Effect of graphite microstructure on their physical parameters and wettability properties

Author(s):  
B. Sułkowski ◽  
G. Boczkal ◽  
P. Pałka ◽  
G. Mrówka-Nowotnik

To produce castings of titanium, nickel, zinc, copper and many other metal alloys, graphite molds can be used. Using graphite molds has many advantages which are no lubricate or coating layers are needed, high cooling rate, easy of production of complicated shapes. However, for good quality of castings there is needed a good quality of graphite with high mechanical properties and good heat transfer coefficient. Because of no room for manipulating of chemical composite of graphite molds, the most important factor influencing the properties of the molds is their production process. Thus, in the present study mechanical properties of two different type of graphite were investigated. There was graphite produced by different technological processes. One of the processes was a typical graphite production process from the isotropic coke, the second process was an electrolytic method production. Investigations included mechanical tests as well as the structure observations by scanning electron microscope. Chemical analysis was determined by Energy Dispersive X-ray Spectroscopy method additionally, phase analysis using the XRD method was performed. Mechanical properties were obtained by compression tests and three points banding tests at room temperature. It was found that the porosity of a graphite is the key parameter for good its mechanical properties. In addition, it was found that the mechanical anisotropy of graphite is the effect of the production method where the size and distribution of pores play an important role. Ill. 7. Ref. 9. 

2019 ◽  
Vol 17 (1) ◽  
pp. 37
Author(s):  
Muas M ◽  
Muhammad Arsyad Suyuti ◽  
Rasul Rasul ◽  
Patta Hajji

The purpose of this research is to know the mechanical properties of the welds due to the current variation of welding joint API 5L using TIG and SMAW welding root methods. Preparation of specimens of pipe API 5L PSL1 grade X56 (Ø 177.8 mm, length 200 mm, width 7 mm), then specimens preparation were made in a single V 600, root gap 2mm, root face 2mm. Filling the welding roots with TIG welding and SMAW using electrodes E7018 with a current variation 70A, 80A, 90A. Mechanical tests consist of tensile, bending and hard test. The results showed that the quality of a good TIG root weld at 70A, the highest tensile strength of the weld joint 52.27 kgf/mm2 (70A), the highest hardnest 164,217 HRB (90A), the bending strength 1.123,061 N/mm2 (70A) using face bend method and 1,172,959 N/mm2 with root bend. In SMAW root welding, the highest tensile strength 54.27 kgf/mm2 (70 A) , the highest hardnest  158.717 HRB (70 A), the highest bending strength 1.115,611 N/mm2 (70 A) using face bend method, and 1.161,748 N/ mm2 with root bend. 


2021 ◽  
Vol 46 (1) ◽  
pp. 27-30
Author(s):  
Aida Imamović ◽  
Raza Sunulahpašić ◽  
Mirsada Oruč ◽  
Omer Kablar ◽  
Derviš Mujagić

The influence of the production method, i.e. casting technology on the cleanliness and thus the quality of carbon steels is best determined through the presence and type of non-metallic inclusions. A large number of inclusions, especially oxide and complex ones, can significantly affect the mechanical properties of carbon steels and limit their application for the production of finished products. This paper presents the influence of the presence, type and amount of non - metallic inclusions in B500B carbon steel according to ASTM / AISI produced by continuous casting technology without and with the application of stream protection.


2021 ◽  
Vol 2083 (2) ◽  
pp. 022079
Author(s):  
Zhengwei Gu ◽  
Yusheng Li ◽  
Ziming Tang ◽  
Ge Yu

Abstract In recent years, the incremental shrinking process has been widely used in the forming process of aluminum alloy components for the railway vehicles. The effect of the incremental shrinking process on the performance and microstructure of 6082-T6 aluminum alloy was investigated through mechanical tests and electron backscatter diffraction (EBSD) analysis. The tensile test specimens prepared in different rolling orientations (0˚,45˚and 90˚) along the original and deformed sheets exhibited the mechanical anisotropy. After the incremental shrinking process, the average microhardness, tensile strength, and yield strength of this alloy were respectively increased by nearly 8.78%,2.26%,2.72%, while the Elongation was decreased by almost 31.67%. By analyzing the EBSD data, the strength of the material is increased by the incremental shrinking process and its mechanical anisotropy is improved, whereas its plasticity is greatly deteriorated.


2013 ◽  
Vol 44 (2s) ◽  
Author(s):  
Claudio Caprara ◽  
Fabio Pezzi

The purpose of these trials was to evaluate possible effects on properties of grapes, particularly the physical and mechanical features, depending on the winter pruning system. The following pruning techniques were carried out: manual pruning (m); mechanical pruning (M); mechanical pre-pruning and subsequent manual finishing (Mm); mechanical pre-pruning and contemporary fast manual finishing, using a wagon facility with two operators equipped with pneumatic scissors (Mw). The trials were carried out on Sangiovese trained to spurred cordon. During the trials were measured: time and cost of pruning, quality of pruning and the vegetative-productive response of vines. During grape harvesting a consolidated analytical method of texture analysis was applied to evaluate the physical parameters of grapevine cultivar: pedicel detachment, skin perforation, skin thickness, grape features as hardness, cohesiveness, springiness. Analysis of working time showed that the manual pruning (m) determined a greater commitment of time, while the mechanized pruning (M) presented a time reduction of 95%. The two mechanized pruning associated with manual finishing reduced the time of 21% (Mm) and 69% (Mw). The lowering cost is less evident but important anyway. Regarding the quality of pruning, the increase in the level of mechanization has produced an increase of spurs and buds density. It was also detected a higher percentage of damaged spurs and in wrong position. The increasing of mechanization levels of pruning also has produced smaller and sparser bunches with smaller berries. The study of mechanical properties of berries showed significant differences in the mechanical behaviours of the different pruning tests. The mechanized pruning presented higher values for the pedicel detachment, skin perforation and cohesiveness, while it gave lower values for thickness of skin and springiness. The results showed that mechanical pruning can modify properties of the berries which influence mechanical harvesting on vineyard.


2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Rajab Mohammed Hussein ◽  
Osama Ibrahim Abd

Brass has an attractive combination of properties, namely, good corrosion resistance, good wear properties, and high thermal and electrical conductivity. In this study, influence of selected alloy additions (Al and Ti) on performance of leaded brass alloys (CuZn39pb3) was investigated. The observation of microstructures, compression tests, and hardness tests were performed. The results of metallographic and mechanical tests indicate some influence of small amount additives of Al and Ti. Optical emission spectrometer (OES), light optical microscope (LOM), micro-Vickers hardness tester, and compression testing machine were used in this investigation. Consequently, Al had a significant effect on microstructure and mechanical properties of CuZn39Pb3 alloy. A larger compression strength at 0.31% wt of Al was obtained, as compared with the other alloys. Adding of Al and Ti led to the modification of the microstructure; thus, the compression strength was increased.


2014 ◽  
Vol 635 ◽  
pp. 139-142 ◽  
Author(s):  
Lucia Fedorová ◽  
Irenej Poláček ◽  
Radovan Hudák ◽  
Mária Mihaliková ◽  
Jozef Živčák

Spinal implants are mechanical equipments that facilitate fusion, correct deformities, and stabilize and strengthen the spine. To make an implant efficient, it has to endure without any failure, especially mechanical damage, stand all the static and dynamic loads incurred in spine during everyday activities, and maintain the necessary position of motive segments during the bone adhesion. [1] Human spine is exposed to the highest load in the lumbar section [2]; therefore, lumbar bilateral implants require higher attention in terms of mechanical parameters verification. The main objective of this paper was to compare mechanical properties of lumbar bilateral systems using the spinal implants manufactured by the conventional method and the Direct Metal Laser Sintering method (DMLS). Detection of mechanical properties enables the assessment of possible replacement of commercial manufacture with the DMLS manufacture. On the basis of the ASTM F1717 standards providing the essentials for the comparison of mechanical properties of spinal systems, twenty mechanical compression tests were carried out. Mechanical tests were carried out using 20 spinal bars with the diameter of 11 mm and the fastening length of 260 mm, manufactured by the DMLS technology while using the EOSINT M280 equipment (EOS, Germany), and 20 identical spinal bars manufactured by the conventional technology. Results obtained in mechanical compression tests indicate that both manufacture methods are comparable and there are no significant differences between them, as for the strength characteristics. Other trials will be focused on static tensile tests and cyclical tests of lumbar bilateral systems.


2021 ◽  
Author(s):  
Massimo Durante ◽  
Luca Boccarusso ◽  
Antonio Formisano ◽  
Dario De Fazio ◽  
Antonio Viscusi ◽  
...  

Metal foams have a number of established niche market and potential applications under investigation due to their peculiarities including thermal, acoustic and mechanical properties at low weight. In order to produce structures resistant at high temperature and acting as barrier to the fire, metals with closed cells are often required, and one of the most consolidate manufacturing process for their production is the gas releasing particles decomposition in semisolids, by means of which a foam is created by a foaming agent dispersed into a precursor. In previous researches, the authors have investigated the possibility of foaming the aluminum starting by a precursor, placed between two skins consisting of steel grids, in order to obtain a sandwich structure at the same time of the foaming step. In line to continue on this topic and to improve the compression strength of the aluminum-foamed core, in this work the steel grid was used both as skins and as a corrugated skeleton inside the core. Different types of sandwich structures were manufactured, following some experimental tests executed to determine the optimal value of temperature and time to foam the precursor. Then, compression tests were carried out, in order to investigate the effectiveness of the proposed solution on the improvement of this mechanical behavior. The mechanical tests highlighted the increase of mechanical properties using this type of corrugated core.


Holzforschung ◽  
2011 ◽  
Vol 65 (5) ◽  
Author(s):  
Guillermo Riesco Muñoz ◽  
Andrés Remacha Gete

Abstract Ring-porous hardwoods such as oak are in high demand for furniture-making, cooperage, flooring, and construction. However, evaluating the quality of such timber is difficult and time consuming, and simpler tests are required. Models for predicting as many mechanical properties as possible, based on easier-to-determine mechanical tests, may help. In this study, the hardness, modulus of elasticity, bending, compression, and impact bending strength parallel to grain were tested on defect-free laths obtained from a sample of 42 oak trees. The relationships between the variables were investigated. Three models that relate the resistance to axial compression with bending strength and stiffness (R2>0.55; P<0.01) are proposed for defect-free oak timber. Selection of models mainly depended on the bias, which was highly variable among the models tested. The prediction models proposed in the international standard EN 384:2004 for structural dimension timber are not suitable for small clear wood specimens, especially in very elastic woods. The relative independence of hardness and impact bending strength as regards the other mechanical properties is also demonstrated.


2015 ◽  
Vol 52 (2) ◽  
pp. 211-223 ◽  
Author(s):  
Paolo Tommasi ◽  
Luca Verrucci ◽  
Tatiana Rotonda

The geotechnical behaviour of very weak pyroclastic rocks controls both the failure mechanisms at the margins of rock mesas, where historic hill towns are often sited, as well as the stability of old underground cavities in urban areas of Central Italy. The study focuses on the mechanical behaviour of one of the pyroclastic materials forming the Orvieto mesa (pozzolana), not unlike other pozzolanas in Central and Southern Italy and other pyroclastites from volcanic districts worldwide. The mechanical properties under static conditions of this weakly cemented rock are reported. A petrographic and physical characterization of the material was preliminary conducted, followed by a wide range of mechanical tests: oedometer, uniaxial, and isotropic compression tests and indirect tensile tests. The stress–strain and strength behaviours of the pozzolana are highlighted and compared with those of the rock materials of the pyroclastic formation (tuff). The mechanical behaviour of the pozzolana is related to its physical and textural characters, with special reference to continuity of the groundmass and porosity. Finally, the role of the material behaviour at the field scale is discussed.


Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1671
Author(s):  
Mohd Shahneel Saharudin ◽  
Jiri Hajnys ◽  
Tomasz Kozior ◽  
Damian Gogolewski ◽  
Paweł Zmarzły

The paper presents the results of mechanical tests of models manufactured with two 3D printing technologies, FDM and CFF. Both technologies use PLA or PA-based materials reinforced with carbon fibers. The work includes both uniaxial tensile tests of the tested materials and metrological measurements of surfaces produced with two 3D printing technologies. The test results showed a significant influence of the type of technology on the strength of the models built and on the quality of the technological surface layer. After the analysis of the parameters of the primary profile, roughness and waviness, it can be clearly stated that the quality of the technological surface layer is much better for the models made with the CFF technology compared to the FDM technology. Furthermore, the tensile strength of the models manufactured of carbon fiber-enriched material is much higher for samples made with CFF technology compared to FDM.


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