Influence Of Sintering Atmosphere Research Articles

Weakly negative permittivity of MWCNT/TiN/CCTO ternary ceramics sintered in argon and nitrogen atmosphere

When seeking for satisfactory metacomposites with negative permittivity behavior, an important factor which should be taken into consideration is how to realize a weakly negative permittivity (less than 100). A novel strategy has been proposed accordingly to prepare ternary multiwalled carbon nanotubes/titanium nitride/copper calcium titanate (MWCNT/TiN/CCTO) composites by a facile sintering method in an inert atmosphere. The negative permittivity was observed after the TiN-MWCNT network was constructed among the composites. TiN provided sufficient free electrons and MWCNT were regarded as transporter bridge. Under the synergistic effect of TiN and MWCNT, the negative permittivity decreased by several orders of magnitude owing to the dilution of overall electron density in the resulting composites. Exceptionally, when the permittivity switched from positive to negative along with a resonance, a Lorentz-like negative permittivity was observed in low frequency region. Meanwhile, the Drude-like negative permittivity derived from plasma oscillation was also observed in the higher frequency region. Further investigation confirmed that the permittivity was closely related to the reactance. The positive-negative reactance transition was consistent with the negative-positive permittivity transition, and the epsilon-near-zero was achieved near the zero-crossing point of permittivity. Moreover, the influence of different sintering atmospheres (nitrogen and argon) on the negative permittivity behavior was also explored. This work provides an effective approach for the realization of weakly negative permittivity, and presents, to our knowledge, the first investigation into the influence of sintering atmosphere on negative permittivity.

Influence of sintering atmospheres on the wetting behaviors of titanium dioxides by molten metals

In this work, we investigated the effects of sintering atmospheres of titanium dioxides on the wetting behaviors with molten metals such as copper, silver and gold by using the sessile drop method. Experimental results showed that titanium dioxides sintered in different atmospheres exhibit a pronounced difference in the wetting behaviors with molten metals. The results were discussed and interpreted in terms of metal–oxygen bonding governing at metal–oxide interfaces.

THE CORRELATION BETWEEN RAW MATERIALS, PREPARATION CONDITIONS, AND PROPERTIES OF SINTERED IRON

Three plain iron powders of different types (sponge-iron, atomized and electrolytic iron powder) were studied with respect to their sintering behaviour and to the influence of manufacturing parameters—i.e., compacting pressure, sintering temperature, and sintering atmosphere—on the microstructure and the properties of sintered compacts. The changes of length, electric conductivity, and strength during sintering are explained in physical and chemical terms. Technical sintering diagrams are presented. The influence of sintering atmospheres on the mechanical properties of sintered compacts is shown for the three types of powder. The correlation between pore structure and strength is discussed; analytical relationships are developed which are in agreement with the experimental results.

Synthesis of Manganese-Zinc Ferrite: Influence of Sintering Atmosphere and Types of the Raw Materials on the Ferrite Properties

The electromagnetic properties of manganese-zinc ferrites are strongly affected by the synthesis parameters. The influence of sintering atmospheres on magnetic permeability, temperature dependence of permeability, loss, disaccommodation and induction were examined. The effect of the types of raw materials used in the synthesis on the magnetic parameters were studied.Based on these studies, commercially important ferrites suitable for various practical applications have been synthesised.