.%Y2O3).
► The effect of plasma treatment parameter on feedstock was investigated deeply.
► The process of plasma treatment was investigated detailedly.