X-ray Transmission Method Research Articles

Study of Measuring True Porosity of Ceramic samples by X-ray Transmission Method

This paper reports a method for measuring the true porosity of ceramic samples based on X-ray transmission. The measurement of the true porosity of ancient Ding kiln white porcelain and two daily white porcelains was carried out by X-ray transmission method. The research results show that the average true porosity of ancient Ding kiln white porcelain, daily white porcelain A, and daily white porcelain B measured by the X-ray transmission method is 5.44%, 9.10%, and 13.97%, respectively; and the values measured by the suspension method were 5.35%, 8.43%, and 12.89%, respectively. Although the true porosity values of the ceramic samples measured by the X-ray transmission method are slightly larger than the measurement value of the suspension method, they are in good agreement with each other. In addition, compared with the suspension method, the X-ray transmission method has significant advantages such as simple operation and short measurement time.

Sensor-Based Ore Sorting—A Review of Current Use of Electromagnetic Spectrum in Sorting

Sensor-based sorting has had a wide range of industrial use in automating and speeding up the process which requires substances or objects to be segregated from each other. The high demand for goods including raw materials, food, minerals, and waste recycling has increased the pressure for high-speed sorting. The first part of this paper presents a comprehensive theoretical and practical survey and comparison of current sorting methods relying on the use of the electromagnetic spectrum. Sorting methods are classified among other things, which portion of the EM spectrum is it, background noise rejection capacity, sample size limitations, sample chemistry limitations, sample surface cleanliness, spatial resolution capacity, spectral resolution, and feed rate limitations. The analysis focuses on color or visible light sorting, gamma-ray sorting, infra-red sorting, x-ray transmission-based sorting and x-ray fluorescence sorting, coupling the findings to the classification criteria outlined. We see a need to define a universal sorting scheme that will in general be applied to most sorting tasks. To do this, the final part of this paper re-looks at the x-ray transmission and x-ray fluorescence sorting scheme in line with the established limitations and proposes a dual x-ray transmission and fluorescence method to mitigate the challenge affecting the different schemes.

Structural, Thermal and Dielectric Properties of Low Dielectric Permittivity Cordierite-Mullite-Glass Substrates at Terahertz Frequencies.

Glass–ceramic composites containing cordierite, mullite, SiO2 glass and SiO2-B2O3-Al2O3-BaO-ZrO2 glass were fabricated in a process comprising solid state synthesis, milling, pressing and sintering. Thermal behavior, microstructure, composition and dielectric properties in the Hz-MHz, GHz and THz ranges were examined using a heating microscope, differential thermal analysis, thermogravimetry, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction analysis, impedance spectroscopy, transmission method and time domain spectroscopy (TDS). The obtained substrates exhibited a low dielectric permittivity of 4.0–4.8. Spontaneously formed closed porosity dependent on the sintering conditions was considered as a factor that decreased the effective dielectric permittivity.

Feasibility study of recycled CRT glass on elastic and radiation shielding properties used as x-ray and gamma-ray shielding materials

Recycled glass derived from discarded cathode ray tubes (CRT) was used as a component for (70-x)CRT–30K2O–xBaO glass systems (where x = 0–20 mol%). Temperature dependence of ultrasonic wave velocities was carried out at 4 MHz frequency using pressure-controlled ultrasonic technique. It was found that the velocities decreased gradually as BaO content increased. However, sound velocities increased with increasing temperature. Then, both velocities were applied to estimate their elastic properties. Based on the obtained results, the elastic moduli and micro hardness of studied glasses increased with the amount of BaO and temperature, while their Poisson's ratio remained almost constant. Radiation shielding properties were investigated in terms of μm and HVL at photon energies of 74.23, 97.14, 122, 662, 1173, and 1332 keV by using narrow beam x-ray attenuation and transmission methods. Their theoretical values were also calculated by WinXCom program and compared with ferrite concrete. The results showed better radiation shielding properties for recycled CRT glass in comparison to ferrite concrete. Furthermore, the values obtained from the experiment in this study are in good agreement with the theoretical data.

In situ X-ray imaging of melt pool dynamics in underwater arc welding

The dynamic behavior of the underwater melt pool was firstly in-situ observed with the X-ray transmission method. A method for quantitatively characterizing the melt pool stability was pioneered. Comparing with conventional melt pool composing metal liquid, the pool was filled with bubbles in underwater environment. By observing the X-ray images and charactering the weld pool waveform, it is confirmed that the underwater melt pool was more volatile than onshore melt pool, which was mainly caused by the evolution of large bubble in the pool. Violent fluctuation of melt pool was the basic reason gaining poor weld and multiple defects in the underwater wet welding. To mitigate pool fluctuations by reducing the size of bubble, the ultrasonic vibration was applied directly on the workpiece, which improved the melt pool stability, uniformized the weld formation, and decreased the weld porosity.

Study of metal transfer control in underwater wet FCAW using pulsed wire feed method

A metal transfer control method based on pulsed wire feed technology is adopted to ameliorate the underwater flux-cored arc wet welding quality. The stability of the welding process is improved with appropriate pulse parameters. The influences of pulse parameters on the metal transfer process are clarified using an X-ray transmission method. Pulse frequency has more of an effect on weld appearance and welding stability than pulse duty factor. Thirty to forty hertz is an appropriate frequency bound for a stable metal transfer process. The repelled metal transfer percentage decreases with increasing droplet growth speed. The inertia force shortens the metal transfer period and prompts droplet transfer into the pool. When the pulse frequency is less than 40 Hz, the base speed time is long enough for the inertia force to act on the droplet. But if the pulse frequency is below 20 Hz, the peak wire feed speed will be sustained for a long time, and the short-circuit frequency increases from 1 to 2.5 Hz; as a result, the welding stability and the welding appearance deteriorate. For the wire employed in this study, better welding stability is obtained at 30 Hz, while the pulse duty factor is 2.

Effects of welding velocity on metal transfer mode and weld morphology in underwater flux-cored wire welding

Metal transfer process in underwater flux-cored welding are investigated by X-ray transmission method for welding velocity from 0.5mm/s to 9.5mm/s. The metal transfer mode of underwater flux-cored wire welding is the mixed transfer mode mainly composed of four fundamental transfer modes i.e. wide-angle globular repelled transfer mode, small-angle globular repelled transfer mode, surface tension transfer mode and short-circuit transfer mode. The category and proportion of fundamental modes constituting the mixed mode depend strongly on the welding velocity owing to the variation of force condition on droplet. With increasing welding velocity, the proportion of the wide-angle globular repelled transfer mode increases continually while that of the surface tension transfer mode and short-circuit transfer mode decreases, and the proportion of the small-angle globular repelled transfer increases firstly and then decreases gradually. The welding appearance and cross-sectional macrostructure of weld specimens at different welding velocities are also investigated. When the welding velocity increases from 0.5mm/s to 3.5mm/s, the weld width decreases from 20mm to 12mm and the weld penetration increases rapidly from 0.8mm to 3.7mm, completely different from in-air welding.

Characterization of spatter in underwater wet welding by X-ray transmission method

Abstract The spatter forming mechanism of underwater flux-cored wire wet welding is characterized by using a self-developed X-ray transmission system. Three representative spatter modes, droplet repelled spatter, explosive spatter and molten pool shock spatter, forming during underwater wet welding have been observed. The generation of droplet repelled spatter is due to the excessive repulsive forces for metal transfer. The diameter of this type of spatter is largest relatively, which can reach about 4.5 mm. In addition, explosive spatter, with size about 2.5 mm, is changed from the droplet with high horizontal speed caused by a slight explosion occurs at the touching location of the droplet and molten surface. Moreover, the dimension of molten pool shock spatter is smallest potentially among the spatter types during underwater wet welding, and it is only about 0.8 mm. It is generated from ridgy liquid column on the molten pool surface because of the relatively severe concussion of the molten pool. The size, macroscopic pattern as well as chemical composition of these three types of spatters are different.

Study of underwater wet welding stability using an X-ray transmission method

The effects of arc voltage on the stability of the underwater wet flux-cored arc welding (FCAW-S 114) process are explained based on studying the droplet transfer process using the X-ray transmission method. The mode of metal transfer and the protective bubble effect, which vary with voltage, affect the stability of the welding process. The results indicate that there is a critical arc voltage (32V). When the arc voltage is less than 32V, an unstable welding process occurs because of the high proportion of short-circuit transfer and limited bubble size. Increase in the arc burning zone must be protected, and the proportion of repelled metal transfer caused by the high arc voltage decreases the stability of the welding process. In this study, stable welding process is acquired when the proportion of repelled metal transfer is less than 20%, the short circuit frequency is lower than 1Hz and the bubble diameter is larger than 24mm.

Metal transfer in underwater flux-cored wire wet welding at shallow water depth

The metal transfer process of underwater flux-cored wire wet welding is successfully observed by an X-ray transmission method. The relatively large retention forces acting on the droplet induced by the electromagnetic force, vaporization force, surface tension resultant force and gas flow drag force make the transfer mode as a combination of globular repelled transfer mode and short circuit transfer mode with the average transfer frequency of 4.3Hz with arc voltage of 24V and welding current of 240A.

Spectral K-edge subtraction imaging

We describe a spectral x-ray transmission method to provide images of independent material components of an object using a synchrotron x-ray source. The imaging system and process is similar to K-edge subtraction (KES) imaging where two imaging energies are prepared above and below the K-absorption edge of a contrast element and a quantifiable image of the contrast element and a water equivalent image are obtained. The spectral method, termed ‘spectral-KES’ employs a continuous spectrum encompassing an absorption edge of an element within the object. The spectrum is prepared by a bent Laue monochromator with good focal and energy dispersive properties. The monochromator focuses the spectral beam at the object location, which then diverges onto an area detector such that one dimension in the detector is an energy axis. A least-squares method is used to interpret the transmitted spectral data with fits to either measured and/or calculated absorption of the contrast and matrix material-water. The spectral-KES system is very simple to implement and is comprised of a bent Laue monochromator, a stage for sample manipulation for projection and computed tomography imaging, and a pixelated area detector. The imaging system and examples of its applications to biological imaging are presented. The system is particularly well suited for a synchrotron bend magnet beamline with white beam access.

Determination of Sulfur Content in Crude Oil Using On-Line X-ray Transmission Technology

Abstract This paper describes the function and use of X-ray Transmission (XRT) analytical instrumentation as applied to the classification and blending of crude oil that contains 0.1–3.3% sulfur by weight. In the XRT method, sulfur absorbs X-rays transmitted between an X-ray source and detector. The technique compensates for density changes in the oil and minimizes the effects of variations in the C/H ratio of the oil. When used on-line the instrument obtains the sulfur measurement in the high-pressure flow conditions required to pump crude oil, typically 800 psig in pipelines. Automatic compensation for variations in oil density and temperature are achieved using integrated densitometer and temperature sensor readings taken by the instrument as the sulfur is being measured. In this paper calibration, precision, and long-term stability results are shown. Experimental data were obtained using a commercially available on-line XRT analyzer.

Comparison of radioactive transmission and mechanical properties of Portland cement and a modified cement with trommel sieve waste

In this study, it was aimed to stabilize trommel sieve waste (TSW) occurring during manufacture of borax from tincal. The effects of TSW added on the mechanical properties and radioactive transmission of modified cement prepared by adding TSW to clinker was investigated. The properties which TSW as additive caused the cement to gain were tested and compared with normal Portland cement. Measurements have been made to determine variation of mass attenuation coefficients of TSW and cement by using an extremely narrow-collimated-beam transmission method in the energy range 15.746–40.930 keV with X-ray transmission method. The characteristic Kα and Kβ X-rays of the different elements (Zr, Mo, Ag, In, Sb, Ba and Pr) passed through TSW and cement were detected with a high-resolution Si(Li) detector. Results are presented and discussed in this paper.

Experimental studies on measurements of mass attenuation coefficients of boric acid at different concentration

Measurements have been made to determine variation of the mass attenuation coefficients of H3BO3 according to percentage increasing concentration of H3BO3 by using an extremely narrow-collimated-beam transmission method in the energy range 15.746–40.930 keV with an X-ray transmission method. The characteristic Kα and Kβ X-rays of the different elements (Zr, Mo, Ag, In, Sb, Ba and Pr) passed through boric acid was detected with a high-resolution Si(Li) detector. Results are presented and discussed in this paper.

A detailed density profile of the Dome Fuji (Antarctica) shallow ice core by X-ray transmission method

AbstractAn X-ray transmission method has been developed to obtain a continuous profile of bulk densities of ice cores. Intensities of X-rays transmitted through an ice-core sample were continuously measured by an X-ray detector during translation of the sample across the X-ray beam. A thick section of an ice core with a constant thickness was prepared by band-sawing followed by microtome planing. The X-ray intensity profile obtained was converted to a density profile using a calibration curve for X-ray absorption vs ice thickness. Using this method, spatial resolution of the density profile was down to 1 mm. X-ray radiographs were also taken on a two-dimensional detector imaging plate, in order to observe layer structures of the ice cores.The method was applied to Dome Fuji (Antarctica) ice cores from the surface to 110 m depth. From the density profile obtained we calculated the power spectrum of the density variation by the discrete Fourier transform, and obtained several peaks at different frequencies. The center period in the spectrum was close to the annual accumulation thickness at the drill site.

Induced uniaxial magnetic anisotropy and preferred orientation in Co and Co–Ni alloy by magnetic annealing

The preferred orientation of hexagonal close packed hcp grains in magnetically annealed Co and Co–20%Ni alloy was studied by both Schulz’s x-ray transmission and reflection methods to clarify the origin of the magnetic anisotropy induced by the magnetic annealing effect. The preferred orientation was first found at a low polar angle α<50° area for both Co and Co–20%Ni alloy. The mechanism of the magnetic anisotropy induced by the field cooling effect was successfully explained qualitatively and quantitatively by this preferred orientation of the grains. The formation of this preferred orientation was discussed in terms of field-induced martensitic transformation. The uniaxial magnetocrystalline anisotropy energy could be the motive energy of the field-induced martensitic transformation.

Dynamics of keyhole and molten pool in laser welding

In laser and electron-beam welding, a deep cavity called a keyhole or beam hole is formed in the weld pool due to the intense recoil pressure of evaporation. The formation of the keyhole leads to a deep penetration weld with a high aspect ratio and this is the most advantageous feature of welding by high-energy-density beams. However, a hole drilled in a liquid is primarily unstable by its nature and the instability of the keyhole also causes the formation of porosity or cavities in the weld metal. In particular, the porosity formation is one of the serious problems in very high-power laser welding, but its mechanism has not been well understood. The authors have conducted systematic studies on observation of keyhole as well as weld pool dynamics and their related phenomena to reveal the mechanism of porosity formation and its suppression methods. The article will describe the real-time observation of keyhole and plume behaviors in the pulsed and continuous-wave laser welding by high-speed optical and x-ray transmission methods, the cavity formation process and its suppression measures.

Layer Silicates from Serpentinite-Pegmatite Contact (Wiry, Lower Silesia, Poland)

AbstractHighly tectonized contact between serpentinite and younger pegmatite in the magnesite mine of Wiry contains various layer silicates. Vermiculite, chlorite, smectite, and interstratified mica-vermiculite were recognized by means of routine XRD examination. Two three component interstratifications of mica-vermiculite-chlorite and chlorite-swelling chlorite-smectite were identified by a combined procedure of deconvolution of the XRD patterns and simulation of XRD tracings. A mineral with large diffraction maxima, displaying “chlorite intergrade” characteristics, appeared to be a mixture of chlorite, mixed layer chlorite-smectite, and vermiculite. Polytypes of phyllosilicates were determined by the X-ray transmission method. Due to the heritage of parent mineral polytype structure by transitional products of alteration, two distinct sequences of layer silicates were observed: one formed from trioctahedral mica (vermiculite, mixed layer mica-vermiculite); and one evolved from chlorite (e.g., mixed layer chlorite-swelling chloritesmectite). A tentative scheme of the primary contact zone structure, not obscured by subsequent brittle tectonics either by transformation of layer silicates, is proposed.

EBIC microscopy for the characterization of semiconductor materials and devices

For dislocation-free silicon crystals, defects generated during semiconductor device fabrication processes are often the end result of inhomogeneities formed during crystal growth. Impurity-point defect complexes are often transformed into a variety of microdefects during subsequent thermal processing. Extensive investigations have been published on the analysis of microdefects such as stacking faults, complex dislocation colonies and impurity precipitates in silicon crystals. For crystals grown with the Czochralski method, oxygen and carbon have been the subject of many recent investigations. Oxygen precipitation during thermal annealing has been identified as a dominant cause of minority carrier lifetime degradation. The investigative methods used in the majority of these studies include: transmission electro microscopy, scanning electron microscopy, I.R. absorption spectroscopy, X-ray transmission methods and chemical decoration etching.Conventional electron microscopy provides no direct information on the relationship between defects in crystals and electrical effects in semiconductor devices.

X-ray Transmission Method with a Hard X-ray Counter

X-ray Transmission Method with a Hard X-ray Counter