Improvement of the wettability of SiMn IF-HSS by liquid zinc by controlling the dew point of the annealing gas atmosphere

The wettability of low-carbon, 0.3 wt%Si–0.4 wt%Mn interstitial-free steel by liquid zinc at 450 °C was investigated using the dispensed sessile drop method. Before the wetting tests, the steel samples were annealed in a 15%H₂–Ar gas atmosphere at three different dew points, namely −60, −40, and 0 °C. It was found that as the dew point was increased from −60 to −40 °C, the wettability became poorer. However, as the dew point was increased further to 0 °C, the wettability was dramatically improved and was better than that of −60 °C. In order to understand the dramatic change in wettability, the surfaces of the steel samples after annealing were analyzed with SEM and TEM. It was found that the surface oxide changed from randomly distributed hemisphere particles of 20–30-nm high on a very thin oxide film to a film-like layer ~15-nm thick as the dew point was increased from −60 to −40 °C, and at the dew point of 0 °C, internal oxidation was so pronounced that a very thin surface oxide layer 1–2-nm thick was formed. It was believed that the improvement of the wettability at the dew point of 0 °C was caused by the short diffusion distance in the surface oxide layer.     

Experimental Investigation of the Cr3C2–C Peritectic Fixed Point

The Cr₃C₂–C (1,826°C) peritectic point was investigated for its performance as a high-temperature fixed point. Dependence on the impurity content was observed, although it was less severe for the higher of the two equilibrium temperatures obtained with the same cell, the Cr₃C₂–C peritectic point, than for the lower, the Cr₇C₃–Cr₃C₂ eutectic point. Thermal history had an effect on the melting plateau duration, but not on the point-of-inflection temperature nor on the melting range. The melting rate had no apparent effect. The repeatability evaluated as the standard deviation of the repeated melting plateaux within a day was 20 mK for the Cr₃C₂–C peritectic point, while for the Cr₇C₃–Cr₃C₂ eutectic point, this was 210 mK. For both the Cr₃C₂–C peritectic and the Cr₇C₃–Cr₃C₂ eutectic, the freezing plateaux often showed deep supercools, which made them unsuitable for use. The observed good repeatability shows the peritectic-point performance to be comparable to the best MC-eutectic high-temperature fixed points investigated so far. The insensitivity to thermal history constitutes an important and practical advantage. The low price of chromium is a clear benefit as compared to Pt–C (1,738°C) or Ru–C (1,953°C) eutectic points, the M–C eutectic points in this temperature range.     

Effect of platinum oxidation on the characteristics of standard platinum resistance thermometers

Platinum oxidation in PTS-10 and PTS-25 standard platinum resistance thermometers has been studied. The experimental results show that heat treatment of a thermometer at 100–300°C can increase its resistance at the triple point of water by the equivalent of 1.5 mK. A procedure for calibration in the range 0–450°C is recommended. Translated from Izmeritel'naya Tekhnika, No. 7, pp. 41–44, July, 1996.     

Evaluation of Cobalt–Carbon and Palladium–Carbon Eutectic Point Cells for Thermocouple Calibration

Two cobalt–carbon (Co–C) eutectic point (1,324 °C) cells and one palladium–carbon (Pd–C) eutectic point (1,492 °C) cell were constructed for thermocouple calibration. The lengths of the Co–C and Pd–C cells were 297 mm, 140 mm, and 140 mm, respectively. The melting and freezing plateaux at the Co–C and Pd–C eutectic points were observed using Pt/Pd thermocouples. The repeatability of the plateau, the effect of the surrounding temperature, and the temperature profile in the cell were measured, and the heat flux effect along the thermometer well was evaluated. When the plateaux of Co–C (297 mm height), Co–C (140 mm height), and Pd–C cells, were measured three times, seven times, and six times, respectively, the standard deviations of the melting points were 0.1 μV, 0.1 μV, and 0.4 μV, respectively. According to the temperature profiles along the thermometer well during the melting plateaux, it was found that the Pt/Pd thermocouple should be inserted at least 9.5 cm, 5 cm, and 6 cm below the surface of the eutectic alloys in the Co–C (297 mm height), Co–C (140 mm height), and Pd–C cells with the furnace set-point 16 °C above the melting point.     

The effect of damping and force application point on the non-linear dynamic behavior of a cracked beam at sub-and superresonance vibrations

The finite element model of an elastic body with a closing crack is presented. Using this model, we show that the non-linear distortions of vibrations at superharmonic and subharmonic resonances are the high sensitive indicators of crack presence. The intensity of these indicators manifestation substantially depends on the level of damping in the system and on the load application point. __________ Translated from Problemy Prochnosti, No. 5, pp. 61–67, September–October, 2006. Report on International Conference “Dynamics, Strength, and Life of Machines and Structures” (1–4 November 2006, Kiev, Ukraine).     

Modernization of the MAS-1 microscope for use in measurements of the spectra of internal conversion electrons

Efforts to increase the speed with which microscopic objects are measured are described. These efforts include the modernization of the MAS-1 automatic scanning microscope and the development of programs to reach an initial point and for carrying out automatic point-to-point linear transitions with a specified step. The error in realizing a transition to a given point with specified coordinates is shown to amount to 1 μm. Translated from Izmeritel’naya Tekhnika, No. 1, pp. 22–24, January, 2009.     

Measurement of Specific Fracture Energy and Surface Tension of Brittle Materials in Powder Form

Studies of the influence of specimen geometry and size–effect on the K _R –curves and the related fracture parameters were carried out by the authors (Kumar and Barai 2008b). The present paper is a supplementary contribution and reports interesting results related to the effect of the loading condition and size–effect studies on the K _R –curves associated with the cohesive stress distribution for complete fracture process, the double–K fracture parameters, the CTOD–curves and the process zone length using two different loading conditions (i.e., three–point bending test and four–point bending test). The laboratory size specimen with initial–notch length/depth ratios 0.3 and 0.5 are considered in the work. The load–crack opening displacement curves for these loading conditions are obtained using well known version of fictitious crack model.     

Injectable thermosensitive hydrogel based on chitosan and quaternized chitosan and the biomedical properties

A novel injectable thermosensitive hydrogel (CS–HTCC/α β-GP) was successfully designed and prepared using chitosan (CS), quaternized chitosan (HTCC) and α,β-glycerophosphate (α,β-GP) without any additional chemical stimulus. The gelation point of CS–HTCC/α β-GP can be set at a temperature close to normal body temperature or other temperature above 25°C. The transition process can be controlled by adjusting the weight ratio of CS to HTCC, or different final concentration of α,β-GP. The optimum formulation is (CS + HTCC) (2% w/v), CS/HTCC (5/1 w/w) and α,β-GP 8.33% or 9.09% (w/v), where the sol–gel transition time was 3 min at 37°C. The drug released over 3 h from the CS–HTCC/α,β-GP thermosensitive hydrogel in artificial saliva pH 6.8. In addition, CS–HTCC/α,β-GP thermosensitive hydrogel exhibited stronger antibacterial activity towards two periodontal pathogens (Porphyromonas gingivalis, P.g and Prevotella intermedia, P.i). CS–HTCC/α, β-GP thermosensitive hydrogel was a considerable candidate as a local drug delivery system for periodontal treatment.     

Optimizing the Implementation of High-Temperature Fixed Points through the Use of Thermal Modeling

High-temperature fixed points (HTFP) have the potential to make a step-change improvement in high-temperature metrology, significantly reducing the uncertainty of scale realization of the current ITS-90 and improving dissemination of high-temperature scales to industry. However, in a practical implementation, the performance of HTFP could be limited, by, for example, injudicious use of insulation in the vicinity of the fixed point, furnace gradients, or incomplete filling. This article investigates some of these aspects for a selection of HTFP. Steady-state modeling of the influence of insulation on the radiance temperature was performed for Co–C (1,324°C), Pd–C (1,492°C), Pt–C (1,738°C), Ru–C (1,953°C), and Re–C (2,474°C) fixed points. This included studying mitigation scenarios through the insertion of different types and designs of insulation. The optimum design was identified to minimize the temperature drop in a particular furnace. It was found that, for the furnace and fixed-point combination modeled, the actual effect of the insulation was almost insignificant. Transient modeling was performed for a Re–C fixed point, to track the evolution of the radiance temperature through the melting transition. The starting point of the model was the beginning of the melt. The evolution of radiance temperature with time in “perfectly” filled cells was modeled with a range of linear temperature gradients across the eutectic cell. The gradient had a significant effect on the duration of the transition and on the structure of the melt itself. Despite the model’s simplicity, it qualitatively demonstrated that the melt transition temperature, as identified by the point of inflection, could be significantly affected by the presence of furnace gradients.     

An analysis of the temperature field of the workpiece in dry continuous grinding

The recent model for heat transfer during intermittent grinding described in Skuratov, Ratis, Selezneva, Pérez, Fernández de Córdoba and Urchueguía (Appl Math Model 31:1039–1047, 2007) is considered. This model is particularized to the case of continuous dry grinding, where an alternative solution is obtained in the steady state. This alternative solution is analytically equivalent to the well-known formula of Jaeger (Proc R Soc NSW 76:204–224, 1942) for the steady–state temperature field created by an infinite moving source of heat and proves to be very useful for evaluating the maximum point of the temperature.     

Numerical study of the effect of nonlinear control on the behavior of a liquid drop in elongational flow with vorticity

The problem of controlling a liquid drop suspended in an arbitrary two-dimensional elongational flow with vorticity is revisited. Bentley and Leal (J Fluid Mech 137:219–240, 1986) kept the drop centroid at the stagnation point using a linear proportional control strategy in a four-roll-mill apparatus that projects the drop’s motion onto the stable flow direction of the stagnation point. A nonlinear strategy based on the Poincaré–Bendixson theory to ensure a periodic motion of the drop centroid inside a prescribed area around the stagnation point is proposed and studied. In addition, a detailed numerical study is presented to illustrate the effect of the control on the drop motion. The present strategy is effective, allowing for deformation and changes in the drop orientation by less than 1% for extreme flow conditions that cannot be achieved by a four-roll-mill setup.     

Analysis of the stressed state of a rectangular wedge loaded by a concentrated force

We construct an analytical solution of the problem of the stressed state of a quarter plane loaded by a concentrated force at a certain distance from its corner point. In constructing the required solution, we use a reflection model similar to reflection of elastic stress waves from a free surface. The stressed state at an arbitrary point of the quadrant is constructed as a superposition of two loads one of which is applied at the same point as the concentrated force and the second (imaginary) one is applied at a point symmetric to the indicated point about the free surface. Translated from Problemy Prochnosti, No. 6, pp. 77–85, November–December, 1997.     

Properties of Perfluorobenzene near the Critical Point

The density of vapor and liquid perfluorobenzene along the liquid–vapor coexistence curve has been studied by a gamma-ray attenuation technique over the temperature range from 299 to 517 K. According to measurements, the coordinates of the critical point are T_C = 516.66 ± 0.05 K and ρ _C = 550.5 ± 2 kg · m⁻³. The critical exponent β of the coexistence curve equals 0.343 ± 0.005, which agrees closely with the non-classical value. The results of our measurements were compared with data available in the literature. The height dependence of the density of a two-phase sample was investigated in relation to the temperature and time. These experiments made it possible to determine the isothermal compressibility of liquid and vapor phases near the critical point.Paper presented at the Seventeenth European Conference on Thermophysical Properties, September 5–8, 2005, Bratislava, Slovak Republic.     

Apparatus for realizing the ITS-90 in the temperature range from the triple point of argon to the melting point of gallium

Systems for realizing the fixed points of the ITS-90 for calibrating column and capsule standard platinum thermometers, namely, the triple points of argon and mercury and the melting point of gallium, are constructed and investigated. The errors of the values of the metrological characteristics of the systems obtained enable one, using platinum resistance thermometers, to reproduce and transfer the temperature scale in the 83.8–302.9 K range. The extended uncertainty in reproducing the temperatures of the fixed points does not exceed 0.4 mK. This paper has been prepared from the contributions presented at the 3rd All-Russia Conference “Temperature 2007”; see the selection of papers in Measurement Techniques, Nos. 8 and 9, 2007. __________ Translated from Izmeritel’naya Tekhnika, No. 11, pp. 26–31, November, 2007.     

Diffraction of SH-waves on interface cracks under the action of concentrated forces

In the mathematically rigorous statement, we solve the problem of diffraction of elastic SH-waves on a finite (semiinfinite) crack located on the plane boundary of two perfectly joined materials. As a sounding field, we consider the field of a point source. The problem is reduced to the Wiener – Hopf functional equation, which is solved by the method of factorization. An approximate solution of this equation is obtained. We numerically study the distribution of the field in the radiation zone and the distinctive features of its formation depending on the location of the source of radiation. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 44, No. 6, pp. 67–77, November–December, 2008.     

Measurement of the electrical parameters of nonlinear objects

Measurement is considered from the point of view of energy exchange. A method of measuring the electrical parameters of nonlinear objects under constant dissipative power conditions is proposed. Translated from Izmeritel’naya Tekhnika, No. 3, pp. 60–62, March, 2009.     

Application of group theory to the analysis of the equations of stationary heat conduction and static thermoelasticity

Similarity transformations are constructed and used to obtain an exact solution of the axially symmetric boundary-value problem of static thermoelasticity for a half space whose free surface is heated by a continuous point heat source. It is shown that this solution agrees with the solution obtained earlier by the method of thermoelastic potentials. Franko L'viv State University, L'viv. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 35, No. 3, pp. 69–73, May–June, 1999.     

Universal nature of the instability of the thermodynamic parameters of transient processes accompanying the melting of crystalline substances in quasistatic regimes

A numerical method of differential thermal analysis was used to study transient processes accompanying the melting of germanium and antimony in quasistatic regimes at heating rates of ∼1 K/min. It is shown that the premelting initiation temperature and the melting initiation point are unstable and depend on the initial conditions. Pis’ma Zh. Tekh. Fiz. 25, 1–5 (February 26, 1999)     

Investigation of TiC–C Eutectic and WC–C Peritectic High-Temperature Fixed Points

TiC–C eutectic (2,761°C) and WC–C peritectic (2,749°C) fixed points were investigated to compare their potential as high-temperature thermometric reference points. Two TiC–C and three WC–C fixed-point cells were constructed, and the melting and freezing plateaux were evaluated by means of radiation thermometry. The repeatability of the TiC–C eutectic within a day was 60 mK with a melting range roughly 200 mK. The repeatability of the melting temperature of the WC–C peritectic within 1 day was 17 mK with a melting range of ∼70 mK. The repeatability of the freezing temperature of the WC–C peritectic was 21 mK with a freezing range less than 20 mK. One of the TiC–C cells was constructed from a TiC and graphite powder mixture. The filling showed the reaction with the graphite crucible was suppressed and the ingot contained less voids, although the lack of high-purity TiC powder poses a problem. The WC–C cells were easily constructed, like metal–carbon eutectic cells, without any evident reaction with the crucible. From these results, it is concluded that the WC–C peritectic has more potential than the TiC–C eutectic as a high-temperature reference point. The investigation of the purification of the TiC–C cell during filling and the plateau observation are also reported.     

Effect of processing conditions on the nucleation and growth of indium-tin-oxide nanowires made by pulsed laser ablation

Indium–tin oxide nanowires were deposited by excimer laser ablation onto catalyst-free oxidized silicon substrates at a low temperature of 500 °C in a nitrogen atmosphere. The nanowires have branches with spheres at the tips, indicating a vapor–liquid–solid (VLS) growth. The deposition time and pressure have a strong influence on the areal density and length of the nanowires. At the earlier stages of growth, lower pressures promote a larger number of nucleation centers. With the increase in deposition time, both the number and length of the wires increase up to an areal density of about 70 wires/μm². After this point all the material arriving at the substrate is used for lengthening the existing wires and their branches. The nanowires present the single-crystalline cubic bixbyite structure of indium oxide, oriented in the 〈100〉 direction. These structures have potential applications in electrical and optical nanoscale devices.