Figure 1 The diagram of electrospray experiment
2.3 Characteristics Analysis
The structures and morphologies of
samples prepared from electrospray method are observed by using field
emission scanning electron microscopy (FE-SEM) (HITACHI High
Technologies Corporation, S-4800II Japan). The secondary electron images
are captured at 15 kV accelerating voltage. As for thermal analysis,
thermogravimetric-differential scanning calorimetry (TG-DSC) (NETZSCH
STA 449C Germany) is introduced to study the thermal properties of
samples. The heating rate is 15 oC
min-1 from room temperature to 800oC at argon atmosphere. The mass of sample in an 80 uL
corundum crucible is about 3 mg. Finally, the X-ray diffraction (XRD)
(Bruker, D8 Advance, Germany) analysis is used to figure out the phase
in residues after thermal analysis.
2.4 Onset combustion test
To verify and record the
characteristics of samples combustion, the heating wire ignition
combustion system is designed and made, as shown in Figure 2. The
diameter of heating wire is about 0.1 mm. The DC is employed as the
power supply. Ignition and combustion processes are recorded by the
high-speed camera (FASTCAM SA-Z Japan) with shutter speed at 50 us per
picture. In each ignition and
combustion test, the mass weight of sample is about 10 mg (±1 mg)
directly touching with the heating wire. Then, the current value on the
heating wire increases slowly and gradually. At the moment of ignition,
the corresponding current value is recorded, which is set as ignition
energy threshold, and in the meanwhile the shutter of high-speed camera
is also pressed. A time period of 200 ms before the shutter time can be
also recorded which ensures that we can fully document the process from
the ignition moment to its extinction. In order to protect the camera
from the burning sparks, a transparent tempered glass is placed between
the sample and camera.