Metal Composite Materials Research Articles

Façade requirements in the 2021 edition of the US International Building Code

SummaryFollowing the Grenfell Tower tragedy in London, the US requirements for fire safety of façades were revisited. The 2018 edition of the key US regulation, the IBC, had associated shortcomings, in spite of the fact that no US fire losses with fatalities have resulted from complying wall assemblies. This is contained in Chapter 14, Exterior Walls.The key fire test used for exterior assemblies (façades) in the US is a large‐scale test, namely NFPA 285. The test evaluates the vertical and lateral flame‐propagation potential of any exterior wall assembly system with combustible components, typically including insulation. The systems are evaluated as flat specimens containing neither corners nor projections. The “typical” fire scenario modeled corresponds to a fire in a room, venting through a window opening and exposing the exterior wall from both inside and outside. The fire test equipment is a two‐story structure with a test room on each story and a window opening. Two burners expose the test specimen: one is placed inside the ground floor test room and the other one is placed outside, near the window opening. The fire test contains pass/fail criteria based on measuring the following phenomena:• Vertical and lateral flame propagation over the exterior,• Vertical and lateral flame propagation inside the combustible core,• Vertical flame penetration into the second story,• Temperature rise on the exterior and within any wall cavities.The IBC includes requirements for a variety of products and also detailed requirements for three specific assemblies: metal composite materials, high‐pressure decorative exterior‐grade compact laminates, and exterior insulation and finish systems (known in Europe as external thermal insulation composite systems). It also includes requirements for fire‐retardant‐treated wood, water‐resistive barriers, and exterior wall coverings, such as siding and very detailed requirements for foam plastic insulation (as tested on its own and within the assemblies). This work shows multiple changes made when revising the 2018 IBC to the 2021 IBC.Concerns have been expressed regarding the applicability of NFPA 285 to fire scenarios associated with the twin effects of either (a) vertical (such as angled walls) or horizontal (such as balconies) projections or (b) wind. No changes to that effect were made for the 2021 IBC.Three concepts were discussed in detail but not adopted into the code using the “16 ft. parallel panel test” (from FM 4880), either as an alternate or as an additional test, incorporating the effect of wind during the NFPA 285 test and considering the effect of corners and/or projections from flat surface during a modified NFPA 285 test. Also a requirement was incorporated into the International Existing Building Code to conduct an NFPA 285 test when façades are added, replaced, or modified.In summary, this work provides a comprehensive overview of the requirements for façades (both materials and assemblies) in the USA in the presently applicable building code (IBC 2018) and in the next edition (2021) of the applicable building code.

Reaction of Spot Radioactive Source with the Energy of 661.7 KeV on the Modification in the Structure of Surface Layer of Metal Composite Material

This paper presents the results of studies of the composite metal radio-protective building material by method of atomic-force probe microscopy, before and after its irradiation with gamma rays of 661.7 keV and absorbed dose up to 2 MGy. Composite metal material is based on the filling of hematite iron ore concentrate and aluminum matrix. This composite material has high technical (physical and mechanical) and radio-protective proprieties. The composite is planned to be employed as a bearing structure at various nuclear facilities.

ИССЛЕДОВАНИЕ ВЛИЯНИЯ ВАКУУМНОЙ ТЕРМИЧЕСКОЙ ОБРАБОТКИ НА ТЕПЛОФИЗИЧЕСКИЕ СВОЙСТВА КОМПОЗИЦИОННОГО МАТЕРИАЛА СИСТЕМЫ Al–SiC С ВЫСОКИМ СОДЕРЖАНИЕМ АРМИРУЮЩЕЙ ФАЗЫ

The results of investigation of thermal treatment influence on thermophysical properties of metal composite material (MCM) based on aluminium casting alloy АК9ч (АЛ4) grade of Al–Si–Mg system reinforced with silicon carbide particles with content of reinforcing particles of 69±1% (volume) are given. MCM is made by solid-phase method followed by vacuum annealing. There are also presented studies of thermophysical characteristics of the material: thermal conductivity, temperature coefficient of linear expansion in the temperature range from 20 to 400 °C and density. It is shown that thermophysical characteristics depend on structural characteristics of the material.

Bottom-up fabrication of the multi-layer carbon metal nanosheets.

Ordered carbon composite materials have great potential for practical applications in many areas such as energy conversion, quantum computing, biotechnologies, and electronics. In this work, we demonstrate a state-of-the-art self-assembly driven building block approach to create new layered carbon–metal composite materials with advanced properties. We fabricate molecular nanocomposites using self-assembled metal intercalated multi-layers of dithiol derivatives. The obtained structures are analysed using different characterization tools (such as X-ray photoelectron and Raman spectroscopy and atomic force microscopy) and their electronic transport properties are studied by four-point probe measurements supplemented by density functional theory calculations. This work demonstrates a new strategy for low-cost, high-yield and eco-friendly nanofabrication of hybrid organometallic membranes.

Distinguishing contributions of ceramic matrix and binder metal to the plasticity of nanocrystalline cermets.

Using the typical WC-Co cemented carbide as an example, the interactions of dislocations within the ceramic matrix and the binder metal, as well as the possible cooperation and competition between the matrix and binder during deformation of the nanocrystalline cermets, were studied by molecular dynamics simulations. It was found that at the same level of strain, the dislocations in Co have more complex configurations in the cermet with higher Co content. With loading, the ratio between mobile and sessile dislocations in Co becomes stable earlier in the high-Co cermet. The strain threshold for the nucleation of dislocations in WC increases with Co content. At the later stage of deformation, the growth rate of WC dislocation density increases more rapidly in the cermet with lower Co content, which exhibits an opposite tendency compared with Co dislocation density. The relative contribution of Co and WC to the plasticity of the cermet varies in the deformation process. With a low Co content, the density of WC dislocations becomes higher than that of Co dislocations at larger strains, indicating that WC may contribute more than Co to the plasticity of the nanocrystalline cermet at the final deformation stage. The findings in the present work will be applicable to a large variety of ceramic-metal composite materials.

Influence of Scale Factor and Surface Condition on 20GS2 Steel Sensitivity to Hydrogen Cracking

Purpose of research . At present, it is found that the process of corrosion-mechanical destruction proceeds in several stages. However, as practice and analysis of numerous destructions of structural elements made of high-strength materials in the construction and engineering industries show, very often in real structures there are already technological defects such as cracks. In such cases, the process of corrosion-mechanical destruction begins directly with crack growth, bypassing the preparatory stages – the incubation time and the formation of a stress concentrator. The goal of this paper is to study the influence of scale factor and surface condition on the sensitivity of 20GS2 steel to hydrogen cracking. Methods . Reinforcing steel of 20GS2 grade (four melts) was chosen to determine the influence of surface condition and scale factor on the long-term corrosion strength in the environment causing hydrogen cracking. Full-scale specimens (l = 300.400 mm) of different diameters (10, 12 and 14 m) with smooth-rolled and die-rolled sections were tested. Also, from 10, 12 and 14 mm diameter full-scale rods (smooth-rolled and with die-rolled sections) there were turned samples with a diameter of the working part from 6 to 10 mm every 1 mm with surface condition of Ra2,5. The long-term corrosion strength was estimated through time preceding failure by testing four samples at each point of the graph. To create the experimental conditions as close as possible to the operational ones, the tests were carried out in an aqueous solution of sulfuric acid with the addition of ammonium rhodanide at room temperature with cathodic polarization and different levels of tensile stresses. Results . It has been experimentally found that full-scale specimens of 20GS2 reinforcing steel in comparison with turned ones have less sensitivity to hydrogen cracking. This circumstance is due to the fact that after mechanical processing by cutting in turned samples, the value of residual tensile stresses is much higher than in full-scale specimens. It has been shown that full-scale specimens of 20GS2 reinforcing steel with a die-rolled section have less resistance to hydrogen cracking, as compared with full-scale smooth-rolled samples. The lower resistance to hydrogen cracking of die-rolled section reinforcement is due to the presence of ribs on its surface which play the role of natural stress concentrators. The experimental results obtained allow us to recommend full-scale specimensto to be tested for corrosion and mechanical destruction in environments that cause hydrogenation of full-scale specimens, since their use makes it possible to approximate the experimental conditions to the actual conditions of operation of products. Conclusion . The results obtained can be used in the creation of resource-saving processes for processing metal alloys and composite materials.

Life Cycle of Products Made of Polymer Composite Materials

The life cycles of products made of metal and polymer composite materials are considered, and their common and distinctive features are determined. Using the mirror of a space antenna (made of carbon-filled plastic) as an example, we analyze the influence of auxiliary materials on the quality indices. A technique is developed to determine the influence of auxiliary materials on the phase composition (polymer matrix content is determined by thermogravimetry). A structure for forming carbon-filled plastic products using vacuum infusion and a system for the implementation of competitive design-technological solutions are presented for the manufacture of carbon-filled plastic products.

Evaluation of the effectiveness of the introduction of a discrete filler in the aluminum matrix melt

Experimental samples of metallic composite materials filled with discrete Al2O3 fibers with a diameter of 10–20 nm were obtained by liquid-phase mechanical mixing. A technology has been developed for the effective introduction of a discrete filler into an aluminum melt, which ensures the absorption of the filler by the matrix. Device for the introduction of the filler was designed and manufactured. Recommendations were given on the choice of the composition and technological regimes for the introduction of a light discrete component of a composite material for sufficient assimilation by its matrix and ensuring the homogeneity of the structure. The structure and properties of the obtained samples of the new material have been studied. The changes made by the introduction of the selected nanodiscrete filler into the aluminum melt and the changes made by additional technological methods are analyzed. The effect of introducing discrete Al2O3 fibers into an aluminum melt was demonstrated.

Construction of a metallic silver nanoparticle-decorated bismuth oxybromide-based composite material as a readily recyclable photocatalyst

Abstract As a consequence of rapid industrialization, there has been a gradual increase in the accumulation of organic pollutants in the aquatic environment, the removal of which has become an urgent problem. In this regard, photocatalysis is considered a sustainable and efficient sewage treatment technology. In this study, an efficiently recyclable composite material for photodegrading organic pollutants was fabricated by anchoring metallic silver nanoparticle-decorated bismuth oxybromide nanosheet (BiOBr) arrays on carboxymethyl cotton fabric. Systematic investigations of the structure and morphology, photocatalytic ability, and antibacterial properties of the generated Ag/BiOBr-carboxymethyl cotton fabric (Ag/BiOBr-CCF) revealed that the BiOBr nanosheets (thickness of ∼40 nm and a size of ∼1 μm in the other two dimensions) were evenly and stably anchored to the carboxymethyl cotton by uniformly distributed metallic Ag nanoparticles (10–20 nm in diameter). Furthermore, the Ag/BiOBr-CCF material can effectively photodegrade >99% of rhodamine B and the herbicide isoproturon in response to irradiation with visible light (λ > 400 nm), and that Ag/BiOBr-CCF has good structural stability and can be readily recycled without additional treatment. The metallic Ag nanoparticles were also demonstrated to confer excellent antibacterial properties to the Ag/BiOBr-CCF, thereby protecting the cotton fabric from microbial degradation. Collectively, the observations indicate that this composite material would be eminently applicable as a readily recyclable photocatalyst for environmental remediation.

Shot peening-induced plastic deformation of individual phases within a coated WC-Co hard metal composite material including stress-strain curves for WC as a function of temperature

The properties of cutting tool inserts made from WC-Co hard metal are often improved by chemical vapour deposited(CVD) α-Al2O3and TiCN coatings. In order to deposit CVD coatings, the insert's substrate has to be heated to the deposition temperature and after deposition cooled down to room temperature. Because the deposition temperature is high, residual stresses in WC and Co develop during heating/cooling due to a mismatch of their expansion coefficients and also due to a mismatch of the coating's and the substrate's expansion coefficient. After deposition, the properties of cutting tool inserts are in the present study additionally improved by a cold working process called shot peening, which is supposed to alter tensile residual stresses present in CVD coatings into the compressive regime. As a side effect, the substrate is also affected by the shot peening treatment. The current work investigates the influence of the deposition and the shot peening process on the stress-strain state of the WC and Co grains of the α-Al2O3 and TiCN coated WC-Co hard metal cutting tool insert by means of the finite element method. All necessary material data are taken either from literature or from own experimental measurements. A special focus is put on the plastification of WC, as an EBSD analysis of compressively loaded hard metal shows some degree of plasticity in a significant fraction of the WC grains. The plastic behaviour of WC is inversely reconstructed and used in simulations.

Mechanical behavior of Al–Cu binary alloy system/ Cu particulates reinforced metal-metal composites

Abstract Aluminium composite metallic materials are prepared by stir-cast technique, reinforcing 5 ​wt% copper powder (50 ​μm size) in Al–5wt% Cu alloy. SEM structures shows Cu particles not alloyed with the matrix material. EDAX studies inveterate the existence of elements in both binary alloys and the composite. Optical microstructures show uniform distribution of Cu particles in the Al–Cu alloy matrix. Richer alloy show 13% greater hardness compared to lean alloy. Enhanced precipitation of CuAl2 population around copper particulates observed. Cast fingers of Al-5wt% and Al-10 ​wt% Cu alloys and composite are homogenized at 100 ​°C for 24 ​h, resulted in more uniform distribution of the CuAl2 population. Standard samples of 3 ​mm thick discs solutionized at 450 ​°C for 2 ​h are aged at 190 ​°C to determine T6 condition. The peripheral increase in hardness is observed due to the increased Cu content because of solid-solution strengthening only. Alloy with 10 ​wt% Cu content show a decrease in tensile strength compared to 5 ​wt% alloy. This is due to the increased phase in interdendritic region of α-phase solid solution. Tensile property of 5 ​wt% Cu alloy is higher compared to 10 ​wt% alloy and composite, after ageing.

Stress concentration around of pin-loaded hole in unidirectional multi-layered metallic matrix composite material

The objective of this study is to examine the stress concentration factor around a pin-loaded hole in a metallic matrix composite material, analytically and numerically. It is assumed that all unidirectional fibers lie in the metallic matrix while the shear stress in fibers is discarded. To generally derive the equilibrium equation for all fibers and the metallic matrix, the previous shear-lag theory had been improved and the extension in the metallic matrix was considered. Afterwards, the equilibrium equation was solved by the eigenvalue method while the displacement field and stress distribution around the pin-loaded hole were computed. Having calculated stress concentration factors and the displacement field in a unidirectional multi-layered composite material, we compared the analytical results with those numerical values from other references. Additionally, the effect of the pin’s diameter, as well as the edge-hole distance on maximum stress concentration factor was investigated. To recapitulate, it is seen that the modified shear-lag theory can simulate the mechanism of the load transfer between metallic matrices.

Simulation Research on Vibration Cutting Mechanism of Metal Matrix Composites

Particle-reinforced metal composite materials have been widely used in the industry due to their excellent abrasion resistance and high strength, but they are typical hard-to-machine materials. A finite element model of the material matrix and enhanced particles have been established by the parametric modeling in this paper. Different from the previous development process, the particle is randomly distributed in this study, so the particle distribution has been better simulated than ever. The study shows that vibration-cutting particle-reinforced composites have reduced the phenomenon of particle suspension on the machined surface compared to conventional cutting, and the high-elastic-modulus reinforcing particles have been subjected to high stress, and the matrix between the particles have acted as a stress-transmitting “channel”. When the particle’s diameter is 20μm and the volume fraction is 30%, there is a stress transmitting channel in a certain range away from the tool tip. When the cutter contacts the particles, the vibration cutting will cause the initial crack near the particle, which cut off part of the stress transmitting channels, make the stress concentrated on the tool tip and lead to the material easier to remove.

Development and Research of Flux-Cored Electrodes For Welding And Surfacing Of Parts From Aluminum And Titanium Alloys

Perpose of research was to study the properties of powder materials obtained from aluminum and titanium waste by the method of electroerosion dispersion for the development of electrodes suitable for welding and surfacing of parts from aluminum and titanium alloys. Methods . To obtain an aluminum powder material by electroerosion dispersion method, an aluminum wire GOST 14838-78 was used, pre-cut to 5-7 cm. the Wire was loaded into a reactor filled with a working liquid – distilled. The process was carried out at the following electrical parameters: discharge capacitor capacity 65 UF, voltage 100 V, pulse frequency 100 Hz. To obtain a titanium powder material by electroerosion dispersion method, shavings of VT6 grade were used. The chips were loaded into a reactor filled with a working liquid – distilled water. The process is carried out at the following electrical parameters: capacity of the bit capacitors 65 µf, a voltage of 150 V, pulse frequency of 250 Hz. The result of the local effects of intermittent electrical discharges between the electrodes was the destruction of the material with the formation of dispersed particles of powder. In order to study the shape and morphology of powder material particles obtained by electroerosion dispersion from aluminum waste, images were taken on a raster (scanning) electron microscope QUANTA 600 FEG. The study of granulometric composition of powder materials obtained by the method of electroerosion dispersion of aluminum and titanium waste was carried out on a laser analyzer particle size Analysette 22 NanoTec. Results. It is established that the most promising and not industrially used materials for the production of electrodes used in welding and surfacing of parts are powder materials obtained by electroerosion dispersion. It is experimentally established that the powder materials obtained by electroerosive dispersion of aluminum and titanium wastes consist of spherical and elliptical particles. The results of the study of the elemental composition of powder materials obtained by electroerosive dispersion of aluminum and titanium waste, it is shown that the main elements of the powders produced and aluminum waste are aluminum and oxygen, and the main elements of the powders produced and shavings of the VT6 BRAND are Ti, Al, O, V, Fe, W and K. Studies of the particle size distribution of powder materials obtained by electroerosion dispersion showed that the average particle size of powders obtained from aluminum waste is 19.08 microns, and the average particle size of powders obtained from titanium waste is 33.12 microns. It is established that the most promising method for the production of electrodes used for welding and surfacing of parts from aluminum and titanium alloys is the method of spark plasma sintering. Conclusion . The obtained results can be used to create resource-saving processes for processing metal alloys and composite materials.

Experimental researches on the tribological analysis of composite materials sintered with iron matrix

In this paper a study is conducted on the abrasion wear behavior of iron matrix composite materials, testing of samples obtained by sintering was made for different values of the applied load as for the relative speed of sliding. Starting from the studied literature, recipes of sintered sintered metal composite materials having iron matrix have been developed which have been tested for their physico-chemical and tribological properties. The prepared powders were dosed according to the formulations (Fe 68%, Cu 13%, Ni 5-7%, Graphite 6%, SiC 8%, SiO 2 8%), and the resulting mixtures were homogenized to achieve homogeneous mixtures to ensure, finally, a good reproducibility of the physico-mechanical properties of the sintered material. For forming, a cylindrical die having a surface area of 2cm2 was used. Working pressures ranged from 5000 ÷ 6000daN/cm2. The densities obtained for the compressed samples were determined by weighing the METTLER analytical balance and measured with the micrometer for the volume calculation. The values of „raw” densities range from 5.12 to 6.3g/cm3.

Study of Porosity of Sintered Samples of Electroerosive Powder Copper

Purpose of research. Powder copper is widely used in various fields of machine engineering for the production of electrical contact and antifriction products. The quality of sintered products is estimated by density and porosity. One of the main methods for determining the porosity of formed and sintered products is a metallographic method with elements of qualitative and quantitative analysis of pore geometry.The properties of sintered products made of electroerosive copper powder have not been studied up to the present, which makes it impossible to predict their properties and scope of practical application.The purpose of the work is to study porosity and pore-size distribution of sintered samples of electroerosive copper powder.Methods. To perform the planned studies, waste of electrical copper wire (GOST 859-2001) was used. As a working fluid distilled water was used. To obtain a powder of copper a unit to produce powders of conductive materials (patent for invention RF № 2449859) was applied. Dispersion parameters were: voltage 220 V, capacity 45.5 µF, pulse repetition rate 100 Hz.Isostatic pressing of electroerosive copper powder obtained in water was carried out in isostatic press "EPSI" CIP 400-200*1000Y. The compacted samples were sintered in a high-temperature furnace "Nabertherm" VHT 8/22 in vacuum at a temperature of 900 °C and 1000 °C for 1 hour.The porosity of the sintered samples of electroerosive copper powder obtained in the water was determined by metallography using optical inverted microscope OLYMPUS GX51 .Results. Based on the results of the conducted studies, it was experimentally proved that the porosity of a sintered sample of electroerosive copper powder at 900 °C is 5.8 %, the porosity of a sintered sample of electroerosive copper powder at 1000 °C is 2.16 %.Conclusion. The obtained experimental data can be used to create resource-saving processes for processing metal alloys and composite materials.

Brown band characteristics of aluminum cladding alloys

Clad materials are a variant of the typical composites, which consist of two or more materials joined on their interface surfaces. Clad materials as metallic composite materials are developed for the needs of user because the single metal often cannot satisfy it application conditions. That is, the advantage of clad materials is that the combination of different properties of materials can satisfy both the need of good mechanical properties and the demand of users such as industrial consumer. The purpose of this study is to study structural aspects in aluminium 3003 clad material with 4343 alloy, after different cladding time. Generally, Al 3003 material is Al–Mn alloy which has superior ductility, but the strength and hardness are low. Aluminium series 4xxx material is Al–Si alloy with high strength and hardness, but low ductility. In our paper we determine the grain sizes of the coated aluminium alloys, before and after cladding, and also the corrosion potentials of these aluminium cladding alloys.

Rationally designed hierarchical NiCo2O4–C@Ni(OH)2 core-shell nanofibers for high performance supercapacitors

Supercapacitor is considered as a favored candidate with promising future for next-generation energy storage applications. In quest of higher electrochemical performance, the integration of carbon-based and metallic-oxide-based materials becomes necessary. Herein, a creative yet effective design of one-dimensional hierarchical nanofibers, composed of a highly conductive core (NiCo2O4 embedded carbon fiber) and a sheath of Ni(OH)2, is devised. The material is systematically fabricated by electrospinning and chemical bath deposition. Optimum electrode material exhibits high energy storage performance (1925 F g−1 at 1 A g−1) and good cycling performance (retained 87% after 5000 cycles) compared to its counterpart without Ni(OH)2 nanosheets (79% after 5000 cycles). Furthermore, the asymmetric supercapacitor assembled by this material and activated carbon delivers excellent specific capacitance performance (135 F g−1 within 1.6 V). Meantime, this asymmetric supercapacitor possesses high power density and energy density, up to 323 W kg−1 and 48 Wh kg−1, respectively, as well as outstanding rate capability, transcending most reported metal oxide carbon-based composite materials.

Inducing surface nanoporosity on Fe-based metallic glass matrix composites by selective dealloying

Nanoporosity (i.e. nanohole formation) is induced at the surface of Fe-based metallic glass matrix composites by selective chemical or electrochemical (at 1 V) etching of a Fe65Cu10Zr10B15 composite material using a 0.065 M HNO3 aqueous electrolyte. While electrochemical treatments are found to remove the Cu-rich precipitates present at the surface of this alloy, chemical etching (in absence of applied potential) only causes partial dissolution of the Fe-rich amorphous matrix. In both cases, the resulting pores exhibit random shapes and their lateral size ranges from a few tens to hundreds of nm. The investigated material is ferromagnetic at room temperature, both before and after dealloying and it does not crystallize during the (electro)chemical etching process. The contact angle in deionized water decreases in the dealloyed states in comparison with the as-spun ribbon. This procedure is appealing for applications that could benefit from the combination of increased surface area and the amorphous character (lack of crystallinity) at the surface of dealloyed metallic glass composite materials.

To the question of thermal joining of composite Al-B materials

This work deals with the application of new approaches to welding production of modern light, strong, and heat-resistant metal composite materials in aeronautical and space technology. The objective of this article is to substantiate introduction of modern technology for welding composites in production, namely the development of argon-arc welding technology and the choice of equipment when using composites of the Al-B system for manufacturing the flame tube of the combustion chamber of an aircraft engine. Based on the study of technical literature and scientific publications, a short analysis of the existing technological processes for welding heat-resistant glass-ceramic composites was carried out. The problems arising in the process of welding aluminum composites reinforced with boron and steel fibers are considered. A modern gas tungsten arc welding based on new technological processes is offered with an example of welding in manufacturing a combustion chamber of a modern gas turbine modified engine.