Terahertz spectroscopy was used to study the sintering process of traditional ceramic by scanning sample with different final temperatures (from 100-1450°C). Absorption coefficient (α) and refractive index (n) were obtained with different final temperatures. The sintering process was divided into four stages on the basis of α and n, which characterized the ceramic sintering process well. The results coincide with the actual situation. Therefore, THz-TDS represents a promising technique to monitor the synthesis process of materials.
This paper aims at presenting an approach for the experimental flow pattern conversion prediction. The water-diesel mixture flowed in the horizontal square tube with water contents of 0, 0.7%, 1.5%, 2.0% and 2.3%, respectively. After the mixture flowed steadily, the sample cell, in horizontal direction, was transmitted by the terahertz radiation and the terahertz time domain spectra were obtained for all the water-diesel mixtures. There is a critical velocity VT to all of the mixtures. If the flow rate is slower than VT, the mixtures flow with water bubbly pattern, however, the mixtures will flow with the water foggy pattern and the loss of the THz ray increased rapidly when the rate is faster than VT. Consequently, the mixture pattern conversion can be predicted by detecting the turning point of the THz ray loss.
The iron tablets, which were exposed in salt spray with different periods, were investigated in the 0.2~2.0 THz using reflection-type terahertz time-domain spectroscopy (THz-TDS) in vacuum environment at room temperature. The sample signals are attenuated in comparison to the reference signals with increasing the corrosion time. The THz spectroscopy peak EP and reflectivity (R) of samples strongly depended on corrosion time t with EP ∝ t-1 and R ∝ t-1. The THz characteristics of iron sheets in salt spray indicate that reflection THz-TDS will contribute to the development of non-destructive testing of corrosion in pipelines.
Optical properties of the group components in crude oil were studied using terahertz time-domain spectroscopy (THz-TDS) under nitrogen environment at ambient temperature. The group composition of crude oil from different oil fields were analyzed on the basis of terahertz spectra. Both time delay and amplitude of terahertz wave were modulated in accordance with group composition. The features of terahertz spectra which contain information from different parts of the crude oil group composition can be qualitatively analyzed to detect the group components of the crude oil.
Fe2O3, Fe3O4 and Fe(OH)3 as three different corrosion products of iron and their mixture were investigated in the 0.2~2.0 THz using terahertz time-domain spectroscopy (THz-TDS) in vacuum environment at room temperature. Frequency and reflectivity of Fe2O3, Fe3O4, Fe(OH)3 and their mixture were calculated by fourier transform. There are no peaks in the THz range, but the reflectivities of samples have significant differences. The results demonstrate that the three different corrosion products of iron and their mixture can be analyzed distinctly according to the characteristics in THz range. THz-TDS can be used in further analysis of iron corrosion and pipeline corrosion detection.
With the rapid development of fiber optic sensing technology, more and more related monitoring programs begin to
play an important role in oil and gas exploration. In the past, down-hole monitoring of temperature and pressure was
dependent on pump partner, electronic pressure gauge and the capillary pressure gauge. However, such devices show
many disadvantages in stability, reliability, accuracy and so on.
In the interest of special anti-corrosion, seals, high temperature, high pressure treatment, and long life, the fiber
optic sensor is critically investigated and a new design approach of fiber temperature and pressure sensor based on Fiber
Bragg Gratings and Fabry-Perot Cavity is presented, respectively. The temperature and pressure resolution of this sensor
can be as high as 0.3°C and 3psi. Meanwhile, the sensor can work under the condition from 0 to 15000psi and from -25
to 300 °C. This paper describes the technical principles, characteristics and field application of the sensor in detail.
Engine oil, most of which is extracted from petroleum, consist of complex mixtures of hydrocarbons of molecular
weights in the range of 250-1000. Variable amounts of different additives are put into them to inhibit oxidation,
improve the viscosity index, decrease the fluidity point and avoid foaming or settling of solid particles among others.
Terahertz (THz) spectroscopy contains rich physical, chemical, and structural information of the materials. Most
low-frequency vibrational and rotational spectra of many petrochemicals lie in this frequency range. In recent years,
much attention has been paid to the THz spectroscopic studies of petroleum products. In this paper, the optical properties
and spectroscopy of selected kinds of engine oil consisting of shell HELIX 10W-40, Mobilube GX 80W-90, GEELY
ENGINE OIL SG 10W-30, SMA engine oil SG 5W-30, SMA engine oil SG 10W-30, SMA engine oil SG 75W-90 have
been studied by the terahertz time-domain spectroscopy (THz-TDS) in the spectral range of 0.6-2.5 THz. Engine oil with
different viscosities in the terahertz spectrum has certain regularity. In the THz-TDS, with the increase of viscosity, time
delay is greater and with the increase of viscosity, refractive indexes also grow and their rank is extremely regular. The
specific kinds of engine oil can be identified according to their different spectral features in the THz range. The
THz-TDS technology has potentially significant impact on the engine oil analysis.