Heat Treatment Research Papers - Academia.edu (original) (raw)

Biomaterials like calcium phosphates are used as bioactive coatings because they increase the osteointegration of the prosthesis surfaces. Micro-arc oxidation (MAO) generates TiO2 and amorphous and crystalline calcium phosphates coatings. Crystallization thermal treatment diminishes the percentage of amorphous phases in the coating. In this study it was evaluated by Electrochemical Impedance Spectroscopy, MAO calcium phosphate coatings formed on Ti6Al4V ELI. It was found that crystallization thermal treatment between 400 and 800°C increases the crystallinity of the coating and diminishes its dissolution rate.

- by and +1
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- Materials Science, Heat Treatment, Electrochemical Impedance Spectroscopy, Coating

The effect of hot water dips (53 °C, 23 min) on chilling injury (CI) and decay of various citrus fruits was compared with the effect of curing (36 °C, 72 h). Experiments were conducted with grapefruit (Citrus paradisi Macf., cv. Marsh),... more

In the field of FTIR spectroscopy, the far infrared (FIR) spectral region has been so far less investigated than the mid-infrared (MIR), even though it presents great advantages in the characterization of those inorganic compounds, which are inactive in the MIR, such as some art pigments, corrosion products, etc. Furthermore, FIR spectroscopy is complementary to Raman spectroscopy if the fluorescence effects caused by the latter analytical technique are considered. In this paper, ATR in the FIR region is proposed as an alternative method to transmission for the analyses of pigments. This methodology was selected in order to reduce the sample amount needed for analysis, which is a must when examining cultural heritage materials. A selection of pigments have been analyzed in both ATR and transmission mode, and the resulting spectra were compared with each other. To better perform this comparison, an evaluation of the possible effect induced by the thermal treatment needed for the preparation of the polyethylene pellets on the transmission spectra of the samples has been carried out. Therefore, pigments have been analyzed in ATR mode before and after heating them at the same temperature employed for the polyethylene pellet preparation. The results showed that while the heating treatment causes only small changes in the intensity of some bands, the ATR spectra were characterized by differences in both intensity and band shifts towards lower frequencies if compared with those recorded in transmission mode. All pigments' transmission and ATR spectra are presented and discussed, and the ATR method was validated on a real case study.

- by SILVIA PRATI
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- Engineering, Cultural Heritage, FTIR spectroscopy, Raman Spectroscopy

Hydrogen gas can be recovered from the microbial fermentation of organic substrates at high concentrations when interspecies hydrogen transfer to methanogens is prevented. Two techniques that have been used to limit methanogenesis in mixed cultures are heat treatment, to remove nonsporeforming methanogens from an inoculum, and low pH during culture growth. We found that high hydrogen gas concentrations (57-72%) were produced in all tests and that heat treatment (HT) of the inoculum (pH 6.2 or 7.5) produced greater hydrogen yields than low pH (6.2) conditions with a nonheat-treated inoculum (NHT). Conversion efficiencies of glucose to hydrogen (based on a theoretical yield of 4 mol-H 2 /mol-glucose) were as follows: 24.2% (HT, pH ) 6.2), 18.5% (HT, pH ) 7.5), 14.9% (NHT, pH ) 6.2), and 12.1% (NHT, pH ) 7.5). The main products of glucose (3 g-COD/L) utilization (g99%) in batch tests were acetate (3.4-24.1%), butyrate (6.4-29.4%), propionate (0.3-12.8%), ethanol (15.4-28.8%), and hydrogen (4.0-8.1%), with lesser amounts of acetone, propanol, and butanol (COD basis). Hydrogen gas phase concentrations in all batch cultures reached a maximum of 57-72% after 30 h but thereafter rapidly declined to nondetectable levels within 80 h. Separate experiments showed substantial hydrogen losses could occur via acetogenesis and that heat treatment did not prevent acetogenesis. Heat treatment consistently eliminated the production of measurable concentrations of methane. The disappearance of ethanol produced during hydrogen production was likely due to acetic acid production as thermodynamic calculations show that this reaction is spontaneous once hydrogen is depleted. Overall, these results show that low pH was, without heat treatment, sufficient to control hydrogen losses to methanogens in mixed batch cultures and suggest that methods will need to be found to limit acetogenesis in order to increase hydrogen gas yields by batch cultures.

- by Steven Van Ginkel
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- Environmental Science, Thermodynamics, Hydrogen, Heat Treatment

Semi-insulating, undoped, Liquid Encapsulated Czochralski (SI-U LEC) GaAs detectors have been irradiated with 24 GeV/c protons at the fluence of 5.6× 1013 p/cm 2. The detector charge collection efficiency, cce, for both electrons and holes is remarkably reduced after irradiation while the reverse current increases. The effect of annealing the detectors at temperatures ranging from 220 °C to 280 °C has been seen to reduce the reverse current and to increase the electron cce, while the recovery of the hole cce is negligible in irradiated detectors. Deep electron traps have been followed in their evolution with the heat treatment temperature by P-DLTS and C-V measurements. They recover by increasing the heat treatment temperature and this can explain the restoration observed in electron cce.

- by Paolo Vanni
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- Mathematical Physics, Quantum Physics, Heat Treatment, Low Temperature

Yam (Dioscorea alata) starch was pregelatinized in a single screw extruder. Response Surface Methodology was used to study the eect of extrusion variables: feed moisture (18, 21, 24%), extruder temperature (120, 150, 180 C) and die diameter (3, 4, 5 mm) on cold viscosity, gel-forming capacity and retrogradation of extruded starches. Cold viscosity was higher from starch samples processed at higher moisture and die diameter, at lower temperatures. Slurries of the extruded starch (8%, w/v, d.b.) formed opaque and ®rm gels. Higher values for gel strength were found in samples extruded at highest and lowest moistures at intermediate temperature and increasing die diameter. Gels of extruded starch had lower retrogradation values than non-extruded gelatinized starch after one and two weeks storage at refrigeration temperature. Prediction equations for the studied functional properties can be used in selecting processing conditions for speci®c food applications.

The crystalline quality of molecular beam epitaxy (MBE)-grown layers of GaN on sapphire strongly depends on the initial stage of film nucleation and growth. Thus, pre-conditioning of the substrate is of vital importance. In this study we use X-ray photoelectron spectroscopy (XPS) and low energy electron diffraction (LEED) to examine in situ the case for surface cleaning and nitridation of c-plane sapphire substrates upon annealing in UHV and exposure to radio frequency (rf) plasmas of hydrogen and nitrogen, respectively. We find that low temperature (200-300°C) heat treatment in a hydrogen plasma offers effective removal of adventitious surface contaminants, contrary to annealing in vacuum. Moreover, our XPS data provide unambiguous evidence for formation of surface nitride upon heat treatment in nitrogen plasma at 300-7OO"C, in agreement with conclusions inferred from reflection high energy electron diffraction (RHEED).

- by Jostein Grepstad
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- Engineering, Heat Treatment, Molecular beam epitaxy, Physical sciences

Titanium-zirconium based alloys containing a small amount of niobium were investigated in order to evaluate their possible use as biomedical materials. Zirconium, which belongs to the IVa group, is known to have good corrosion resistance and biocompatibility similar to titanium. As the titanium-zirconium system shows a complete solid solution, a wide variation of alloy design is available and large quantities of solid-solution hardening must be possible. Niobium, having a beta-phase stabilizing effect, was chosen as a ternary element in order to control desirably the microstructure. There have been no reports which suggest its harm to a living body. The alloys containing 2% or 3% niobium showed the highest hardness value after aging heat treatment at 773 K. In contrast to this, no alteration of hardness was seen in specimens aged at 1073 K. Through conventional X-ray diffractometry and in situ X-ray analysis using a hot stage, beta-phase precipitation in the A matrix was identified....

- by Serena Best
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- Materials Engineering, Biomedical Engineering, Titanium, Heat Treatment

The exoskeleton of the lobster Homarus americanus is a multiphase biological composite material which consists of an organic matrix (crystalline α-chitin fibers and various types of non-crystalline proteins) and minerals (mainly calcite). In this study we discuss experimental data about the mesoscopic structure and the crystallographic texture (orientation distribution) of the α-chitin–protein fiber network in this material. The synchrotron measurements reveal very strong crystallographic textures of the α-chitin. According to these data, a large fraction of the α-chitin lattice cells is arranged with their longest axis parallel to the normal of the surface of the exoskeleton. Additionally, a smaller fraction of the α-chitin cells is oriented with their longest axis perpendicular to the cuticle surface. These structural investigations reveal the pronounced role of crystallographic orientation distributions in mineralized biological composite materials which may be of relevance for an improved understanding of biological and bio-inspired nano-composites.

- by Dierk Raabe
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- Materials Engineering, Mechanical Engineering, Materials Science, Crystallography

Positron annihilation lifetime and Doppler broadening of annihilation line techniques have been used to obtain information about the small-pore structure of SiO 2 prepared by the alkoxide method in dierent experimental conditions. Samples prepared in strong acidic environment (pH 2) contain only small pores with mean radius R $ 5 # A, while those prepared at pH 6 and pH 9 contain pores of two sizes, R $ 5 and R $ 17±26 # A. The in¯uence of pH, water/alkoxide molar ratio and temperature of heat-treatment of the samples on their pore structure has been studied. Ó

The work shows the effect of heat treatment T6 (solution and controlled precipitation of CuAl 2 ) on the microstructure of rheocast Al-4.5wt.% Cu alloy. Rheocast structures were obtained by partial melting to 40% liquid fraction from dendritic material with initial different grain sizes. Globular structures with grain sizes varying from 15 to 170 mm were produced and characterized for grain size, morphology, and Cu distribution and were mechanically tested, in both as-rheocast and T6 conditions. Results showed that increasing grain size results in a decrease in tensile and yield strengths, the latter according to a Hall -Petch type of relation. Elongation and constriction increase as grain diameter increases to a certain extent; for higher increase in grain diameter, these properties decrease. Concerning the effect of heat treatment in the structure, rheocast material requires more time for complete dissolution of the eutectic phase than cast structures, can keep higher Cu content in solution and prevents grain growth during holding. Greater improvement in mechanical properties is achieved by heat treatment in rheocast material.

Stoichiometric films were prepared by rf-magnetron sputtering from a Pb(Zr 0.54 Ti 0.46 )O 3 ceramic target onto Au-electroded substrates of alumina. During deposition the substrate holder was kept at a temperature of 300 • C. Post-deposition heat treatment in air at 650 • C was carried to promote the full crystallization and to result in pure perovskite PZT phase. SEM-EDX measurements for the films were performed both on surface and on cross-section. The impedance spectroscopy data demonstrates that the films have rather good dielectric properties and low losses. The recorded P-E loops prove their macroscopic ferroelectric characteristics, while piezoresponse force microscopy experiments confirm a nanoscale switching mechanism based on domain nucleation-growth.

Microstructural changes in a metallic oxidation protection coating (Ni-Co-Cr-Al-Y) applied on a nickel base superalloy were investigated by means of scanning and transmission electron microscopy. The changes are due either to thermal mechanical fatigue testing under high thermal gradients or to defined isothermal heat treatments. The coated specimens were quenched from temperatures between 840 and 1100 • C to ambient temperature. The resultant phases, their local distribution and compositions were determined by energy dispersive X-ray (EDX) spectroscopy and electron diffraction. Phase equilibria at respective temperatures were determined by thermodynamic calculations based on the CALPHAD method. The calculated and experimentally determined phase distributions were compared. A particular microstructural feature, namely the existence and spatial distribution of spherical ␥ Ni 3 Al precipitates in the coating and the diffusion zone between substrate and coating, was used as a postmortem indicator for the maximum temperature experienced by the specimen during testing. This paper gives a road map for developing a microstructural-based temperature calibration for complex metallic materials using thermodynamic simulations.

The performance of copper/nickel oxide catalysts supported on ceramic monoliths of ␥-alumina/silicate, for the selective catalytic reduction (SCR) of nitrogen oxides in flue gas from nitric acid plants ([NO]/[NO x ] = 0.7) has been studied. The monoliths prepared were characterised by thermogravimetry, nitrogen adsorption-desorption, mercury intrusion porosimetry (MIP), X-ray diffraction (XRD), electron probe microanalysis wavelength dispersion spectroscopy (EPMA-WDS) and their mechanical strengths were measured. The support composition and heat-treatment temperature was optimised to obtain monolithic structures with satisfactory mechanical and textural properties. Thus, a monolith with a ␥-alumina/silicate weight ratio of 2/3 was selected to give the best combination of textual and mechanical properties. The influence of active phase (CuO/NiO) content and operating conditions (residence time, [NH 3 ]/[NO x ] ratio) on the NO x conversion and ammonia slip was studied at laboratory scale to determine the optimum conditions for operation at pilot-plant scale. The maximum catalytic activity was achieved for a catalyst with CuO content of 6.3 wt.%. At higher active phase concentration a decrease in the catalytic activity was observed, related to the formation of copper oxides crystals detected by XRD. The presence of these species increase the reaction rate of the competitive ammonia oxidation reaction and thus, reduce the ammonia concentration in the outlet. The selected monolithic catalyst was tested at pilot-plant scale with real gases from a nitric acid production plant achieving NO x conversions of around 90 vol.%, with ammonia emissions lower than 10 ppm, at 230 • C and GSHV (NTP) of 10,600 h −1 .

- by Pedro Avila
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- Chemical Engineering, Heat Treatment, Copper, Nitrogen

Titanium dioxide (TiO2) is widely used in optical coating technology because of its stability and high index of refraction. The homogeneity of the chemical composition (stoichiometry) of the optical thin films plays an important role in the quality of the layers. Increasing the homogeneity increases the transmission coefficient and the laser-induced damage threshold and decreases the absorption coefficient. To increase the homogeneity of the layers, various methods are used during and after the process of film coating. Annealing (heating the deposited films up to a certain temperature) is a common technique. After the coating process, TiO2 thin film is uniformly heated to 400 °C to obtain the homogenization of the stoichiometry. In this research, the dependence of the homogeneity of the stoichiometry of TiO2 optical thin films on the rate of heat treatment (a gradual increase of heat treatment temperature over time) is investigated by X-ray Photoelectron Spectroscopy (XPS) of the samples. So, the 400 nm thick TiO2 layers are coated on the BK7 optical glass, utilizing an electron gun. Then, each sample is subjected to heat treatment at different rates. The data obtained from the XPS analysis show that the samples subjected to slow heat treatment (2.2 °C per minute, up to a final temperature of 400 °C) have a more homogeneous stoichiometry and contain higher amounts of TiO2. Based on the results, the laser-induced damage threshold of laser mirrors can be improved in the nanosecond and femtosecond regimes of radiation.

- by IJAP Iranian Journal of Applied Physics and +1
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- Materials Science, Heat Treatment, Thin film (Physics), X-Ray Photoelectron Spectroscopy

Fresh tomato (Solanum lycopersicum) is one of the most consumed fruits and the preservation of its quality and shelf-life extension is a continuous challenge. An understanding of fruit deterioration factors allows the investigation of new approaches to reach this objective. Fruit preservation is achieved by destroying enzymes and microorganisms , and reducing physiological disorders, using treatments such as chlorinated water (HIPO), ozone, low or high temperatures, ultrasounds, UV-C radiation, modified atmosphere packaging, edible coatings and 1-methylcyclopropene. In this review, a description of action, advantages and disadvantages of each preservation treatment, and corresponding effects on tomato quality and safety are presented. The development of a green technology for tomato has advantages for all fresh chain interventions, with direct or indirect impacts on human health.

- by Elsa M Gonçalves
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- Heat Treatment, Modified atmosphere packaging, Ultrasounds
- by Manuel Valiente
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- Materials Engineering, Heat Treatment, Encapsulation, Ion Exchange

Largely as a result of international trade, hundreds of species of bark-and wood-infesting insects have become established in countries outside their native range. Many of these exotic insects have caused severe economic and environmental impact to urban and forest trees in the receiving countries. Most bark-and wood-infesting insects have been transported to new countries by means of the wood packaging material (WPM) pathway, which includes products such as pallets and crating. The international community responded to the phytosanitary risk posed by untreated WPM by approving ISPM (International Standards for Phytosanitary Measures) No. 15 in 2002 that specifies treatments designed to kill wood pests in WPM used in international trade. In response to new research findings, ISPM 15 was revised in 2006 and 2009. The goal of ISPM 15, as stated in the 2009 revision, is to 'reduce significantly the risk of introduction and spread of most quarantine pests.' Since 2002, heat treatment and methyl bromide fumigation have been the only two approved phytosanitary treatments for WPM. New treatments are urgently needed given that the use of methyl bromide is being phased out worldwide. This paper presents background information on (a) ISPM 15, (b) changes that were made to ISPM 15 during each of the two revisions, (c) research highlights from projects that were used to support the revisions, (d) incidence of insects of quarantine significance that were found in WPM during surveys conducted before and after implementation of ISPM 15, and (e) research needs to further improve ISPM 15.

- by Robert Haack
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- Risk, Heat Treatment, Introduced species, Pallets

Bioactive related compounds of fresh-cut green bell peppers (Capsicum annuum, L.) exposed to water immersion at 55°C and 60°C per 180 s were evaluated during storage. Their sensorial and microbial quality, acidity, sugar and chlorophyll content were also determined. Beneficial effects on sensorial attributes were observed in treated peppers with longer shelf life than in non-treated ones (5 days at 4°C, 2 days at 10°C). At the end of storage at 4°C, phenols increased to 11% and quercetin and antioxidant capacity were retained, but in control peppers ascorbic acid dropped 16%. At 10°C, there was no change in phenols; quercetin, ascorbic acid and antioxidant activity decreased (15%, 13% and 10% respectively) in treated peppers. Changes were more noticeable in non-treated products (phenols increased 21%, ascorbic acid decreased 28% and antioxidant activity 20%). Mild heat treatments applied to fresh-cut peppers seemed to preserve some of their bioactive compounds during storage.

- by Maria Pereyra
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- Food, Pepper, Heat Treatment, Food Science and Technology

Nickel-based alloy 625 was investigated by means of a conventional corrosion test (Streicher-test according to ASTM G28A [1]) and an electrochemical potentiokinetic reactivation test (according to ASTM G108 [1], with some modifications). Susceptibility to intergranular corrosion after various heat treatments was examined by using both test methods and the results were compared. Dependent on the type of heat treatment applied, both methods showed partially different results. Possibilities and limitations of replacing Streicher-test with EPR-test are pointed out and commentated. In conclusion, the EPR-test presents itself as a promising and quick investigation technique for detecting susceptibility to intergranular corrosion in nickel-based alloys.

- by Giulio Mori
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- Materials Engineering, Mechanical Engineering, Civil Engineering, Corrosion Science

The central solenoid and toroidal field coils of ITER are designed with cable-in-conduit Nb 3 Sn superconducting conductors jacketed with Incoloy 908. This material, developed to limit the critical current degradation of the Nb 3 Sn strands, shows excellent mechanical properties at 4 K, particularly under cycling. Nevertheless, it is a crack prone material when heat treated in the presence of oxygen, which requires careful control of the atmosphere during manufacture. A programme of extensive mechanical testing of samples and manufacture of a pancake with incoloy conductor jacket was carried out in Europe. The origin of cracks in the incoloy jacket after heat treatment was investigated.

Glasses were prepared by the melt-quenching method in the ternary system Pb(PO 3 ) 2 -WO 3 -PbF 2 and doped with Er 3+ in order to prepare luminescent transparent glass-ceramics. This work focused on thermal and structural characterization of tungsten lead-phosphate glasses and crystallization study for preparing transparent glass-ceramics. Thermal properties such as thermal stability and crystallization behavior upon heating were investigated by DSC in function of PbF 2 content. For low PbF 2 concentrations, only one crystallization peak due to Pb 3 (PO 4 ) 2 is observed whereas samples containing more than 15% of PbF 2 present another exothermic event at lower temperatures related with precipitation of PbF 2 , Pb 2 P 2 O 7 and Pb 2 OF 2 . Structural investigations by Raman spectroscopy suggest that PbF 2 modifies the tungsten-phosphate network through the formation of P-F and P-O-Pb bonds but the average network connectivity remains almost constant. A crystallization study has been performed by DSC to investigate the dominant crystallization mechanisms in these glasses and it has been established that Pb 3 (PO 4 ) 2 is nucleated on the surface whereas PbF 2 , Pb 2 P 2 O 7 and Pb 2 OF 2 crystallize dominantly from the glassy bulk. Transparent glass-ceramics containing nanosized PbF 2 crystallites were also prepared by suitable heat-treatment on the glass sample containing 20% of PbF 2 and Raman microscopy of these glass-ceramics supports the crystallization mechanisms determined by DSC.

- by camila pereira
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- Materials Engineering, Raman Spectroscopy, Heat Treatment, Non crystalline solids

Fe 3 O 4 nanoparticles were prepared by carbothermal reduction method using glucose as carbon source. Heating temperature and holding time effects on crystalline phase composition and magnetic properties of Fe 3 O 4 nanoparticles were investigated by X-ray diffraction, field-emission scanning electron microscopy and vibrating sample magnetometer. Pure Fe 3 O 4 nanoparticles with an average crystallite size of 48 nm was obtained at higher heating temperature of 650 • C and shorter holding time of 0.5 h, or at lower heating temperature of 450 • C and longer holding time of more than 6 h. The crystallite size of Fe 3 O 4 nanoparticles increases with heating temperature and holding time. Fe 3 O 4 nanoparticles heated at 650 • C for 2 h have the highest saturation magnetization (M s = 97.99 emu g −1 ), higher than Fe 3 O 4 prepared by other techniques due to better microstructure, crystallinity and expanded crystalline cell.

The variation of transformation temperatures with heat treatment has been studied for the near equiatomic, 40% prior cold worked Nitinol by the DSC measurements. The austenitic and martensitic start and finish temperatures are found to be almost independent of heat-treat temperature in the range 525-680°C. Intermediate R phase is found to be stable only in the range 340-410°C. The Electrical resistivity probe is found to be better than the DSC probe in the study of hysteresis associated with R-phase transformation. Large and sharp changes in electrical resistivity in R A transformation is expected to be useful in applications.

- by Karimbi K. Mahesh
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- Condensed Matter Physics, Quantum Physics, Heat Treatment, Hysteresis

Measurement Uncertainty Sensitivity analysis Carburizing Heat treatment a b s t r a c t

- by Lingxue Kong
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- Materials Engineering, Mechanical Engineering, Kinetics, Heat Treatment

A three variables-five levels central composite design was used to study the effects of pH (3.5, 4.0, 4.5, 5.0 and 5.5), cinnamaldehyde (0, 40, 80, 120 and 160 ppm) and heating temperature (80, 84, 88, 92 and 96°C) on the spores of Alicyclobacillus acidoterrestris in malt extract broth (MEB). The heat shock resulted in a slight decrease of spore number from 3.2 to 2.5 log CFU mL )1 and occurred at 80-85°C depending on the pH of the medium. Otherwise, cinnamaldehyde acted as an additional hurdle within the storage time; the critical amounts to be used were included in the range 41.35-44.42 ppm of cinnamaldehyde and were related positively to the pH, i.e. the critical amount of active compound decreased with the decreasing of the pH.

The influence of human whole saliva on selected alcohols, aldehydes, 3-alkyl-2-methoxypyrazines, and phenols in food-relevant concentrations was investigated. At pH 7.5-8 it was found that the alcohols, methoxyphenols, methoxypyrazines, and 3-hydroxy-4,5-dimethyl-2(5H)-furanone remained unmodified by saliva, whereas aldehydes were reduced to their corresponding alcohols. Generally, the processes were found to be dependent on the salivary activity of the panelists as well as on the concentration of the applied odorants. Reduction of the aldehydes did not occur after thermal treatment of the saliva. These investigations are aimed at finding an explanation for longer lasting aftertaste in humans, as it is induced by some odor-active compounds after the consumption of food materials.

- by Andrea Buettner
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- Engineering, Heat Treatment, Comparative Study, Food Analysis

The intercalation of Li ions in natural graphite that was purified by chemical and thermal processes was investigated. A new chemical process was developed that involved a mixed aqueous solution containing 30% H 2 SO 4 and 30% NH x F y heated to 90 8C. The results of this process are compared to those obtained by heating the natural graphite from 1500 to 2400 8C in an inert environment (thermal process). The first-cycle coulombic efficiency of the purified natural graphite obtained by the chemical process is 91 and 84% after the thermal process at 2400 8C. Grinding the natural graphite before or after purification had no significant effect on electrochemical performance at low currents. However, grinding to a very small particle size before purification permitted optimization of the size distribution of the particles, which gives rise to a more homogenous electrode. The impurities in the graphite play a role as microabrasion agents during grinding which enhances its hardness and improves its mechanical properties. Grinding also modifies the particle morphology from a 2-to a 3-D structure (similar in shape to a potato). This potato-shaped natural graphite shows high reversible capacity at high current densities (about 90% at 1C rate). Our analysis suggests that thermal processing is considerably more expensive than the chemical process to obtain purified natural graphite. #

- by Abdelbast Guerfi and +1
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- Engineering, Heat Treatment, Potato, Current Density

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- by Recai KUŞ
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- Materials Engineering, Mechanical Engineering, Materials Science, Microstructure

Austenitic stainless steels (hereafter A-STS) such as STS304 and STS316 are paramagnetic metals. However, a small amount of partial magnetization is generated in A-STS because of the imperfect final heat treatment and mechanical processing. Surface cracks on paramagnetic metal with a partially magnetized region (hereafter PMR) are difficult to inspect. In this paper, we propose a method for high speed inspection and evaluation of a crack on A-STS. Cracks can be inspected with high speed by using 64 arrayed Hall sensors (HSA) with 3.5 mm spatial resolution and a sheet type induced current (STIC). Then, a crack can be evaluated quantitatively by using the detailed distribution of the magnetic field obtained by using single Hall sensor scanning (SSS) around the inspected crack area. Several cracks on A-STS with partially magnetized areas were examined and the experimental formulas were derived.

- by Jinyi Lee
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- Mechanical Engineering, Applied Mathematics, Heat Treatment, Nondestructive Evaluation

Thepreparation andproperties of NbjO, coatings made bythesol-gel process were investigated. Thefilms were deposited byspincoating on In203:Snlglass and quartz substrates from a polymeric solutions of niobia derived from niobium ethoxide. The films were characterized byinvestigation ofthestoichiometry.refractive index, optical transmission, electrochemical behavior. andthemicrostructure. X-ray diffraction studies showed the films to be amorphous forheat treatments below 450°C. X-ray photoelectron spectroscopy (XPS) measurement revealed theO:Nbatomic stoichiometry tobe5:2. Cyclic voltammetric measurements showed thattheNb 20S / 1M LiClOcpropylene carbonate system exhibits electrochemical reversibility beyond I 200 cycles without change in performance. In situ UV-Vis-NIR spectroelectrochemical measurement revealed that Nb 2 0 s films exhibit an electrochromic effect in the spectral range 300<A<2100 nm and remain unchanged in the infrared spectral range. The change in visible transmittance was 40% for a 250nm thick electrode. XPS spectra indicate thatNb(V) is reduced to a lower valence state Nb(IV) in a colored state with injected Li ". The bronze coloration is due to a simultaneous injection of electrons and Li + ions into Nb 20S ' The sol-gel-deposited Nb 20S films are useful for cathodically coloring electrochromic electrodes in electrochromic devices.

- by Carl Lampert and +1
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- Engineering, Technology, Microstructure, Electrochemistry

Thin films of CdS, deposited by chemical bath deposition (CBD) onto films of fluorine-doped tin oxide/glass (glass/FTO) substrates were prepared and investigated for photoelectrochemical conversion (PEC) of light into electricity. Knowing the hazardous nature of CdS, the focal theme of this work was to modify the electrodes by simple economic ways to maximize their conversion efficiency and minimize their degradation under PEC conditions. This was to avoid leaching out of hazardous Cd2+ ions. Different parameters have been investigated for this purpose. Multi-deposition preparation, redox couple, and electrode etching affected electrode PEC characteristics. Consistent with earlier literature, annealing the electrode enhanced its conversion efficiency and stability. On the other hand, effect of cooling rate of pre-annealed CdS electrodes, prepared by CBD, on their PEC characteristics has been investigated here for the first time. Controlling the cooling rate was one major factor that affected CdS surface morphology, conversion efficiency and stability under PEC conditions. The major recommendation coming out here is that PEC characteristics of CdS thin film electrodes can be significantly enhanced by pre-annealing the electrode at ∼250 °C followed by its slow cooling.

- by Ahed Zyoud
- •
- Engineering, Heat Treatment, Stability, FTO - Fluorine-doped tin oxide

Five different fractions of the biodegradable municipal solid waste (BMSW) were evaluated as potential animal feedstuffs. For each source of waste (meat waste (MW), fish waste (FW), fruit and vegetables waste (FVW), restaurant waste (RW), household waste (HW)), samples were obtained from small shops (butchers, fishmongers, fruit and vegetable shops), restaurants and a MSW treatment plant (household waste). The chemical composition, microbiological characterization, dioxins, furans, PCBÕs and mineral content were determined for every type of waste fraction.

- by Maria Márquez
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- Environmental Engineering, Arsenic, Waste Management, Heat Treatment

The accurate description of the relaxation phenomenon near the glass transition temperature allows a better interpretation of differential scanning calorimetry (DSC) curves, since it can be separated from other thermal effects such as crystallization, melting, and recrystallization. The structural relaxation model of Narayanaswamy and Moynihan for thermorheological simple glasses was numerically explored for obtaining a grasp of the functional influence of the different parameters: i.e. relaxation enthalpy Δh, non-linear parameter x, amplitude exponential distribution parameter b, and pre-exponential parameter A.It is known that when the relationship between the velocity of heat transfer in the cooling run (qc) and the velocity of heating in the heating run (qh) is equal to unity, the curves obtained in a DSC suffer only an horizontal translation for different absolute values of cooling and heating rates. It was found in this work that this criterion can be generalized, and curves also overlap by means of a horizontal translation when qc/qh is a constant different from one, whichever the particular values of qc or qh will be.Finally, changes in the shape of the curves when using different values of qh and qc with a fixed qc/qh relationship can be used as an indicator of the occurrence of other phenomena (i.e. recrystallization, melting, etc.) in addition to structural relaxation.

- by Andrea Nieto
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- Food Engineering, Heat Transfer, Heat Treatment, Differential scanning calorimetry

The analysis of the mineralogical composition of most rock wastes shows the presence of a high percentage of minerals with SiO2 and Al2O3, which could be used as raw materials for ceramic products. The main objective of this work is to recover wastes from one primary rock industry, utilised in the production of tiles and flooring, for the manufacturing of ceramics, using powder technology: pressing and sintering. The sinterability of the powders, with and without previous heat treatment, was studied in order to obtain a product with the best performance. Powders from different quarries after being uniaxial pressed at 40 MPa, or isostatic pressed at 170 MPa and sintered within the range 1150–1170°C present properties as follows: (a) hardness: 5.5–7.5 GPa; (b) transverse rupture strength: 55–94 MPa; (c) abrasion and erosion wear better than that of bulk to be drawn materials, and (d) water absorption of less than 0.5%. The results allow the conclusion that these wastes can be recovered and used successfully in the manufacture of ceramics with better performance than traditional tiles and flooring.

- by Marcos Oliveira
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- Materials Engineering, Mechanical Engineering, Materials, Heat Treatment
- by Stuart Maloy and +1
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- Materials Engineering, Heat Treatment, Nuclear Materials, Neutron Diffraction

The effect of hot water dipping (HWD) at 40, 44 and 48°C for 6 and 12 min on germination of conidia of brown rot fungus (Monilinia laxa) in vitro and the effect of HWD at 48°C for 6 and 12 min on the fruit quality and development of M. laxa on peach cv. "Roig" and nectarine cv. "Venus" after artificial inoculation in cold storage were studied. Temperature and duration of treatment significantly affected germination of conidia. After HWD at 48°C for 12 min, the lowest germination of conidia (9%) was recorded, which was more than 10 times lower than control (93%). After 3 days from inoculation, there were 80% of inoculated spots with visual symptoms of decay caused by M. laxa on control peaches and 40% of such spots on control nectarines. Successful infections were recorded on only 5% of inoculated spots of nectarine and 10% of inoculated spots of peach after HWD at 48°C for 12 min. HWD at 48°C for 12 min significantly decreased titratable acidity and increased soluble solids concentration/titratable acidity ratio in nectarines. No visual symptoms of heat damage were found on fruits as a consequence of any of the studied treatments. The results show that it is possible to control postharvest brown rot (M. laxa) on peach using HWD at 48°C for 12 min and on nectarine using HWD at 48°C for 6 min without a significant loss of fruit quality.

- by Goran Fruk and +1
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- Heat Treatment, Cold Storage, Fruit Quality, Prunus Persica

The prothoracicotropic hormone (PTTH) of Drosophila melanogaster is a modulator of ecdysteroid (molting hormone) synthesis and was isolated and characterized from extracts of whole larvae (approximately 4 x 10(5) larvae). The purification protocol included delipidation, salt-extraction, heat treatment, conventional column chromatography, and HPLC, and yielded about 50 microg of pure hormone. Biological activity was followed using a ring gland in vitro assay in which ecdysteroidogenesis by control ring glands as measured by radioimmunoassay was compared with ring gland incubations containing active fractions. The molecular weight of the purified PTTH was 45 kDa and N-terminal amino acid sequence analysis indicated that those analyzed sequences displayed no significant homology with known peptides or peptide hormones, including PTTH from the silkmoth, Bombyx mori. Western blot analysis indicated that the native form of Drosophila PTTH was a single 66-kDa polypeptide with N-linked carbohydrate chains and intrachain disulfide bonds. The purified 45-kDa peptide is the deglycosylated form, a result of glycosidase activity present during preparation of the PTTH extract. The deglycosylated form shows heterogeneity, presumably as a result of varying degrees of deglycosylation at the N terminus.

- by Chung Lee
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- Immunohistochemistry, Drosophila melanogaster, Heat Treatment, Multidisciplinary

Page 1. ORIGINAL ARTICLE Design of an advanced incremental fuzzy logic controller for laser surface heat treatments José Antonio Pérez &amp; José Luis Ocaña &amp; Carlos Molpeceres Received: 5 July 2006 /Accepted: 7... more

- by José-Luis Ocaña
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- Engineering, Fuzzy Logic, Heat Treatment, Mathematical Sciences

The effect of isothermal exposure on elevated-temperature time-dependent fatigue crack propagation (FCP) in INCONEL Ò alloy 783 is investigated. Commercially produced alloy 783 was annealed and aged following the standard heat treatment procedure. One set of specimens was then isothermally exposed at 500°C for 3000 hours. Both set of specimens were subjected to FCP tests with various hold time periods and sustained loading crack growth tests at 538°C and 650°C in laboratory air environment. Without hold time, as produced and isothermally exposed materials had comparable fatigue crack growth rates (FCGR) at both test temperatures. With hold times of 100s and 300s, as-produced and isothermally exposed specimens had comparable FCPR at 538°C. Hold time testing of as-produced material at 650°C showed abnormal time-dependent FCP and sustained loading crack growth retardation. However, hold time testing of isothermally exposed material at 650°C showed steady sustained loading crack growth and full time-dependent FCP typically observed in many superalloys. Comparison with alloy 718 data from the literature shows that FCP rates of as-produced alloy 718 and isothermally exposed alloy 783 are comparable at 650°C. A full time-dependent FCP model based on the damage zone concept and thermal activation equation is proposed to characterize the fatigue crack growth behaviors.

Finnish wood heat treatment technology, Ther-moWood, was recently introduced to Québec, Canada by Ohlin Thermo Tech. Subsequently, a large number of initial trials were conducted on five commercially important Québec wood species, spruce (Picea spp.), pine (Pinus spp.), fir (Abies spp.), aspen (Populus spp.), and birch (Betula spp.). These species were thermally-modified in different batches at temperatures of 200 • C or higher. The static bending and hardness of the thermally-modified wood were examined. Decreases of 0% to 49% were observed in modulus of rupture of heat-treated spruce, pine, fir, and aspen depending on species and treatment schedules used; modulus of rupture of birch increased slightly after the heat treatment. The decrease in modulus of elasticity of heat-treated spruce and pine ranged from 4% to 28%; but the modulus of elasticity of heat-treated fir, aspen, and birch increased except one trial for fir. Hardness of the heat-treated wood increased or decreased depending on the species, test directions (radial, tangential, and longitudinal), and treatment schedules.

- by Duygu Kocaefe
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- Heat Treatment, Populus, Building, Forestry Sciences

Oxide coverage of molybdenum plays an important role in several applications, for example in lighting industry. Surface conditioning procedures were simulated in an XPS instrument by in situ heat treatments while monitoring the surface composition and changes in the chemical states of molybdenum. Heat treatments have been made at different temperatures between 435 and 690°C under vacuum conditions. It has been observed that during heating the molybdenum test samples the native MoO 3 layer on the surface dissociates, and a layer of suboxides forms on the surface. This layer hinders the further reduction of the surface, thus reaction speed decreases after the initial phase. It has been established that in the second phase of the heat treatment the activation energy of the process is 1.1 ± 0.2 eV. Reduction of MoO 3 to elemental molybdenum runs through two intermediate states: Mo 6+ ? Mo 5+ ? Mo 4+ ? Mo 0 .

- by Agoston Boroczki
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- Materials Engineering, Heat Treatment, Activation Energy

El inhibidor de tripsina es un factor nutricional presente en la soya, que debe ser degradado en los productos que se elaboran a partir de esta semilla. Bebidas de soya preparadas con diferente proporción soya-agua, utilizando grano previamente remojado y escaldado, fueron sometidas a tratamiento térmico a 80°C y a intervalos de 5 min, se midió la actividad de la enzima ureasa y del inhibidor de tripsina. Se pudo comprobar que el tiempo requerido para que la bebida sea nutricionalmente aceptable depende de la proporción soya-agua empleada. Mediante regresión multivariada utilizando Mínimos Cuadrados Ordinarios se determinó una función que permite predecir el valor de la actividad del inhibidor de tripsina en la bebida a partir del tiempo de tratamiento y de la actividad de la enzima ureasa. Palabras clave: bebida de soya, inhibidor de tripsina, ureasa, tratamiento térmico.

- by Luis Alfonso Caicedo
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- Heat Treatment, Vitae

Usually aspects related to the level of impurities and specific alloying elements are analyzed regarding their influence on the susceptibility to temper embrittlement of a 2.25% Cr-0.5% Mo steel. Heat treatments are employed to simulate in-service degradation on an accelerated basis. Of the possible heat treatments, step cooling has been the most widely employed. However, it is evident that, while there has been an evolution in steel manufacturing processes, the same cannot be said for the simulation techniques (accelerated tests) or the verification of their accuracy. In the present work, samples of a 1.25% Cr-0.5% Mo steel removed from industrial equipment after 250,000 h of operation at 540 8C revealed a significant loss in toughness. This same material, subjected to de-embrittlement and recovery heat treatments, showed an improvement in the level of absorbed energy on Charpy impact testing, as compared to the material in the postservice condition. This material was then utilized as the base material for further testing. The subsequent application of the conventional step cooling heat treatment to this recovered material in order to simulate the service conditions resulted in Charpy impact energy levels superior to those exhibited by the original material (degraded by actual service conditions), thereby suggesting that the step cooling was not able to simulate satisfactorily such service conditions for this material.

- by Ivani S Bott
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- Materials Engineering, Mechanical Engineering, Materials, Heat Treatment

The leather waste generated by the footwear industry is considered dangerous due to the presence of trivalent chromium, derived from the salt utilized to tan hides. In Brazil, the majority of this waste is disposed on landfills and only about 3% are recycled. The thermal treatment is an alternative method for purification of such residues. By using this technique it is possible to generate energy and recover the chromium present in the ash for the production of basic chromium sulfate (tanning industry), high carbon ferrochromium or carbon-free ferrochromium (steel industry). In the last 10 years, the gasification and combustion of footwear leather waste have been intensively studied at the Federal University of Rio Grande do Sul. The research experiment for characterization of the emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) were carried out in a semi-pilot unit (350 kW th ). From new investments the thermal capacity of the unit will increase to 600 kW th . The unit will produce power from the heat generated in the combustion. The experimental results indicated that during the thermal treatment of footwear leather wastes, the formation mechanism of PCDD/F is the de novo synthesis. Most of PCDD/F were found in the particulate phase (>95%). A kinetic model was used for discussion of the achieved experimental results. The model is based in the carbon gasification, PCDD/F formation, desorption and degradation. From the conclusions obtained in this work will be possible minimize the PCDD/F formation in process of combustion of footwear leather wastes.

- by Leonardo Marcílio
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- Engineering, Production, Modeling, Combustion

The characteristics of resistive switching of TiN/HfO2/Ti/HfO2/Pt/Ti stacks on SiO2/Si substrates were investigated and compared to TiN/HfO2/Pt/Ti stacks in order to study Ti interlayer effects on resistive switching. The Ti interlayers were deposited in situ during the reactive sputtering of HfO2 films. The current–voltage measurements showed that the Ti interlayers enhanced the memory window but reduced the endurance of SET/RESET operations. The energy filtered images by TEM showed asymmetric oxygen accumulation at the Ti/HfOx interfaces. Subsequent heat treatment improved the endurance of SET/RESET operation of TiN/HfO2/Ti/HfO2/Pt/Ti stacks.

- by Hyunchul Sohn
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- Condensed Matter Physics, Heat Treatment

The influence of soy protein subunit composition on the particle size distribution and solid content of soymilk and various supernatant fractions was investigated. A well-established seed variety (Harovinton), containing all protein subunits, and eleven null soybean genotypes lacking specific glycinin and b-conglycinin subunits were investigated, to determine the effect of protein composition on the physicochemical characteristic of soymilk. Soymilk made from Harovinton and soybean lines null in glycinin showed significantly higher total solid yields than the other genotypes evaluated. Soymilks prepared from soybeans null for glycinin or lacking glycinin's group I (A 1 , A 2 ) showed a smaller particle size distribution compared to soybean lines containing glycinin. In general, unheated soymilk made from lines having glycinin showed a bimodal size distribution with large particles, with a decrease in the particle size distribution after heating and heating with homogenization. The results of this work will help in the evaluation of breeding lines with a specific protein composition tailored to a specific processing functionality.

- by Milena Corredig
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- Heat Treatment, Animal Production, Soybean, Size Distribution