Thermal degradation of organic additives used in colloidal shaping of ceramics investigated by the coupled DTA/TG/MS analysis

This paper focused on the characterization of the composites containing nickel aluminate spinel from Al 2 O 3 /NiO and Al 2 O 3 /Ni systems. The composites were prepared by die pressing of powders and subsequent sintering of green bodies in air atmosphere. Composites were characterized by XRD, SEM, EDS and DTA/TG/MS analyses. The physical properties of the composites were measured by Archimedes method. Quantitative description of the composites microstructure was made on the basis of SEM images using computer image analysis. The XRD studies and SEM observations of composites confirmed the presence of two phases Al 2 O 3 and NiAl 2 O 4 in the whole volume of samples from both systems. Spinel phase was evenly distributed throughout the volume of the material. Morphology of NiAl 2 O 4 obtained from both systems was characterized by the presence of voids. The DTA/TG/MS measurements showed the characteristics of organic binder decomposition and type of gases released to the atmosphere during thermal treatment. Moreover, the DTA/TG analysis showed the temperature of spinel-phase formation for both systems. It was found that the spinel-phase NiAl 2 O 4 formation retards the process of densification. Therefore, it can be concluded that densification of samples with spinel phase depends mainly on the volume of spinel phase in composite material and does not depend on the substrates used to prepare spinel phase. The values of the selected properties of Al 2 O 3 -Ni-and Al 2 O 3 -NiO-based materials confirmed that the physical properties depend on the type of substrates used in the fabrication of composites. The type of powder influences the open porosity of samples. For composites produced using NiO powder, open porosity is lower than for samples formed with nickel powder.

Section: Resultssupporting

confidence: 52%

Characterization of composites containing NiAl2O4 spinel phase from Al2O3/NiO and Al2O3/Ni systems

Zygmuntowicz

Wiecińska

Miazga

et al. 2016

“…The mass spectrometer has detected two m/z values of relatively high intensities: 18, 44, and two m/z values of low intensities: 45 and 46. Mass 18 can be ascribed to water vapor, while mass 44 to carbon dioxide [33]. Masses 45 and 46 may come from the low-chain (C 3 and C 4 ) hydrocarbons [34].…”

Section: Resultsmentioning

confidence: 99%

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

Zygmuntowicz

Wiecińska

Miazga

et al. 2017

Self Cite

Composite material with a gradient concentration of the metallic phase was prepared by the novel gelcentrifugal casting method. This method combines the consolidation of powders by the centrifugal force with the reaction of radical polymerization of an organic monomer which simultaneously proceeds within the composite slurry. The combination of the centrifugal casting with gelcasting permits production of ceramic-metal composites, including materials with a gradient distribution of metallic particles in a ceramic matrix. Special attention was paid to the thermal analysis of the composite Al 2 O 3 -Ni green bodies and the binder used in the fabrication of the material. The experiments were performed on the simultaneous thermal analyzer coupled with the mass spectrometer. The measurements were carried out in air and the inert atmosphere (argon) what allowed to determine the effects characteristic for organic binder decomposition and type of gases released to the atmosphere during thermal treatment. The measurements allowed also to establish the sintering program of the green composite samples and evaluate whether harmful gases are released to the atmosphere. The thermal experiments were complemented with physical and structural measurements, including X-ray diffraction and scanning electron microscopy.

“…Due to differential thermal analysis (DTA) apparatus with mass spectrometry, it is possible to observe type of gases released to the atmosphere during decomposition of any substances. DSC and DTA analysis allows to gain knowledge about glass transition temperature and thermal stability of materials as well as their environmental hazard [6][7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Copolymers dispersions designed to shaping of ceramic materials

Żurowski

Głuszek

Antosik

et al. 2018

The paper concerns the synthesis and the characterization of new water-thinnable binder such as poly(acrylic-styrene) with the addition of a new amphiphilic macromonomer and it application in shaping of unmodified and modified (by silanization) Al 2 O 3 by die pressing. The organic additives decomposed thermally to non-toxic gases which is beneficial from ecological point of view. Thus, the careful thermal analysis of synthesized binder was done. To characterize the synthesized binder, the glass transition temperature, wetting angle and diameter of polymer particles size in water were also measured. In the next step of the work, the density, porosity, tensile and bending strength, and microstructure observations have been done for modified and unmodified Al 2 O 3 samples obtained by die pressing. The results confirmed that the synthesized binder is eco-friendly, because it decomposed to non-toxic gases such as carbon dioxide and water vapor during heating up to ca. 527°C. The synthesized binders are characterized by low glass transition temperatures 5.6°C and -0.5°C which are much lower than that of PVA (42°C). It provided the high tensile strength (0.22 ± 0.01 MPa) of green bodies, 57% higher than strength of bodies with commercially available PVA and bending strength around 192 MPa. Density of sintered samples was around 95% of TD. Nevertheless, the best results were obtain for bodies based on modified Al 2 O 3 where tensile strength of green bodies and bending strength of sintered samples were 0.30 ± 0.04 MPa and 237 ± 19 MPa, respectively.