Characterization of glass-ceramics microstructure, chemical composition and mechanical properties

Author(s):  
E Lodins ◽  
I Rozenstrauha ◽  
L Krage ◽  
L Lindina ◽  
M Drille ◽  
...  
2006 ◽  
Vol 509 ◽  
pp. 165-170 ◽  
Author(s):  
Alla Kabatskaia Ivanovna ◽  
Victor M. López-Hirata ◽  
Eduardo Oliva López ◽  
Ricardo Rodríguez Figueroa ◽  
Jorge Rodríguez Miramontes

Microstructural and mechanical characterization of Nitinol gas tungsten arc weld (GTAW) and furnace brazing (FB) welds for grade 1 titanium plates are carried out in order to study the microstructure developed after welding and its effect on the mechanical properties of welds. The GTAW process yields the highest hardness weld. The constituents for this weld consist of a dendritic structure of NiTi and NiTi2 intermetallic phases. The FB process promotes a change of the welds chemical composition due to atomic diffusion of Ti. The weld microconstituents consist of a mixture of a Ti-rich and NiTi2 eutectic and a proeutectic Ti-rich phase.


2013 ◽  
Vol 8 (22) ◽  
pp. 37
Author(s):  
Mauro Carlos Souza ◽  
Antonio Carlos de Araújo Santos ◽  
Wilma Clemente de Lima Pinto ◽  
Mila Rosendal Avelino

The mechanical properties of cast metallic materials are strongly influenced by processing parameters, such as percentage of silicate, sand granulometry, and metallurgical processing. The ductile iron cast produced by the CO2 process depends on variables that determine the behavior of the material in service, such as the cooling rate and chemical composition. This study evaluated the influence of the cooling rate on the spheroidic graphite. In order to determine this effect, a simulation was performed in specimens with 20, 25, and 30 mm in thickness, through the characterization of type, measurement of nodule size, and distribution of nodules. Chemical analysis and mechanical resistance tests were performed. The 25 mm thick specimen showed the best behavior among the three thicknesses evaluated, presenting the formation of many small nodules and a small amount of larger nodules in the center.


Author(s):  
Hongyan Qi ◽  
Guixiong Gao ◽  
Huixin Wang ◽  
Yunhai Ma ◽  
Hubiao Wang ◽  
...  

The naked mole rat incisors (NMRI) exhibit excellent mechanical properties, which makes it a good prototype for design and fabrication of bionic mechanical systems and materials. In this work, we characterized the chemical composition, microstructure and mechanical properties of NMRI, and further compared these properties with the laboratory rat incisors (LRI). We found that (1) Enamel and dentin are composed of organic matter, inorganic matter and water. The ratio of Ca/P in NMRI enamel is higher than that of LRI enamel. (2) The dentin has a porous structure. The enamel has a three-dimensional reticular structure, which is more complex, regular and denser than the lamellar structure of LRI enamel. (3) Enamel has anisotropy. Its longitudinal nano-hardness is greater than that of transverse nano-hardness, and both of them are higher than that of LRI enamel. Their nano-hardness and elastic modulus increase with the increment of distance from the enamel-dentin boundary. The nano-hardness of dentin is smaller than that of enamel. The chemical composition and microstructure are considered to be the reasons for the excellent properties of NMRI. The chemical composition and unique microstructure can provide inspiration and guidelines for the design of bionic machinery and materials.


2011 ◽  
Vol 312-315 ◽  
pp. 199-204
Author(s):  
K. Khenfer ◽  
S. Lebaili ◽  
S. Hamar-Thibault

The mechanical engineering industry is always in the search of new hardfacing alloys which nowadays make it possible to solve considerable delicate problems of abrasive wear and corrosion. These alloys are heterogeneous materials and are generally composed of a ductile matrix and a significant proportion in hard phases (carbides, borides or silicides), which give a good wear resistance and corrosion. The following studies made on alloys containing Ni, rich in Silicon and tungsten. We noted that addition of these elements (Si and W) got interesting mechanical properties. The alloys that we chose for this study contain the elements C, B, Si, Cr and W with additions in Ti and Mo. The aim of this work is the characterisation of the various phases formed during solidification, to study chemical affinities in this system poly-constitutes and to make a correlation between the chemical composition, the conditions of development and the microstructures obtained.


2014 ◽  
Vol 805 ◽  
pp. 700-705
Author(s):  
Sergio Ciampolini Nogueira de Lima ◽  
Edson Pereira Soares ◽  
Marco Andreoli ◽  
Rubens Chiba ◽  
Emília Satoshi Miyamaru Seo

When used commercially, the zirconium alloys are utilized in the shape of tubes to encapsulate the UO2 pellets in the PWR and BWR Power reactors. The metallic zirconium is an essential metallic element for the types of alloys in which the obtainment route rests in the ore opening for the production of zirconium oxide followed by the processes of pelletizing, chlorination, purification, reduction and distillation. Through the technique of X-Ray Diffraction the present phases were identified. Using the Fluorescence of an X ray it was possible to determined the chemical composition of the zirconium sponge. The mechanical properties of Vickers microhardness were obtained using a microdurometer. As a result, it was established that it is possible to define a methodology for the preparation of a sample of metallic zirconium for the microstructure analysis, as well as that its chemical purity is 97,265% linked to the microhardness of approximately 51 HV.


2011 ◽  
Vol 3 (1-2) ◽  
Author(s):  
Biljana Angjusheva

The fly ash, produced by power plant in Republic of Macedonia have been milled and sintered with addition of waste glass to obtain glass-ceramics. The physical, chemical and mechanical properties of fly ash and waste glass were determined. Through adequate sintering time and temperature, the glass-ceramic materials were manufactured. Chemical, physical and mechanical properties of the obtained composites were defined. The optimal composition of the composite was fly ash with the addition of 40% waste glass. Optimal sintering condition was 1000oC with 1h isothermal time at final temperature and heating rate of 10o/min. The addition of 40%wt of waste glass in the fly ashes increased the E-modulus from 4.24±1 to 30.55±2 GPa and increased the bending strength from 9.93±1 to 63.18±4 MPa Porosity of the compacts decreased from 44.34±3 to 14.32±2%. Investigation of durability of the produced systems did not show presence of any harmful elements in the obtained solution. Owning to combination of the macroscopic appearance, microstructure, mechanical and thermal properties developed, dense materials could be used in the civil engineering.


2018 ◽  
Vol 11 (3) ◽  
pp. 474-498
Author(s):  
C. E. T. BALESTRA ◽  
M. G. LIMA ◽  
A. Z. MENDES ◽  
R. A. MEDEIROS-JUNIOR

Abstract This paper studies the influence of the corrosion degree calculated by the mass loss and by the smaller diameters on the yield strength, ultimate strength and final elongation. Reinforcements buried and naturally corroded for 60 years were studied. The mechanical properties of the protruding reinforcing steel were compared to reference bars, which also remained buried for 60 years, but without going through the corrosion process. Micrographs, besides the chemical composition and the characterization of the aggressiveness of the soil were realized. The micrographs and the chemical composition show the presence of pits in the reinforcements and sulfur contents for steel above the prescriptions of the time when the foundations were initially implement, respectively. The results also show that the effects of pitting corrosion on the mechanical properties of the naturally corroded bars may not be adequately expressed by the mass loss. This type of corrosion (pits) produces geometric variations in the cross sections along the length of the test specimens, generating stress gradients between successive sections. This has a noticeable impact on the mechanical properties of the reinforcements. In general, the effects of corrosion are more pronounced on the ductility of the reinforcement. Regarding the aggressiveness of the soil, high corrosion rates were identified in the reinforcement, even with the soil being classified as essentially non-corrosive.


2013 ◽  
Vol 8 (22) ◽  
pp. 37-41
Author(s):  
Mauro Carlos Souza ◽  
Antonio Carlos de Araújo Santos ◽  
Wilma Clemente de Lima Pinto ◽  
Mila Rosendal Avelino

The mechanical properties of cast metallic materials are strongly influenced by processing parameters, such as percentage of silicate, sand granulometry, and metallurgical processing. The ductile iron cast produced by the CO2 process depends on variables that determine the behavior of the material in service, such as the cooling rate and chemical composition. This study evaluated the influence of the cooling rate on the spheroidic graphite. In order to determine this effect, a simulation was performed in specimens with 20, 25, and 30 mm in thickness, through the characterization of type, measurement of nodule size, and distribution of nodules. Chemical analysis and mechanical resistance tests were performed. The 25 mm thick specimen showed the best behavior among the three thicknesses evaluated, presenting the formation of many small nodules and a small amount of larger nodules in the center.


Author(s):  
Gyeung Ho Kim ◽  
Mehmet Sarikaya ◽  
D. L. Milius ◽  
I. A. Aksay

Cermets are designed to optimize the mechanical properties of ceramics (hard and strong component) and metals (ductile and tough component) into one system. However, the processing of such systems is a problem in obtaining fully dense composite without deleterious reaction products. In the lightweight (2.65 g/cc) B4C-Al cermet, many of the processing problems have been circumvented. It is now possible to process fully dense B4C-Al cermet with tailored microstructures and achieve unique combination of mechanical properties (fracture strength of over 600 MPa and fracture toughness of 12 MPa-m1/2). In this paper, microstructure and fractography of B4C-Al cermets, tested under dynamic and static loading conditions, are described.The cermet is prepared by infiltration of Al at 1150°C into partially sintered B4C compact under vacuum to full density. Fracture surface replicas were prepared by using cellulose acetate and thin-film carbon deposition. Samples were observed with a Philips 3000 at 100 kV.


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