Al2O3/Ni functionally graded materials (FGM) obtained by centrifugal-slip casting method

Abstract

The fabrication and the characterization of Al 2 O 3 /Ni composites with a gradient distribution of the Ni particles are reported. The composites have been obtained by centrifugal-slip casting and subsequent sintering and had the shape of a hollow cylinder. TG/DTA analysis was done for the nickel powder with the addition of the dispersant used in centrifugal-slip casting as well as for the composite green body. The measurements were performed in two atmospheres: argon and the mixture of argon and hydrogen (1:1). Additionally, coupling the thermobalance with the mass spectrometer allowed to determine type of gases released from the samples during thermal treatment. The morphology and chemical composition of the produced composites were analyzed using a scanning electron microscope equipped with an EDS detector. Interface between alumina and nickel was described. Moreover, the X-ray diffraction was made. The stereological analysis confirmed that the nickel particles are distributed in the composite in a gradient way.

Thermoanalytical studies of the ceramic-metal composites obtained by gel-centrifugal casting

“…Citric acid (CA) (Sigma-Aldrich) and diammonium hydrocitrate (DAC) (Sigma-Aldrich) were applied as dispersants in the composite slurries. The selection of dispersant was made based on previous research [18,24,25]. Deionized Milli-Q water was used as a solvent.…”

“…The centrifugal slip casting (CSC) combines the effects of slip casting and centrifugation [15,[18][19][20]. The use of porous gypsum molds in the CSC method allows the removal of the liquid medium from the slurry what leads to densification of the composites.…”

“…Previous own research has shown that in centrifugal slip casting method lower value of centrifugal acceleration can be applied than in the classical method of centrifugal casting of the composites with the metal matrix [15,19]. This technology allows to obtain the finished product in the shape of a hollow cylinder [15,[18][19][20] characterized by high relative density after sintering.…”

“…Centrifugal slip casting method enables the production of axially symmetric composites. So far, studies have revealed that the resulting composites are composed of three different zones differing in the content of the metallic phase [15,[18][19][20]. It was observed that the outer part of the graded region was formed as a result of removing water by the capillary forces active in the gypsum mold.…”

Thermoanalytical and dilatometric studies of the Al2O3–Cu–Mo hybrid composite

“…In literature exists information about composites with molybdenum used as a metallic phase [12]. As well, Al 2 O 3 -Mo composite is described well [13]. Chmielewski et al [2] revealed experimental procedure to obtain Al 2 O 3 -Mo characterized by high density and very stable bonding between ceramic and metal phase.…”