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Self-consolidation mechanism of nanostructured Ti5Si3 compact induced by electrical discharge.

Lee WH, Cheon YW, Jo YH, Seong JG, Jo YJ, Kim YH, Noh MS, Jeong HG, Van Tyne CJ, Chang SY - ScientificWorldJournal (2015)

Bottom Line: A solid bulk of nanostructured Ti5Si3 with no compositional deviation was obtained in times as short as 159 μsec by the discharge.Followed rapid cooling preserved the nanostructure of consolidated Ti5Si3 compact.Complete conversion yielding a single phase Ti5Si3 is primarily dominated by the solid-liquid mechanism.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 143-747, Republic of Korea.

ABSTRACT
Electrical discharge using a capacitance of 450 μF at 7.0 and 8.0 kJ input energies was applied to mechanical alloyed Ti5Si3 powder without applying any external pressure. A solid bulk of nanostructured Ti5Si3 with no compositional deviation was obtained in times as short as 159 μsec by the discharge. During an electrical discharge, the heat generated is the required parameter possibly to melt the Ti5Si3 particles and the pinch force can pressurize the melted powder without allowing the formation of pores. Followed rapid cooling preserved the nanostructure of consolidated Ti5Si3 compact. Three stepped processes during an electrical discharge for the formation of nanostructured Ti5Si3 compact are proposed: (a) a physical breakdown of the surface oxide of Ti5Si3 powder particles, (b) melting and condensation of Ti5Si3 powder by the heat and pinch pressure, respectively, and (c) rapid cooling for the preservation of nanostructure. Complete conversion yielding a single phase Ti5Si3 is primarily dominated by the solid-liquid mechanism.

No MeSH data available.


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(a) Typical discharge curve measured current and voltage on oscilloscope and (b) typical power curve versus discharge time (discharge condition: 450 μF, 7.0 kJ).
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fig7: (a) Typical discharge curve measured current and voltage on oscilloscope and (b) typical power curve versus discharge time (discharge condition: 450 μF, 7.0 kJ).

Mentions: To investigate the consolidation mechanism of nanostructured Ti5Si3 solid compact by electrical discharge, electrical discharging characteristics were considered in terms of input energy and capacitance under current experimental conditions. A typical discharge curve (Figure 7(a)) shows voltage and current in terms of discharge time. 450 μF of capacitance and 5.58 kV of input voltage were employed to yield 7.0 kJ. The input energy (E) is predetermined by controlling input voltage (V) according to (1)E=CV22,where C is the capacitance of a capacitor. Figure 7(a) shows that the peak current was 58.4 kA and the peak voltage was 5.04 kV. From the results shown in Figure 7(a), the power (watt) curve is plotted in Figure 7(b) against the discharge time. The power was obtained from the following equation: (2)P(watt)=current(A)×voltage(V)=I2R (J/sec).The discharge times for the duration of the first cycle at two different input energies are identical to be approximately 159 μsec. The amount of heat generated (ΔH) during a discharge can be obtained by using(3)ΔH=∑i2tRtΔt.Typical discharge characteristics under the current conditions are tabulated in Table 2 in terms of peak current, peak voltage, discharge time, and ΔH. It is known that ΔH increases with an increase in input energy at constant capacitance.


Self-consolidation mechanism of nanostructured Ti5Si3 compact induced by electrical discharge.

Lee WH, Cheon YW, Jo YH, Seong JG, Jo YJ, Kim YH, Noh MS, Jeong HG, Van Tyne CJ, Chang SY - ScientificWorldJournal (2015)

(a) Typical discharge curve measured current and voltage on oscilloscope and (b) typical power curve versus discharge time (discharge condition: 450 μF, 7.0 kJ).
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4389978&req=5

fig7: (a) Typical discharge curve measured current and voltage on oscilloscope and (b) typical power curve versus discharge time (discharge condition: 450 μF, 7.0 kJ).
Mentions: To investigate the consolidation mechanism of nanostructured Ti5Si3 solid compact by electrical discharge, electrical discharging characteristics were considered in terms of input energy and capacitance under current experimental conditions. A typical discharge curve (Figure 7(a)) shows voltage and current in terms of discharge time. 450 μF of capacitance and 5.58 kV of input voltage were employed to yield 7.0 kJ. The input energy (E) is predetermined by controlling input voltage (V) according to (1)E=CV22,where C is the capacitance of a capacitor. Figure 7(a) shows that the peak current was 58.4 kA and the peak voltage was 5.04 kV. From the results shown in Figure 7(a), the power (watt) curve is plotted in Figure 7(b) against the discharge time. The power was obtained from the following equation: (2)P(watt)=current(A)×voltage(V)=I2R (J/sec).The discharge times for the duration of the first cycle at two different input energies are identical to be approximately 159 μsec. The amount of heat generated (ΔH) during a discharge can be obtained by using(3)ΔH=∑i2tRtΔt.Typical discharge characteristics under the current conditions are tabulated in Table 2 in terms of peak current, peak voltage, discharge time, and ΔH. It is known that ΔH increases with an increase in input energy at constant capacitance.

Bottom Line: A solid bulk of nanostructured Ti5Si3 with no compositional deviation was obtained in times as short as 159 μsec by the discharge.Followed rapid cooling preserved the nanostructure of consolidated Ti5Si3 compact.Complete conversion yielding a single phase Ti5Si3 is primarily dominated by the solid-liquid mechanism.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 143-747, Republic of Korea.

ABSTRACT
Electrical discharge using a capacitance of 450 μF at 7.0 and 8.0 kJ input energies was applied to mechanical alloyed Ti5Si3 powder without applying any external pressure. A solid bulk of nanostructured Ti5Si3 with no compositional deviation was obtained in times as short as 159 μsec by the discharge. During an electrical discharge, the heat generated is the required parameter possibly to melt the Ti5Si3 particles and the pinch force can pressurize the melted powder without allowing the formation of pores. Followed rapid cooling preserved the nanostructure of consolidated Ti5Si3 compact. Three stepped processes during an electrical discharge for the formation of nanostructured Ti5Si3 compact are proposed: (a) a physical breakdown of the surface oxide of Ti5Si3 powder particles, (b) melting and condensation of Ti5Si3 powder by the heat and pinch pressure, respectively, and (c) rapid cooling for the preservation of nanostructure. Complete conversion yielding a single phase Ti5Si3 is primarily dominated by the solid-liquid mechanism.

No MeSH data available.


Related in: MedlinePlus