Heat-insulating Materials Research Articles

Improved Mechanical Properties of Polyurethane-Driven 4D Printing of Aluminum Oxide Ceramics

The current deformation scheme used in the 4D printing of ceramics has several disadvantages, such as a poor deformation capacity, high process complexity, and the poor mechanical properties of the product. In order to solve these problems, the deformation scheme introduced in this study utilizes the pyrolytic expansion of polyurethane and the resulting pores to hinder the contraction of the specimen during the ceramization stage. Then, the specimen is composited with a polyurethane-free portion that has a high rate of shrinkage, and deformation is initiated through the interlayer stress mismatch generated by the difference in the shrinkage of the different layers, thus enabling the preparation of complex structural ceramics. This solution is simple and efficient; heat treatment is performed in a single pass, and the precursor specimen is highly deformable. The incorporation capacity of the aluminum oxide ceramic powder was increased by replacing part of the Dow Corning SE 1700 polydimethylsiloxane silicone rubber in the raw material with Dow Corning DC 184 polydimethylsiloxane silicone rubber, which, in turn, improved the mechanical properties of the obtained ceramics by enhancing the solid-phase content of the ceramic powder. Due to the introduction of polyurethane, the ceramic has a secondary pore structure, which has the potential for application in the field of engineering materials and heat insulation materials.

Обоснование выбора методики расчета суммарных теплопоступлений в кабину железнодорожного крана

The study analyses the most common methods of calculation of heat inputs into a railway crane driver’s cabin for the correct determination of the climate system heat load. The ways of heat supply to the cabin due to the heat conductivity of multilayered walls from external air infiltration, the driver, illumination, electrical equipment, and solar radiation have been considered. One of the objectives of the study is a detailed analysis and a selection of a rational method to calculate heat supplies from solar radiation as the main input most contributing to the total heat input. To implement the task, the most common methodologies of solar radiation calculation have been described and thoroughly analyzed; the most accurate of these has been recommended. The method of N.N. Bogoslovsky (considering the side of the horizon and solar radiation changes during the day) can be recommended for automated calculations by Excel or Python as well as for the primary identification of «in-depth» model calculations by ANSYS Fluent. The analysis of calculation results of various heat supplies has shown that the highest amount of heat from solar radiation penetrates the cabin not only through translucent barriers but also through massive multilayered walls due to the increase of their heat conductivity when heated, which comprises around 80 % of the total heat input. Side walls have the highest solar radiation throughput capacity due to the large surface area (46 % of total heat input) as well as the front wall (35 %) due to the lower number of layers of heat-insulating materials compared to side walls. Correct calculation of components of thermal balance helps to determine accurately the capacity of the designed climate system of the cabin, which ensures optimal conditions at the railway crane driver’s workplace.

Physicochemical Studies of Opoka as a Raw Material Component of Sodium Silicate Mixture for Subsequent Synthesis of Foam Glass Material Based on It

The present article presents the results of physical and chemical studies of opoka. In particular, the opoka was subjected to chemical analysis, X-ray phase, differential thermal analysis, scanning microscopy, and X-ray energy dispersive elemental microanalysis. The opoka was studied with the aim of using it as an available raw material for obtaining a sodium silicate mixture and, in the future, developing an energy-saving technology for obtaining a building heat-insulating and sound-insulating foam glass material based on it, using synthesis. As a result of the studies, the chemical composition of the opoka was determined, which is 69–80% represented by silica. The elemental composition of the opoka was established, which is represented by 94.25% oxides of Si, Al, and Fe. The presence of such oxides makes it an ideal raw material component of a silicate-sodium mixture for the subsequent synthesis of foam glass material from it. Experimental exploratory studies on the synthesis of foam glass based on opoka have been carried out. The experimentally obtained sample of foam glass material consists of 93.37% Si, Al, Mg, and Na oxides, has a porous structure with a pore size of 2–5 microns, an average density of 375 kg/m3, thermal conductivity of 0.063 W/(m °C) at 25 °C, and noise absorption of 51.6 Db.

Terahertz Spectroscopy of Construction Materials

Pulsed terahertz spectroscopy is widely used in scientific research of fast processes in various structures at nano-, meso- and macrolevels. Terahertz radiation has not been not applied in construction technologies until very recently. With the development of terahertz spectroscopy, it successfully complements classical methods of physical and chemical analysis of building materials for various engineering purposes, especially for heat-insulating materials in a wide range of density and electrical insulating properties. These studies are currently relevant for the development of compositions and technologies of effective thermal insulation materials based on wastes of the pulp and paper industry, including various types of substandard raw materials.Purpose: The aim of the work is to substantiate the application of terahertz spectroscopy in studying the formation of curing structures of building materials of different nature.Methodology: Terahertz spectroscopy and strength analysis to study ongoing processes.Research findings: It is found that the system based on modified polyurethane and paper filler, has the highest performance characteristics. It is shown that the highest absorption of terahertz radiation in the samples occurs in the frequency range above 1 to 2 THz.

Difficulties in operating a self-propelled drilling rig when drilling geological exploration wells in the Far North conditions

The article describes a method for eliminating the problem of freezing of the hydraulic system of the URB-2A2 drilling rig when drilling exploration wells in the freezing conditions of the Sakha Republic (Yakutia). During the study, we analyzed the long-term experience of industrial companies engaged in drilling operations in Yakutia. In this regard, in the regions of the Far North, an important task is to develop innovative methods aimed at improving the working conditions of workers and the quality of technologies for protecting the hydraulic systems of drilling rigs operating in the harsh climate of the region.As a measure to prevent and combat freezing of the hydraulic system, we propose insulating the hydraulic equipment of the drilling rig using heat-insulating materials. Based on the diagnostics and calculations, we were able to develop an effective way to solve the problem of freezing of the hydraulic system. This method does not require significant changes in the existing equipment and does not entail large financial costs. At the next stage, we will test the proposed method for solving the problem in the conditions of the Far North on the URB-2A2 self-propelled drilling rig.

МЕТОДИКА ОБОСНОВАНИЯ ХАРАКТЕРИСТИК ТЕПЛОИЗОЛЯЦИОННОГО МАТЕРИАЛА В СОСТАВЕ ОГРАЖДАЮЩЕЙ КОНСТРУКЦИИ С ИСПОЛЬЗОВАНИЕМ СРЕДСТВ КВАДРАТИЧНОГО ПРОГРАММИРОВАНИЯ

Abstract: Relevance of the research is connected to the importance of the problems related to the determination of the characteristics for structural solutions used in the construction or reconstruction of buildings and structures (taking into account the indicators of energy and economic efficiency), as well as the relatively low practical significance of the relevant scientific developments. Problem statement. It is necessary to determine the most preferred variant (model) of heat-insulating material used as an additional layer in the wall structure on the basis of the criteria related to the provided heat transfer resistance and the payback period of the corresponding design solution. Research aim. Development of tools for determination of the characteristics for thermal insulation material as part of wall structure within a residential building. Research tasks are the following: 1. Review and comparative analysis of scientific developments in the field of research. 2. Development of the procedure for determination of the characteristics for the heat-insulating material as part of the wall structure with the use of quadratic optimization tools. 3. Implementation of the developed procedure on a practical example. Results. Procedure for determination of the characteristics for the heat-insulating material as part of the wall structure with the use of quadratic optimization tools has been developed. The procedure has been implemented using a practical example, and the received results have been analyzed. Findings. The results of the procedure’s implementation on a practical example confirm the high practical significance of the developed tool. Thus, quadratic optimization tools can be effectively used to solve the problem related to the determination of the characteristics for heat-insulating material as part of an wall structure.

3D-печать текстиль-бетонных конструкций

A paper proposes the technological solution for the use of textile reinforcement with the additive technologies in the construction. This solution involves the preliminary manufacture of reinforcing frames. Those are the textile reinforcing net made of an alkali-resistant basic knitted fiberglass with an integrated layer of wall insulation. The treatment of reinforcing net with liquid glass increases the strength characteristics of the resulting composite – textile reinforced concrete. The technology consists in spreading of the prepared frames on the printed structure as a nozzle of 3D printer moves. The use of reinforcing net allows ones to reduce the manual labour costs for the connection of the external and internal surfaces of the printed wall, makes it possible to embed heat-insulating material into the wall under construction in the printing process. Moreover, the technology reduces the requirements for the concrete mix, since the reinforcing net acts as a formwork and prevents spreading during printing.

USING COAL FLOTATION WASTE AS A HEAT-INSULATING BILLING FOR THE HEAD PART OF A FORGING INGOT

The experience of using coal flotation waste as a weakly exothermic insulating backfill for insulating the head part of forging dead-melted steel ingots is presented. It has been shown that when using weakly exothermic fills based on single-component fills in the form of coal flotation waste, it is possible to reduce the chemical heterogeneity of the ingot by producing a closed shrinkage cavity, which allows halving heat loss and depth of penetration of shrinkage looseness into the body of the ingot, reducing the segregation of impurities, compacting the head part of the ingot and increasing the yield; moreover, the profitable part of the ingot is more dense and less contaminated with nonmetallic inclusions. The studied patterns of the formation of a closed shrinkage cavity with a dense “bridge” in the head part of a dead-melted steel ingot made it possible to develop and implement a technology for casting large forging ingots of sufficiently high quality using weakly exothermic heat-insulating materials based on metallurgical waste (coke screenings, coal flotation waste)

DEVELOPMENT OF METHODS FOR CONTROLLING THE TECHNOLOGICAL PROCESS OF STRUCTURE FORMATION OF CONCRETE BASED ON CEMENT-DIATOMITE BINDERS BY ACOUSTIC EMISSION METHOD

The most important task of modern construction is to improve the efficiency, quality, environmental safety, reliability, and durability of structures and facilities, considering the reduction of material intensity and capital costs. Heat-insulating materials constitute a significant group of construction materials by volume and importance. The use of lightweight concrete in construction makes it possible to create enclosing structures that meet the modern requirements of housing comfort, architecture, urban planning, to reduce material intensity and costs of erecting buildings and their operation. Enclosing constructions from cellular concrete with high ecological characteristics are getting more and more application. The paper presents the results of research into the production of effective heat-insulating materials based on diatomites by forming cellular structures in the field of high frequency currents. The study also presents the substantiation of the principles of formulation and technological regulation of their properties. In the process of research, the technological modes of creation of cellular structures by sources of internal heat have been studied. The method of control and management of the processes of structure formation of porous materials obtained by the technology of internal heating in the fields of microwave currents has been developed. The studied control method allows using the average temperature mode of the system, not exceeding the optimum hydration temperature for microwave molding of cellular structures.

Adoption of Heat Insulation Materials for Lithium‐Ion Battery Fire Blanket Coating and Earlier Fire Alarming

Adoption of Heat Insulation Materials for Lithium‐Ion Battery Fire Blanket Coating and Earlier Fire Alarming

SIMULATION OF PREHEATING AND HEATING WHEN CONNECTING POLYETHYLENE PIPES WITH ELECTROFUSION COUPLINGS

Existing machines for electrofusion welding of polyethylene pipes provide a high-quality connection at air temperatures no lower than minus 10 °C. However, if welding is required at lower temperatures, a layer of heat-insulating material is used to reduce the cooling rate. This insulation is selected based on the air temperature and the size of the welded pipes. This paper investigates the dynamics of temperature fields at the stages of heating, temperature equalization and heating using a new technology of welding at low temperatures. The proposed technology eliminates the use of thermal insulation material and allows welding to be carried out automatically.The paper presents a mathematical model that describes the thermal process when performing all welding operations at low temperatures. The model describes the thermal process with and without phase transformation. The well-known method of end-to-end calculation with the introduction of effective heat capacity is used to consider the heat of phase transition in the temperature range. The model also considers the dependence of the thermophysical properties of polyethylene on the degree of crystallinity.The following text presents the results of preheating and temperature equalization calculations for welding polyethylene pipes of the PE 100 SDR 11 brand with a diameter of 160 mm at an air temperature of minus 40 °C. To accurately describe the thermal process of real welding, experimental temperature data was used for parametric identification. It is shown that as a result of preheating and temperature equalization in the weld and thermally affected zones and outside them at a distance of more than 10 mm, the temperature values do not exceed acceptable limits. The resulting temperature distribution allows heating according to the standard welding mode. Calculations show that when the heating is completed, the volume of the polyethylene melt corresponds to the volume of the welding melt at the allowed air temperature.These findings can be used to develop a technique for controlling the movement of the crystallization front during welding at low temperatures.

The Flammability and Thermal Stability of Filling Epoxy Foam Plastics for Construction Purposes.

An effective type of polymer heat-insulating material (foams) based on reactive oligomers is casting epoxy foams with high technological and operational parameters. However, polyepoxide foams are highly flammable, which significantly restrains their application in the construction industry. The aim of this work was to develop effective methods for reducing the flammability of filling epoxy foams. In order to achieve the objective, the following objectives were addressed: determining the influence of the chemical nature and content of additive and reactive bromine- and phosphorus-containing compounds on the thermal stability, flammability and operational properties of filling epoxy foams, and the development of polyepoxy foams of reduced flammability with high-quality physical and mechanical characteristics. When estimating the flammability of epoxy foams, we used both state-approved methods and the methods described in scientific and technical literature. The thermal properties of epoxy foams were studied with the help of multimodular thermoanalytical complex DuPont-9900. The data on the influence of the apparent density of foams and oxygen concentration in the oxidant flow on the flame propagation speed on the horizontal surface of polyepoxy foams are presented. It was revealed that the chemical nature of amine hardeners does not affect the thermal stability and flammability of epoxy foams. It was established that phosphate plasticizers are ineffective flame retardants of foamed epoxy resin, and the chemical structure of additive organobromic flame retardants insignificantly affects their efficiency. It was shown that microencapsulated flame retardants are inferior in flame retardant efficiency to additive flame retardants. It was found that effective flame retardants for casting polyepoxy foams are phosphorus-containing oligoether methacrylate and epoxidized waste from the production of tetrabromodiphenylpropane. The results of this research will form the basis for the production of an experimental industrial batch of samples of pouring epoxy foams of reduced flammability.

ХАРАКТЕРИСТИКИ ДЕРЕВИННИХ КОМПОЗИТІВ НА ОСНОВІ СТЕБЕЛ РІПАКУ ТА МІНЕРАЛЬНОГО В’ЯЖУЧОГО

The dependence of the physical and mechanical characteristics of arbolite products on the specific content of rapeseed particles and mineral binder in the original composition was established. The results were obtained, which ensure the establishment of patterns of influence of technological parameters on the properties of wood composite material made using rapeseed waste. The main factors affecting the strength of the material are substantiated, in particular, the content of water-soluble substances in the lignocellulosic filler, the adhesion of the filler to the cement binder, the strength of the filler, the activity of cement and its consumption per 1 m3 of this material. It was found that the increased content of mineral substances in rapeseed stalks has a positive effect on adhesion with mineral binders. It was found that the presence of highly porous internal parenchyma tissue in rapeseed stalks makes it possible to use it with a content of more than 35% in the chip mass for the production of heat-insulating wood composite materials based on a mineral binder. It has been experimentally proven that wood composite materials made by conventional technology, with the addition of wood particles to the composite materials up to 35% of rapeseed particles, have mechanical indicators that meet the requirements of the state standard DSTU EN 312-2:2003. Methods of manufacturing composite materials based on mineral binder using rapeseed waste are proposed, which make it possible to expand the raw material base for the production of these materials thanks to the involvement of biomass of agricultural production – rapeseed raw material, reduce the cost of arbolite and, accordingly, save valuable wood raw materials.

PAM material that instantly gives ordinary fabrics excellent flame retardant and thermal insulation properties for fire rescue

PAM material that instantly gives ordinary fabrics excellent flame retardant and thermal insulation properties for fire rescue

Jute-reinforced hybrid biocomposite incorporated with low thermal conductive silica aerogel for improved resistance to conductive and radiative heat

Jute-reinforced hybrid biocomposite incorporated with low thermal conductive silica aerogel for improved resistance to conductive and radiative heat

Theoretical investigation of the thermal conductivity of Ga2O3 polymorphs

Theoretical investigation of the thermal conductivity of Ga2O3 polymorphs

Study of the thermal measurement depth of a skin calorimeter using simple RC and TF models

Study of the thermal measurement depth of a skin calorimeter using simple RC and TF models

Analysis of technologies of disposal and use fibrous paper skopje

The article examines the current state and trends in the development of waste management technologies in the pulp and paper industry, with the aim of analyzing the reasons that hinder, and sometimes make impossible, the effective utilization of fibrous waste paper to obtain environmentally safe materials and raw products. The production of paper products is one of the most capital-intensive and energy-intensive industries, second only to the metallurgical and chemical industries, with a correspondingly large amount of waste and a negative impact on the environment. The technological processes of scum formation as a result of waste paper recycling and paper production wastewater treatment are considered and analyzed. Skopje is the final waste of the pulp and paper industry, which is formed at various stages of the paper and cardboard manufacturing process, therefore it is deposited in landfills. Multiton volumes of skopje require significant areas for its storage. Despite the low IV hazard class, this leads to serious environmental problems, as the leachate from the skopje landfill pollutes surface and ground water. Technologies of possible disposal and reuse of skopje, known in domestic and foreign literature, are described and analyzed. The technology of reusing scoop is determined by its relatively environmentally safe physicochemical composition. The indicated fibrous, mineral, extractive constituents and lignin determine the possibility of reusing skopje, mainly for the construction industry. The perspective of the complex use of multi-tonnage waste – slag, sludge, ash and slag of thermal power plants as plasticizers, fillers, binders and binding components in the production of building structural and heat-insulating materials is named. Technologies for using scapula as a filler in the production of building materials require a high content of inorganic compounds and a minimum amount of organic compounds. A high content of fibrous particles and a low content of mineral substances is necessary when using scapula in the production of composite wood composite materials. The specified technological limitations ensure only small amounts of skopje use in the production of building materials. The effectiveness of using skopje as an additive to the asphalt mixture for road construction and production of fuel materials is determined by the economic costs of transportation and dewatering. It is noted that the high humidity, ash content and low calorific value of scum are the main reason for the lack of effective technologies for its utilization. The solution to the problem is the use of low-energy technologies through the direct use of osprey as a component of the soil mixture for biological reclamation of man-made landscapes. The article substantiates an environmentally safe and socially favourable option for using a soil substrate based on osprey. It is emphasised that the humidity and organic viscosity of the plant origin of osprey form the agrotechnical properties of soil substrates of prolonged action, which ensure optimal technological efficiency of phytomelioration of degraded lands. The reclaimed areas will reduce greenhouse gas emissions from the soil, prevent wind and water erosion, and ensure the environmental safety of natural and man-made ecosystems.

Experimentation of Heat-Insulating Materials for Surrounding Rocks in Deep Mines and Simulation Study of Temperature Reduction

With the increasing depletion of shallow resources, mining has gradually shifted to deeper levels, and the high-temperature problem of deep mining has restricted the efficient and safe development of mining. In this study, five types of thermal insulation materials for surrounding rocks with different ratios were produced using tailings, P.O.32.5 clinker, aluminum powder, glass beads, quick lime, and slaked lime as test materials. Based on the uniaxial compression test, the thermal constant analysis test, and numerical simulation analysis technology, the change rule of mortar compressive strength and thermal conductivity was analyzed, and the cooling effect of surrounding-rock thermal insulation materials with different ratios was discussed. The results showed that the compressive strength of the surrounding-rock thermal insulation materials ranged from 0.39 to 0.53 MPa, and the thermal conductivity ranged from 0.261 to 0.387 W/(K·m), with the compressive strength of ratio E being the largest and the thermal conductivity of ratio A being the lowest. In the numerical simulation analysis results, the thermal insulation layer thickness was taken as a value of 10 cm when, at this time, the best thermal insulation effect and economic benefits involved a temperature reduction of 0.9 K. In the case of changing the thermal conductivity and inlet wind speed, the original temperature of the rock temperature reduction was also very clear, with maximum reductions of 0.92 K, 0.92 K, and 1.42 K.

Study on Preparation of Porous Light Refractory from Waste Electric Porcelain

AbstractIn the process of the development of the ceramic industry, a large amount of ceramic solid waste is generated, and how to make high‐value reuse of ceramic solid waste has also become a problem of common concern. In this article, a new method of making porous thermal insulation materials reusing waste electric porcelain was successfully developed. In this work, a porous light refractory with bulk density of 0.99 g/cm3 and apparent porosity of 59% was prepared by the novel method. Which room temperature flexural and compressive strengths are 11.52 MPa and 1.84 MPa, respectively. These properties makes the waste electric porcelain‐based porous light refractory can be applicated as lightweight heat insulation materials for high‐temperature kilns, high‐temperature catalyst carriers, high‐temperature phase‐change heat storage support materials, etc., which will create higher application value and research significance.