Temat: thermal shock - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: The effect of graphite flake diameter on the resistance to thermal shock, microstructure and mechanical properties of silicon carbide nanomaterials
Autorzy:: Mahmood, Mohammed H.
Khalaf, Wekar M.
Azeez, Kafel
Tematy:: graphite
flake diameter
thermal shock
microstructure; Pokaż więcej
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Powiązania:: https://bibliotekanauki.pl/articles/59256825.pdf Link otwiera się w nowym oknie
Opis:: To ascertain the impact of graphite flake diameter on the microstructure and mechani- cal properties as well as resistance to thermal shock, graphite flakes of various diameters have been added to zirconium dibromide (ZrB2) 20 vol.% nano-silicon carbide (SiC) 20 vol.% graphite (ZSnpG) ceramics. The objective of this study is to investigate the effect of graphite flake diameter on silicon carbide nanomaterials. The study aims to identify a strategy for achieving high comprehensive performance of ZrB2-based ceramics incorporating graphite for future research on ultra-high temperature ceramics (UHTCs). The dispersion of mea- surements has been conducted by combining a solid powder with ethanol at various mass fractions. The results demonstrated that, while no changing fracture toughness considerably, the relative density and flexural strength of ZSnpG ceramics initially increased and then de- clined with graphite diameter increasing. The micro-crack length reduction due to residual thermal stress, appearance of silicon carbide nanoparticles within granulation, and manage- ment of graphite distribution all contributed significantly to the improvement of flexural strength ZSnpG ceramics. According to the computed thermal shock parameters, ZSnpG ceramics fracture propagation was constrained by graphite with a larger starting diameter and prevented with a finer starting diameter.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Analysis and research of piston working conditions of combustion engine in high thermal load conditions
Autorzy:: Jankowska-Sieminska, B.
Jankowski, A.
Slezak, M.
Tematy:: combustion engine
piston
thermal load
thermal expansion
thermal shock; Pokaż więcej
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Powiązania:: https://bibliotekanauki.pl/articles/243400.pdf Link otwiera się w nowym oknie
Opis:: Explanation of phenomena occurring in pistons of combustion engines which appear during heating and cooling processes in reference to standard materials and composite materials of high material proprieties is aim of the paper. Bring over researches were mostly directed on measurements of difference dimensions which appear during the piston work in the combustion engine. The paper concentrates on phenomenon of different proprieties of materials. The thermal stresses and shocks differ. In the thermal shock, thermal stresses are caused by instantaneous temperature gradients which appear at high engine speed. These stresses are determined thro temperature distribution and they do not differ from stresses in steady-state conditions. Researches concerning thermal expansions were performed by means of sensitive dilatometer which can work in simple and differential system. Changes of dimensions versus temperature function were measured with inductive sensor and the sensitive Pt-ptrh thermocouple, and results were referred to reference material-Platinum. Research results are illustrated on diagrams of different courses of changes of the of thermal expansion coefficient during heating and cooling of standard and composite materials. Values of the thermal expansion coefficient a for the heating and cooling are smaller for composite alloys. The course of the coefficient â during cooling can be higher or lower from the coefficient a during heating. Similar values were also received. Maximum differences were of 10%. Smaller values of the coefficient a for composite alloys cause that for such the same thermal loads temperature gradients will be smaller for composite alloys. Courses of changes of the coefficient â have a different characteristics suited from chemical composition of alloy, granularity of the composite component and thermal treatment.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Reliability Examinations of SAC Lead Free Solder Material
Autorzy:: Koncz-Horváth, D.
Gergely, G.
Gyökér, Z.
Gácsi, Z.
Tematy:: SAC
thermal shock test
intermetallic layer
crack; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/354957.pdf Link otwiera się w nowym oknie
Opis:: In this paper the effect of soldering technique and thermal shock test were investigated on SAC 305 solder joints, produced by two different solder method. The solder joints were subjected to different cycle numbers up to 5000 thermal shock tests with two different thermal profiles of –30/+110°C and –40/+125°C. Microstructural properties of the tested joints were examined with the focus on intermetallic layer thickness and crack formation/propagation. Thickness of the scallop shaped Cu6Sn5 intermetallic layer was increased with increasing cycle number for both THRS and multiwave joints, but the thickening was more effective for the THRS joints. Cracks typically formed at the solder alloy/PTH barrel and the solder alloy/pin interfaces and propagated along grain boundaries and precipitations of intermetallic compound.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Problems of the starting and operating of hydraulic components and systems in low ambient temperature (Part IV) Modelling the heating process and determining the serviceability of hydraulic components during the starting-up in low ambient temperature
Autorzy:: Jasiński, R.
Tematy:: hydraulic drive
hydraulic components
thermal shock
computer simulation; Pokaż więcej
Wydawca:: Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Powiązania:: https://bibliotekanauki.pl/articles/260163.pdf Link otwiera się w nowym oknie
Opis:: Designers of hydraulically driven machines and devices are obliged to ensure during design process their high service life with taking into account their operational conditions. Some of the machines may be started in low ambient temperature and even in thermal shock conditions (due to delivering hot working medium to cold components). In order to put such devices into operation appropriate investigations, including experimental ones - usually very expensive and time-consuming, are carried out. For this reason numerical calculations can be used to determine serviceability of a hydraulic component or system operating in thermal shock conditions. Application of numerical calculation methods is much less expensive in comparison to experimental ones. This paper presents a numerical calculation method which makes it possible to solve issues of heat exchange in elements of investigated hydraulic components by using finite elements method. For performing the simulations the following data are necessary: ambient temperature, oil temperature, heat transfer coefficient between oil and surfaces of elements, as well as areas of surfaces being in contact with oil. By means of computer simulation method values of clearance between cooperating elements as well as ranges of parameters of correct and incorrect operation of hydraulic components have been determined. In this paper results of computer simulation of some experimentally tested hydraulic components such as axial piston pump and proportional spool valve, are presented. The computer simulation results were compared with the experimental ones and high conformity was obtained.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Problems of the starting and operating of hydraulic components and systems in low ambient temperature (Part V) methods ensuring correct start-up of hydraulic components of ship’s onboard devices in low ambient temperatures
Autorzy:: Jasiński, R.
Tematy:: hydraulic drive
hydraulic components
thermal shock
computer simulation; Pokaż więcej
Wydawca:: Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Powiązania:: https://bibliotekanauki.pl/articles/259768.pdf Link otwiera się w nowym oknie
Opis:: A large number of hydraulic devices and systems are started in low ambient temperatures. A good example of such a device is the hoisting winch on the ship. Starting hydraulic drive units in thermal shock conditions (rapid supply of hot oil to the cold unit) may lead to incorrect operation of the actuating system, for instance, due to the loss of clearance between cooperating elements. The article presents methods to prevent the disappearance of effective clearance in a hydraulic motor started in thermal shock conditions. For this reason, the structure of the hydraulic satellite motor was complemented by elements creating special channels through which hot oil could flow and additionally heat fixed parts of the motor. This solution ensures faster heating of motor housing, thus decreasing the temperature difference between the housing and the satellites during motor start-up in thermal shock conditions.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Sensitivity of ‘Monika’ Cucumis sativus seedlings to low temperature and induction of chilling tolerance
Autorzy:: Górnik, Krzysztof
Tematy:: chilling sensitivity
cucumber
thermal shock
temperature stress
chilling resistance; Pokaż więcej
Wydawca:: Instytut Hodowli i Aklimatyzacji Roślin
Powiązania:: https://bibliotekanauki.pl/articles/2199620.pdf Link otwiera się w nowym oknie
Opis:: The aim of the research was to investigate the chilling sensitivity of cucumber seedlings and to alleviate its negative effects by short-term shock temperature applied during seeds imbibition, before radicle protrusion. The chilling sensitivity was investigated depending on initial root length (1, 3, 5 and 7 mm) and duration of chilling exposure (0, 1, 3, 7, 14, 21 days) at 0˘C and was evaluated by measurements of roots and hypocotyls growth, electrolyte leakage and dehydrogenases activity. To assess whether short-term shock temperature applied before radicle protrusion can increase chilling tolerance in cucumber seedlings the seeds were imbibed at 25°C for 16 h, exposed to temperatures of 0; 2,5; 5; 35; 40, 45°C for 0; 0,5; 1; 2; 4 h. The obtained results indicated that cucumber seedlings sensitivity depended on duration of chilling exposure and initial root length during which the seedlings were subjected to these conditions. Chilling sensitivity were manifested by drop in the roots and hypocotyls elongation, reduction in dehydrogenases activity and membrane integrity expressed by electrolyte leakage. Seedlings with 1 mm roots was relatively tolerant to 3 days of chilling at 0°C. Their chilling sensitivity increased as roots elongated. Seedling with 3, 5, 7 mm of roots subjected to chilling suffered a subsequent 71, 75 and 81% of growth inhibition, respectively. The presented results showed that a short-term of low (0; 2,5 or 5°C) or high (35; 40 or 45°C) temperature treatments applied before radicle protrusion i.e. after 16 h of seeds imbibition significantly counteracted the negative effects of chilling on seedlings. The best results expressed by increased length and the number of roots were obtained when imbibed seeds were exposed to 45°C for 2 and 4 h. The increased chilling tolerance of cucumber seedlings induced as early as at the stage of seed imbibition, before radicle protrusion indicates on the possibility of application of this method in practice. The positive response of such treatment on cucumber chilling tolerance are discussed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Sensitivity of ‘Monika’ Cucumis sativus seedlings to low temperature and induction of chilling tolerance
Autorzy:: Górnik, Krzysztof
Tematy:: chilling sensitivity
cucumber
thermal shock
temperature stress
chilling resistance; Pokaż więcej
Wydawca:: Instytut Hodowli i Aklimatyzacji Roślin
Powiązania:: https://bibliotekanauki.pl/articles/55928220.pdf Link otwiera się w nowym oknie
Opis:: The aim of the research was to investigate the chilling sensitivity of cucumber seedlings and to alleviate its negative effects by short-term shock temperature applied during seeds imbibition, before radicle protrusion. The chilling sensitivity was investigated depending on initial root length (1, 3, 5 and 7 mm) and duration of chilling exposure (0, 1, 3, 7, 14, 21 days) at 0˘C and was evaluated by measurements of roots and hypocotyls growth, electrolyte leakage and dehydrogenases activity. To assess whether short-term shock temperature applied before radicle protrusion can increase chilling tolerance in cucumber seedlings the seeds were imbibed at 25°C for 16 h, exposed to temperatures of 0; 2,5; 5; 35; 40, 45°C for 0; 0,5; 1; 2; 4 h. The obtained results indicated that cucumber seedlings sensitivity depended on duration of chilling exposure and initial root length during which the seedlings were subjected to these conditions. Chilling sensitivity were manifested by drop in the roots and hypocotyls elongation, reduction in dehydrogenases activity and membrane integrity expressed by electrolyte leakage. Seedlings with 1 mm roots was relatively tolerant to 3 days of chilling at 0°C. Their chilling sensitivity increased as roots elongated. Seedling with 3, 5, 7 mm of roots subjected to chilling suffered a subsequent 71, 75 and 81% of growth inhibition, respectively. The presented results showed that a short-term of low (0; 2,5 or 5°C) or high (35; 40 or 45°C) temperature treatments applied before radicle protrusion i.e. after 16 h of seeds imbibition significantly counteracted the negative effects of chilling on seedlings. The best results expressed by increased length and the number of roots were obtained when imbibed seeds were exposed to 45°C for 2 and 4 h. The increased chilling tolerance of cucumber seedlings induced as early as at the stage of seed imbibition, before radicle protrusion indicates on the possibility of application of this method in practice. The positive response of such treatment on cucumber chilling tolerance are discussed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Life Prediction Mechanism of Ladle Composite Structure Body Based on Simulation Technology
Autorzy:: Li, Gongfa
Jiang, Du
Sun, Ying
Jiang, Guozhang
Tao, Bo
Tematy:: ladle life prediction
initiative maintenance
crack propagation
thermal shock method; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/353596.pdf Link otwiera się w nowym oknie
Opis:: Ladle plays an important role in the metallurgical industry whose maintenance directly affects the production efficiency of enterprises. In view of the problems such as low maintenance efficiency and untimely maintenance in the current ladle passive maintenance scheme, the life prediction mechanism for ladle composite structures is established which bases on the stress analysis of steel shell and ladle lining in the production process, combining conventional fatigue analysis and extended fracture theory. The mechanism is accurate and effective according to the simulation results. Through which, the useful life of steel shell can be accurately predicted by detecting the crack length of it. Due to the large number of factors affecting the life of the lining of the ladle, it is difficult to accurately predict the life of the ladle lining, so a forecasting mean based on the thermal shock method is proposed to predict the service life of the ladle lining in this paper. The life prediction mechanism can provide data support and theoretical guidance for the active maintenance of the ladle, which is the prerequisite for scientifically formulating ladle initiative maintenance program.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Impact of thermal fatigue on young’s modulus of epoxy adhesives
Autorzy:: Kłonica, M.
Tematy:: Young's modulus
epoxy adhesive
Hysol 9466
Hysol 3421
thermal shock; Pokaż więcej
Wydawca:: Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Powiązania:: https://bibliotekanauki.pl/articles/102676.pdf Link otwiera się w nowym oknie
Opis:: The following paper presents a comparative analysis of two epoxy-based adhesives: Hysol 9466 and Hysol 3421, prior to and after thermal shock testing. The tests focused on determining Young’s modulus. Epoxy-based materials are among the most widespread adhesive materials used as universal structural adhesives. The prepared epoxy samples (Hysol 9466 and Hysol 3421) were subjected to thermal shock cycling tests, according to a specified programme, in a thermal shock testing chamber, at a temperature range –40 °C to +60 °C and in the number of 200 cycles. Conclusions from the tests are presented at the final stage of the paper.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: The experimental and theoretical investigations of damage development and distribution in double-forged tungsten under plasma irradiation-initiated extreme heat loads
Autorzy:: Väli, B.
Laas, T.
Paju, J.
Shirokova, V.
Paduch, M.
Gribkov, V. A.
Demina, E. V.
Pimenov, V. N.
Makhlaj, V. A.
Antonov, M.
Tematy:: divertor material
nuclear fusion
off-normal events
thermal shock
tungsten; Pokaż więcej
Wydawca:: Instytut Chemii i Techniki Jądrowej
Powiązania:: https://bibliotekanauki.pl/articles/148167.pdf Link otwiera się w nowym oknie
Opis:: The influence of extreme heat loads, as produced by a multiple pulses of non-homogeneous flow of slow plasma (0.1–1 keV) and fast ions (100 keV), on double-forged tungsten (DFW) was investigated. For generation of deuterium plasma and fast deuterons, plasma-focus devices PF-12 and PF-1000 are used. Depending on devices and conditions, the power flux density of plasma varied in a range of 107–1010 W/cm2 with pulse duration of 50–100 ns. Power flux density of fast ions was 1010–1012 W/cm2 at the pulse duration of 10–50 ns. To achieve the combined effect of different kind of plasmas, the samples were later irradiated with hydrogen plasma (105 W/cm2, 0.25 ms) by a QSPA Kh-50 plasma generator. Surface modification was analysed by scanning electron microscopy (SEM) and microroughness measurements. For estimation of damages in the bulk of material, an electrical conductivity method was used. Investigations showed that irradiation of DFW with multiple plasma pulses generated a mesh of micro- and macrocracks due to high heat load. A comparison with single forged tungsten (W) and tungsten doped with 1% lanthanum-oxide (WL10) reveals the better crack-resistance of DFW. Also, sizes of cells formed between the cracks on the DFW’s surface were larger than in cases of W or WL10. Measurements of electrical conductivity indicated a layer of decreased conductivity, which reached up to 500 µm. It depended mainly on values of power flux density of fast ions, but not on the number of pulses. Thus, it may be concluded that bulk defects (weakening bonds between grains and crystals, dislocations, point-defects) were generated due to mechanical shock wave, which was generated by the fast ions flux. Damages and erosion of materials under different combined radiation conditions have also been discussed.
Dostawca treści:: Biblioteka Nauki

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