scholarly journals FEATURES OF THE STRUCTURE FORMATION OF SPODUMENS-CONTAINING GLASS-CRYSTAL MATERIALS AFTER HEAT TREATMENT

Author(s):  
Oksana Savvova ◽  
Gennady Voronov ◽  
Svіatoslav Rіabinin ◽  
Alexey Fesenko ◽  
Dmitry Svishov

The promising areas of application of spodumene–containing glass–crystalline materials in various branches of science and technology, in particular, to increase the defense capability of the state, have been determined. The relevance of the development of lightweight high–strength sitalls based on them, taking into account the aspects of energy saving for obtaining armored elements, has been determined. It has been established that the use of IR spectroscopy is promising for studying the nanostructure of glass–crystalline materials. The compositions of lithium aluminum silicate glasses and the modes of their heat treatment have been developed. The features of the structure formation of spodumene–containing glass–crystalline materials obtained under the conditions of two–stage low–temperature heat treatment have been investigated. Taking into account the analysis of the nature of the IR spectra of chain silicates, the structure of glass–crystalline materials was investigated according to the IR spectra and the nature of structure formation was established depending on the initial composition of the glass. It has been established that the formation of a structural glass network with the participation of tetrahedra [AlO4], [BO4] and [SiO4] and the presence of cybotaxic groups [Si2O6] allows, under conditions of two–stage low–temperature treatment, to provide bulk crystallization of spodumene–containing glass–crystalline materials. It has been established that the formation of the vitrified structure of glass–crystalline materials allows to ensure their high values of Vickers hardness, microhardness and crack resistance and by the presence of a glass phase, which plays the role of a damper, to ensure their high armor resistance. This will increase the efficiency and make it possible to use them as an energy–destructive and energy–absorbing layer in the composition of the armor element «metal alloy – ceramics – sitall». The introduction of spodumene–containing glass–crystalline materials will increase the competitiveness of competitive domestic armored elements for personal protection.

Author(s):  
E. Bischoff ◽  
O. Sbaizero

Fiber or whisker reinforced ceramics show improved toughness and strength. Bridging by intact fibers in the crack wake and fiber pull-out after failure contribute to the additional toughness. These processes are strongly influenced by the sliding and debonding resistance of the interfacial region. The present study examines the interface in a laminated 0/90 composite consisting of SiC (Nicalon) fibers in a lithium-aluminum-silicate (LAS) glass-ceramic matrix. The material shows systematic changes in sliding resistance upon heat treatment.As-processed samples were annealed in air at 800 °C for 2, 4, 8, 16 and 100 h, and for comparison, in helium at 800 °C for 4 h. TEM specimen preparation of as processed and annealed material was performed with special care by cutting along directions having the fibers normal and parallel to the section plane, ultrasonic drilling, dimpling to 100 pm and final ionthinning. The specimen were lightly coated with Carbon and examined in an analytical TEM operated at 200 kV.


2007 ◽  
Vol 330-332 ◽  
pp. 51-54 ◽  
Author(s):  
Kui Cheng

Biphasic α-tricalcium phosphate/hydroxyapatite (α-TCP/HA) calcium phosphate (BCP) is prepared through a modified slip casting based method: α-TCP powders are dispersed in the HA precursor solutions to form castable slurries, then the slurries are poured into round mold. After curing, the slurries turn into cakes. Room temperature curing leads the cakes to contain α-TCP and HA phases. Higher temperature heat treatment will result in the increase of HA content, while even higher temperature will leads the cakes to be triphasic. Low temperature derived BCP have particular microstructure with HA covers the surface of α-TCP powders, and these powders further agglomerate into large blocks. After higher temperature treatment, β-TCP dominates the cake and microporous structure is resulted.


2019 ◽  
Vol 98 ◽  
pp. 02003
Author(s):  
Natalia Chukhareva ◽  
Oksana Zarubina ◽  
Alexey Zarubin

Humic acids are perspective complicated natural objects for different purposes. The problem of humic acids functional composition regularization is very important. The effect of heat treatment on peat humic acids group composition alteration was evaluated to solve this problem. The projection study by principal component analysis of IR-spectra data is presented. The possibility of peat humic acids functional composition regularization by temperature treatment and subsequent storage was found.


Alloy Digest ◽  
1965 ◽  
Vol 14 (1) ◽  

Abstract Jessair is a manganese, chromium, molybdenum alloy steel combining the deep harding characteristics of air-hardening steels with the simplicity of low temperature heat treatment possible in many oil-hardening steels. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and bend strength as well as fracture toughness and fatigue. It also includes information on forming, heat treating, machining, and joining. Filing Code: TS-157. Producer or source: Jessop Steel Company.


2020 ◽  
Vol 70 (12) ◽  
pp. 4519-4524

The efficiency of time-temperature treatment (T-TT) on metal melts can be microstructurally analysed through their degree of purity in non-metallic inclusions. In the case of the Ni-based super alloy under discussion (MSRR 7045) the heat treatment was the undercooling consequences both on the durability of the casting environment (ingots-refractories) and on the internal structure of the metal (porosity, microstructural isotropy). Keywords: time-temperature treatment, undercooled melt, non-metallic inclusions, purity, microstructural isotropy


Vsyo o myase ◽  
2020 ◽  
pp. 22-24
Author(s):  
Nasonova V.V. ◽  
◽  
Tunieva E.K. ◽  
Motovilina A.A. ◽  
Mileenkova E.V. ◽  
...  

The paper presents the results of the study on the effect of low-temperature heat treatment on color characteristics and protein oxidation products depending on the method, temperature and duration of heat treatment of culinary products from turkey meat. At present, the use of low-temperature processing in the production technology for meat products with improved organoleptic indices is a topical direction.


1992 ◽  
Vol 57 (12) ◽  
pp. 2475-2480 ◽  
Author(s):  
Milan Brutovský ◽  
Štefan Gerej ◽  
Ján Novák ◽  
Lucia Ferdinandyová

Catalysts were prepared from VOPO4.xH2O.yH3PO4 (x = 0.3-2, y = 0.2-0.85) by reduction with SO2 up to a final temperature of 750-800 °C, and activated in a reaction mixture of 1.0-1.4% butane in air up to 500 °C. The structure characteristics and phase composition of the catalysts were found to be affected by the preparation procedure and heat treatment regime. Their diffraction lines and IR spectra revealed that the catalysts from larger and less defective crystals than catalysts which were obtained from the VOHPO4.xH2O.yH3PO4 precursor and activated in the reaction mixture at temperatures up to 500 °C. In the catalysts prepared by the above procedure, the tendency to the formation of phases of higher-condensed phosphates, in particular VO(PO3)2 or even V(PO3)3, increases with increasing n(P):n(V) ratio and is then more pronounced than with vanadium-phosphorus catalysts prepared by other procedures. The tendency to the formation of the catalytically less active condensed phosphates is partly suppressed by the embedding of modifying metal cations (Fe or Cu in this case).


Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4102
Author(s):  
Jan Stindt ◽  
Patrick Forman ◽  
Peter Mark

Resource-efficient precast concrete elements can be produced using high-performance concrete (HPC). A heat treatment accelerates hardening and thus enables early stripping. To minimise damages to the concrete structure, treatment time and temperature are regulated. This leads to temperature treatment times of more than 24 h, what seems too long for quick serial production (flow production) of HPC. To overcome this shortcoming and to accelerate production speed, the heat treatment is started here immediately after concreting. This in turn influences the shrinkage behaviour and the concrete strength. Therefore, shrinkage is investigated on prisms made from HPC with and without steel fibres, as well as on short beams with reinforcement ratios of 1.8% and 3.1%. Furthermore, the flexural and compressive strengths of the prisms are measured directly after heating and later on after 28 d. The specimens are heat-treated between 1 and 24 h at 80 °C and a relative humidity of 60%. Specimens without heating serve for reference. The results show that the shrinkage strain is pronouncedly reduced with increasing temperature duration and rebar ratio. Moreover, the compressive and flexural strength decrease with decreasing temperature duration, whereby the loss of strength can be compensated by adding steel fibres.


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