Fabrication of Nanostructured Gradient Tungsten-Cobalt Alloy Using Carbon Deficiency Powder

2018 ◽  
Vol 386 ◽  
pp. 370-376
Author(s):  
Maksim Dvornik ◽  
Elena Mikhailenko
Keyword(s):  
Surface Layer ◽  
Hard Alloy ◽  
Wide Temperature Range ◽  
Cobalt Content ◽  
Functionally Graded ◽  
Powder Layer ◽  
Maximum Hardness ◽  
Cobalt Alloy ◽  
Cobalt Deficiency ◽  
Normal Carbon

A nanostructured functionally graded hard alloy was obtained by sintering at temperatures from 1350 to 1410 ° C of two-layer "green bodies", each consisting of layer of powder with normal carbon content (WC-15Co-0.4VC-0.4Cr2C3) and powder layer with deficit of carbon (WC-8Co-0.4VC-0.4Cr2C3). The formation of the η phase (Co3W3C) in the layer with cobalt deficiency causes the migration of cobalt to it and prevents the return of cobalt back in a wide temperature range of temperatures (1350-1410). The porosity of the resulting nanocrystalline hard alloy at 1410 ° C is reduced to 2%, and the maximum hardness of the surface layer with a low cobalt content (10%) reaches 1945HV.

Microstructure of Electro-Eroded Cemented Carbide Surfaces

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°.

CYCLOPS M4

Alloy Digest ◽  
1978 ◽  
Vol 27 (7) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Abrasion Resistance ◽  
High Speed ◽  
Heat Treating ◽  
Heavy Duty ◽  
Maximum Hardness ◽  
Temperature Performance ◽  
Sharp Edges ◽  
Normal Carbon

Abstract CYCLOPS M4 is a deep-hardening steel that was developed to utilize the excellent abrasion resistance that results from higher-than-normal carbon and vanadium contents in the molybdenum-tungsten family of high-speed steels. It is recommended for heavy-duty cutting operations and for sharp edges for fine cuts. Cyclops M4 should always be used at or near maximum hardness. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: TS-335. Producer or source: Cyclops Corporation.

Fabrication of α-TCP, HAp Functionally Graded Porous Beads

2008 ◽  
Vol 57 ◽  
pp. 135-138
Author(s):  
Yuji Kajihata ◽  
Teruo Asaoka ◽  
Katsuko S. Furukawa ◽  
Takashi Ushida ◽  
T. Tateishi
Keyword(s):  
Surface Layer ◽  
High Strength ◽  
Functionally Graded ◽  
The Body ◽  
Acid Solutions ◽  
Bioactive Material ◽  
Hydrolytic Reaction ◽  
Rate Of Absorption ◽  
Porous Beads ◽  
Good Cell

HAp (Hydroxyapatite) and α-TCP (alpha tribasic calcium phosphate) are non-toxic to human cells and, thus, have been studied for applications as biomaterials. HAp is a bioactive material that is not readily absorbed by the body; it offers both high strength and better tissueadhesive properties than α-TCP. In contrast, α-TCP is highly bioabsorbable; it is quickly absorbed by the body, and, therefore, for example, disappears before bone is completely replaced. If porous beads could be fabricated that would take advantage of the useful properties of α-TCP and HAp, they could be used as excellent scaffolds for cultivating cells. In the present study, ceramic beads with α-TCP at the center were fabricated and coated with a functionally graded film of HAp. A scaffold based on this configuration would be expected to have the following characteristics: good cell adhesion; strong beads; and a rate of absorption into the body that would be easy to control. In addition, to accelerate the formation of porous structure, some acid solutions were used to dissolve the beads surface layer and to penetrate pores toward inside of the bead. HAp formation through hydrolytic reaction seemed to be promoted by these acid solutions.

scholarly journals Study on Microstructure and Hardness of Hard Alloy Powder Layer Inserted by Molten Cast Steel.

2002 ◽  
Vol 15 (1) ◽  
pp. 1-7
Author(s):  
Kazuhiko OKADA ◽  
Hiroyuki IKE ◽  
Shoji GOTO ◽  
Setsuo ASO ◽  
Yoshinari KOMATSU
Keyword(s):  
Hard Alloy ◽  
Alloy Powder ◽  
Cast Steel ◽  
Powder Layer

scholarly journals Features of the diamond films growth on the tungsten carbide surface by a copper underlayer

2019 ◽  
pp. 72-81
Author(s):  
D. S. Vokhmyanin ◽  
S. A. Oglezneva
Keyword(s):  
Surface Layer ◽  
Phase Composition ◽  
Hard Alloy ◽  
Diamond Film ◽  
Diamond Films ◽  
Surface Preparation ◽  
Growth Stages ◽  
Compressive Stresses ◽  
Diamond Crystals ◽  
Cuso4 Solution

Surface preparation is a prerequisite for ensuring the required properties of a diamond film obtained by gas-phase deposition. The paper considers the effect of temperature and concentration of the etchant CuSO4 on the structural and phase composition of the surface of hard-alloy materials. The structural and phase composition of a continuous polycrystalline diamond film at its growth stages was also studied. Adhesion of the obtained diamond films to the surface of carbide materials was qualitatively determined. It has been established that surface treatment of a hard alloy in a CuSO4 solution at a temperature t = 23 °C leads to unequal removal of the cobalt bond with chipping of WC grains and the formation of a porous structure in the surface layer of the WC–6%Co alloy. The treatment with an etchant CuSO4 at t = –2 °С ensures uniform etching of the Co-bond along the WC grain boundaries and the formation of a chemically uniform surface. The orientational growth and adhesion of the diamond film depend on the elemental composition of the surface of the WC–Co alloy after treatment with a CuSO4 solution. If the treatment was carried out at a tsolution = 23 °C, then during the synthesis of the diamond film, the removal of copper from the defective surface layer of WC is difficult. This provides the multidirectional growth of diamond crystals in the film in two directions: <111> and <110>, which causes critical biaxial compressive stresses (2,5 GPa) and leads to low adhesion of the film to the surface of the hard alloy. If the treatment was carried out at tsolution = –2 °C, then the orientational growth of diamond crystals in the film occurs in one preferential crystallographic direction <111>. It reduces the biaxial compressive stresses (1,7 GPa) and increases the adhesive adhesion of the film to the surface of the hard alloy . The structure defect, calculated from the ratio of the lines of integrated intensities I1333 / I1580 using the Raman spectroscopy, decreases with concentration growth for negative temperatures and increases for positive ones of CuSO4 solution during surface preparation.

scholarly journals Potential of electrospun chitosan fibers as a surface layer in functionally graded GTR membrane for periodontal regeneration

2017 ◽  
Vol 33 (1) ◽  
pp. 71-83 ◽  
Author(s):  
Saad B. Qasim ◽  
Shariq Najeeb ◽  
Robin M. Delaine-Smith ◽  
Andrew Rawlinson ◽  
Ihtesham Ur Rehman
Keyword(s):  
Surface Layer ◽  
Periodontal Regeneration ◽  
Functionally Graded

Toughness Enhancement of Al2O3/Ce-TZP Functionally Graded Materials by Annealing in Inert Atmosphere

2005 ◽  
Vol 492-493 ◽  
pp. 699-704 ◽  
Author(s):  
Jef Vleugels ◽  
Chao Zhao ◽  
Omer Van der Biest
Keyword(s):  
Surface Layer ◽  
Functionally Graded Materials ◽  
Inert Atmosphere ◽  
Functionally Graded ◽  
Pressureless Sintering ◽  
Graded Materials ◽  
Gradient Layer ◽  
Annealing Cycle ◽  
Toughness Enhancement ◽  
Annealing Experiments

CeO2-stabilised ZrO2-based functionally graded materials (FGMs) can be successfully produced using electrophoretic deposition and pressureless sintering in air. A cylindrical Al2O3/ZrO2 FGM, for instance, shows an ideal structure for applications such as drill blanks. It has a central hole with a diameter less than 0.5 mm, a tough Ce-ZrO2 core with a diameter of about 3 mm, a gradient layer of about 1 mm, and a hard Al2O3-rich surface layer. The Ce-ZrO2 core shows a Vickers hardness between 10 and 11 GPa and an excellent toughness (>10 MPa m1/2). In the gradient layer, hardness and toughness vary continuously along the radius. The Al2O3-rich surface layer has a hardness of 15.2 GPa but a modest toughness of 2 MPa m1/2. Annealing experiments of the air-sintered FGM in inert atmosphere (Ar + 5 vol % N2) allows a significant toughness enhancement, especially in the surface layer (up to 8 MPa m1/2). The experimental results indicate that a proper controlled reduction of the Ce-TZP phase allows a modification of the toughness of the Ce-TZP phase. The influence of the annealing cycle on the properties of the FGM are reported and elucidated.

COBALT STATUS IN QUEBEC SOILS

1967 ◽  
Vol 47 (2) ◽  
pp. 83-88 ◽  
Author(s):  
S. K. Rana ◽  
G. J. Ouellette
Keyword(s):  
Mineral Soil ◽  
Organic Matter Content ◽  
Clay Content ◽  
Cobalt Content ◽  
Matter Content ◽  
Organic Soils ◽  
Soil Series ◽  
Acid Digestion ◽  
Cobalt Deficiency ◽  
Mineral Soils

Studies on thirty mineral soil series and five organic soils from the broad cultivated areas of Quebec indicated that total cobalt, extracted with 70% perchloric acid digestion, ranged from 1.1 to 21.6 ppm and 2.5% acetic acid-extractable cobalt from 0.3 to 0.83 ppm. Extractable cobalt in the surface soils was significantly correlated with total cobalt, which in turn was highly dependent on the clay content of the soil. The soil pH or the organic matter content did not seem to have any influence on the cobalt content in the cultivated soils. Light-textured and podzolized soils are likely to be low m cobalt, while soils with richer clay content are higher. Organic soils, in general, were found to be lower in cobalt content than mineral soils. Nineteen out of the thirty mineral soils studied and all the organic soils contained less than 0.25 ppm of extractable cobalt and may be considered as critical or deficient because forage grown on such soils is likely to cause cobalt deficiency in livestock.

Functionally graded porous ceramics with dense surface layer produced by freeze-casting

2011 ◽  
Vol 37 (8) ◽  
pp. 3717-3722 ◽  
Author(s):  
Changqing Hong ◽  
Jiancong Du ◽  
Jun Liang ◽  
Xinghong Zhang ◽  
Jiecai Han
Keyword(s):  
Surface Layer ◽  
Porous Ceramics ◽  
Functionally Graded ◽  
Freeze Casting

scholarly journals Microstructural Analysis of Sintered Gradient Materials Based on Distaloy SE Powder

2016 ◽  
Vol 61 (2) ◽  
pp. 613-620
Author(s):  
K. Zarębski ◽  
M. Nykiel
Keyword(s):  
Surface Layer ◽  
Cross Section ◽  
Microstructural Analysis ◽  
Functionally Graded ◽  
Gradient Materials ◽  
The Core ◽  
Graded Structure ◽  
Die Filling ◽  
Manufactured Products ◽  
Different Types

Abstract The study describes the microstructural analysis of cylindrically-shaped functionally graded products sintered from iron powder with scheduled graded structure on the cross-section running from the core to the surface layer of the sinter. Different types of structure were produced using Distaloy SE powder in two compositions - one without the addition of carbon, and another with 0.6wt% C. Two methods were used to fill the die cavity and shape the products. The first method involving a two-step compaction of individual layers. The second method using an original technique of die filling enabled the formation of transition zone between the outer layer and the core still at the stage of product shaping. As part of microstructural analysis, structural constituents were identified and voids morphology was examined. Studies covered the effect of the type of the applied method on properties of the graded zone obtained in the manufactured products

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