ULTRASONIC STRENGTHENING OF SURFACE LAYER OF STEEL 20 FORMED IN ELECTROLYTE-PLASMA HEATING CONDITIONS

The Purpose of paper is to conduct studies to assess the possibility of increasing the hardness of the surface layer of steel St3 grade by plasma heating of the applied surface coating containing powder alloy PR-N80X13S2R. Mixtures of pasta were divided into 2 groups: for furnace chemical-thermal treatment and plasma surface melting. The study of the microstructure showed a difference in the depth of the saturated layer, depending on the processing method, during chemical-thermal treatment-1 mm, plasma fusion - 2 mm. The results of measuring the surface micro-hardness showed that, the obtained coating from a mixture of PR-N80X13S2R + Cr2O3 + NH4Cl has a uniform high surface hardness (31-64 HRC), from a mixture of only PR-N80X13S2R - the surface hardness varies in a wide range (15-60 HRC). The study of the microhardness of the cross section of the surface layer showed that, the diffusion region: from a mixture of powder PR-N80X13S2R + Cr2O3 + NH4Cl has uniform hardness (450-490 HV); from a mixture of PR-N80X13S2R - hardness increases in the depth of the molten region (from 300 to 600 HV), and sharply decreases in the heat affected zone (210-170 HV). The use of PR-N80X13S2R alloy powder as the main component in the composition of the paste deposited on the St3 surface during plasma treatment leads to the formation of a doped surface layer with high hardness.

Download Full-text

Study of wear resistance of plasma coatings from a mixture of CuSn/CrxCy alloys

10.36652/1813-1336-2021-17-8-371-377 ◽

2021 ◽

pp. 371-377

Author(s):

A.E. Balanovsky ◽

N.A. Astafeva ◽

A.G. Tikhonov ◽

Nguyen Van Trieu

Keyword(s):

Wear Resistance ◽

Surface Layer ◽

Cross Section ◽

Chromium Carbide ◽

Coating Layer ◽

Plasma Heating ◽

Tin Bronze ◽

Alloyed Surface ◽

Plasma Coatings ◽

Wear Tests

There is studied the wear resistance of coatings obtained by plasma heating of the mixture based on tin-bronze and chromium carbide. Measurement of the microhardness of the cross-section of the coatings showed that the thickness of the coating layer strongly affects the formation of the alloyed surface layer, and the addition of chromium carbide strongly leads to stronger hardening. Wear tests have shown that alloying with bronze provides the ability to improve the surface of the steel, and the CuSn + CrxCy type coating has the highest wear resistance.

Download Full-text

Study of the Formation of the Alloyed Surface Layer During Plasma Heating of Mixtures of Cu-Sn/CrXCY Alloys

Tribology in Industry ◽

10.24874/ti.1070.03.21.05 ◽

2021 ◽

Vol 43 (3) ◽

pp. 386-396

Author(s):

V.T. Nguyen ◽

N.A. Astafeva ◽

A.E. Balanovskiy

Keyword(s):

Surface Layer ◽

Plasma Heating ◽

Alloyed Surface

Download Full-text

THE ESTIMATION OF ROLLER STRENGTHENING INFLUENCE ON THE ENDURANCE LIMIT OF SHAFTS WITH PRESSURIZED HUB

Journal of Dynamics and Vibroacoustics ◽

10.18287/2409-4579-2019-5-4-29-35 ◽

2020 ◽

Vol 5 (4) ◽

pp. 29-35

Author(s):

Valentin Fyodorovich Pavlov ◽

Vladimir Stepanovich Vakulyuk ◽

Vyacheslav Petrovich Sazanov ◽

Arsenij Vital'evich Efrosinin

Keyword(s):

Surface Layer ◽

Residual Stresses ◽

Endurance Limit ◽

A Value ◽

Surface Residual Stresses ◽

Section Surface ◽

Steel 20 ◽

Compressive Residual Stresses ◽

Surface Layer Thickness ◽

Dangerous Section

The influence of roller strengthening on endurance limit under bending of the 25 mm and 50 mm diameter shafts made of steel 20 and 25 mm diameter shafts made of steel 40X with a pressurized hub has been examined. It’s been stated that the endurance limit of roller strengthened shafts with a pressurized hub depends not only on a value of compressive residual stresses in their dangerous section but on the character of its distribution. The valuation of a surface hardening influence on the endurance limit of shafts by the surface residual stresses criterion and the average integral residual stresses criterion has been shown that the average integral residual stresses criterion calculated through the part’s dangerous section surface layer thickness equal the critical depth of the non-propagating fatigue crack can be recommended for the hardened shafts with a pressurized hub endurance limit increase prediction. It’s been shown that on a diameter of a shaft with a pressurized hub raising it is necessary to increase a thickness of a hardened surface layer with compressive residual stresses.

Download Full-text

The oxidation of Inconel alloy MA754 at low oxidation potential

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074884 ◽

1983 ◽

Vol 41 ◽

pp. 218-219

Author(s):

D. N. Braski ◽

P. D. Goodell ◽

J. V. Cathcart ◽

R. H. Kane

Keyword(s):

Surface Layer ◽

Oxidation Potential ◽

Metal Interface ◽

Elevated Temperature Strength ◽

Surface Conditions ◽

Inconel Alloy ◽

Inco Alloy ◽

Resistance To Oxidation ◽

Oxide Particles ◽

Cold Worked

It has been known for some time that the addition of small oxide particles to an 80 Ni—20 Cr alloy not only increases its elevated-temperature strength, but also markedly improves its resistance to oxidation. The mechanism by which the oxide dispersoid enhances the oxidation resistance is being studied collaboratively by ORNL and INCO Alloy Products Company.Initial experiments were performed using INCONEL alloy MA754, which is nominally: 78 Ni, 20 Cr, 0.05 C, 0.3 Al, 0.5 Ti, 1.0 Fe, and 0.6 Y2O3 (wt %).Small disks (3 mm diam × 0.38 mm thick) were cut from MA754 plate stock and prepared with two different surface conditions. The first was prepared by mechanically polishing one side of a disk through 0.5 μm diamond on a syntron polisher while the second used an additional sulfuric acid-methanol electropolishing treatment to remove the cold-worked surface layer. Disks having both surface treatments were oxidized in a radiantly heated furnace for 30 s at 1000°C. Three different environments were investigated: hydrogen with nominal dew points of 0°C, —25°C, and —55°C. The oxide particles and films were examined in TEM by using extraction replicas (carbon) and by backpolishing to the oxide/metal interface. The particles were analyzed by EDS and SAD.

Download Full-text

Structural analysis of the surface-layer protein of spirillum serpens by high-resolution electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100077268 ◽

1983 ◽

Vol 41 ◽

pp. 738-739

Author(s):

W. H. Wu ◽

R. M. Glaeser

Keyword(s):

Electron Microscopy ◽

Surface Layer ◽

Structural Analysis ◽

High Resolution ◽

Low Dose ◽

High Resolution Electron Microscopy ◽

Optical Diffraction ◽

Surface Layer Protein ◽

Morphological Unit ◽

Resolution Electron

Spirillum serpens possesses a surface layer protein which exhibits a regular hexagonal packing of the morphological subunits. A morphological model of the structure of the protein has been proposed at a resolution of about 25 Å, in which the morphological unit might be described as having the appearance of a flared-out, hollow cylinder with six ÅspokesÅ at the flared end. In order to understand the detailed association of the macromolecules, it is necessary to do a high resolution structural analysis. Large, single layered arrays of the surface layer protein have been obtained for this purpose by means of extensive heating in high CaCl2, a procedure derived from that of Buckmire and Murray. Low dose, low temperature electron microscopy has been applied to the large arrays.As a first step, the samples were negatively stained with neutralized phosphotungstic acid, and the specimens were imaged at 40,000 magnification by use of a high resolution cold stage on a JE0L 100B. Low dose images were recorded with exposures of 7-9 electrons/Å2. The micrographs obtained (Fig. 1) were examined by use of optical diffraction (Fig. 2) to tell what areas were especially well ordered.

Download Full-text

Electron-Mirror Microscopic Aspects of Ferroelectric Domains of BaTiO3 And Ca2Sr (C2H5CO2)6

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069387 ◽

1970 ◽

Vol 28 ◽

pp. 478-479

Author(s):

Teruo Someya ◽

Jinzo Kobayashi

Keyword(s):

Surface Layer ◽

Electric Fields ◽

Quantitative Study ◽

Recent Progress ◽

Ferroelectric Domain ◽

Resolving Power ◽

Surface Pattern ◽

Crystal Surfaces ◽

One Dimensional ◽

Ferroelectric Domains

Recent progress in the electron-mirror microscopy (EMM), e.g., an improvement of its resolving power together with an increase of the magnification makes it useful for investigating the ferroelectric domain physics. English has recently observed the domain texture in the surface layer of BaTiO3. The present authors ) have developed a theory by which one can evaluate small one-dimensional electric fields and/or topographic step heights in the crystal surfaces from their EMM pictures. This theory was applied to a quantitative study of the surface pattern of BaTiO3).

Download Full-text

Microstructure of Electro-Eroded Cemented Carbide Surfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101165 ◽

1968 ◽

Vol 26 ◽

pp. 284-285

Author(s):

V. N. Filimonenko ◽

M. H. Richman ◽

J. Gurland

Keyword(s):

Surface Layer ◽

Cobalt Content ◽

Cemented Carbides ◽

Face Centered Cubic ◽

X Ray Diffraction ◽

Metallographic Examination ◽

Standard Procedures ◽

Face Centered ◽

Diamond Paste ◽

Plastic Carbon

The high temperatures and pressures that are found in a spark gap during electrical discharging lead to a sharp phase transition and structural transformation in the surface layer of cemented carbides containing WC and cobalt. By means of X-ray diffraction both W2C and a high-temperature monocarbide of tungsten (face-centered cubic) were detected after electro-erosion. The W2C forms as a result of the peritectic reaction, WC → W2C+C. The existence and amount of the phases depend on both the energy of the electro-spark discharge and the cobalt content. In the case of a low-energy discharge (i.e. C=0.01μF, V = 300v), WC(f.c.c.) is generally formed in the surface layer. However, at high energies, (e.g. C=30μF, V = 300v), W2C is formed at the surface in preference to the monocarbide. The phase transformations in the surface layer are retarded by the presence of larger percentages of cobalt.Metallographic examination of the electro-eroded surfaces of cemented carbides was carried out on samples with 5-30% cobalt content. The specimens were first metallographically polished using diamond paste and standard procedures and then subjected to various electrical discharges on a Servomet spark machining device. The samples were then repolished and etched in a 3% NH4OH electrolyte at -0.5 amp/cm2. Two stage plastic-carbon replicas were then made and shadowed with chromium at 27°.

Download Full-text

The concerted use of SEM, TEM, and SCM for examination of resin-dentin interfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100170116 ◽

1994 ◽

Vol 52 ◽

pp. 476-477

Author(s):

B. Van Meerbeek ◽

L. J. Conn ◽

E. S. Duke

Keyword(s):

Surface Layer ◽

Stress Distribution ◽

Phosphoric Acid ◽

Bonding Mechanism ◽

Restorative Dentistry ◽

Dental Adhesive ◽

Low Viscosity ◽

Dentin Adhesives ◽

Acid Etch ◽

Tooth Tissue

Restoration of decayed teeth with tooth-colored materials that can be bonded to tooth tissue has been a highly desirable property in restorative dentistry for many years. Advantages of such an adhesive restorative technique over conventional techniques using non-adhesive metal-based restoratives include improved restoration retention with minimal sacrifice of sound tooth tissue for retention purposes, superior adaptation and sealing of the restoration margins in prevention of caries recurrence, improved stress distribution across the tooth-restoration interface throughout the whole tooth, and even reinforcement of weakened tooth structures. The dental adhesive technology is rapidly changing. An efficient resin bond to enamel has already long been achieved. Its bonding mechanism has been fully elucidated and has proven to be a durable and reliable clinical treatment. However, bonding to dentin represents a greater challenge. After the failures of a dentin acid-etch technique in imitation of the enamel phosphoric-acid-etch technique and a bonding procedure based on chemical adhesion, modern dentin adhesives are currently believed to bond to dentin by a micromechanical hybridization process. This process is developed by an initial demineralization of the dentin surface layer with acid etchants exposing a collagen fibril arrangement with interfibrillar microporosities that subsequently become impregnated by low-viscosity monomers. Although the development of such a hybridization process has well been documented in the literature, questions remain with respect to parameters of-primary importance to adhesive efficacy.

Download Full-text

Plasma Components which Interfere with Ristocetin-induced Platelet Aggregation

Thrombosis and Haemostasis ◽

10.1055/s-0038-1647847 ◽

1975 ◽

Vol 33 (03) ◽

pp. 540-546 ◽

Cited By ~ 3

Author(s):

Robert F Baugh ◽

James E Brown ◽

Cecil Hougie

Keyword(s):

Platelet Aggregation ◽

Human Plasma ◽

Plasma Proteins ◽

Binding Protein ◽

Plasma Heating ◽

Protein S ◽

Fold Increase ◽

Normal Human Plasma ◽

Preliminary Examination ◽

Normal Human

SummaryNormal human plasma contains a component or components which interfere with ristocetin-induced platelet aggregation. Preliminary examination suggests a protein (or proteins) which binds ristocetin and competes more effectively for ristocetin than do the proteins involved in ristocetin-induced platelet aggregation. The presence of this protein in normal human plasma also prevents ristocetin-induced precipitation of plasma proteins at levels of ristocetin necessary to produce platelet aggregation (0.5–2.0 mg/ml). Serum contains an apparent two-fold increase of this component when compared with plasma. Heating serum at 56° for one hour results in an additional 2 to 4 fold increase. The presence of a ristocetin-binding protein in normal human plasma requires that this protein be saturated with ristocetin before ristocetin-induced platelet aggregation will occur. Variations in the ristocetin-binding protein(s) will cause apparent discrepancies in ristocetin-induced platelet aggregation in normal human plasmas.

Download Full-text