A method of investigating the electric-contact sintering of powder materials

1986 ◽  
Vol 25 (1) ◽  
pp. 19-21 ◽  
Author(s):  
W. Hermel ◽  
S. Siegel ◽  
S. P. Oshkaderov ◽  
L. O. Andrushchik ◽  
V. A. Shvitai ◽  
...  
Keyword(s):  
Powder Materials ◽  
Electric Contact

Investigation of pre-sprayed powders for electric contact welding

2020 ◽  
pp. 143-149
Author(s):  
Dinar R. Masalimov ◽  
Roman R. Galiullin ◽  
Rinat N. Sayfullin ◽  
Azamat F. Fayurshin ◽  
Linar F. Islamov
Keyword(s):  
Adhesion Strength ◽  
Electrical Contact ◽  
Research Purpose ◽  
Flame Spraying ◽  
Powder Materials ◽  
Electric Contact ◽  
Metal Powders ◽  
Unstable Flow ◽  
Gas Flame ◽  
Contact Welding

There are a number of difficulties in the electrical contact welding of powder materials: shedding of powder from the surface of a cylindrical part, impossibility of hardening the layer during welding due to flushing of the powders with coolant and unstable flow of powder into the welding zone. One solution is pre-spraying the powder in some way. (Research purpose). The research purpose is investigating the possibility of electric contact welding of metal powders preliminarily sprayed by a gas-flame method, namely, adhesion strength and losses during preliminary gas-flame spraying of powders. (Materials and methods) Powders of grades PG-NA-01, PrKhIIG4SR, PRZh3.200.28 were sprayed onto flat samples of St3 steel, polished to a roughness of Ra 1.25. The strength of powder adhesion to the base was studied by the cut method. (Results and discussion) The percentage loss of the powder as a whole is 3-23 percent for all the distances studied. The greatest powder losses appear at a distance of more than 180 millimeter from the tip of the burner for powders of grades PG-NA-01 and PrKhIIG4SR. The smallest powder losses were observed for PrZh3.200.28 powder, which totaled 3-7 percent. The maximum adhesion strength of the sprayed powders to the surface was 22.1 megapascals' when spraying the PG-NA-01 powder. The adhesion strength of powders of the grades PrKhIIG4SR and PrZh3.200.28 is small and amounts to 0.2-3 megapascals'. (Conclusions) The use of preliminary flame spraying of powders for their further electric contact welding is possible using PG-NA-01 grade powder, while the best adhesion to the base (that is more than 20 megapascals') is achieved with a spraying distance of 120-140 millimeter. The smallest powder losses during flame spraying are achieved at a spraying distance of 100-160 centimeters', at which the powder loss for the studied grades was 4-12 percent.

Electron microscopy study of shock synthesis of silicides

1993 ◽  
Vol 51 ◽  
pp. 1162-1163
Author(s):  
Kenneth S. Vecchio
Keyword(s):  
Shock Wave ◽  
Plastic Deformation ◽  
Close Contact ◽  
Microscopy Study ◽  
High Energy ◽  
Electron Microscopy Study ◽  
Powder Materials ◽  
Porous Powder ◽  
Wave Effects ◽  
Wave Passage

Shock-induced reactions (or shock synthesis) have been studied since the 1960’s but are still poorly understood, partly due to the fact that the reaction kinetics are very fast making experimental analysis of the reaction difficult. Shock synthesis is closely related to combustion synthesis, and occurs in the same systems that undergo exothermic gasless combustion reactions. The thermite reaction (Fe2O3 + 2Al -> 2Fe + Al2O3) is prototypical of this class of reactions. The effects of shock-wave passage through porous (powder) materials are complex, because intense and non-uniform plastic deformation is coupled with the shock-wave effects. Thus, the particle interiors experience primarily the effects of shock waves, while the surfaces undergo intense plastic deformation which can often result in interfacial melting. Shock synthesis of compounds from powders is triggered by the extraordinarily high energy deposition rate at the surfaces of the powders, forcing them in close contact, activating them by introducing defects, and heating them close to or even above their melting temperatures.

Analysis of electro- and thermophysical processes occurring during electrocontact baking of flour products.

2020 ◽  
Vol 29 (11) ◽  
pp. 50-55
Author(s):  
V.I. Maklyukov ◽  
◽  
E.O. Gerasimova ◽  
N. V. Labutina ◽  
E.N. Rogozkin ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Theoretical Calculation ◽  
Heat Balance ◽  
Electric Contact ◽  
Wheat Dough ◽  
Baking Process ◽  
Free Moisture ◽  
Contact Heating ◽  
The Heat Balance

The article considers the results of research conducted during electric contact heating of rye-wheat dough pieces. It is established that the electrical conductivity of the crumb dough does not depend on the total humidity of the material, but mainly on the amount of free moisture. Using the current and temperature graphs, you can imagine how free moisture changes during the baking process and the influence of the thermophysical and colloidal process on the change in the value of free moisture. Experimentally determined the amount of heat that is spent on baking 1 kg of bread. The accuracy of the theoretical calculation of this parameter in the heat balance of the baking chamber is confirmed.

Electric Contact Stability and Wear Durability at a Nanoscale Sliding Electric Contact

2013 ◽  
Vol 133 (6) ◽  
pp. 229-236
Author(s):  
Yasushi Tomizawa ◽  
Yongfang Li ◽  
Akihiro Koga ◽  
Hiroshi Toshiyoshi ◽  
Yasuhisa Ando ◽  
...  
Keyword(s):  
Electric Contact ◽  
Contact Stability ◽  
Sliding Electric Contact

Study of the microstructure and particles of vanadium (III) oxide, vanadium (V) oxide and lithium aluminate powders

2020 ◽  
Vol 86 (1) ◽  
pp. 32-37
Author(s):  
Valeria A. Brodskaya ◽  
Oksana A. Molkova ◽  
Kira B. Zhogova ◽  
Inga V. Astakhova
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Vanadium Oxide ◽  
Size Distribution ◽  
Microstructural Analysis ◽  
Coherent Scattering ◽  
Powder Materials ◽  
Lithium Aluminate ◽  
Range Limit ◽  
Oxide Particles

Powder materials are widely used in the manufacture of electrochemical elements of thermal chemical sources of current. Electrochemical behavior of the powders depends on the shape and size of their particles. The results of the study of the microstructure and particles of the powders of vanadium (III), (V) oxides and lithium aluminate obtained by transmission electron and atomic force microscopy, X-ray diffraction and gas adsorption analyses are presented. It is found that the sizes of vanadium (III) and vanadium (V) oxide particles range within 70 – 600 and 40 – 350 nm, respectively. The size of the coherent-scattering regions of the vanadium oxide particles lies in the lower range limit which can be attributed to small size of the structural elements (crystallites). An average volumetric-surface diameter calculated on the basis of the surface specific area is close to the upper range limit which can be explained by the partial agglomeration of the powder particles. Unlike the vanadium oxide particles, the range of the particle size distribution of the lithium aluminate powder is narrower — 50 – 110 nm. The values of crystallite sizes are close to the maximum of the particle size distribution. Microstructural analysis showed that the particles in the samples of vanadium oxides have a rounded (V2O3) or elongated (V2O5) shape; whereas the particles of lithium aluminate powder exhibit lamellar structure. At the same time, for different batches of the same material, the particle size distribution is similar, which indicates the reproducibility of the technologies for their manufacture. The data obtained can be used to control the constancy of the particle size distribution of powder materials.

INCREASING THE WEAR RESISTANCE OF THE WORKING BODIES OF AGRICULTURAL MACHINES BY THE HDTV METHOD WITH ADDING POWDER OF THE EED METHOD

2020 ◽  
Vol 4 (141) ◽  
pp. 123-131
Author(s):  
IL’YA ROMANOV ◽  
Keyword(s):  
Wear Resistance ◽  
Abrasive Wear ◽  
High Frequency ◽  
Machine Building ◽  
Abrasive Wear Resistance ◽  
Research Purpose ◽  
Powder Materials ◽  
Agricultural Machinery ◽  
Resource Saving ◽  
Working Bodies

The development of energy and resource-saving methods and technologies for strengthening and restoring the working bodies of agricultural machinery will increase their abrasive wear resistance and durability by using materials from machine-building waste and reduce the cost by 10-30 percent without reducing operational characteristics. (Research purpose) The research purpose is in increasing the abrasive wear resistance and durability of cultivator legs by surfacing powder materials obtained by electroerosive dispersion from solid alloy waste by high-frequency currents. (Materials and methods) Authors obtained a powder for research on their own experimental installations of the CCP "Nano-Center" of electroerosive dispersion from waste of sintered hard alloys of the T15K6 brand. The microhardness of powders and coatings on microshifts was measured using the PMT-3 device, and the hardness of coatings with the KMT-1 microhardometer was measured using the Rockwell method according to GOST 9013-59. The microwave-40AV installation was used to assess the wear resistance of materials of working bodies of tillage machines. (Results and discussion) In the course of laboratory wear tests the relative wear resistance of samples hardened by high-frequency surfacing currents significantly exceeds the wear resistance of non-hardened samples made OF 65g steel, accepted as the reference standard. (Conclusions) Based on the results of experimental studies, the article proposes a new resource-saving technological process for strengthening the working bodies of agricultural machinery through the use of materials from machine-building waste, which allows increasing the abrasive wear resistance of working bodies by 1.5-2 times due to the use of tungsten-containing materials.

Nanostructured powders based on aluminum reinforced by silicon nitride designed for spraying of multifunctional strengthened coatings

2019 ◽  
pp. 65-73
Author(s):  
T. I. Bobkova ◽  
B. V. Farmakovsky ◽  
N. A. Sokolova
Keyword(s):  
Silicon Nitride ◽  
Composite Powder ◽  
High Energy ◽  
Cold Gas Dynamic Spraying ◽  
Powder Materials ◽  
Structure And Properties ◽  
Gas Dynamic ◽  
Composition Structure ◽  
New Phase ◽  
Nanostructured Powders

The work deals with topical issues such as development of composite nanostructured powder materials. The results of creating powders based on the system “aluminum–nitride of silicon” are presented. Complex investigations of the composition, structure and properties of powder materials, as well as coatings formed on their basis by supersonic cold gas dynamic spraying, were carried out. It has been found that the high-energy treatment of a powder mixture of aluminum with nanofibers of silicon nitride provides the formation of a composite powder in which a new phase of the Si(1-х)AlхO(1-х)Nх type is formed, which additionally increases the hardness in the coatings to be sprayed.

Composite cladded powders for spraying of protective coatings

2019 ◽  
pp. 59-64
Author(s):  
E. Yu. Gerashchenkova ◽  
T. I. Bobkova ◽  
E. A. Samodelkin ◽  
B. V. Farmakovsky
Keyword(s):  
Tungsten Carbide ◽  
Gas Phase ◽  
High Speed ◽  
Protective Coatings ◽  
Powder Materials ◽  
Nanosized Particles

The paper presents results of the development of technology for producing cladded and surfacealloyed powder materials. High-speed mechanosynthesis of matrix powders of FeCrAl and solid nanosized particles of tungsten carbide occurs in a disintegrator in the presence of an active gas phase (nitrogen).

Technology for the production of nanostructured coatings from nanoparticles of tungsten carbide and metal chromium

2020 ◽  
pp. 117-124
Author(s):  
T. I. Bobkova ◽  
R. Yu. Bystrov ◽  
A. A. Grigoriev ◽  
E. A. Samodelkin ◽  
B. V. Farmakovsky
Keyword(s):  
Tungsten Carbide ◽  
Composite Powder ◽  
Nanostructured Coatings ◽  
Powder Materials ◽  
Metallic Chromium ◽  
Complex Processes ◽  
Functionally Gradient ◽  
High Microhardness ◽  
Gradient Coatings ◽  
Technological Methods

This paper presents results of a study of complex processes for producing composite powder materials from tungsten carbide and metallic chromium. Technological methods for the formation of functionally gradient coatings with high microhardness up to 426 HV through microplasma spraying technology are disclosed.

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