scholarly journals Influence of pulse-plasma modification with titanium and silicon carbide of the surface of hard VK10KS alloy on its structure and properties

2021 ◽  
Vol 63 (11-12) ◽  
pp. 922-928
Author(s):  
T. N. Oskolkova ◽  
A. S. Simachev ◽  
S. I. Yares’ko
Keyword(s):  
Electron Microscopy ◽  
Silicon Carbide ◽  
Plasma Treatment ◽  
Hard Alloy ◽  
Plasma Modification ◽  
Pulse Plasma ◽  
Carbide Powder ◽  
Hard Alloys ◽  
Tungsten Carbides ◽  
Near Surface

Electro-explosive alloying as a method of pulse-plasma treatment consists in accumulation of energy by a battery of pulsed capacitors and its subsequent discharge for 100 μs through a conductor in form of titanium foil with silicon carbide powder, while conductor is under explosive destruction. Method of electro-explosive alloying of tungsten-cobalt hard alloy includes melting of surface and its saturation with explosion products, followed by self-hardening by removing heat deep into the material and environment. On the surface of VK10KS hard alloy, the coating was obtained with thickness of up to 15 – 20 microns with nanohardness of 26,000 MPa. Using X-ray phase analysis and scanning electron microscopy, it has been established that new phases of TiC, W2C, (W, Ti)C1 – x , WSi2 with high hardness were formed in the surface layer. As a result, friction coefficient decreased to 0.18 compared to the initial 0.41. Investigations with transmission electron microscopy have revealed changes during electro-explosive alloying that occur in surface carbide and near-surface cobalt phases. Dislocations accumulations were found in the carbide phase. In cobalt binder, deformation bands (slip bands), single dislocations, and finely dispersed precipitates of tungsten carbides were revealed. This change can be explained by stabilization of cubic modification of cobalt, crystal lattice of which has a large number of slip planes upon deformation and greater ability to harden in comparison with hexagonal modification of cobalt. Additional alloying with cobalt binder in heat affected zone after pulse-plasma treatment have a positive effect on the service life of tungsten-cobalt hard alloys as a whole due to their stabilization.

scholarly journals Influence of pulse-plasma modification of VK10KS solid alloy surface by titanium and boron on its structure and properties

2020 ◽  
Vol 63 (5) ◽  
pp. 351-356
Author(s):  
T. N. Oskolkova ◽  
A. S. Simachev
Keyword(s):  
Friction Coefficient ◽  
Tungsten Carbide ◽  
Plasma Modification ◽  
Pulse Plasma ◽  
Solid Alloy ◽  
Deformation Bands ◽  
Near Surface ◽  
Scanning Transmission ◽  
Electroexplosive Alloying ◽  
Slip Planes

Modification of the surface of VK10KS solid alloy with titanium alongside with boron by the method of pulse-plasma exposure (electro-explosive alloying) is considered. In this case, a superhard (27,500 MPa nanohardness) layer is formed with a thickness of 2.0 – 2.5 μm and a low (μ = 0.10) friction coefficient compared to the friction coefficient of a hard alloy in the sintered state (μ = 0.41). This layer consists of finely dispersed high-hard phases TiB2, (Ti, W)C, W2C (according to scanning, transmission electron microscopy and X-ray phase analysis). Below is a hardened (with a nanohardness of 17,000 MPa) surface layer (heat affected zone) 10 – 15 μm thick, identified by W2C and WC carbides and alloyed with a cobalt binder. This layer smoothly passes into the base. By profilometric studies it was established that after electroexplosive alloying with titanium and boron, the roughness increases (Ra = 2.00 μm) compared to the initial one (Ra = 1.32 μm), but remains within the specifications (Ra = 2.50 μm). The authors have revealed changes that occur in the surface carbide and near-surface cobalt phases during electroexplosive alloying. In the carbide phase, accumulations of dislocations were indicated. In the cobalt binder, deformation bands (slip bands), single dislocations, and also finely dispersed tungsten carbide precipitates were found. This change can be explained by stabilization of the cubic modification of cobalt, the crystal lattice of which has a large number of slip planes during deformation and a greater ability to harden compared to the hexagonal modification of cobalt. Additional alloying with a cobalt binder will positively affect the operational stability of tungsten carbide alloys as a whole due to their stabilization.

Preparation of Backthinned Ceramic Specimens

1985 ◽  
Vol 43 ◽  
pp. 182-183
Author(s):  
A. T. Fisher ◽  
P. Angelini
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Vacuum System ◽  
Back Surface ◽  
Surface Microstructure ◽  
Ion Milling ◽  
Near Surface ◽  
Depth Profiles ◽  
Analytical Electron ◽  
Ion Implanted

Analytical electron microscopy (AEM) of the near surface microstructure of ion implanted ceramics can provide much information about these materials. Backthinning of specimens results in relatively large thin areas for analysis of precipitates, voids, dislocations, depth profiles of implanted species and other features. One of the most critical stages in the backthinning process is the ion milling procedure. Material sputtered during ion milling can redeposit on the back surface thereby contaminating the specimen with impurities such as Fe, Cr, Ni, Mo, Si, etc. These impurities may originate from the specimen, specimen platform and clamping plates, vacuum system, and other components. The contamination may take the form of discrete particles or continuous films [Fig. 1] and compromises many of the compositional and microstructural analyses. A method is being developed to protect the implanted surface by coating it with NaCl prior to backthinning. Impurities which deposit on the continuous NaCl film during ion milling are removed by immersing the specimen in water and floating the contaminants from the specimen as the salt dissolves.

Analytical Electron Microscopy of Ion-Implanted Metals

1985 ◽  
Vol 43 ◽  
pp. 282-285
Author(s):  
D.I. Potter ◽  
M. Ahmed ◽  
K. Ruffing
Keyword(s):  
Electron Microscopy ◽  
Ion Implantation ◽  
Friction And Wear ◽  
Analytical Electron Microscopy ◽  
Chemical Compositions ◽  
Surface Chemical ◽  
Near Surface ◽  
The Past ◽  
Analytical Electron ◽  
Property Changes

Ion implantation, used extensively for the past decade in fabricating semiconductor devices, now provides a unique means for altering the near-surface chemical compositions and microstructures of metals. These alterations often significantly improve physical properties that depend on the surface of the material; for example, catalysis, corrosion, oxidation, hardness, friction and wear. Frequently the mechanisms causing these beneficial alterations and property changes remain obscure and much of the current research in the area of ion implantation metallurgy is aimed at identifying such mechanisms. Investigators thus confront two immediate questions: To what extent is the chemical composition changed by implantation? What is the resulting microstructure? These two questions can be investigated very fruitfully with analytical electron microscopy (AEM), as described below.

scholarly journals Site Specific Three-dimensional Structural Analysis in Tissues and Cells Using Automated DualBeam Slice &View

2007 ◽  
Vol 15 (2) ◽  
pp. 26-31 ◽  
Author(s):  
Ben Lich
Keyword(s):  
Electron Microscopy ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Three Dimensional ◽  
Surface Region ◽  
Dimensional Structure ◽  
Near Surface ◽  
Imaging Capability ◽  
Fluorescent Markers ◽  
Confocal And Electron Microscopy

DualBeam instruments that combine the imaging capability of scanning electron microscopy (SEM) with the cutting and deposition capability of a focused ion beam (FIB) provide biologists with a powerful tool for investigating three-dimensional structure with nanoscale (1 nm-100 nm) resolution. Ever since Van Leeuwenhoek used the first microscope to describe bacteria more than 300 years ago, microscopy has played a central role in scientists' efforts to understand biological systems. Light microscopy is generally limited to a useful resolution of about a micrometer. More recently the use of confocal and electron microscopy has enabled investigations at higher resolution. Used with fluorescent markers, confocal microscopy can detect and localize molecular scale features, but its imaging resolution is still limited. SEM is capable of nanometer resolution, but is limited to the near surface region of the sample.

Influence of Oxygen Plasma Modification Carbon Fiber on Flexural Strength and Hydrothermal Properties of CF/PES Composite

2014 ◽  
Vol 926-930 ◽  
pp. 141-144
Author(s):  
Xu Cui ◽  
Yan Jiao Huang ◽  
Yu Gao ◽  
Shuo Wang
Keyword(s):  
Composite Material ◽  
Carbon Fiber ◽  
Flexural Strength ◽  
Plasma Treatment ◽  
Oxygen Plasma ◽  
Retention Rate ◽  
Test Method ◽  
Plasma Modification ◽  
Resin Matrix ◽  
Strength Retention

In this paper, low temperature oxygen plasma treatment method was adopted to process the carbon fiber surface. Flexural Strength test method was utilized to represent f composite material flexural strength. This paper observed flexural failure morphology of composite material by aid of SEM, then it compared the mechanical property, hygroscopicitiy and flexural strength retention rate of composite material before and after the plasma treatment. Results showed that the optimum treatment conditions of carbon fiber were 300W treatment power and 15-minute treatment time. Under the condition, the highest flexural strength value be increased by 19.55%.Saturated bibulous is low and bibulous rate is slow, flexural strength retention rate is 94.9%. And at the same time PES-C resin matrix can be strengthened, which will further improve the mechanical properties of composite materials.

Nanoscale Mechanical Properties of In-Situ Tribofilms Generated from ZDDP and F-ZDDP with and without Antioxidants

2007 ◽  
Vol 7 (12) ◽  
pp. 4378-4390 ◽  
Author(s):  
Anuradha Somayaji ◽  
Ramoun Mourhatch ◽  
Pranesh B. Aswath
Keyword(s):  
Electron Microscopy ◽  
Wear Debris ◽  
Surface Region ◽  
Nucleation And Growth ◽  
Near Surface ◽  
Transmission Electron ◽  
Dialkyl Dithiophosphates ◽  
Wear Tests ◽  
Diphenyl Amine

Tribofilms with thickness ranging from 100–200 nm were developed in-situ during wear tests using a zinc dialkyl dithiophosphates (ZDDP) and fluorinated ZDDP (F-ZDDP). The influence of the antioxidant alkylated diphenyl amine on the formation and properties of these tribofilm is examined. Results indicate that the thickness of the tribofilms formed when F-ZDDP is used is always thicker than the tribofilm formed with ZDDP. In addition, in the presence of antioxidants the tribofilm thickness is increased. The hardness of these tribofilms in the absence of the antioxidants is significantly higher at the near surface region (0–30 nm) when compared to the films formed in the presence of antioxidant. Nanoscratch tests conducted to examine the abrasion resistance of the tribofilms also indicate that the tribofilms formed by F-ZDDP are more resistant to scratch compared to films formed by ZDDP. In the presence of antioxidant, tribofilms formed by F-ZDDP are significantly thicker while both films behave in a similar fashion in nanoscratch tests. Transmission electron microscopy of the wear debris formed during the tests were examined and results indicate the nucleation and growth of nanoparticles of Fe3O4 with an approximate size of 5–10 nm embedded within an otherwise amorphous tribofilm.

scholarly journals High Resolution Transmission Electron Microscopy of Metallic Film/Laser-Irradiated Alumina Couples.

1994 ◽  
Vol 357 ◽  
Author(s):  
A. J. Pedraza ◽  
Siqi Cao ◽  
L. F. Allard ◽  
D. H. Lowndes
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Copper Film ◽  
Interfacial Structure ◽  
Diffuse Interface ◽  
Cross Sectional ◽  
Polycrystalline Alumina ◽  
Near Surface ◽  
Transmission Electron

AbstractA near-surface thin layer is melted when single crystal alumina (sapphire) is pulsed laserirradiated in an Ar-4%H2 atmosphere. γ-alumina grows epitaxially from the (0001) face of axalumina (sapphire) during the rapid solidification of this layer that occurs once the laser pulse is over. Cross sectional high resolution transmission electron microscopy (HRTEM) reveals that the interface between unmelted sapphire and γ-alumina is atomistically flat with steps of one to a few close-packed oxygen layers; however, pronounced lattice distortions exist in the resolidified γ-alumina. HRTEM also is used to study the metal-ceramic interface of a copper film deposited on a laser-irradiated alumina substrate. The observed changes of the interfacial structure relative to that of unexposed substrates are correlated with the strong enhancement of film-substrate bonding promoted by laser irradiation. HRTEM shows that a thin amorphous film is produced after irradiation of 99.6% polycrystalline alumina. Formation of a diffuse interface and atomic rearrangements that can take place in metastable phases contribute to enhance the bonding strength of copper to laser-irradiated alumina.

Nanowire Fabrication of Silicon-Based Materials

2007 ◽  
Vol 561-565 ◽  
pp. 1197-1199
Author(s):  
Hideo Kohno ◽  
Seiji Takeda
Keyword(s):  
Electron Microscopy ◽  
Silicon Carbide ◽  
Silicon Germanium ◽  
Iron Silicide ◽  
Growth Mechanisms ◽  
Step Process ◽  
One Step ◽  
Silicon Based

This paper describes our recent achievements in fabricating various kinds of nanowires of silicon-based materials including beta iron-silicide, silicon carbide, and silicon germanium. Some of them can be grown directly at one-step process, while the others can be fabricated using nanowire templates. We discuss their structures, growth mechanisms, and properties based on electron microscopy observations.

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