Niobium—Al2O3 Reactions Yielding Condensed and Volatile Products

Grossman, L.

doi:10.1063/1.1726593

Cited by 9 publications

(3 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, the interface between Nb and Al 2 O 3 should be stable at high temperatures in an inert atmosphere [12,13,14,15,16,17,18,19,20]. Mechanical properties [6,7,10,11], wear behavior [21], chemical stability [19,22] and thermal conductivity [23] of the sintered mixtures of Nb and Al 2 O 3 were reported only for components made of very fine powders. In particular, fine-grained tantalum-alumina composites were studied as a potential material for femoral head in total hip arthroplasty [24].…”

Section: Introductionmentioning

confidence: 99%

Mechanical High-Temperature Properties and Damage Behavior of Coarse-Grained Alumina Refractory Metal Composites

et al. 2019

View full text Add to dashboard Cite

The present study provides the mechanical properties of a new generation of refractory composites based on coarse-grained Al2O3 ceramic and the refractory metals Nb and Ta. The materials were manufactured by refractory castable technology and subsequently sintered at 1600 °C for 4 h. The mechanical properties and the damage behavior of the coarse-grained refractory composites were investigated at high temperatures between 1300 and 1500 °C. The compressive strength is given as a function of temperature for materials with two different volume fractions of the refractory metals Ta and Nb. It is demonstrated that these refractory composites do not fail in a completely brittle manner in the studied temperature range. The compressive strength for all materials significantly decreases with increasing temperature. Failure occurred due to the formation of cracks along the ceramic/metal interfaces of the coarse-grained Al2O3 particles. In microstructural observations of sintered specimens, the formation of tantalates, as well as niobium oxides, were observed. The lower compressive strength of coarse-grained Nb-Al2O3 refractory composites compared to Ta-Al2O3 is probably attributed to the formation of niobium oxides. The formation of tantalates, however, seems to have no detrimental effect on compressive strength.

show abstract

Section: Introductionmentioning

confidence: 99%

Mechanical High-Temperature Properties and Damage Behavior of Coarse-Grained Alumina Refractory Metal Composites

et al. 2019

View full text Add to dashboard Cite

show abstract

“…The reactions of V02 with SrC03 (118), (NH4)2S04 with Ta205 (98), and KHS04 with Nb203 (97) are other examples of such work. Together with mass spectrometry, TGA was used to study the reaction of Nb with A1203 to form Al suboxides (163).…”

Section: Thermogravimetric Analysis (Tga)mentioning

confidence: 99%

Thermal analysis

Murphy¹

1968

Anal. Chem.

View full text Add to dashboard Cite

“…40). The enhanced total pressure for this system compared with W -A1203 and Mo-A1203 suggests that caution must be exercised in using Nb-A1203 contacts in thermionic systems at elevated temperatures.…”

Section: Reactions Between Metals and Insulatorsmentioning

confidence: 99%

Literature survey of some surface and subsurface processes affecting materials in thermionic diodes

1972

Microelectronics Reliability

View full text Add to dashboard Cite

I Supplementary Notes AbstractThis report is a literature survey of surface and subsurface chemical and physical processes affecting materials in the thermionic diode. The processes considered were the evaporation and condensation of substrate materials, the bulk diffusion of metallic substrate materials, reactions between insulators and metals, and the surface self-diffusion and reconstruction of clean surfaces, faceting, and other surface reconstruction caused by contaminants or additives, solution, and oxidation. Author(s1) 18. Key Words (Suggested by SUMMARYThis report is a literature survey of surface and subsurface chemical and physical processes affecting materials in the ther mionic diode. The processes considered were the evaporation and condensation of substrate materials, the bulk diffusion of metallic substrate materials, the reactions between insulators and metals, the surface selfdiffusion and reconstruction of clean surfaces, faceting and other surface reconstruction caused by contaminants o r additives, solution, and oxidation. INTRODUC TIONThe thermionic diode is a collection of interfaces o r spaces between materials of unlike composition. Because of these inhomogeneities, processes result that can be lumped under the general heading of surface chemistry. There a r e interfaces between the solid conductors, insulators o r containment walls and the gas o r vacuum phases. There a r e contacts between insulators and metallic conductors. Also, there a r e contacts between unlike metals.Figure 1 summarizes these contacts and some of the resulting physico-chemical p r oc e s s e s which a r e surveyed herein. F o r the purpose of discussionin this report, two broad subdivisions of topics a r e made in the processes indicated in figure 1. In category I a r e placed those interfacial p r o c e s s e s that can be expected in all diodes including the highly idealized vacuum diode: evaporation and condenstation of substrate materials, bulk diffusion of metallic substrate materials, reactions between insulators and metals, and s u rface self -diffusion and reconstruction of clean surfaces.In practice, no t r u e vacuum diode can be constructed. T o the foregoing processes must be added those surface processes resulting from inevitable gaseous contaminants.The inability ' EQ c r e a t e perfect laboratory vacua gives r i s e to atmospheric contaminants, In addiliora, construction materials evolve gaseous contaminants either because of chernieal decomposition, as in the ease of insulator compounds, o r because ol impurr"ces.Although some gas phase contaminants a r e unavoidably present, additional conkminants may be deliberately introd~aced to affect the properties of the surface or the gas phase. Cesium, of course, i s the most familiar example of such a n additive. Cesium, barium, and other metallic additives will not be considered here since little chemical effect on substrate materials has been reported for them. However, the use of such electronegative additives as oxygen and fluorine in conjunction...

show abstract

Niobium—Al2O3 Reactions Yielding Condensed and Volatile Products

Cited by 9 publications

References 11 publications

Mechanical High-Temperature Properties and Damage Behavior of Coarse-Grained Alumina Refractory Metal Composites

Mechanical High-Temperature Properties and Damage Behavior of Coarse-Grained Alumina Refractory Metal Composites

Thermal analysis

Literature survey of some surface and subsurface processes affecting materials in thermionic diodes

Contact Info

Product

Resources

About