STUDY ON BEHAVIOR OF TRAPPED HYDROGEN IN 18Ni MARAGING STEEL BY THERMAL HYDROGEN EVOLUTION TECHNIQUE

The interaction of hydrogen with interface between the precipitates and the martensitie matrix in 18Ni maraging steel has been studied by means of thermal evolution hydrogen technique us- ing gas chromatograph as hydrogen detector.An evolution rate peak has been observed at 451 K.The height of the peak relates to the amount and distribution of the precipitates.The activation energy for hydrogen escaping from the trap sites is 23.2 kJ/mol.

Technological advancements in millet dehulling and polishing process: An insight into pretreatment methods, machineries and impact on nutritional quality

Millets are widely recognized for their nutritional significance;however, the methods employed for their processing are currently lacking. This article primarily focuses on the advanced technologies and progressions in millet dehulling and polishing. These technologies operate based on the fundamental principles of compression-shearing, abrasion-friction, and centrifugal-impact forces. Processing of millets can be challenging because of the physical characteristics and tight attachment of hull and bran to the endosperm. However, several dehullers have been designed to solve this problem for different kinds of millets. In addition, the nutritional and anti-nutritional characteristics undergo alterations due to both dehulling and polishing processes. These alterations are thoroughly examined and discussed in this article. Specifically, anti-nutrients such as tannins and phytate are predominantly found in the outer pericarp of the grain and experience a reduction after undergoing dehulling and polishing. The nutritional properties are also subjected to a reduction;however, this reduction can be mitigated by subjecting the grains to certain pretreatments before dehulling and polishing. These treatments serve to enhance dehulling efficiency and nutrient digestibility while simultaneously reducing the presence of anti-nutrients. Novel thermal and non-thermal methodologies such as microwave, hydrothermal, high-pressure processing, and ohmic heating can be employed for processing millets, thereby diminishing the loss of nutrients. Additional research can be carried out to investigate their impact on the dehulling and polishing of millets.

Purification of copper foils driven by single crystallization

High-purity copper(Cu) with excellent thermal and electrical conductivity, is crucial in modern technological applications, including heat exchangers, integrated circuits, and superconducting magnets. The current purification process is mainly based on the zone/electrolytic refining or anion exchange, however, which excessively relies on specific integrated equipment with ultra-high vacuum or chemical solution environment, and is also bothered by external contaminants and energy consumption. Here we report a simple approach to purify the Cu foils from 99.9%(3N) to 99.99%(4N) by a temperature-gradient thermal annealing technique, accompanied by the kinetic evolution of single crystallization of Cu.The success of purification mainly relies on(i) the segregation of elements with low effective distribution coefficient driven by grain-boundary movements and(ii) the high-temperature evaporation of elements with high saturated vapor pressure.The purified Cu foils display higher flexibility(elongation of 70%) and electrical conductivity(104% IACS) than that of the original commercial rolled Cu foils(elongation of 10%, electrical conductivity of ~ 100% IACS). Our results provide an effective strategy to optimize the as-produced metal medium, and therefore will facilitate the potential applications of Cu foils in precision electronic products and high-frequency printed circuit boards.

Advances in thermal-related analysis techniques for solid-state lithium batteries

Solid-state lithium batteries(SSLBs)have been broadly accepted as a promising candidate for the next generation lithium-ion batteries(LIBs)with high energy density,long duration,and high safety.The intrinsic non-flammable nature and electrochemical/thermal/mechanical stability of solid electrolytes are expected to fundamentally solve the safety problems of conventional LIBs.However,thermal degradation and thermal runaway could also happen in SSLBs.For example,the large interfacial resistance between solid electrolytes and electrodes could aggravate the joule heat generation;the anisotropic thermal diffusion could trigger the uneven temperature distribution and formation of hotspots further leading to lithium dendrite growth.Considerable research efforts have been devoted to exploring solid electrolytes with outstanding performance and harmonizing interfacial incompatibility in the past decades.There have been fewer comprehensive reports investigating the thermal reaction process,thermal degradation,and thermal runaway of SSLBs.This review seeks to highlight advanced thermal-related analysis techniques for SSLBs,by focusing particularly on multiscale and multidimensional thermal-related characterization,thermal monitoring techniques such as sensors,thermal experimental techniques imitating the abuse operating condition,and thermalrelated advanced simulations.Insightful perspectives are proposed to bridge fundamental studies to technological relevance for better understanding and performance optimization of SSLBs.

Synthesis of Aligned ZnO Nanorod Array on Silicon and Sapphire Substrates by Thermal Evaporation Technique

High density ZnO nanorods were grown by thermal evaporation of Zn powder at 700℃ on Si （100） and sapphire （0001） substrates at atmospheric pressure without adding any catalyst. The nanorods were characterizated in terms of their structural and optical properties. The nanorods grown on Si have a diameter of 350-400 nm and a length of 1.2 μm while those on sapphire have a diameter of 600-800 nm and a length of 2.5 μm. During the structural characterization, it is noticed that the rods grow along the （0002） plane with perfect hexagonal facet. The room temperature photoluminescence spectrum showed a strong UV emission peak at 385 nm with a weak green band emission, which confirms that nanorods have good optical properties. It is observed that the oxygen partial pressure plays an important role to control the shape and size of the nanorods in thermal evaporation growth technique.

Detection of Thermophysical Properties for High Strength Concrete after Exposure to High Temperature

Using the detection principle of infrared thermal imaging technique and the detection principle of DRH thermal conductivity tester laboratory,we investigated the infrared thermal image inspection,coefficient of thermal conductivity,apparent density,and compressive strength test on C80 high-strength concrete（HSC） in the presence and absence of polypropylene fibers under completely heated conditions.Only slight damages were detected below 400 ℃,whereas more and more severe deterioration events were expected when the temperature was above 500 ℃.The results show that the elevated temperature through infrared images generally exhibits an upward trend with increasing temperature,while the coefficient of thermal conductivity and apparent density decrease gradually.Additionally,the addition of polypropylene fibers with appropriate length,diameter,and quantity contributes to the improvement of the high-temperature resistance of HSC.

A novel approach to fabricate Zn coating on Mg foam through a modified thermal evaporation technique

Zn enriched coatings with distinct microstructures and properties were fabricated on Mg foams by a modified thermal evaporation technique using a tubular resistance furnace. As the temperature and kinetic energy of Zn vapor varied along the tubular system, a spatial variation of preparation conditions was created and the obtained coatings were found to follow two growth mechanisms： a thermal diffusion pattern in high-temperature zone and the a relatively low-temperature deposition model. AZn-based deposition coating with dense texture and nearly uniform structure was acquired while Mg foam was placed 20 cm far from the evaporation source, where the Zn vapor deposition model dominated the coating growth.Mechanical properties and bio-corrosion behaviors of the samples were investigated. Results showed that the Zn coatings brought dramatic improvements in compression strength, but exhibited differently in biodegradation performance. It was confirmed that the diffusion layer accelerated corrosion of Mg foam due to the galvanic effect, while the Zn-based deposition coating displayed excellent anti-corrosion performance, showing great potential as bone implant materials. This technique provides a novel and convenient approach to tailor the biodegradability of Mg foams for biomedical applications.

Measuring the thermal conductivity and interfacial thermal resistance of suspended MoS2 using electron beam self-heating technique

Establishment of a new technique or extension of an existing technique for thermal and thermoelectric measurements to a more challenging system is an important task to explore the thermal and thermoelectric properties of various materials and systems. The bottleneck lies in the challenges in measuring the thermal contact resistance. In this work, we applied electron beam self-heating technique to derive the intrinsic thermal conductivity of suspended Molybdenum Disulfide （MoS2） ribbons and the thermal contact resistance, with which the interracial thermal resistance between few-layer MoS2 and Pt electrodes was calculated. The measured room temperature thermal conductivity of MoS2 is around -30 W/（m K）, while the estimated interracial thermal resistance is around -2 × 10 -6 m-2 K/W. Our experiments extend a useful branch in application of this technique for studying thermal properties of suspended layered ribbons and have potential application in investigating the interracial thermal resistance of different twodimensional （2D） heterojunctions.

A technique for enhancing the thermal stability of hydrogen-loaded fiber Bragg grating

Heat treatment with the presence of hydrogen (H2) that react with GeE' centers (Ge≡) at high temperature will weaken the refractive index modulation of grating fabricated in hydrogen-loaded normal germanosilicate fiber. Pre-annealing treatment of the above fiber was demonstrated to be able to enhance the grating's thermal stability effectively. 0.37-nm blue-shift of the reflected Bragg wavelength was observed.

Substrate Temperature-Dependent Physical Properties of Thermally Evaporated Sn4Sb6S13 Thin Films

In this work, the homogenous thin films of sulfosalt Sn4Sb6S13 were successfully synthesized by the thermal evaporation technique onto coming 7059 glass substrates heated at various temperatures in the range of 30--200 ℃. The surface morphology and structural characteristics of Sn4Sb6S13 films were analyzed by atomic force microscopy, X-ray diffraction, and energy-dispersive X-ray, respectively. The X-ray diffraction analysis revealed that Sn4Sb6S13 thin films crystallized in monoclinic structure according to a preferential direction （6 11）. An improvement in the structural properties by increasing the substrate temperature was observed. The values of some important parameters such as absorption coefficient （x）, band gap （Eg）, refractive index （n）, extinction coefficient （k）, and dielectric constant （Eg） of thin film were determined. The absorption coefficient was larger than 105 cm-l in the visible range. The electron transition of Sn4Sb6S13 films was direct allowed with the values that decreased （2-1.69 eV） by increasing substrate temperature from 30 to 200 ℃,The dispersion data obeyed the single oscillator relation of the Wemple-DiDomenico model and Cauchy model. The electrical free carrier susceptibility and the carrier concentration of the effective mass ratio were estimated according to the model of Spitzer and Fan.

Structural Morphological and Optical Properties of SnSb_2S_4 Thin Films Grown by Vacuum Evaporation Method

SnSb2S4 thin films were prepared from powder by thermal evaporation under vacuum of 1.33 × 10^-4 Pa （ 10^-6 Torr） on unheated glass substrates. The effect of thickness on the structural, morphological and optical properties of SnSb2S4 thin films was investigated. Films thickness measured by interference fringes method varied from 50 to 700 nm. X-ray diffraction analysis revealed that all the SnSb2S4 films were polycrystalline in spite without heating the substrates and the crystallinity was improved with increasing film thickness. The microstructure parameters： crystallite size, strain and dislocation density were calculated. It was observed that the crystallite size increased and the crystal defects decreased with increasing film thickness. In addition, by increasing the film thickness, an enhancement in the surface roughness root-mean-square （RMS） increased from 2.0 to 6.6 nm. The fundamental optical parameters like band gap, absorption and extinction coefficient were calculated in the strong absorption region of transmittance and reflectance spectrum. The optical absorption measurements indicated that the band （Eg） gap of the thin films decreased from 2.10 to 1.65 eV with increasing film thickness. The refractive indexes were evaluated in transparent region in terms of envelope method, which was suggested by Swanepoul. It was observed that the refractive index increased with increasing film thickness.