Relationship between Thermal Diffusivity and Mechanical Properties of Wood

This paper describes an experimental study of the relationships between thermal diffusivity and mechanical characteristics including Brinell hardness, microhardness, and Young’s modulus of common pine (Pinus sylvestris L.), pedunculate oak (Quercus robur L.), and small-leaf lime (Tilia cordata Mill.) wood. A dependence of Brinell hardness and thermal diffusivity tensor components upon humidity for common pine wood is found. The results of the measurement of Brinell hardness, microhardness, Young’s modulus, and main components of thermal diffusivity tensor for three perpendicular cuts are found to be correlated. It is shown that the mechanical properties correlate better with the ratio of longitude to transversal thermal diffusivity coefficients than with the respective individual absolute values. The mechanical characteristics with the highest correlation with the abovementioned ratio are found to be the ratio of Young’s moduli in longitude and transversal directions. Our technique allows a comparative express assessment of wood mechanical properties by means of a contactless non-destructive measurement of its thermal properties using dynamic thermal imaging instead of laborious and material-consuming destructive mechanical tests.

Effect of Homogenization Annealing on Wear Properties of Thixo-Extrued Copper Alloy

The semi-solid extruded CuSn10P1 alloy bushings were homogenization annealed. The effects of annealing process on the hardness and wear properties of bushings were researched. The results show the Brinell hardness increases firstly and then decreases with the increase of annealing temperature and annealing time. With the annealing temperature increasing, the grinding loss rate and friction factor decrease firstly and then increase. At the annealing time of 120 min, the grinding loss rate decreases from 7% at the annealing temperature of 450 °C to 6% at 500 °C, and then increases from 6% at 500 °C to 12% at 600 °C. The friction factor decreases from 0.54 to 0.48 and then increases to 0.83. At the annealing temperature of 500 °C, the grinding loss rate decreases from 11% at the annealing time of 60 min to 6% at 120 min, and then increases to 15% at 150 min. The friction factor decreases from 0.67 to 0.48 and then increases to 0.72. The best wear performance and Brinell hardness can be obtained at annealing temperature of 500 °C for 120 min.

Small Diameter Tube Post-Weld Heat Treatment Process with Brinell Hardness and Microstructure Inspection

The local post-weld heat treatment (PWHT) process test of 9Cr-3W-3Co small-diameter pipe welded joints was carried out using rope-type resistance heaters with different parameters, and the Brinell hardness test and microstructure observation were carried out on the welded joints after heat treatment. The results show that when the heating width was 200mm, the constant temperature was 790°C-800°C, and the constant temperature time was 2 hours, the Brinell hardness of the weld was in the range of 246HBW-265HBW, which had good performance. After tempering at 760°C-800°C, the welds all showed a clear tempered lath martensite.

ESTIMATION OF THE DEPENDENCE PARAMETERS OF NUCLEAR STRUCTURAL MATERIALS HARDNESS ON THE CONTENT OF GAS IMPURITIES: AN INTERVAL APPROACH

The applications of the interval and standard probabilistic approaches for verifying the reliability of the results of an experiment studying the mechanical properties of nuclear materials are compared. The presence of “outliers” in a sample of hardness values for hafnium ingots is studied with for fixed oxygen mass content. The situation of measurement error limitation without reliable information about its distribution is considered. The correctness of the application of numerical methods of interval analysis for processing experimental data under conditions of uncertainty and noisy experimental data is shown. Determination of the dependence of the Brinell hardness of refined hafnium samples on the mass oxygen content was performed by a combination of methods: removal of anomalous measurements by interval analysis methods and approximation of data from truncated samples by the method Levenberg-Marquardt minimization.

STUDY OF THE SUITABILITY OF VARIOUS TYPES OF CASTING MATERIALS FOR THE MANUFACTURE OF A SHIP ENGINE

The objective of this work was to study the suitability of three types of cast iron for the manufacture of a ship engine: EN-GJS-500-7U for the manufacture of the engine block, EN-GJS-400-15U for the cylinder head and EN-GJL-200 for the liner. Tensile tests were carried out to obtain the ultimate tensile strength (UTS) of each material. The results for the UTS were: 460 MPa for EN-GJS-500-7U, 390 MPa for EN-GJS-400-15U and 170 MPa for EN-GJL-200. Likewise, Brinell-hardness measurements were carried out and the elements present in the materials were determined with spectrometry. Finally, the size of graphite particles in each sample was determined.

Multivariate Analysis of the Brinell Hardness of Silver Birch (Betula pendula Roth.) Wood in Poland

An analysis was undertaken of the Brinell hardness of silver birch wood and its dependence on stand location, tree age, tree thickness and forest habitat type, and the interactions between these factors. Wood was obtained from 12 forest districts throughout Poland, from trees aged approximately 30, 50, and 70 years. A total of 51 study plots was established, from which 306 trees were taken. Hardness was measured on three surfaces (transverse, radial, and tangential sections) for 4777 samples, giving a total of 14,331 measurements. It was shown that the hardness of silver birch wood in Poland is significantly influenced by location, tree age, tree thickness, and habitat type, and by interactions between those factors. Habitat type was not shown to affect radial hardness, except in the case of Giżycko forest district. For the whole of the analysed material, the mean hardness on a transverse section was calculated as 66.26 MPa, corresponding to a very hard wood on Mörath’s scale, whereas the values for the longitudinal sections (radial 44.06 MPa, tangential 44.02 MPa) correspond to a soft wood.

Mechanical characterization of polyester resin composite with natural fibers

In this paper, composite materials reinforced with natural fibers were studied, such as: Jute (MC-RY) and Manta (MC-RM) as a proposal for new materials for the manufacture of a prototype for automotive defense. The materials were manufactured as laminates and characterized mechanically through stress, bending, impact and Brinell hardness index tests. The results indicated that both reinforcers improved the mechanical strength of the matrix by up to 71%, as well as the impact energy absorption by 14%. The mechanical properties for MC-RY determined in flexure (bending = 56 MPa, Eflection = 4.16 GPa and maximum = 14 mm) were used to perform an impact simulation in two different models created in SolidWork, the results indicated that the MC-RY could be used for the construction of the defense using 3 layers of this material.

Experimental Investigation of Aluminium Hybrid Composites Reinforced with ZnS, TiO2 and BaTiO3 Produced Through Powder Metallurgy

Semiconductors like ZnS, TiO2 and BaTiO3 were reinforced with Al-Al2O3 Metal Matrix Composites (MMCs) and were made through powder metallurgy in order to have high strength, high hardness and good thermal conductivity compared with conventional materials. Three MMC of test specimens were prepared with varying reinforcement ratio Al-Al2O3-ZnS(94-5-1), Al-Al2O3-TiO2(94-5-1), Al-Al2O3-BaTiO3(94-5-1) percentage by weight respectively. The hardness test has been made by using Brinell hardness testing instrument. Hardness test revealed that the addition of reinforcement TiO2, BaTiO3 increases the hardness value. However, the addition of ZnS to the Al-Al2O3 MMCs showed decrease in the hardness value. The crystal structure of the 3 composites were examined through X-Ray Diffraction (XRD) peaks.

Testing of Sinters Made of Copper Powders Coated with Carbon Structure Containing Graphene

This paper presents the results of preliminary tests on specimens made from mixtures of dendritic copper powder (CuE) with the graphene-coated copper powder (CuG) in a range from 20% to 100% (CuG). The properties of the powder mixtures, green compacts and sinters were determined. To study the properties of the powder mixtures, the following tests were carried out: a measurement of the CuG powder grain size after the grinding process, measurements of the bulk density and tap density of the prepared powder mixtures. The porosity of the produced green compacts and the sinters was calculated as well as the densification capabilities of the powder mixtures by die pressing, cold isostatic pressing and sintering in a reducing atmosphere were tested. Moreover, the nature of the porosity formation was analysed using an optical microscope and the Brinell hardness was determined. The measured Brinell hardness was in the range of 17 HB for sinters made from CuG to 34 HB for sinters made from a 20% CuG powder mixture. More than six hundred measurements that were made in this study show that the high CuG content in the powder mixture reduce the hardness of the sinters as well increase their porosity.