scholarly journals Study of the mechanical behavior of light mortars produced by thermal treatment, with coal waste of Jerada mine (eastern Morocco)

2019 ◽  
Vol 286 ◽  
pp. 03006
Author(s):  
R. Addou ◽  
K. Hannawi Salmo ◽  
Z. Zenasni ◽  
W. P. Agbodjan ◽  
M. Zenasni

This paper investigates the mechanical properties of light mortars containing coal waste of Jerada mine, as a volume replacement for sand, with different percentages of substitution: 10%, 20% and 50%. The results revealed a decrease in the mechanical properties of composite mortars, including uniaxial compression and flexural strength as well as rigidity modulus. However, the heat treatment improves their ductility, and delays the propagation of cracks. Thus, the developed material is interesting for use in construction, serving as a basis for manufacturing prefabricated blocks treated at 600°C. These elements can be used for applications with large deformations, or with mechanical or acoustic vibrations.

2015 ◽  
Vol 651-653 ◽  
pp. 677-682 ◽  
Author(s):  
Anatoliy Popovich ◽  
Vadim Sufiiarov ◽  
Evgenii Borisov ◽  
Igor Polozov

The article presents results of a study of phase composition and microstructure of initial material and samples obtained by selective laser melting of titanium-based alloy, as well as samples after heat treatment. The effect of heat treatment on microstructure and mechanical properties of specimens was shown. It was studied mechanical behavior of manufactured specimens before and after heat treatment at room and elevated temperatures as well. The heat treatment allows obtaining sufficient mechanical properties of material at room and elevated temperatures such as increase in ductility of material. The fractography of samples showed that they feature ductile fracture with brittle elements.


2016 ◽  
Vol 688 ◽  
pp. 44-49 ◽  
Author(s):  
Iveta Čabalová ◽  
František Kačík ◽  
Tereza Tribulová

Samples prepared from oak (Quercusrobur L.) wood were exposed to heat treatment at temperatures of 160, 180, 200 and 220 oC for 3, 6, 9 and 12 hours. In both untreated and thermally treated wood there were determined extractives and lignin by National Renewable Energy Laboratory (NREL) procedures, cellulose by Seifert's method, holocellulose according to Wise, hemicelluloses as difference between holocellulose and cellulose. Monosaccharides were determined by high performance liquid chromatography (NREL).The results show that hemicelluloses are less stable at thermal treatment than cellulose. The amounts of lignin and extractives rose by increasing both temperature and time of the treatment while the amounts of hemicelluloses decreased. Thermal treatment also resulted in significant decreases of the yields of non-glucosic saccharides. Degradation of carbohydrates can cause the deterioration of mechanical properties of wood.


Author(s):  
G.V. Shlyakhova ◽  
◽  
A.V. Bochkareva ◽  
M.V. Nadezhkin ◽  
◽  
...  

This study presents experimental results of structural analysis, such as phase composition, grains size assessment, strength and hardness of Ni-SPAN-C alloy 902 after various heat treatment modes (hardening and aging for stress relaxation). A thermal treatment mode has been selected to obtain higher physical and mechanical properties of the elinvar alloy. It is shown that the improvement of the alloy structure in thermal treatment occurs due to the thermic stresses, as well as the formation and dissolution of intermetallides.


Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 778 ◽  
Author(s):  
Omid Hajizad ◽  
Ankit Kumar ◽  
Zili Li ◽  
Roumen H. Petrov ◽  
Jilt Sietsma ◽  
...  

Wheel–rail contact creates high stresses in both rails and wheels, which can lead to different damage, such as plastic deformation, wear and rolling contact fatigue (RCF). It is important to use high-quality steels that are resistant to these damages. Mechanical properties and failure of steels are determined by various microstructural features, such as grain size, phase fraction, as well as spatial distribution and morphology of these phases in the microstructure. To quantify the mechanical behavior of bainitic rail steels, uniaxial tensile experiments and hardness measurements were performed. In order to characterize the influence of microstructure on the mechanical behavior, various microscopy techniques, such as light optical microscopy (LOM), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD), were used. Three bainitic grades industrially known as B360, B1400 plus and Cr-Bainitic together with commonly used R350HT pearlitic grade were studied. Influence of isothermal bainitic heat treatment on the microstructure and mechanical properties of the bainitic grades was investigated and compared with B360, B1400 plus, Cr-Bainitic and R350HT in as-received (AR) condition from the industry. The results show that the carbide-free bainitic steel (B360) after an isothermal heat treatment offers the best mechanical performance among these steels due to a very fine, carbide-free bainitic microstructure consisting of bainitic ferrite and retained austenite laths.


2015 ◽  
Vol 1088 ◽  
pp. 621-625 ◽  
Author(s):  
Wei Meng

Through experimental research under the condition of different ratio of polymer and SAE of modified mortar, compressive and flexural strength of change trend, also studied the 1% content of steel fiber on the mechanical behavior of the SAE modified mortar, for in both cases, examined the mortar specimens respectively than the law of the change of compressive and flexural strength, and the conclusion is given.


2015 ◽  
Vol 1765 ◽  
pp. 65-70
Author(s):  
Adriana Reyes-Mayer ◽  
Angel Romo-Uribe ◽  
Michael Jaffe

ABSTRACTSmall-angle light scattering (SALS) and wide-angle X-ray scattering (WAXS) were used to study the influence of heat treatment on the texture and microstructure of extruded films of high-performance thermotropic liquid crystal polymers (LCPs). The microstructure was correlated with tensile mechanical properties. LCPs based on random units of hydroxybenzoic acid (B), hydroxynaphthoic acid (N), terephthalic acid (TA) and biphenol (BP) were supplied by the former Hoechst Celanese Corp. as 50 μm thick extruded films. The LCPs, denoted B-N, COTBP and RD1000, have B and N as common co-monomers and vary the other co-monomers. Thus, this study also enabled the investigation of the influence of monomer composition on microstructure and mechanical properties. Heat treatments were carried out at temperatures close to the solid-to-nematic transition (Ts→n) for periods up to 5 h, under dry air conditions. The thermal treatment produced either two endotherms or a small increase of Ts→n (B-N and RD1000), or Ts→n increased significantly (COTBP). Moreover, when heat treatment was carried out approximately 40°C below the respective Ts→n, the mechanical Young’s modulus, E, along the extrusion axis increased for all LCPs. Strikingly, for COTBP, E increased over 100% relative to the as-extruded film. The results also showed that the optimum treatment time for improving the Young modulus was between 3 and 4 h. Wide-angle X-ray scattering showed a significant sharpening of crystalline reflections and concentration of the 002 meridional reflection as a result of thermal treatment, suggesting the elimination of defects and a better alignment of the molecular chains along the extrusion axis. This would explain the increase in tensile modulus.


2015 ◽  
Vol 1120-1121 ◽  
pp. 1269-1275
Author(s):  
Anatoly A. Popovich ◽  
Vadim Sh. Sufiiarov ◽  
Igor A. Polozov ◽  
Evgenii V. Borisov ◽  
Maxim Y. Maximov

The article presents the results of selective laser melting of Ti-6Al-4V alloy. It was studied phase composition and microstructure of the initial powder material, the specimens manufactured by Selective Laser Melting and also the specimens after heat treatment. The effect of heat treatment on microstructure and mechanical properties of the specimens was shown. It was studied the mechanical behavior of the manufactured specimens before and after heat treatment at room and elevated temperatures as well. After heat treatment tests showed that the specimens have decent mechanical properties both at room and elevated temperatures.


2015 ◽  
Vol 60 (3) ◽  
pp. 1755-1762 ◽  
Author(s):  
J. Wozniak ◽  
M. Kostecki ◽  
K. Broniszewski ◽  
W. Bochniak ◽  
A. Olszyna

Abstract This paper discusses the influence of thermal treatment parameters on mechanical properties of AA6061+x% vol. SiCp (x = 0, 2.5, 5, 7.5, 10) composites. The composites were consolidated via powder metallurgy processing using the unconventional method of extrusion (the KoBo method). In order to establish the optimum parameters of the heat treatment two different temperatures of supersaturation (530 and 558ºC) were applied. The aging curves were determined at various aging temperatures such as 140, 160, 180 and 200ºC. The effects of applied parameters were studied using the microstructure observations and hardness measurements. Obtained results show that the solution treatment at 530ºC is sufficient to complete dissolution of the precipitates. Higher temperature of the process resulted in accelerating the aged-hardening. The suitable age treating parameters for the AA6061-5 vol. % SiCp composites were 160 - 180ºC for 12 - 16 hours.


2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Renata A. Esteves ◽  
Letícia C. C. Boaro ◽  
Flávia Gonçalves ◽  
Luiza M. P. Campos ◽  
Cecy M. Silva ◽  
...  

This study evaluated the influence of formulation and thermal treatment on the degree of conversion, fracture toughness, flexural strength, and elastic modulus of experimental composites. Six composites were analyzed at BisGMA : TEGDMA molar ratios of 1 : 1 and 7 : 3 with filler at 30, 50, and 70 wt%. The degree of conversion was analyzed by Fourier transform infrared spectroscopy, fracture toughness was measured using the single-edge notched beam, and flexural strength and elastic modulus were measured with the 3-point bend test. For all tests, one-half of the specimens received thermal treatment at 170°C for 10 min. Data were analyzed by the Kruskal-Wallis or ANOVA/Tukey’s test (α = 5%). The 1 : 1 BisGMA : TEGDMA ratio showed higher properties than the 7 : 3 ratio. Although the material with 70% filler had a conversion lower than the one with 50%, it showed higher mechanical properties. The thermal treatment improved all properties in all materials. Therefore, the use of an equimolar ratio of BisGMA : TEGDMA can be paired with 70 wt% filler to design dental composites that possess increased advantageous physical and chemical properties. Furthermore, the simple and low-cost method of thermal treatment proposed for use in clinical dentistry has been shown to effectively improve the properties of all evaluated materials.


2018 ◽  
Vol 34 (1) ◽  
pp. 1-11
Author(s):  
Ariana Freire Andrade ◽  
Rodrigo Bíscaro Nogueira

We investigated the mechanical behavior of freshwater mollusk shells, Pomacea dolioides, collected from a floodplain area located in Amazonas, Brazil. With the purpose of characterizing the mechanical properties of the shells, bending, hardness and roughness tests were carried out. To determine the shell flexural strength, a new methodology was proposed for the calculation of it, considering the curved geometry of the specimens taken from the shells. It was also described the mechanical properties as a function of shell position and thickness, variation of the surface hardness along the shell and the low level of superficial irregularity in the inner layer of the shells. Shell presented a mean flexural rupture modulus (MOR) of 128.0 MPa, Rockwell HR15N hardness = 50 ± 8.3 and a low level of irregularities in the inner layer, roughness Ra = 0.160 μm.


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