Polymer-filler derived Mo2C ceramics

Kaindl, A.; Lehner, Wolfgang; Greil, Peter; Kim, Deug Joong

doi:10.1016/s0921-5093(98)00987-3

Cited by 30 publications

(19 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This different behaviour can be explained by the presence of the higher carbon content in the polymer, sufficient to develop the reaction Nb + C ⇒ NbC, thus avoiding free niobium and consequently the niobium oxidation. The behaviour observed in this work is in agreement with the results reported in the literature 11 . This work shows that the use of a polymer with low carbon content leads to the formation of niobium oxides.…”

Section: Methodssupporting

confidence: 93%

“…The photoelectrons excited and analyzed during the XPS experiments have an average escape depth of 20 Å, so the data from the interior are not included. X ray diffraction, infrared spectrum and scanning microscopy were also used to investigate the formation of niobium carbide 10,11 . The purpose of this work was to investigate the formation of niobium carbide on the surface of the composite material.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Surface characterization of alumina reinforced with niobium carbide obtained by polymer precursor

Acchar

Silva

2006

Mat. Res.

View full text Add to dashboard Cite

Active filler controlled pyrolysis of polymers (AFCOP) is a recent method for obtaining near-net shaped ceramic bodies. Alumina based composites have been developed for use as cutting tools, so knowledge of the surface composition is extremely important because it is directly related to the hardness and wear resistance Samples containing a fixed concentration of 60 wt. (%) of polysiloxane and a mixture of metallic niobium and alumina powder were homogenized, uniaxially warm pressed at 80 °C and subsequently pyrolyzed in flowing argon at 1200, 1400 and 1500 °C. Analysis of the surface composition was carried out by X ray photoelectron spectroscopy, infrared spectroscopy, X ray diffraction and scanning electron microscopy. The results have indicated that the formation of the phases on the surface depends strongly on the niobium/carbon ratio in the raw materials.

show abstract

Section: Methodssupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Surface characterization of alumina reinforced with niobium carbide obtained by polymer precursor

Acchar

Silva

2006

Mat. Res.

View full text Add to dashboard Cite

show abstract

“…Figure 1 shows the XRD pattern of the specimen with 70 vol.% TiH 2 pyrolyzed at 850°C in an N 2 atmosphere. During the heating process, the decomposition of the polymer started above 400°C and was almost completed at 800°C [15]. At 650°C, TiH 2 as a filler was decomposed into titanium and hydrogen gas by an endothermic reaction.…”

Section: Resultsmentioning

confidence: 99%

Formation of high-density TiN/Ti5Si3 ceramic composites using preceramic polymer

2010

Self Cite

View full text Add to dashboard Cite

The formation, microstructure and properties of high-density TiN/Ti5Si3 ceramic composites created by the pyrolysis of preceramic polymer with filler were investigated. Methylpolysiloxane was mixed with TiH2 as filler and ceramic composites prepared by pyrolysis at 1200°C to 1600°C under N2, Ar and vacuum were studied. When a specimen with 70 vol.% TiH2 was pyrolyzed up to 1600°C in a vacuum after a preheat treatment at 850°C in a N2 atmosphere and subsequently heat-treated at 1600°C for 1 h under Ar at a pressure of 2 MPa, a ceramic composite with full density was obtained. The microstructure of the ceramic composite was composed of TiN and Ti5Si3 phases. Under specific pyrolysis conditions, a ceramic composite with a density of 99.2 TD%, a Vickers hardness of 18 GPa, a fracture toughness of 3.5 MPam 1/2 , a flexural strength of 270 MPa and a electrical conductivity of 6200 ohm −1 ·cm −1 was obtained.

show abstract

“…This different behaviour can be explained by the presence of the higher carbon content in the polymer, sufficient to develop the reaction Nb + C ) NbC, thus avoiding niobium oxidation. Results in the literature show that a polymer with low carbon content leads to the formation of niobium oxides [17].…”

Section: Methodsmentioning

confidence: 99%

Study of the Surface Composition on Alumina-NbC Composites

Silva

Acchar

Costa

et al. 2001

phys. stat. sol. (a)

View full text Add to dashboard Cite

The aim of this work is to analyse an alumina-NbC based composite ceramic made from a polymeric precursor (polysiloxane), alumina and metallic niobium. The materials have a fixed concentration of 60 wt% of polymer and 40% of a mixture of niobium and alumina. These materials are mixed and sintered at 1450 C for 6 h. Alumina based composites have been proposed as excellent materials for use as cutting tools, so knowledge of the superficial composition is extremely important because it is directly related to the hardness and abrasion resistance. Analysis of the surface composition was carried out by electron spectroscopy. It should be emphasized that there may be a meaningful difference between the surface and the interior composition due to a eventual processes such as element segregation to the surface and/or diffusion of elements from the surface to the sample bulk. The analysis was performed by XPS and Auger for three niobium concentrations 10, 20 and 40 wt%, and the results show the appearance of niobium on the surface only at the Nb composition of 10 wt%; this appears to be due to a process of niobium atom migration to the interior of the sample or one involving niobium bonds. For the 10 wt% sample after sintering, the formation of NbC on the surface and the presence of niobium Auger peaks were observed. However, for concentrations larger than 10 wt%, oxides and sub-oxides (NbO, NbO 2 , etc.) were formed which may result in the absence of niobium peaks in the spectra. The analysis of the ratio of niobium to carbon atoms at the surface shows a value of 0.1 which reveals that the quantity of niobium and carbon is not sufficient for ideal formation of niobium carbide (NbC). Under these conditions it is verified that there is only a slight formation of niobium carbide on the surface, which is harmful to the hardness of the material. The excess niobium tends to diffuse towards the interior of the sample and react with the oxygen forming sub-oxides.

show abstract

Polymer-filler derived Mo2C ceramics

Cited by 30 publications

References 9 publications

Surface characterization of alumina reinforced with niobium carbide obtained by polymer precursor

Surface characterization of alumina reinforced with niobium carbide obtained by polymer precursor

Formation of high-density TiN/Ti5Si3 ceramic composites using preceramic polymer

Study of the Surface Composition on Alumina-NbC Composites

Contact Info

Product

Resources

About