Structure and properties of compact articles from high-alloyed iron powder with adding of boron nitride

The results of the research of structure and properties of a composite compact from 13 Cr – 2 Мо and BN powders depending on the concentration of boron nitride are provided. It is shown that adding boron nitride in an amount of more than 2% by weight of the charge mixture leads to the formation of extended grain boundary porosity and finely dispersed BN layers in the structure, which provides a high level of wearing properties of the material. The effect of boron nitride concentration on physical and mechanical properties is determined. It was found that the introduction of a small amount of BN (up to 2 % by weight) into the compacts leads to an increase in plasticity, bending strength, and toughness by reducing the friction forces between the metal powder particles during pressing and a more complete grain boundary diffusion process during sintering. The formation of a regulated structure-phase composition of powder compacts of 13 Cr – 2 Mо – BN when the content of boron nitride changes in them allows us to provide the specified physical and mechanical properties in a wide range. The obtained results of studies of the physical and mechanical characteristics of the developed material allow us to reasonably choose the necessary composition of the powder compact for sealing structures of the flow part of steam turbines, depending on their operating conditions.

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Boron nitride for modification of rubber based on isoprene elastomer

Voprosy Materialovedeniya ◽

10.22349/1994-6716-2019-100-4-105-112 ◽

2020 ◽

pp. 105-112

Author(s):

K. S. Zhansakova ◽

E. N. Eremin ◽

G. S. Russkikh ◽

O. V. Kropotin

Keyword(s):

Mechanical Properties ◽

Boron Nitride ◽

Gradual Increase ◽

Physical And Mechanical Properties ◽

Curing Time ◽

Cross Link ◽

Start Time ◽

Link Density ◽

Cross Link Density ◽

Isoprene Rubber

The work studies vulcanization characteristics of elastomers based on isoprene rubber filled with carbon black N330 and boron nitride (BN). The influence of the boron nitride (BN) concentration on technological, dynamic, physical and mechanical properties of elastomers has been researched. The application of boron nitride for producing rubber with good properties has been considered. With a gradual increase of the inert filler BN concentration up to 35%, a decrease in the curing rate by 33% and polymer cross-link density by 26% is observed. Moreover, the start time of vulcanization increases by almost 300%, the optimal curing time by 200%.

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Eco-Friendly, High-Density Fiberboards Bonded with Urea-Formaldehyde and Ammonium Lignosulfonate

Polymers ◽

10.3390/polym13020220 ◽

2021 ◽

Vol 13 (2) ◽

pp. 220

Author(s):

Petar Antov ◽

Viktor Savov ◽

Ľuboš Krišťák ◽

Roman Réh ◽

George I. Mantanis

Keyword(s):

Mechanical Properties ◽

Bending Strength ◽

Urea Formaldehyde ◽

Physical And Mechanical Properties ◽

High Density ◽

Thickness Swelling ◽

Formaldehyde Content ◽

Uf Resin ◽

Natural Wood ◽

European Standards

The potential of producing eco-friendly, formaldehyde-free, high-density fiberboard (HDF) panels from hardwood fibers bonded with urea-formaldehyde (UF) resin and a novel ammonium lignosulfonate (ALS) is investigated in this paper. HDF panels were fabricated in the laboratory by applying a very low UF gluing factor (3%) and ALS content varying from 6% to 10% (based on the dry fibers). The physical and mechanical properties of the fiberboards, such as water absorption (WA), thickness swelling (TS), modulus of elasticity (MOE), bending strength (MOR), internal bond strength (IB), as well as formaldehyde content, were determined in accordance with the corresponding European standards. Overall, the HDF panels exhibited very satisfactory physical and mechanical properties, fully complying with the standard requirements of HDF for use in load-bearing applications in humid conditions. Markedly, the formaldehyde content of the laboratory fabricated panels was extremely low, ranging between 0.7–1.0 mg/100 g, which is, in fact, equivalent to the formaldehyde release of natural wood.

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INVESTIGATING THE INFLUENCE OF ENVIRONMENTAL CONDITIONING ON EPOXY RESINS AT QUASISTATIC AND HIGH STRAIN RATES FOR MATERIAL OPERATING LIMIT

10.12783/asc36/35745 ◽

2021 ◽

Author(s):

SAGAR M. DOSHI, SAGAR M. DOSHI, ◽

NITHINKUMAR MANOHARAN ◽

BAZLE Z. (GAMA) HAQUE, ◽

JOSEPH DEITZEL ◽

JOHN W. GILLESPIE, JR.

Keyword(s):

Mechanical Properties ◽

Epoxy Resin ◽

Yield Stress ◽

High Strain ◽

Operating Conditions ◽

Strain Rates ◽

High Strain Rates ◽

Stress Strain ◽

Wide Range ◽

Environmental Aging

Epoxy resin-based composite panels used for armors may be subjected to a wide range of operating temperatures (-55°C to 76°C) and high strain rates on the order of 103-104 s-1. Over the life cycle, various environmental factors also affect the resin properties and hence influence the performance of the composites. Therefore, it is critical to determine the stress-strain behavior of the epoxy resin over a wide range of strain rates and temperatures for accurate multi-scale modeling of composites and to investigate the influence of environmental aging on the resin properties. Additionally, the characterization of key mechanical properties such as yield stress, modulus, and energy absorption (i.e. area under the stress-strain curve) at varying temperatures and moisture can provide critical data to calculate the material operating limits. In this study, we characterize mechanical properties of neat epoxy resin, SC-15 (currently used in structural armor) and RDL-RDC using uniaxial compression testing. RDL-RDC, developed by Huntsman Corporation, has a glass transition temperature of ~ 120°C, compared to ~ 85°C of SC-15. A split Hopkinson pressure bar is used for high strain rate testing. Quasistatic testing is conducted using a screw-driven testing machine (Instron 4484) at 10-3 s-1 and 10-1 s-1 strain rates and varying temperatures. The yield stress is fit to a modified Eyring model over the varying strain rates at room temperature. For rapid investigation of resistance to environmental aging, accelerated aging tests are conducted by immersing the specimens in 100°C water for 48 hours. Specimens are conditioned in an environmental chamber at 76 °C and 88% RH until they reach equilibrium. Tests are then conducted at five different temperatures from 0°C to 95°C, and key mechanical properties are then plotted vs. temperature. The results presented are an important step towards developing a methodology to identify environmental operating conditions for composite ground vehicle applications.

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Control of properties and structure of steel vessels by cooling in various media at the outlet of rolling and pressing lines

Chernye Metally ◽

10.17580/chm.2021.02.06 ◽

2021 ◽

pp. 34-38

Author(s):

R. L. Shatalov ◽

V. A. Medvedev

Keyword(s):

Mechanical Properties ◽

Physical And Mechanical Properties ◽

Metal Structure ◽

Machine Building ◽

Regression Equations ◽

Wide Range ◽

Industrial Mineral ◽

Cooling Media ◽

Technological Limitations ◽

Non Destructive

When controlling the mechanical properties and structure of vessels made of carbon structural steels manufactured by hot deformation on rolling and pressing lines (PPL) of machine-building enterprises of Russia, such cooling media as water, I20 industrial mineral oil, air are used. The applied cooling media are able to provide the workpieces with a given structure with a wide range of mechanical properties. However, the cooling media have a number of technological limitations and conditions of the use, non-compliance with which leads to reject. When cooled in oil, the probability of ignition is high; when cooled in water, hardening cracks may form, and air is not always able to provide the required rate and uniformity of heat transfer to the environment. The efficiency of control of physical and mechanical properties and structure of deformed vessels made of 50 steel by cooling in TERMAT polymer aqueous solutions in different concentrations on PPL of the plant of JSC NPO Pribor was studied. The effect of varying the concentration from 2 to 9% of TERMAT polymer on the formation of metal structure, as well as physical and mechanical properties of hot-deformed vessels was studied. The results of testing the strength and plastic characteristics of vessels by destructive and non-destructive control methods are presented. According to the results of physical and mechanical properties, regression equations were obtained with at least 95% reliability of R2, which establish the relationship between the controlled plastic and strength parameters of the vessel metal`s properties. The conducted researches allowed to compare the indicators of the main physical and mechanical properties of steel vessels at the PPL outlet and to propose methods of inhomogeneity control that reduce time and material costs by 5–10% during the tests.

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Pressure losses and oscillations in a compact valve of a steam turbine

MATEC Web of Conferences ◽

10.1051/matecconf/202134500027 ◽

2021 ◽

Vol 345 ◽

pp. 00027

Author(s):

Václav Sláma ◽

David Šimurda ◽

Lukáš Mrózek ◽

Ladislav Tajč ◽

Jindřich Hála ◽

...

Keyword(s):

Numerical Simulations ◽

Pressure Oscillation ◽

Operational Reliability ◽

Operating Conditions ◽

Steam Turbines ◽

Valve Seat ◽

Pressure Losses ◽

Oscillation Analysis ◽

Seat Angle ◽

Wide Range

Characteristics of a new compact valve design for steam turbines are analysed by measuring pressure losses and oscillations on the valve model. It is the model of an intercept valve of the intermediate-pressure turbine part. This valve is relatively smaller hence cheaper than usual control and intercept valves. Besides, four different valve seat angles were tested in order to investigate the valve seat angle influence. In order to further clarify measured phenomena, the wide range of numerical simulations were also carried out. Measurements were performed in the Aerodynamic laboratory of the Institute of Thermomechanics of the Czech Academy of Sciences in an air test rig installed in a modular aerodynamic tunnel. Numerical simulations were performed in the Doosan Skoda Power Company using a package of ANSYS software tools. Measurement results are compared with numerical and generalized in the form of valve characteristics and pressure oscillation maps. As a result of the pressure loss analysis, pressure losses in similar valve assemblies can be predicted with required accuracy for each new turbine where modern compact valves are used. As a result of the pressure oscillation analysis, operating conditions at which dangerous flow instabilities can occur were identified. Thanks to this, the areas of safe and dangerous operating conditions can be predicted so that the operational reliability of the valve can be guaranteed.

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Selected physical and mechanical properties of Scots pine (Pinus sylvestris L.) wood from stands of younger age classes as criteria for rational utilization of timber

BALTIC FORESTRY ◽

10.46490/bf363 ◽

2021 ◽

Vol 27 (1) ◽

Author(s):

Przemysław Marcin Pikiński ◽

Jaroslav Szaban ◽

Gerda Šilingienė ◽

Robert Korzeniewicz ◽

Witold Pazdrowski

Keyword(s):

Mechanical Properties ◽

Pinus Sylvestris ◽

Scots Pine ◽

Bending Strength ◽

Physical And Mechanical Properties ◽

Growth Conditions ◽

Tree Age ◽

Coniferous Forests ◽

Forest Site ◽

Quality Coefficient

The aim of this study was to assess the quality of Scots pine (Pinus sylvestris L.) wood depending on the age of trees, forest site conditions and social class of tree position in the stand. Analyses were based on the determination of specific density and static bending strength, as well as the strength quality coefficient. It was to determine changes in physical and mechanical properties of timber depending on tree age as well as growth conditions reflected in the forest site such as fresh mixed coniferous forests and fresh mixed broadleaved forests. Experimental plots were established in 6 localities with 30, 40 and 60-year-old trees. In each of the stands, a 1-hectare experimental plot was established. Based on the measured DBH and tree height, dimensions of three mean sample trees were calculated, while the classification of social class of tree position in the stand developed by Kraft (1884) was also applied. Analyses were conducted on wood samples with 12% moisture content. Strength tests on wood samples were performed on an Instron 33RH204 universal strength testing machine. A detailed analysis showed properties of pine wood are improved with an increase of tree age in both forest sites. Statistically significant differences were observed for wood density and static bending strength. More advantageous properties were observed for wood of pines from the less fertile forest site, i.e., fresh mixed coniferous forests. Density and static bending strength were markedly determined by tree age and growth conditions. The static bending strength quality coefficient from pines growing in the fresh mixed coniferous forests increased between 30 and 40 years, similarly as it was for the fresh mixed broadleaved forests, while between 40 and 60 years, it deteriorated for the fresh mixed coniferous forests. Wood density from the fresh mixed coniferous forests was by 3% to 7% greater than pines growing in fresh mixed broadleaved forests. In turn, static bending strength of wood from pines growing in fresh mixed coniferous forests was by 4% to 10% greater than trees from the fresh mixed broadleaved forests. Keywords: Scots pine, wood properties, forest site, Poland

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Mechanical properties and freeze-thaw resistances of bronze-concrete composites

Challenge Journal of Concrete Research Letters ◽

10.20528/cjcrl.2021.02.001 ◽

2021 ◽

Vol 12 (2) ◽

pp. 39

Author(s):

Tuba Bahtli ◽

Nesibe Sevde Ozbay

Keyword(s):

Mechanical Properties ◽

Bending Strength ◽

Physical And Mechanical Properties ◽

Ultrasonic Pulse Velocity ◽

Ultrasonic Pulse ◽

Test Methods ◽

Pulse Velocity ◽

Plastic Energy ◽

Freeze Thaw ◽

Schmidt Rebound Hammer

Studies in the literature show that the physical and mechanical properties of concrete could be improved by the incorporation of different kinds of industrial waste, including waste tire rubber and tire steel. Recycling of waste is important for economic gain and to curb environmental problems. In this study, finely ground CuAl10Ni bronze is used to improve the physical and mechanical properties, and freeze-thaw resistances of C30 concrete. The density, cold crushing strength, 3-point bending strength, elastic modulus, toughness, and freeze-thaw resistances of concrete are determined. In addition, the Schmidt Rebound Hammer (SRH) and the ultrasonic pulse velocity (UPV) tests, which are non-destructive test methods, are applied. SEM/EDX analyses are also carried out. It is noted that a more compacted structure of concrete is achieved with the addition of bronze sawdust. Then higher density and strength values are obtained for concretes that are produced by bronze addition. In addition, concretes including bronze sawdust generally show higher toughness due to high plastic energy capacities than pure concrete.

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An attempt to use „Tetra Pak” waste material in particleboard technology

Annals of WULS, Forestry and Wood Technology ◽

10.5604/01.3001.0015.2376 ◽

2021 ◽

Vol 114 ◽

pp. 70-75

Author(s):

Radosław Auriga ◽

Piotr Borysiuk ◽

Alicja Auriga

Keyword(s):

Mechanical Properties ◽

Water Absorption ◽

Bending Strength ◽

Physical And Mechanical Properties ◽

Core Layer ◽

Waste Material ◽

Thickness Swelling ◽

The Core ◽

Tetra Pak ◽

The Impact

An attempt to use „Tetra Pak” waste material in particleboard technology. The study investigates the effect of addition Tetra Pak waste material in the core layer on physical and mechanical properties of chipboard. Three-layer chipboards with a thickness of 16 mm and a density of 650 kg / m3 were manufactured. The share of Tetra Pak waste material in the boards was varied: 0%, 5%, 10% and 25%. The density profile was measured to determine the impact of Tetra Pak share on the density distribution. In addition, the manufactured boards were tested for strength (MOR, MOE, IB), thickness swelling and water absorption after immersion in water for 2 and 24 hours. The tests revealed that Tetra Pak share does not affect significantly the value of static bending strength and modulus of elasticity of the chipboard, but it significantly decreases IB. Also, it has been found that Tetra Pak insignificantly decreases the value of swelling and water absorption of the chipboards.

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Contribution of the hybrid component to the structure and properties of ceramics based on metastable phases Al2O3

Voprosy Materialovedeniya ◽

10.22349/1994-6716-2021-106-2-127-136 ◽

2021 ◽

pp. 127-136

Author(s):

A. V. Maletsky ◽

T. E. Konstantinova ◽

D. R. Belichko ◽

G. K. Volkova ◽

V. V. Burkhovetsky

Keyword(s):

Mechanical Properties ◽

Yttrium Aluminum Garnet ◽

Metastable Phase ◽

Physical And Mechanical Properties ◽

Structure And Properties ◽

X Ray Diffraction ◽

Mutual Inhibition ◽

X Ray ◽

Tetragonal Lattice ◽

Yttrium Aluminum

The paper presents results of the study of the effect of doping with yttrium oxide on ceramics of the composition (γ + θ) Al2O3 + nY2O3 (n = 0, 1, 2, 3 wt%), sintered at 1550°C for 2 h, from powders of the specified composition annealed at temperatures of 500 , 800, 1000°С. X-ray diffraction analysis established the formation in ceramics of yttrium aluminum garnet Y3Al5O12 (YAG) and a metastable phase of the same composition with a tetragonal lattice type in powders at temperatures above 1200°C. The effect of YAG on the physical and mechanical properties was established: high properties were demonstrated by ceramics of the composition α-Al2O3 + 2wt% Y2O3, obtained from a powder annealed at 1000°C. In addition, high physical and mechanical properties were observed in ceramics of the composition α-Al2O3 + 0wt% Y2O3, obtained from a powder annealed at 800°C. The effect of the so-called “mutual protection against crystallization” was discovered, which consists in the mutual inhibition of crystallization processes in powders of the Al2O3 – Y2O3 system.

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The Impact of Paraffin-Thermal Modification of Beech Wood on Its Biological, Physical and Mechanical Properties

Forests ◽

10.3390/f10121102 ◽

2019 ◽

Vol 10 (12) ◽

pp. 1102 ◽

Cited By ~ 3

Author(s):

Ladislav Reinprecht ◽

Miroslav Repák

Keyword(s):

Mechanical Properties ◽

Bending Strength ◽

Beech Wood ◽

Physical And Mechanical Properties ◽

Brown Rot ◽

European Beech ◽

White Rot ◽

White Rot Fungus ◽

Poria Placenta ◽

The Impact

The European beech (Fagus sylvatica L.) wood was thermally modified in the presence of paraffin at the temperatures of 190 or 210 °C for 1, 2, 3 or 4 h. A significant increase in its resistance to the brown-rot fungus Poria placenta (by 71.4%–98.4%) and the white-rot fungus Trametes versicolor (by 50.1%–99.5%) was observed as a result of all modification modes. However, an increase in the resistance of beech wood surfaces to the mold Aspergillus niger was achieved only under more severe modification regimes taking 4 h at 190 or 210 °C. Water resistance of paraffin-thermally modified beech wood improved—soaking reduced by 30.2%–35.8% and volume swelling by 26.8%–62.9% after 336 h of exposure in water. On the contrary, its mechanical properties worsened—impact bending strength decreased by 17.8%–48.3% and Brinell hardness by 2.4%–63.9%.

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