Temperature Coefficient Of Linear Expansion Research Articles

ВПЛИВ ОПТИЧНОГО СКЛА ЯК ПІДКЛАДКИ В ППР-СЕНСОРАХ НА ТЕМПЕРАТУРНУ СТАБІЛЬНІСТЬ РЕЗУЛЬТАТІВ ВИМІРЮВАННЯ

The influence of the properties of the substrate made from optical glass of surface plasmon resonance (SPR) sensors on the temperature stability of measurements at a temperature change from 20 to 30°C, in which research is most often carried out, was studied. The phenomenon of surface plasmon resonance is very sensitive to any changes at the metal-dielectric interface, so studying the influence of the temperature factor is an actual task. Research in the infrared region of the spectrum is important because in this case the possible thickness of the research object increases, and it is also possible to reduce the thickness of the gold layer that is sprayed to the glass substrate of the sensory element from 50 nm to 30 nm. But heating the sensitive element with an IR laser can introduce an additional error into the measurement results. The sensitive element of the SPR device consists of a plate made of optical glass and a thin layer of gold deposited on it. It is known that materials expand when heated. The difference in temperature coefficients of linear expansion of glass and gold applied to it can lead to unequal expansion of glass (74x10 -7 ) and gold (14.2x10 -6 ), respectively, causing elastic stresses in the gold sensitive layer of the sensor. Sensory elements with a 30 nm gold layer are used for the IR range of measurements, and 50 nm for the visible range. Therefore, we investigated the stability of the results of measuring the angle of surface plasmon resonance minimum at a wavelength of 650 nm (Plasmon-6 device). It was determined that the optical glass of the substrate affects the stability of measurements of the SPR index of air from temperature fluctuations. The period of stabilization of measurement results in the visible range when the temperature changes from 20 to 30 °C to the change in the angle of the SPR minimum changes from 0.0006 degrees/min for Zerodur to 0.0032 degrees/min for flints, i.e. almost 5 times with the thickness of the gold nanolayer 50 nm, and for a thickness of 30 nm it varies from 0.0010 deg/min for crowns and quartz to 0.0013 deg/min for flints. The lowest value corresponds to Zerodur substrates with practically zero temperature coefficient of linear expansion and quartz in this temperature range. To ensure the stability of the results of measurements of SPR characteristics against temperature fluctuations in the range of 20-30°С, it is recommended to use Zerodur, quartz and crowns for the substrates of SPR sensors

Temperature coefficient of linear expansion of glass-ceramic materials based on MoSi2

The influence of temperature-time parameters on the temperature coefficient of linear expansion (TCLR) of materials based on MoSi2‒B‒Al2O3 has been established. It is shown that by changing the composition of the composition and the conditions of heat treatment, it is possible to significantly influence the value of TCLR.

Использование хвостов Каджаранского медно-молибденового комбината (ХКММК) для синтеза стёкол с магнитными свойствами

The area of glass formation in the systems TKCMC - Li2O - B2O3 and TKCMC - LiFe5O8 - B2O3 has been studied. The most interesting compositions have been determined and the density and temperature coefficient of linear expansion (TCLE) of glasses have been investigated. It was found that the glasses exhibit weak magnetic properties. The study of the magnetic properties of crystallized glass samples showed that crystallization greatly enhances the magnetic properties, reaching values of practical application due to the precipitation of lithium ferrospinel in the samples. Research on the specific volume electrical resistivity of crystallized lithium ferrite system samples showed that they exhibit pronounced positive temperature coefficient effects at different temperatures, which will allow their use in various types of sensors. The work done shows that the tailings of the Kajaran copper-molybdenum production can be successfully used to produce electronic materials.

Designing engobe coatings for ceramic bricks

This paper reports research into the development of compositions of engobe coatings for ceramic bricks and investigating the influence of technological production factors on their physical and mechanical properties. The results of this work make it possible to solve the task of expanding the range and improving the operational properties of building ceramics. The data obtained have made it possible to establish physicochemical processes occurring during the formation of the phase composition and structure of engobe coatings. This has revealed the possibilities for designing engobe for various types of ceramic bricks, which differ in technological parameters of production and operational properties. The charge compositions were designed in a three-component system "refractory clay – quartz sand – cullet", taking into account the possibility of their practical implementation in large-tonnage production. It has been established that the most important condition for obtaining high-quality products is the correlation of shrinkage and temperature coefficients of linear expansion of the ceramic shard and engobe coating. To prevent various defects, these indicators should vary by no more than 10 %. The crystal-phase composition of engobe is represented by b-quartz and a small amount of devitrite, which are evenly distributed in a vitreous dense layer of coating on the surface of the ceramic shard. Distinctive features of the results relate to the fact that a solution to the problem of designing engobe coatings for ceramic bricks has been proposed and the physicochemical bases of production have been highlighted. This paper also suggests ways to achieve coordination of finely dispersed coatings with coarse-grained ceramic masses by shrinkage and thermal processes. The results reported here could be applied in typical production of face, clinker, and in some cases – ordinary brick or ceramic stone with firing temperatures of 950–1150 °C

METALLIZED GLAZES FOR THE DECORATION OF PORCELAIN STONEWARE USING RAW MATERIALS OF THE REPUBLIC OF BELARUS

The aim of this research was to study the possibility of obtaining metallic (metallized) raw glazes for porcelain stoneware using the raw materials of the Republic of Belarus. Fusible clay, quartz sand, dolomite, kaolin and copper oxide were used to prepare the glazes. The glazed porcelain stoneware obtained under the industrial conditions of Berezastroimaterialy JSC had dark grey surface with a metallic appearance. The research on the physico-chemical properties of the synthesized samples was carried out under the requirements of existing international standards. The temperature coefficient of linear expansion of glazes was (65.9–73.4)∙10–7 K–1, resistance to surface abrasion (PEI) – 1–2, resistance to thermal shock – 150±5 °C. The structure of glaze coatings was characterized by X-ray diffraction analysis and scanning electron microscopy. The glassy matrix was established to be the predominant phase. Anorthite and tenorite were the crystalline components. Their amount varied depending on the glaze composition. Due to the crystalline phases, glazed porcelain stoneware has a relatively high degree of resistance to surface abrasion. A hot-stage microscope and differential scanning calorimeter were used to study the melting behavior of the experimental glazes. The characteristic temperatures (sintering, sphere, half-sphere, fusion), as well as the contact angle and shrinkage of glazes in the temperature range of 500–1400 ℃ were determined. It was found that an increase in the content of copper oxide from 12.5 to 22.5 % contributes to a decrease in the sintering temperature by 10–50 ℃. However, the prevailing influence on the surface tension of the glazes at temperatures 1050–1200 °C had the percentage of dolomite. For citation: Shymanskaya H.M., Popov R.Yu., Pospelov A.V. Metallized glazes for the decoration of porcelain stoneware using raw materials of the Republic of Belarus. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 6. P. 69-75. DOI: 10.6060/ivkkt.20236606.6808.

СИНТЕЗ И ИССЛЕДОВАНИЕ ФИЗИКО-ХИМИЧЕСКИХ И МЕХАНИЧЕСКИХ СВОЙСТВ В СИСТЕМЕ SrO-Al2O2-SiO2

14 samples were prepared in the SrO-Al2O2-SiO2 system by solid-phase synthesis. The degree of interaction of the initial reagents during the synthesis was controlled by X-ray phase analysis on a DRON-3M diffractometer using CuKα radiation. The identification of crystalline phases was carried out using the PDF-2 powder diffractometry database. The following crystalline phases were identified in the samples: SrAl2Si2O8; SrAl12O19; Sr2Al2SiO7; SrAl2O4; Sr2SiO4; Sr3Al2O6; Sr4Al2O7; Sr3SiO5; Sr6Al18Si2O37; Al2O3. The results of a study of the physicochemical and mechanical properties of samples synthesized in SrO-Al2O2-SiO2 system are presented. The temperature coefficients of linear expansion, the values of densities, melting temperatures, and Young's modul were determined. The values of the characteristics obtained for the samples under investigation make them promising for use as materials for a wide range of technical applications.

Functionally Gradient Material Fabrication Based on Cr, Ti, Fe, Ni, Co, Cu Metal Layers via Spark Plasma Sintering

The paper presents a method of obtaining functionally graded material (FGM) of heterogeneous (layered) type based on joined metals Cr-Ti-Fe-Co-Ni-Cu using spark plasma sintering (SPS) technology. The structure, elemental and phase composition of FGM obtained on the basis of joined metals with different values of the temperature coefficient of linear expansion (CTLE) were studied by SEM, EDS and XRD methods with regard to the phase states of the alloy system. Based on the Vickers microhardness data, the evaluation of the mechanical characteristics of FGM in the whole sample body and locally at the contact boundaries of the joined metals was carried out. The results of the study are new and represent a potential for FGM, as well as functionally graded coatings (FGC), which have special physical, chemical and mechanical properties and are highly demanded for the manufacture of structures and products for industrial applications.

Investigation of the effect of electric heating of expanded clay concrete mixture on the structure and properties of lightweight expanded clay concrete exposed to high temperatures

Objective. The aim of the study is to study the effect of preliminary electrical heating of the concrete mixture on the structure and properties of heat-resistant expanded clay concrete on a composite binder before drying at a temperature of 105°C. Method. It is based on domestic and foreign experience in studying the effect of preliminary electrical heating on the properties and structure of various concretes, including heat-resistant ones. Result. A laboratory stand for preliminary electrical heating of mixtures has been developed and tested. The influence of preliminary electric heating on the process of self-steaming of heat-resistant expanded clay concrete has been studied. A mode of preliminary electric heating of a heat-resistant expanded clay concrete mixture in time has been developed. Stress dependences are obtained due to the difference in the temperature coefficients of linear expansion of coarse and fine aggregates and the mortar part on the heating temperature, as well as the dependences of the ultimate strength of expanded clay concrete on the heating temperature of the expanded clay concrete mixture under various modes of preheating with a composite binder with a ratio of components: Portland cement 70%, mineral additive 30%. Conclusion. Based on the results obtained and the analysis of the studies carried out in the field of preliminary electrical heating of concrete mixtures, it can be concluded that the preliminary electrical heating of a mixture for heatresistant concrete with expanded clay filler based on an activated composite binder will make it possible to obtain concrete with higher physico-thermal and operational characteristics, as well as to reduce the technological process of manufacturing heat-resistant products, the drying period and bringing the thermal unit to the operating mode.

ВПЛИВ ТЕМПЕРАТУРИ НАВКОЛИШНЬОГО СЕРЕДОВИЩА НА МЕХАНІЧНУ НАПРУГУ ОПТИЧНОГО КАБЕЛЮ

To ensure the quality and reliability of the fiber-optic communication line during the exploitation, it is necessary to constantly monitor the technical condition of the optical cable (OC), first of all, the tension in the fiber. Mechanical tensions in the optical fiber due to macro- and microbends lead to a change the signal’s attenuation coefficient. Therefore, the study of the effect of the temperature of the operating environment of the optical cable on its mechanical tensions is relevant. The purpose of the work is to determine the mechanical stress of the dielectric optical cable as a function of the temperature change (tx) at constant values of the tension in the cable, which correspond to the corresponding elongation of the cable (εр). The article investigates the effect of ambient temperature on the mechanical tensions in the cable (σ0x). Conducted on the example of a cable type OKL-3-D1 of the domestic manufacturer "Odeskabel" with a dielectric central power element made of fiberglass of the "Polystal" type, and a peripheral power element – made of aramid threads "Twaron 2200-1055". An estimate of the mechanical tension in this OC was obtained at different temperature values from -40 °C to 60 °C and at different elongations. For this purpose, the values of the temperature coefficient of linear expansion, Young’s modulus of such a cable were obtained in the work. In the studies, the values of constant tensile loads of the cable, which correspond to its elongation from 0.2 % to 0.6 %, were used. According to the results of the study, at a constant mechanical load of a given type of cable, which corresponds to its certain elongation εр = 0.6 %, a decrease in mechanical tensions up to 7 % was obtained. Due to the fact that the mechanical stress in the optical cable consists of two parts, the first of which depends on the mechanical loads, and the second depends on the temperature change of the cable's operating environment. According to the work [2], the first component is much larger than the second, but its changes, established in this work, in critical situations for fiber-optic communication lines are of significant importance, which must be taken into account during the design and operation of lines. In general, the study of σ0x made it possible to establish that the mechanical stresses of the OC de crease with temperature increase due to the negative temperature coefficient of linear expansion of the aramid threads.

Determining the influence of the microstructure and phase composition of glass-metal-ceramic coatings on their basic physical-technical properties

Given the development of new heat-resistant nickel alloys that operate at temperatures up to 1,250 °C, as well as the introduction of additive technologies for the production of various parts, it is a relevant task to devise new compositions of highly heat-resistant coatings. Determining the influence of the phase composition of glass-metal-ceramic coatings on its basic properties could improve the effectiveness of protecting those parts that operate under extreme conditions. Therefore, it is promising to conduct a study aimed at establishing the relationship between the microstructure and phase composition of glass-metal-ceramic coatings and the main physical-technical characteristics. This study's results have established that the most high-quality coatings were obtained on the basis of non-crystallizing glass. Such glass is characterized by a temperature coefficient of linear expansion of 92·10-7 degrees-1, a glass transition temperature of 625 °C, and surface tension of 260·10-3 N/m at 850 °C. These properties contribute to the formation of a defect-free coating, providing uniform spreading and high-quality adhesion to the substrate. The resulting optimal coating is characterized by the adhesion strength of 98 %, the thermal resistance (mode 950↔20 °C) of 50 cycles, and the high heat resistance (a weight gain after 100 h in the temperature range of 1,000‒1,050 °C) of 0.03 g/m2·h. Coatings with a minimum amount of glass bonding are distinguished by uniformity and high quality. The optimal ratio of phases "glass:metal-ceramic composition" is 10:90. The structure of the recommended coating is uniform, characterized by the homogeneous distribution of components, the absence of cracks, visible defects, and high quality. The phase composition of the coating after firing is represented by crystals of metallic nickel and silicon, as well as a small amount of residual glass phase.

ВУГЛЕПЛАСТИК КОНСТРУКЦІЙНОГО ПРИЗНАЧЕННЯ НА ОСНОВІ АРОМАТИЧНОГО ПОЛІАМІДУ І МЕТАЛ-ВМІСНОГО ВУГЛЕЦЕВОГО ВОЛОКНА

Досліджені основні теплофізичні і фізико-механічні характеристики ароматичного поліаміду фенілон С-2, армованого метал-вмісним вуглецевим волокном. Показано, що армування поліамідного в’яжучого хром-вміснимвуглецевим волокном у кількості 17 мас. % суттєво знижує питому теплоємність і температурний коефіцієнтлінійного розширення, а також покращує його фізико-механічні властивості

Determination of the Temperature Coefficient of Linear Expansion of Materials Based on Silicon Carbide

Information on the temperature coefficient of linear expansion (TCLE) of materials based on silicon carbide is presented. It is shown that the different polytypes 3C (cubic modification) and 4H and 6H (hexagonal modifications) are characterized by different thermal expansions, the difference between the values of which increases with increasing temperature. The TCLEs of reaction-sintered, liquid-phase-sintered, and hot-pressed silicon carbide materials are determined in the range 20 – 1800°C.

Determination of the temperature coefficient of linear expansion of materials based on silicon carbide

.

МОДЕЛЮВАННЯ ВПЛИВУ ГЕТЕРОГЕННОЇ СТРУКТУРИ СПЛАВІВ НА ЗАБЕЗПЕЧЕННЯ ЯКІСНИХ ХАРАКТЕРИСТИК ПОВЕРХНЕВОГО ШАРУ НА ФІНІШНИХ ОПЕРАЦІЯХ

У роботі запропоновано моделювання термомеханічних явищ, які формуються у виробах на фінішних операціях і впливають на якість поверхневого шару з урахуванням спадкових неоднорідностей, сформованих на попередніх технологічних операціях, встановлення впливу їх на тріщино- і припікоутворення на основі кількісного аналізу теплового і напруженого стану і з урахуванням гетерогенності матеріалу виробів. Коефіцієнти інтенсивності напружень

Borosilicate Radiation Shielding Glass

The results of studies of the electrophysical and thermophysical characteristics of borosilicate glass designed to attenuate electromagnetic radiation in the microwave range are presented. The compositions of glass with the minimal tendency to crystallization are determined. The effect of the chemical composition of glass on its thermophysical (temperature coefficient of linear expansion (TCLE) and heat capacity) and electrophysical (attenuation index, standing wave ratio, and dielectric loss tangent) properties is found. The proposed glass compositions can be recommended for the manufacturing of products used as shielding against radiation.

Manufacturing features, structure, and properties of high-purity Mo-Re thin sheets

Manufacturing features, structure and properties of low-alloyed molybdenum sheets 0.5 mm thick made from the experimental Mo-3 wt.% Re single crystal are described and discussed in the present work. The developed technological scheme includes warm rolling of the initial ingot at a temperature of 1150 °C, with heating in the argon protective atmosphere, subsequent annealing at 850 °C for 2/3 h in a vacuum, no less than 1 ·103 mmHg, cold rolling at a temperature of 400 °C, and post-deformation annealing at 800 C for 1/2 h. The results of micro structure analysis, physical and mechanical studies show that thin sheets are characterized by simultaneously high strength and plasticity, as well as the required temperature coefficient of linear expansion (TCLE), necessary for bonding with a glass by a thermo-compression welding. Obtained results reveal perspectives for the development of the application of thin Mo-3 wt.% Re sheets in vacuum engineering for the vacuum-tight metal-glass parts.

ВЛИЯНИЕ НЕОКСИДНЫХ ДОБАВОК НА СВОЙСТВА СТЕКЛОКЕРАМИЧЕСКИХ ПОКРЫТИЙ ДЛЯ ДЕТАЛЕЙ ИЗ ЖАРОПРОЧНЫХ СПЛАВОВ (обзор)

A review of the scientific and technical literature is presented, which provides examples of improving glass-based coatings by introducing non-oxide modifying additives. The main groups of chemical compounds that are used to improve the properties of glass-ceramic coatings are considered. Such substances include compounds based on boron, silicon and rare earth metals. It is concluded that these additives have a positive effect on the following properties of coatings: heat resistance, heat resistance, mechanical strength, coating formation temperature, temperature coefficient of linear expansion and adhesion strength to the protected material.

ИССЛЕДОВАНИЕ ОСНОВНЫХ СВОЙСТВ СТЕКЛОТЕКСТОЛИТОВ ДЛЯ ПЕЧАТНЫХ ПЛАТ И ОЦЕНКА ВЛИЯНИЯ КЛИМАТИЧЕСКИХ ВОЗДЕЙСТВИЙ НА ПОКАЗАТЕЛИ ИХ ДИЭЛЕКТРИЧЕСКОЙ ПРОНИЦАЕМОСТИ

In this paper, the main properties of glass fiber laminates – dielectric composite materials for printed circuit boards are considered: glass transition temperature, temperature coefficient of linear expansion, ultimate strength in bending, water resistance. The influence of climatic influences (increased ambient temperature, low ambient temperature, increased air humidity, the effect of temperature changes, the effect of salt fog) on the dielectric constant of glass fiber laminates has been evaluated.

Calculation of thermal expansion, glass transition temperature and glass density in the system RO–Al2O3–B2O3–SiO2 (where RO=BaO, SrO, CaO, MgO, ZnO)

Glasses of the system RO–Al2O3–B2O3–SiO2 are used as a base for the fabrication of heat-resistant nonmetallic materials and general-purpose products. The purpose of this work is to develop mathematical models for calculating the temperature coefficient of linear expansion, glass transition temperature and density as a function of the composition of glass in the oxide system RO–Al2O3–B2O3–SiO2 where RO=BaO, SrO, CaO, MgO, ZnO. The disadvantage of the known models is that the range of their application is limited by the quantitative content of components in the glass. At the same time, an increase in the sample size of experimental compositions made it possible to obtain more accurate mathematical models for calculating these properties. The glasses included in the experimental sample are distinguished by a wide range of temperature coefficient of linear expansion (from 30 to 10510–7 К–1). The glass transition temperature of these glasses is within the range of 580–7100C, which allows a reasonable approach to the choice of temperature regime for the formation of the structure vitreous and glass-ceramic materials for different functional purposes. The mathematical models were developed with the use of the experimental and statistical method. The obtained mathematical models are adequate to the experimental data and allow calculating the thermal expansion, glass transition temperature and density of glasses; the mean-square deviations of temperature coefficient of linear expansion, glass transition temperature and density being 1.910–7 К–1, 16.00C and 0.06 g cm–3, respectively. Their accuracy is sufficient for the development of basic glass compositions for various functional purposes.

Constructive approach to reduce the influence of temperature on spring suspension eigenfrequencies

PurposeOne of the problems encountered by developers of inertial systems, such as gyroscopes and accelerometers, is the critical dependence of the eigenfrequencies of elastic suspensions (ES) on temperature when using substrates for sensors made of dielectric materials, such as borosilicate glass. The internal stresses arising in the ES caused by the difference in the temperature coefficients of linear expansion (TCLE) lead to deformation of the sensor and complication of the electronic part of the sensor. The purpose of this paper is to approach for in-plane and out-of-plane ES are considered that allow for minimization of the influence of internal stresses on eigenfrequencies.Design/methodology/approachAnalytical, finite element and experimental results are considered. The temperature coefficient of thermal expansion, the Young’s modulus and the Poisson ratio are given as a function of temperature. The shape of the spring elements (SEs) and the construction of the elastic suspension are the main topics of focus in this study. The authors’ out-of-plane ES based on a meander-like spring element implemented via finite element modeling show good agreement with the experimental results.FindingsMeander-like SEs have been developed that have lower temperature errors in comparison with traditional types of SEs. The main contribution to the change in the eigenfrequency from temperature is made by internal stresses that arose from the deformation of the bonded materials with different TCLE. The change of eigenfrequency from the temperatures that were calculated by finite element method did not exceed 0.15%, however, in practice, the scatter of the obtained characteristics for different samples showed a change of up to 0.3%.Originality/valueThis study shows a way to design and optimize the structure and theoretical background for the development of the microelectromechanical systems (MEMS) inertial module combining the functions of gyroscope and accelerometer. The obtained results will improve and expand the manufacturing technology of MEMS gyroscopes and accelerometers.