scholarly journals Influence of alloying components on diffusion and bonding processes in powder materials

2021 ◽  
Vol 2131 (4) ◽  
pp. 042024
Author(s):  
M Egorov ◽  
R Egorova ◽  
A Atrohov ◽  
V Ekilik
Keyword(s):  
Powder Metallurgy ◽  
Rapid Development ◽  
Alloying Elements ◽  
Powder Materials ◽  
Iron Powders ◽  
Cast Steels ◽  
Wide Range ◽  
Aerospace Technology ◽  
Alloy Steels ◽  
Characteristic Features

Abstract At present, powder materials are used in practically all branches of industry, from medicine to aerospace technology. This is a wide range of materials ranging from constructional and instrumental materials and ending with special-purpose materials and medical implants. Powder metallurgy methods are most often used where the manufacture of products with desired properties is impossible using traditional methods: casting, stamping, etc. The production of all these materials is based on such basic operations as: obtaining starting materials, molding from these materials blanks of a given shape, size and strength, and sintering, intended for the final formation of the required properties and dimensions. The peculiarity of powder metallurgy technology allows creating a huge variety of developed technological schemes, which puts these technologies to a new level and allows for the rapid development of many industries. Alloying powder steels, in contrast to cast steels, has a number of characteristic features due to the specificity of their production. The structure of powder alloy steels and their properties depend on the methods of obtaining steels and technological features of their production. The following main methods of obtaining powder alloyed steels can be named: preparation of multicomponent mixtures of powders of iron and alloying elements and their subsequent processing; the use of alloyed iron powders, to which, if necessary, add carbon or other alloying elements; impregnation with liquid alloying metals or diffusion saturation of frameworks sintered from iron powders.

scholarly journals Features of phase transformations in powder steels upon heating

2021 ◽  
Vol 2131 (4) ◽  
pp. 042011
Author(s):  
M Egorov ◽  
R Egorova ◽  
A Atrohov ◽  
V Ekilik
Keyword(s):  
Heat Treatment ◽  
Physical And Mechanical Properties ◽  
Structural Heterogeneity ◽  
Powder Materials ◽  
Heating And Cooling ◽  
Cast Steels ◽  
Wide Range ◽  
Aerospace Technology ◽  
Powder Steels ◽  
Powder Metallurgy Methods

Abstract At present, powder materials are used in practically all branches of industry, from medicine to aerospace technology. This is a wide range of materials ranging from constructional and instrumental materials and ending with special-purpose materials and medical implants. Powder metallurgy methods are most often used where the manufacture of products with desired properties is impossible using traditional methods: casting, stamping, etc. Heat treatment is understood as a set of operations of heating, holding at high temperatures and cooling in order to change the structure and workability of the material, improve the combination of its mechanical and physical properties without changing the shape and size of products. Heat treatment is an effective method for improving the physical and mechanical properties and wear resistance of steel. The specific features of sintered steels (porosity, structural heterogeneity, high oxidizability, etc.) make it difficult to use the technological modes of heat treatment developed for cast steels, although the main regularities of the processes occurring during heating and cooling of compact steel can be transferred to sintered materials. Heat treatment of powder steels has a number of features, primarily due to residual porosity, as well as chemical and structural heterogeneity.

Microstructure Development in Powder Metallurgy Steels: Effect of Alloying Elements and Process Variables

2014 ◽  
Vol 782 ◽  
pp. 467-472 ◽  
Author(s):  
Eduard Hryha ◽  
Lars Nyborg
Keyword(s):  
Powder Metallurgy ◽  
Carbon Sources ◽  
Processing Parameters ◽  
Alloying Elements ◽  
Microstructure Formation ◽  
Prealloyed Powder ◽  
Conventional Sintering ◽  
The Difference ◽  
Characteristic Features ◽  
Effect Of Alloying

Microstructure of the powder metallurgy (PM) steels and especially mechanism of its formation differs significantly from the microstructure of the conventional steels even if composition will be exactly the same. The difference is not only connected to the presence of the pores, which are inalienable feature of the PM parts. Presence of the prior inter-particle boundaries, which can be contaminated by residual oxides, as well as microstructure heterogeneity are another characteristic features of the microstructure of PM steels. Microstructure heterogeneity is connected to the PM manufacturing process: powder mix, consisting of the base powder and additional alloying elements is compacted and then sintered. Fully prealloyed powder is not always possible to use in standard press & sintering route due to the solid solution strengthening of the ferrite resulting in bad powder compressibility. Hence, in order to provide good powder compressibility only pure iron or low-alloyed (typically <3 wt.%) powders are used. Required alloying elements and carbon (added as graphite) are further admixed in the powder form and are distributed during sintering by diffusion into iron particles at high temperatures. To assure satisfactory distribution of alloying elements, oxide layer, covering surface of the powder particles and hindering mass-transfer of the alloying elements, has to be removed first. This can be done by gaseous reducing agents as hydrogen and carbon monoxide. However, their cost and/or purity are of issue for modern alloyed PM steels. Admixed carbon, additionally to its function as alloying element, plays a role of effective reducing agent at higher temperatures. Paper summarizes the main features of microstructure formation during the whole sintering cycle (heating and isothermal sintering) and effect of alloying additives (different carbon sources, alloying elements) and processing parameters (sintering atmosphere composition, temperature profile) on the microstructure formation during conventional sintering process. Results indicate that for successful sintering of alloyed PM steels with homogeneous defect-free microstructure, hydrogen-rich atmospheres and high-temperature sintering are required.

scholarly journals FEATURES OF ALLOYED A MATRYX OF WATER-DISPERSED IRON POWDERS

2021 ◽  
Vol 3 ◽  
pp. 226-231
Author(s):  
Ivanka Miteva ◽  
Ivan Vinev ◽  
Ivan Mitev
Keyword(s):  
Powder Metallurgy ◽  
Technological Process ◽  
Alloying Elements ◽  
Iron Matrix ◽  
Iron Powders ◽  
Dimensional Changes ◽  
Copper Nickel ◽  
Special Place ◽  
The Matrix

The publication examines the peculiarities of alloying a matrix of water-dispersed iron powders of the type ASC 100.29, AHC 100.29 and ABC 100.30. The possible ways of alloying in powder metallurgy are presented. The influence of the main alloying elements - copper, nickel, phosphorus, molybdenum, etc. was traced. on the technological process in the production of powder metallurgical details. A special place is given to the alloying elements intensifying the process of coagulation of the pores in the matrix during sintering - copper and phosphorus. Graphical dependences for the influence of copper on the dimensional changes of the iron matrix at different sintering temperatures are presented. 

Calculation of plasma centrifugal spraying parameters of fine granules of heat-resistant nickel alloys

2020 ◽  
pp. 471-474
Author(s):  
M.G. Yagodin ◽  
E.I. Starovoytenko
Keyword(s):  
Powder Metallurgy ◽  
Nickel Alloys ◽  
Dynamic Pressure ◽  
Calculated Data ◽  
Powder Size ◽  
Metal Powders ◽  
Heat Resistant ◽  
Gas Dynamic ◽  
Spraying Parameters ◽  
Wide Range

The equipment for the production of wide range of metal powders purposed for powder metallurgy is described. The possibility for producing of powders by the plasma centrifugal spraying is considered taking into account the gas dynamic pressure. The calculated data on the powder size for different materials are given.

scholarly journals Advanced Functional Materials Based on Nanocellulose for Pharmaceutical/Medical Applications

Pharmaceutics ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1125
Author(s):  
Raluca Nicu ◽  
Florin Ciolacu ◽  
Diana E. Ciolacu
Keyword(s):  
Rapid Development ◽  
Cellulose Nanofibrils ◽  
Functional Materials ◽  
Medical Applications ◽  
Bacterial Nanocellulose ◽  
Green Materials ◽  
Wide Range ◽  
In Vivo Cytotoxicity

Nanocelluloses (NCs), with their remarkable characteristics, have proven to be one of the most promising “green” materials of our times and have received special attention from researchers in nanomaterials. A diversity of new functional materials with a wide range of biomedical applications has been designed based on the most desirable properties of NCs, such as biocompatibility, biodegradability, and their special physicochemical properties. In this context and under the pressure of rapid development of this field, it is imperative to synthesize the successes and the new requirements in a comprehensive review. The first part of this work provides a brief review of the characteristics of the NCs (cellulose nanocrystals—CNC, cellulose nanofibrils—CNF, and bacterial nanocellulose—BNC), as well as of the main functional materials based on NCs (hydrogels, nanogels, and nanocomposites). The second part presents an extensive review of research over the past five years on promising pharmaceutical and medical applications of nanocellulose-based materials, which have been discussed in three important areas: drug-delivery systems, materials for wound-healing applications, as well as tissue engineering. Finally, an in-depth assessment of the in vitro and in vivo cytotoxicity of NCs-based materials, as well as the challenges related to their biodegradability, is performed.

scholarly journals Single and Double Infections with Wolbachia in the Parasitic Wasp Nasonia vitripennis Effects on Compatibility

Genetics ◽  
1996 ◽  
Vol 143 (2) ◽  
pp. 961-972 ◽  
Author(s):  
Marie-Jeanne Perrot-Minnot ◽  
Li Rong Guo ◽  
John H Werren
Keyword(s):  
Genomic Dna ◽  
Rapid Development ◽  
Parasitic Wasp ◽  
Pcr Amplification ◽  
Bacterial Strains ◽  
Nasonia Vitripennis ◽  
Larval Diapause ◽  
Wide Range ◽  
Reproductive Incompatibility ◽  
Infected Line

Abstract Wolbachia are cytoplasmically inherited bacteria responsible for reproductive incompatibility in a wide range of insects. There has been little exploration, however, of within species Wolbachia polymorphisms and their effects on compatibility. Here we show that some strains of the parasitic wasp Nasonia vitripennis are infected with two distinct bacterial strains (A and B) whereas others are singly infected (A or B). Double and single infections are confirmed by both PCR amplification and Southern analysis of genomic DNA. Furthermore, it is shown that prolonged larval diapause (the overwintering stage of the wasp) of a double-infected strain can lead to stochastic loss of one or both bacterial strains. After diapause of a double-infected line, sublines were produced with AB, A only, B only or no Wolbachia. A and B sublines are bidirectionally incompatible, whereas males from AB lines are unidirectionally incompatible with females of A and B sublines. Results therefore show rapid development of bidirectional incompatibility within a species due to segregation of associated symbiotic bacteria.

ORGANIZATION OF ROAD TRAFFIC TAKING INTO ACCOUNT ELECTRIC ROUTE PASSENGER TRANSPORT

2021 ◽  
Vol 2 (65) ◽  
pp. 66-77
Author(s):  
Denis V. Kapsky ◽  
◽  
Sergey S. Semchenkov ◽  
Evgeny N. Kot ◽  
◽  
...  
Keyword(s):  
Traffic Management ◽  
Road Traffic ◽  
Rapid Development ◽  
Living Environment ◽  
Transport Sector ◽  
Passenger Transport ◽  
Wide Range ◽  
Practical Development ◽  
The Republic ◽  
Conducting Research

The rapid development of the transport sector leads not only to positive changes in the life of cities and towns, to an increase in convenience and comfort for residents, but also worsens the ecology and their living environment. The “profitable-safe” dilemma can be solved by the approach of environmentally oriented selection of the type of route passenger transport and decisionmaking in favor of electric route passenger transport. The article discusses the types of such transport on the example of the experience of their use in the Republic of Belarus. The classification and systematization developed by the authors are presented with subsequent recommendations for its application. On the basis of the results of the authors’ research, the issues of interaction of rail and non-rail route vehicles with an electric drive with the organization of road traffic are separately considered. The presented materials can be useful to a wide range of readers, as well as to specialists conducting research and practical development in the field of electrically powered route vehicles and traffic management.

scholarly journals DISTRIBUTION OF BRYOPHYTES OF AGALYK BASIN (KARATEPA MOUNTAINS OF ZERAVSHAN MOUNTAIN RANGE)

2015 ◽  
Vol 4 (2) ◽  
pp. 80-82
Author(s):  
Holmurod Akimovich Zhalov
Keyword(s):  
Species Composition ◽  
Point Of View ◽  
Mountain Range ◽  
Decayed Wood ◽  
Moss Species ◽  
Comparative Analyses ◽  
Wide Range ◽  
Identification Of Species ◽  
Characteristic Features ◽  
Research Period

From bryological point of view Zeravshan mountain range remains one of the least studied region. Identification of species composition of true mosses and their ecological-biological peculiarities were not earlier aimed for this region. In the territory of Agalyk basin Karatepa mountains can be divided into four types of substrates where moss species occur: soil, bark of living trees, decayed wood, stones. Characteristics of substrate groups become complicated due to wide range of ecological valency of moss species. Most species select not only one, but several substrates for their settling. During the research period in the soils of Agaliksay basin 20 species were recorded belonging to 13 genera and 10 family. On decayed wood 9 species were recorded belonging to 7 genera and 5 family. On the bark of living trees 15 moss species were recorded belonging to 8 genera and 6 family. Epilyte bryophytes occurred on rocky substrates. On rocky substrates of Agaliksay basin 34 moss species were recorded from 16 genera and 13 family. On the basis of results obtained during the study of substrate groups of mosses in Agaliksay basin, we have conducted comparative analyses of studied substrate groups with the purpose of determining their characteristic features.

scholarly journals Culinary and Medicinal Mushrooms: Insight into Growing Technologies

2021 ◽  
Vol 55 (2) ◽  
Author(s):  
Piotr Zięba ◽  
Agnieszka Sękara ◽  
Katarzyna Sułkowska-Ziaja ◽  
Bożena Muszyńska
Keyword(s):  
Rapid Development ◽  
Essential Elements ◽  
Market Demand ◽  
Fruiting Bodies ◽  
Mushroom Species ◽  
Medicinal Mushrooms ◽  
Wide Range ◽  
Growing Conditions ◽  
Natural Medicines ◽  
Modern Technologies

Humans have used mushrooms from the beginning of their history. However, during the last few decades, the market demand for these fruiting bodies has increased significantly owing to the spread in the capabilities of culinary and pharmacological exploitation. Natural mushroom resources have become insufficient to meet the support needs. Therefore, traditional methods of extensive cultivation as well as modern technologies have been exploited to develop effective growing recommendations for dozens of economically important mushroom species. Mushrooms can decompose a wide range of organic materials, including organic waste. They play a fundamental role in nutrient cycling and exchange in the environment. The challenge is a proper substrate composition, including bio-fortified essential elements, and the application of growing conditions to enable a continuous supply of fruiting bodies of market quality and stabilized chemical composition. Many mushroom species are used for food preparation. Moreover, they are treated as functional foods, because they have health benefits beyond their nutritional value, and are used as natural medicines in many countries. Owing to the rapid development of mushroom farming, we reviewed the growing technologies used worldwide for mushroom species developed for food, processing, and pharmacological industries.

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